I
EPA460/3-74-023-a
NOVEMBER 1974
PROCESS DEMONSTRATION
AND COST ANALYSIS
OF A MASS PRODUCTION
FORGING TECHNIQUE
FOR AUTOMOTIVE
TURBINE WHEELS
- PHASE I
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Alternative Automotive Power Systems Division
Ann Arbor, Michigan 48105
-------
EPA-460/3-74-023-a
PROCESS DEMONSTRATION
AND COST ANALYSIS
OF A MASS PRODUCTION
FORGING TECHNIQUE
FOR AUTOMOTIVE TURBINE WHEELS -
PHASE I
by
M. M. Allen, D. J. Hill, and B. H. Walker
Pratt & Whitney Aircraft
Florida R&D Center
P. O. Box 2691
West Palm Beach, Florida 33402
Contract No. 68-01-0477
Project Officer: P. L. Stone
Lewis Research Center, NASA
Project Coordinator: R. B. Schulz
Office of Air and Waste Management, EPA
Prepared for
U. S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Alternative Automotive Power Systems Division
Ann Arbor, Michigan 48105
November 1974
1670
•''..,' A' ..,'.1 -,- a r;; •. --t, F.oom
Chicago, IL
-------
This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the Air
Pollution Technical Information Center, Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
This report was furnished to the U. S. Environmental Protection Agency
by Pratt & Whitney Aircraft, in fulfillment of Contract No. 68-01-0477,
which was administered by the Lewis Research Center, NASA, under an
EPA-NASA interagency agreement. This report has been reviewed and
approved for publication by the Environmental Protection Agency. Approval
does not signify that the contents necessarily reflect the views and policies
of the agency. The material presented in this report may be based on an
extrapolation of the "State-of-the-art." Each assumption must be carefully
analyzed by the reader to assure that it is acceptable for his purpose.
Results and conclusions should be viewed correspondingly. Mention of
trade names or commercial products does not constitute endorsement or
recommendation for use.
Publication No. EPA-460/3-74-023-a
11
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-460/3-74-023-a
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Process Demonstration and Cost Analysis of A Mass
Production Forging Technique for Automotive Turbine
Wheels - Phase I
5. REPORT DATE
November 1974
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
M. M. Allen, D. J. Hill, B. H. Walker
8. PERFORMING ORGANIZATION REPORT NO.
FR-6690
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Pratt & Whitney Aircraft
Florida Research and Development Center
P.O. Box 2691
West Palm Beach, Florida 33402
10. PROGRAM ELEMENT NO.
1 AB 017
11. CONTRACT/GRANT NO.
68-01-0477
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Mobile Source Air Pollution Control
Alternative Automative Power Systems Development Division
Ann Arbor, Michigan 48105
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Low cost fabrication of integrally-bladed automotive turbine wheels utilizing the
GATORIZING™ forging process was demonstrated. Basic forging parameters
were developed for the nickel-base alloy IN 100. Several wheels were produced
and post forging heat-treating studies were conducted to develop an optimum com-
bination of stress-rupture and LCF properties. Target goals for these properties
were higher than those achieved in this initial study. The capabilities and limita-
tions of the forging process are defined along with an estimate of turbine wheel
cost in large production quantities.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Gas turbine engine
Automative engine
Turbine wheel
Forging technique
8. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
iii
-------
Pratt & Whitney Rircraft
FR-6690
FOREWORD
This report is submitted in accordance with the requirements of Con-
tract EPA 68-01-0477. It is the Phase I Final Engineering Report and covers
all the work performed under the contract from 26 April 1973 to 26 July 1974.
Mr. Marvin M. Allen, Senior Project Metallurgist, is the program
manager. Messrs. Bryant H. Walker, Senior Materials Test Engineer, and
David J. Hill, Metallurgist, are the responsible engineers. This report carries
the internal designation PWA FR-6690.
The EPA Project Officer for this contract is Phillip L. Stone, Materials
and Structures Division, NASA-Lewis Research Center. Mr. Stone is working
with EPA under a special technical assistance agreement between NASA and
EPA. The EPA Project Coordinator for this contract is Robert B. Schulz,
Office of Air and Waste Management.
IV
-------
Pratt & Whitney Rircraft
FR-6690
ABSTRACT
Low cost fabrication of integrally-bladed automotive turbine wheels
utilizing the GATORIZING™ forging process was demonstrated. Basic forging
parameters were developed for the nickel-base alloy IN 100. Several wheels
were produced and post forging heat-treating studies were conducted to develop
an optimum combination of stress-rupture and LCF properties. Target goals
for these properties were higher than those achieved in this initial study. The
capabilities and limitations of the forging process are defined along with an
estimate of turbine wheel costs in large production quantities.
-------
Pratt & Whitney fiircraft
FR-6690
CONTENTS
SECTION PAGE
ILLUSTRATIONS vii
SUMMARY 1
I INTRODUCTION 2
H PROGRAM ELEMENTS AND DISCUSSION 4
A. Task 1 - Basic Process Demonstration 4
B. Task 2 - Process Parameter Evaluation 15
C. Task 3 - Generation of Design Data 35
D. Task 4 - Definition of Manufacturing Process .... 46
E. Task 5 - Manufacturing Cost Study 56
IE SUMMARY OF RESULTS 62
IV RECOMMENDATIONS 63
VI
-------
Pratt & Whitney fi ire raft
FR-6690
ILLUSTRATIONS
FIGURE PAGE
1 Phase I - Feasibility Demonstration and Cost Analysis;
Task 1 - Basic Process Demonstration 5
IN 100 Mult Ready for Canning Prior to
Second Extrusion
IN 100 Canned Extrusion Billet, 152.4 MM (6 In.)
Diameter by 438. 2 MM (17 1/4 In.) Long
IN 100 Extrusion - 62.23 MM (2.45 In.) Cut in Tow
Pieces for Shipping
5 Typical Microstructure of Double-Extruded IN 100
Billet Stock 8
6 Cross Section of Phase I Disk Preform 10
7 Tooling for Phase I - Task 1 Preform 10
8 Finish Machined Preform Tooling 11
9 Task I Wheel Preform 12
10 Diagram for Test Specimens Machined from
Preform and Wheel 13
11 Task 1 Preform Microstructure Baseline Heat Treat ... 15
12 Phase I - Feasibility Demonstration and Cost Analysis;
Task 2 - Process Parameter Evaluation 16
13 Blade Gradient Study 20
14 Room Temperature Tensile Properties vs Forging
Temperature 24
15 760°C (1400°F) Tensile Properties vs Forging
Temperature 25
16 Tooling for Phase I - Task II Bladed Wheel 26
17 Blade Insert Concept Used for Finish Die Design 26
18 Finish Machined Bladed Wheel Tooling Preform 27
19 Initial Bladed Wheel Forging 28
20 Modified Blade Cross-Section 28
21 Fully Bladed Wheel Forging 29
22 Task II Alternate Heat Treatment Evaluation -
Electron Photomicrographs 34
23 Tensile Properties vs Heat Treatment 36
24 Stress Rupture Capability vs Heat Treatment 37
25 927°C (1700°F) LCF Capability vs Heat Treatment 38
vn
-------
Pratt & Whitney fiircraft
FR-6690
ILLUSTRATIONS (Continued)
FIGURE PAGE
26 Phase I - Feasibility Demonstration and Cost Analysis;
Task 3 - Generation of Design Data 39
27 Tensile Properties vs Solution Temperature Preform
Data 1038°C (1900°F) Forge Temperature 40
28 Stress Rupture Capability vs Solution Temperature .... 41
29 Automotive Turbine Wheel Design Data Tensile
Properties of Wrought IN 100 52
30 EPA Automotive Turbine Wheel Design Data LCF
927°C (1700°F) IN 100 53
31 EPA Automotive Turbine Wheel Design Data IN 100
Larson-Miller Plot of 1. 0% Creep Life 54
32 EPA Automotive Turbine Wheel Design Data IN 100
Larson-Miller Plot of Stress Rupture Life 55
33 Trade-Off Curve: LCF and Rupture vs Grain Size 56
34 Plant Layout EPA Rotor Production 191, 000 sq ft 57
viii
-------
Pratt & Whitney Pircraft
FR-6690
SUMMARY
This report describes the work performed under Phase I of a two-phase
program. The objective of the overall program is to develop a low-cost forging
technique for the production of integrally-bladed automotive gas turbine wheels.
The Pratt & Whitney Aircraft GATORIZING™ forging technique is being used.
Phase I consisted of a process definition, process demonstration, mechanical
properties determination, and a manufacturing cost estimate per unit based on a
production rate of 1, 000, 000 wheels per year. The wheel selected as a model
was the compressor-turbine wheel for the EPA/Chrysler Baseline Gas Turbine
Engine. This wheel is 14.0 cm (5. 5 in.) in diameter tip-to-tip. The material
selected was the Ni-base alloy IN100.
In Phase I, the basic forging parameters for producing integrally-bladed
turbine wheels were developed and several wheels were successfully produced.
The optimum forging strain rate was determined to be 0. 25 cm/cm/min
(0.1 in./in. /min), with a preform forging temperature of 1038°C (1900°F) and
final wheel forging temperature of 1093°C (2000°F). The heat treatment selected
to achieve an optimum combination of stress-rupture and low cycle fatigue
(LCF) properties was a double solution at 1177°C (2150°F) and 1066°C (1950°F)
followed by precipitation at 871°C (1600°F) and 982°C (1800°F), and aging at
649°C (1200°F) and 760°C (1400°F). Design data was obtained from wheels heat
treated as described above. These data indicated that neither the stress rupture
nor the low cycle fatigue properties met the target values of a 100 hr, 955°C
(1750°F) stress-rupture strength of 121 MN/m2 (17.5 ksi), and 5000 LCF cycles
to failure at 927°C (1700°F) and a 0. 5% strain range. The typical properties
were, however, close to the target values (100 MN/m2, 14.5 ksi and 3200 cycles,
respectively) and were considered as good a combination of properties as could
be achieved within the limits of the investigation using GATORIZED™ IN 100.
Design data curves and turbine wheel manufacturing flow sheets were
prepared and are included in this report along with a description of the capa-
bilities and limitations of the forging process. The estimated cost per finished
wheel was about $50 in quantities of 1, 000, 000 per year.
-------
Pratt & Whitney fiircraft
FR-6690
SECTION I
INTRODUCTION
In 1970, the Environmental Protection Agency (EPA) initiated a research
program with United Aircraft Research Laboratories (UARL) to conduct a study
of several selected automotive gas turbine engine concepts that appeared to have
the best possibility of meeting the U.S. Government's automotive engine exhaust
emission standards for 1976. The study1 included estimating the probable manu-
facturing cost of several versions of gas turbine engines in quantities of 100, 000
and 1, 000, 000 units annually and comparing the cost of the candidate engines to
current piston engines.
The major unknown in estimating the cost of the gas turbine engine was
the manufacturing cost of the turbine wheel. It was assumed that, at the
1, 000, 000 unit annual rate, high-ductility, close-tolerance forging techniques
would be used to produce the turbine wheels to nearly finished dimensions from
the relatively expensive materials specified. Several proprietary versions of
these basic techniques have been developed by United Aircraft for current military
aircraft engine programs. The basic United Aircraft-patented process, developed
and reduced to practice at the Florida Research and Development Center (FRDC)
of Pratt & Whitney Aircraft (P&WA), is referred to as the GATORIZING™ forging
process.
This process differs from previous hot isothermal forging methods in that
the temperature and forging rate are controlled either to produce a condition of
superplasticity in the material being forged, or to maintain a condition of super-
plasticity in material previously placed in that condition by special processing
techniques. This condition is essentially one wherein a material, over a specific
temperature and strain rate, flows at a very low stress and exhibits extreme
ductility. Exploiting the superplastic state of the material allows forging of com-
plex, contoured shaped wheels to extremely close tolerances, which substantially
reduces the input weight of the material required and also reduces machining costs.
In addition, smaller, less costly forging equipment than that required for conven-
tional nickel base superalloy or titanium alloy forging can be used.
United Aircraft Research Laboratories Report K-971017-4, "Manufacturing
Cost Study of Selected Gas Turbine Automotive Engine Concepts," dated
August 1971.
-------
Pratt & Whitney fiircraft
FR-6690
The forged product produced by the GATORIZING process has two distinct
advantages over a cast wheel. The enhanced ductility, toughness and cyclic
capability inherent in a wrought product will contribute to the reliability and
durability of the small turbine engine wheels. Another advantage of a forging
is the greater consistency of part quality and freedom from internal defects.
In November 1972, EPA contracted with Chrysler Corporation for the
development of an experimental gas turbine engine which would meet the 1976
Federal Emissions Standards, have good fuel economy, and would be competi-
tive in performance, reliability and potential manufacturing cost with the con-
ventional piston-engine-powered, standard size American automobile (EPA
Contract No. 68-01-0459).
In support of the above program, EPA contracted with Pratt & Whitney
Aircraft, Florida Research and Development Center, to demonstrate the feasi-
bility of low-cost production of integrally-bladed automotive turbine wheels.
'This contract is being conducted as a two-phase program. The first phase,
described herein, consisted of several major task areas: basic process demon-
stration, process parameter evaluation, generation of design data, definition
of the manufacturing sequence, and a manufacturing cost estimate for IN 100
Chrysler-type compressor-turbine wheels. IN 100 was selected for several
reasons: Pratt & Whitney Aircraft has a great amount of past experience
forging the alloy; and it had the potential of meeting the Chrysler stress-rupture
and low cycle fatigue life targets. Phase n of the contract has recently been
initiated. In Phase II, the forging technique will be further refined and a
material will be selected and characterized so as to meet the latest EPA/
Chrysler Upgraded Engine Requirements.
-------
Pratt & Whitney Pircraft
FR-6690
SECTION II
PROGRAM ELEMENTS AND DISCUSSION
A. TASK 1 - BASIC PROCESS DEMONSTRATION
Task 1 involved the selection of the processing parameters for the raw
material, the initial GATORIZING parameters, and the selection of the baseline
heat treatment. These parameters were based on extensive experience with
IN 100. The raw material was procured, the preform dies were designed and
manufactured, and the initial preform was forged and evaluated. Task 1 is
shown schematically in figure 1.
1. Raw Material Procurement and Evaluation
IN 100 material, vacuum-induction melted and vacuum-arc remelted from
virgin metals, was provided by Allvac Metals. The material was supplied from
Allvac heat No. E-073, and the chemistries were within the acceptable range.
The material was machined and canned in stainless steel for subsequent extru-
sion. Cameron Iron Works extruded the material at 1066°C (1950°F) through a
205.7 mm (8.1 in.) orifice, resulting in a reduction ratio of 6. 8:1. The extruded
material was then remachined to a 139. 7 mm (5. 5 in.) diameter mult, figure 2,
and recanned in stainless steel, as shown in figure 3. This mult was re-extruded
at RMI at 1066°C through a 62.23 mm (2.45 in.) diameter orifice. The extrusion
breakthrough pressure was 805.3 MN/m2 (58.4 ksi) and the run pressure was
722.6 MN/m^ (52.4 ksi). The as-extruded material is shown in figure 4. The
material structure, as-extruded, was 95 to 98% recrystallized fine grains, ASTM
11.5 to 16, with some isolated unrecrystallized areas. Representative photomicro-
graphs are shown in figure 5. Standard tensile specimens were machined, and
superplasticity tests were run. The test results, shown in table I, verified that
the material was in a superplastic condition.
2. Preform Die Design and Fabrication
The dies used for the program were manufactured from TZM molybdenum.
This material was selected because of its excellent thermal conductivity, elevated
temperature strength, and wear resistance. It is very important that temperature
uniformity be achieved from the center to the edge of the die stack in the GATORIZING
process; experience has shown that temperature gradients are minimal in the radial
direction in TZM molybdenum die stacks up to 76.2 cm (30. 0 in.) in diameter.
-------
VISUAL INSPECTION
TENSILE
RT, 760°C (1400°F)
SELECT BASELINE
PARAMETERS
DESIGN AND
FABRICATE DIES
FORGE ONE PREFORM
BASELINE
HEAT TREATMENT
CUT-UP EVALUATION
LCF
927°C (1700°F)
NDI EVALUATION
(ZYGLO, SONIC)
CREEP-RUPTURE
927°C(1700°F)
MACROSTRUCTURE
AND
MICROSTRUCTURE
Figure 1. Phase I - Feasibility Demonstration and Cost Analysis; Task 1 - Basic Process Demonstration FD 72646A
O
-------
Pratt & Whitney Oircraft
Figure 2. IN 100 Mult Ready for Canning Prior to
Second Extrusion
FC 29014
Figure 3. IN 100 Canned Extrusion Billet,
152.4 MM (6 In.) Diameter by
438.2 MM (17 1/4 In.) Long
FAL 28671
-------
FE 131243
Figure 4. IN100 Extrusion - 62.23 mm (2.45 in.) Cut in Two Pieces for Shipping
FD 74444
T
rV
D
o
-------
00
FAM 81111
EDGE TRANSVERSE
FAM 81110
CENTER TRANSVERSE
EDGE LONGFTUDINAL
Figure 5. Typical Microstructure of Double-Extruded INIOO Billet Stock
FAM 81109
CENTER LONGITUDINAL
FD 74445
BO
|
r-T
0>
p
o
-------
Pratt & Whitney fiircraft
FR-6690
Table I. IN100 Double Extruded Superplasticity Test Results
Specification Flow Stress, Elongation, Reduction of
No. Temperature N/m2 x 106 psi % Area, %
1
2
1079°C (1975°F)
1079°C (1975° F)
67.7
58.7
9820
8510
445
295
99.7
99.7
Most of P&WA's experience with the GATORIZING forging process has
been with this die material. Conventional machining and electrical discharge
machining (EDM) techniques have been well established. The design of the dies
to forge the preform and bladed wheel was based on our experience with die and
insert designs, lubricants, and metal flow characteristics.
A two-step forging sequence was selected to GATORIZE the wheels. The
first step produced a nonbladed oversized preform, which had a two-fold pur-
pose: (1) to ensure proper metal distribution for forging the bladed wheel;
and (2) to further enhance the forgeability of the material. The second forging
step was for the purpose of reducing the disk area to final dimensions and filling
the blade die insert cavities.
The preform configuration (figure 6) and preform dies were designed and
the tooling fabricated. A cross-sectional view of the preform tooling is shown
in figure 7 and photographs of the actual tooling are shown in figure 8.
3. Preform Forging and Evaluation
One forging mult, 44.45 mm (1.75 in.) in diameter by 85.85 mm (3.38 in.),
was machined from the extruded stock. The baseline forging and heat treatment
parameters had been established by prior experience with wrought IN 100. The
mult was coated with a boron nitride lubricant and GATORIZED at 1038°C (1900°F)
to the preform configuration. The forging completely filled the tooling with a
50% reduction flow stress of 23.4 N/m2 (3400 psi) and exhibited an excellent
surface finish. The strain rate averaged 0.25 cm/cm/min (0.10 in./in./min).
The preform was subsequently dimensionally checked, visually and die
penetrant inspected for laps and other surface defects, and inspected for internal
defects by X-ray and ultrasonic inspection techniques. The preform was within
allowable dimensional tolerances and had no surface or internal defects. The
as-forged preform exhibited a uniform, fully recrystallized fine grained struc-
ture (ASTM 14. 5 to 16. 5). The forging mult, forged preform, and representa-
tive microstructure are shown in figure 9.
9
-------
Pratt & Whitney fiircraft
0.076 cm
(0.030 in.) R
10.617 cm (4.180 in.) DIA
5.588 cm
•"(2.200 in.) DIA~"
1.930 cm
(0.760 in.)
(R
0.203 cm
(0.080 in.)
t
wi~r<
EF)
f
3.38£
-(1.334
I
11.201 cm (4.410 in.) DIA-
Figure 6. Cross Section of Phase I Disk Preform
1.458 cm
(0.574 in.)
FD 71221A
TOP KNOCK OUT
BOTTOM DIE
TOP DIE
PREFORM
CAVITY
I— BOTTOM KNOCK OUT
Figure 7. Tooling for Phase I - Task 1 Preform FD 72643
10
-------
Pratt & Whitney Rircraft
10.16 em
(4.00 in.)
10.16 em
(4.00 in.)
10.16 em
(4.00 in,)
\ ^fl^. 20.1
32 em
(8.00 in.)
Figues 8. Ftaiih Maehtntd
Tooling
FI 13077IA
FI 130773A
FD 7580SA
11
-------
Pratt & Whitney Rircraft
BILLET
FORGING
FAE 131443
MAG: 100X
TYPICAL MICROSTRUCTURE
FD 75604A
Figure 9. Task I Wheel Preform
The selected baseline heat treatment was one which would give the high
strength and LCF life typically required in a turbine disk alloy. At the time,
it was anticipated that it might be necessary to preferentially heat treat the
blades to establish the elevated temperature stress rupture capability. The
baseline heat treatment was as follows:
Solution:
Precipitation:
Age:
1121°C (2050°F)/2 hr/OQ (oil quench)
871°C (1600°F)/40 min/AC (air cool)
982°C (1800°F)/45 min/AC
649°C (1200°F)/24 hr/AC
760°C (1400°F)/4 hr/AC
12
-------
Pratt & Whitney fiircraft
The preform was heat treated to the baseline heat treatment and test
specimens were subsequently machined from the preform according to the
diagram of figure 10. This cut-up procedure was essentially the same for all
subsequent preform and bladed wheel evaluations.
CREEP RUPTURE
LCF
V-NOTCH
RUPTURE
CREEP RUPTURE
\
\
Figure 10. Diagram for Test Specimens Machined
from Preform and Wheel
FD 79231A
Task 1 mechanical property tests conducted included room temperature
and 760°C (1400°F) tensile tests; 927°C (1700°F) creep rupture tests at 103.4 MN/m2
(15 ksi); 68. 9 MN/m2 (10 ksi), and 34. 5 MN/m2 (5 ksi); 871°C (1600°F) creep
rupture tests at 68.9 MN/m2 (10 ksi); notch rupture tests at 927°C and
103.4 MN/m2; and 927°C LCF tests at 1. 0% and 2. 0% total strain range. Time
to 1% creep and time to rupture were recorded on the creep rupture tests. The
results of the tests are tabulated in table II.
The heat treated preform exhibited a uniform fine grain microstructure
with an ASTM grain size predominantly 10. 5 to 13. 5 with occasional 9. 5.
Electron microscopic review showed the structure to be typical of that afforded
by the baseline heat treatment. Representative photomicrographs at 100X and
1000X are shown in figure 11. The question of preferential heat treatment of
the blades was resolved in Task 2.
13
-------
Table II. Results of Task 1 Evaluations
Heat Treatment:
Preform S/N:
Forge Temperature:
Baseline
2-4
1038°C (1900°F)
TENSILE
Test
°C
RT
760
760
Temperature,
°F
RT
1400
1400
Test Temperature,
°C
927
927
927
927
871
927
927
Test
°C
927
927
°F
1700
1700
1700
1700
1600
1700
1700
Temperature,
°F
1700
1700
0.2% Yield
MN/m2 ksi
Ultimate Elongation,
MN/m2 ksi %
1132.9 164.2 1421.3 206.0 11.3
1059.1 153.5 1135.0 164.5 12.0
1063.2 154.1 1139.1 165.1 11.3
CREEP RUPTURE
Stress Level
Mj^/m2 ksi
103.4
103.4
68.9
34.5
68.9
103.4
103.4
15
15
10
5
10
15
15
Total Strain,
%
2.0
1.0
Rupture
hr
1.6
1.8
4.8
14.6
35.7
—
—
STRAIN
Life, Elongation,
Red. of Area, Time to 1
Red. of Area,
11.1
16.4
10.4
. 0% V/N Rupture,
% % Creep, hr hr
100.8
101.0
133.0
108.8
68.0
—
—
CONTROL LCF
Mean Strain,
%
1.0
0.5
70.0 0.1
68.2 0.1
84.7 0.2
92.0 1.0
83.6 2.2
— —
—
Total Cycles
28
335
__
—
—
—
—
3. 1
3.9
Remarks
Failed
Failed
3
Co
0>
«q
S W
o :$
-------
Pratt & Whitney Oircraft
CM
MAG: 100X
MAG: 1000X
FD 84120
Figure 11. Task 1 Preform Microstructure Baseline
Heat Treat
B. TASK 2 - PROCESS PARAMETER EVALUATION
Task 2 was designed to evaluate critical processing parameters, forging
temperatures, forging strain rate, and heat treatment. Task 2 is shown
schematically in figure 12. One of two preforms initially forged was used for
gradient bars and heat treat samples to evaluate the microstructural response
to thermal treatment. The second preform was heat treated to baseline param-
eters and evaluated in an identical fashion as the Task 1 part to further establish
baseline properties. Subsequently six additional parts were forged to assess the
effect of forging temperatures, strain rates, and heat treat variables on the final
part. Only one parameter was varied at a time, the others being baseline. The
forging temperature, forging strain rate, and heat treatment which yielded the
best part consistent with mass production economics was applied to the Task 3
design data generation.
1. Preform Forging
The eight forging multiples were machined from the extruded stock and
boron nitride coated. Four of these mults were forged into the preform con-
figuration per Task 1 baseline parameters (i. e., 1038°C, 1900°F and 0. 25 cm/cm/min,
0.10 in. /in. /min). Three mults were forged at alternate forging temperatures of
1010 °C (1850 °F), 1066°C (1950 °F), and 1093°C (2000 °F). One mult was forged at
1038 °C (1900 °F) at an accelerated strain rate of 0.38 cm/cm/min (0. 15 in./in./min).
15
-------
FORGE TWO ADDITIONAL
TASK I PREFORMS
1
HEAT TREAT
(SAME AS TASK I)
CUT-UP FOR
GRADIENT BAR STUDY
I
VISUAL AND NDI
EVALUATION
MECHANICAL PROPERTY
AND STRUCTURAL EVALUATION
(SAME AS TASK I)
J
SELECT ALTERNATE
PROCESSING PARAMETERS
J_
THREE ADDITIONAL
FORGE TEMPERATURES
T2, T3 AND T4
L
ONE ADDITIONAL
STRAIN RATE
1
TWO ADDITIONAL HEAT TREATMENTS
AS DETERMINED FROM GRADIENT
BAR EVALUATION S2A2 AND S3A3
_L
FORGE 6 TASK 2 WHEELS
MECHANICAL PROPERTY AND
STRUCTURAL EVALUATION
(SAME AS TASK I)
SELECT PROCESSING
PARAMETERS
Figure 12. Phase I - Feasibility Demonstration and Cost Analysis; Task 2 - Process Parameter Evaluation FD 72647A
CD
<
5
o
-------
Pratt & Whitney fiircraft
All eight were visually inspected, dimensionally checked, and found to be satis-
factory. These preforms were used in the Task 2 evaluations as summarized in
table III.
2. Additional Baseline Property Evaluation
Two of the four preforms forged at the baseline parameters (S/N 2-10
and 2-11) and the preform forged at the alternate strain rate (S/N 2-9) were held
for subsequent reforging into the bladed wheel configuration. The third baseline
preform (S/N 2-5) was given the baseline heat treatment, inspected by nondestruc-
tive inspection techniques, and evaluated using the same procedure as the Task 1
preform. The results are tabulated in table IV, and are equivalent to the Task 1
baseline properties.
3. Structural Response to Heat Treatment
Gradient bars were cut from the fourth baseline preform (S/N 2-6) to
establish the structural response to heat treatment. These slices were held at
various solution temperatures up to 1232°C (2250°F). Significant grain growth
occurred at temperatures above 1149°C (2100°F). Typical microstructures from
this study are shown in figure 13. The gradient bar study showed as expected
that a notable variation in grain size was achievable in the material by varying
the solution heat treatment temperature. The heat treatments for the Task 2
alternate heat treatment study and the Task 3 blade heat treatments were selected
based on the results of this study.
4. Effect of Varying Forging Temperature
The final form dies were not yet completed, so it was decided to evaluate
the effects of forge temperature on the preforms, rather than delay the program.
Therefore, the three preforms forged at the alternate forge temperatures (S/N 2-3,
2-8, and 2-7) were heat treated to the baseline heat treat and evaluated per the
Task 1 procedures. The data from the evaluations are tabulated in table V.
17
-------
Table III. Summary of Task 2 Evaluations
S/N
Forge Temperature,
Preform Wheel
°C (°F) °C (°
Heat Treatment
Program Use
ASTM Grain Size
Predominate Occasional
2-5
2-3
1038
1010
1900 -
1850 -
Baseline:
1121°C (20i
50°F)
Solution,
Baseline
Forge Te
Data
:mperature
10.
! 10.
5 -
5 -
13.5
13.5
9.5
10.0
2-8 1066 1950 -
2-7 1093 2000 -
2-6 1038 1900 -
2-9 1038 1900 1093 2000
» 2-10 1038 1900 1093 2000
2-11 1038 1900 1093 2000
Oil Quench
871°C (1600°F) Air Cool
982°C (1800°F) Air Cool
649°C (1200°F) Air Cool
760°C (1400°F) Air Cool
Various
Baseline
1177°C (2150°F) Solution,
Air Cool + 1121°C (2050°F)
Solution, Air Cool + Base-
line Precipitation and Age
1177°C (2150°F) Solution,
Air Cool + 1066°C (1950°F)
Solution, Air Cool + Base-
line Precipitation and Age
Study
Forge Temperature
Study
Forge Temperature
Study
Gradient Bar Study
Alternate Strain
Rate Study
Alternate Heat
Treat Study
Alternate Heat
Treat Study
11.5 - 13.5
9. 5 - 12.5
11.5 - 13.5
3.0 - 4.0
4.0 - 6.0
13.5
7.0-10.0
7.0 - 8.0
03
D
0>
O
8
-------
Table IV. Results of Task 2 Baseline Evaluation
Heat Treatment:
Preform S/N:
Forge Temperature:
Baseline
2-5
1038°C (1900°F)
TENSILE
Test
°C
RT
760
760
£ Test
°C
871
871
871
871
871
871
Temperature,
°F
RT
1400
1400
Temperature,
1700
1700
1700
1700
1700
1700
0. 2% Yield
M|
o 3
-------
Pratt & Whitney Pircraft
1149°C FAM 81096
(2100°F)
1 163 °C
(2125°F)
1190°C FAM 81084
(2175°F)
1204 °C FAM 81oa6
(2200 °F)
MAGNIFICATION: 100X
1218°C FAM 81092
(2225 °F)
Figure 13. Blade Gradient Study
1232°C FAM 81095
(2250 °F)
ETCHANT: KALLING'S
FD 74447
20
-------
Table V. Results of Task 2 Alternate Forge Temperature Evaluation
Heat Treatment: Baseline
Preform S/N: 2-3, 2-7, 2-8
Forge Temperature: 1010°C (1850° F)
1093°C (2000°F)
1066°C (1950°F)
TENSILE
Test
°C
RT
RT
RT
RT
760
760
760
760
760
760
Temperature,
°F
RT
RT
RT
RT
1400
1400
1400
1400
1400
1400
0. 2% Yield
S/N
2-3
2-7
2-8
2-8
2-3
2-3
2-7
2-7
2-8
2-8
MN/m2
1159.1
1106.7
1116.3
1108.7
1070.8
1054. 9
1057.0
1067.4
1062.5
1034.2
ksi
168.0
160.4
161.9
160.8
155.2
152.9
153.2
154.7
154.1
150.0
Ultimate
M^/m2
1331.6
1486.8
1572.0
1509.9
1121.9
1115.0
1131.5
1155.7
1130.0
1111.4
ksi
193.0
215.5
228.0
219.0
162.6
161.6
164.0
167.5
163.9
161.2
Elongation
%
9.3
12.7
24.6
14.7
12.0
13.3
3.3
10.0
14.7
13.3
Red. of Area,
%
12.1
15.9
28.0
16.9
14.5
18.3
4.3
9.5
17.2
12.4
BO
D
CD
to
o
-------
Table V. Results of Task 2 Alternate Forge Temperature Evaluation (Continued)
CREEP RUPTURE
Test Temperature,
°C °F
871
871
927
927
927
927
927
927
927
927
927
927
927
to 927
«*> 927
927
927
927
927
927
927
927
1600
1600
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
S/N
2-3
2-7
2-3
2-3
2-7
2-7
2-3
2-3
2-7
2-7
2-3
2-7
2-3
2-7
2-8
2-8
2-8
2-8
2-8
2-8
2-8
2-8
Test Temperature,
°C °F
927
927
1700
1700
Stress Level Rupture Life, Elongation, Red. of Area Time to 1. 0% V/N Rupture,
MN/m2 ksi hr % % Creep, hr hr
68.9
68.9
103.4
103.4
103.4
103.4
103.4
103.4
103.4
103.4
68.9
68.9
34.5
34.5
103.4
103.4
103.4
103.4
68.9
68.9
34.5
34.5
S/N
2-7
2-7
10
10
15
15
15
15
15
15
15
15
10
10
5
5
15
15
15
15
10
10
5
5
25.2
64.7
0.6
1.3
3.0
3.5
—
—
_
-
2.6
5.2
12.5
27.3
1.6
2.1
—
-
4.9
4.6
15.7
23.9
STRAIN
Total Strain,
%
2.0
2.0
159.0
88.7
142.0
115.0
41.9
104.8
-
-
-
-
83.0
90.1
192.5
232.9
57.9
69.4
-
-
100.2
100.3
139.0
269.0
CONTROL LCF
Mean Strain,
%
1.0
1.0
87.8
81.2
68.2
70.3
62.0
68.0
-
-
-
-
86.0
82.0
92.8
91.5
68.4
72.8
-
-
85.6
84.8
89.5
91.6
1.3
5.8
<0. 1
<0. 1
0.2
<0. 1
-
-
-
-
0.1
0.3
0.5
1.6
0.15
0.18
-
-
<0.3
0.2
0.8
1.6
Total Cycles
21
13
_
—
—
-
-
—
2.6
2.2
6.9
5.7
—
—
—
-
-
—
4.9
4.0
-
—
—
—
Remarks
Failed
Failed
TJ
03
I
05
O
0>
5
o
3
-------
Pratt & Whitney fiircraft
The forging temperature study showed that mechanical properties did not
vary significantly with forging temperatures over the 1038°C (1900°F) to 1093°C
(2000°F) range investigated. Room temperature tensile properties are shown in
figure 14. There appeared to be a degradation in room temperature ultimate
tensile strength with the 1010°C (1850°F) forging temperature. The reasons for
the variation in tensile ductility have not been explained at this time. Elevated
temperature ultimate and yield strength were insensitive to forging temperature
over the entire range investigated as shown in figure 15. Again a degree of in-
consistency in ductility was noted. The low cycle fatigue (LCF) test specimens
from the preforms forged at 1010°C and 1098°C (S/N 2-3 and 2-8) were incor-
rectly machined and could not be tested. The LCF life of the preform forged at
1093°C (2000°F) was similar to the LCF properties of the baseline forgings.
However, all of these initial tests were conducted at an excessively high, and
unrealistic strain range. Subsequent LCF testing was done at a lower and more
appropriate strain level of 0. 5%. This lower strain range was selected based
on the results of an analytical analysis of the wheel using stresses and tempera-
ture gradients supplied by the Baseline Engine Contractor.
5. Bladed Wheel Die Design and Manufacture
The final integrally bladed wheel tooling was designed per Chrysler
drawing No. 2443630, with the exception of the pockets located in both sides of
the disk rim. The pockets were excluded for the Phase I feasibility demonstra-
tion for two reasons: (1) it was felt that the primary goal of this initial program
was to demonstrate the feasibility of economically GATORIZING an integrally
bladed wheel of the type used in automotive gas turbines, and (2) it is highly
probable that the final wheel design can be modified to exclude pockets, because
of the improved structural uniformity and higher levels of mechanical properties,
especially LCF, associated with the wrought product.
A cross section of the tooling for the final bladed wheel design is shown
in figure 16. The cavities for the 53 blades are formed by simple split inserts.
This concept is shown by the 5X model in figure 17. The finished machined
tooling is shown in figure 18.
23
-------
WHEEL PREFORM DATA BASELINE HEAT TREATMENT
ibl/
CM
E 1070
S
S 1741
a •
z
UJ
IT
to 1103
96B
^u
'« 200
I
I-
U 180
UJ
oc
CO
160
140
c
c
i
3
3 J
5 ]
] [
G
1 r
J L
O • ULTIMATE STRENGTH
D - 0.2% YIELD STRENGTH
to
A
- % ELONGATION
s?
Z
g
<
o
0
UJ
Figure 14.
13
14
13
12
11
10
9
98
180
Room r.
L
A
\
L
2°C 1010°C 1038°C 1066°C 1093
0°F 1850°F 1900°F 1950°F 200C
FORGE TEMPERATURE
Femperature Tensile Properties vs Forging Temperature FD 79
Pratt & Whitney Pircraft
<
m
o u- co
^1 . o q_ M
-------
WHEEL PREFORM DATA BASELINE HEAT TREATMENT
to
CJ1
1172
CM
.E
5
I
1-
0
£ 1034
I-
965
Figure 15.
170
i
i-
(3
Z
LU
£ 150
CO
140
16
14
59 12
Z
0 10
1-
0 8
O
4
2
98
180
760°C
e
E
s c
^ r
? \
[
? [
] C
O
] °
~i
J
O - ULTIMATE STRENGTH (~) . o.2% YIELD STRENGTH A - % ELONGATION
A
A AzruiiMia .
A A
2
5
\
Z
TJ
^ !
2°C 1010°C 1038°C 1066°C 1093°C ^
0°F 1850°F 1900°F 1950°C 2000°F =£
FORGE TEMPERATURE ^
(1400°F) Tensile Properties vs Forging Temperature FD 79234A 5
0
3
-------
Pratt & Whitney Rircraft
r—^-^-\/~
TOP KNOCKOUT PIN
TOP DIE
BOTTOM DIE
-BOTTOM KNOCKOUT
SYSTEM
Figure 16. Tooling for Phase I - Task II Bladed Wheel FD 74448B
Figure 17. Blade Insert Concept Used for Finish
Die Design
FE 129863A
26
-------
Pratt & Whitney fiircraft
Figure 18. Finish Machined Bladed Wheel Tooling FC 29992
Preform FD 79228A
6. Wheel Forging
The remaining three Task 2 preforms were machined to clean up the out-
side diameter and assure concentricity in the final form die. The preforms
were coated with the boron nitride lubricant. Because the Task 2 forging tem-
perature study indicated that forging temperature had no significant effect on
mechanical properties, a forging temperature of 1093°C (2000°F) was selected
to assure optimum forgeability. The baseline strain rate was used for the initial
trials. The first bladed wheel forging trial (S/N 2-10) resulted in the partially
bladed wheel shown in figure 19. The lack of blade fill was attributed to the
degree of taper in the airfoil thickness (root to tip). The blade cavities were
opened up 0. 25 mm to 0. 51 mm (0. 01 to 0. 02 in.) to minimize the frictional
forces. In addition, there were problems removing the inserts at room tem-
perature due to the large difference in coefficient of thermal expansion between
IN 100 and the TZM molybdenum dies. Because tooling was not available (re-
quired tooling will be available in Phase II) to remove the inserts while at the
forging temperature a portion of the twist was taken out of the airfoil to facilitate
insert removal at room temperature. The resulting modified blade cross sections
are shown in figure 20. The first forging attempt with the modified blade inserts
(S/N 2-14) resulted in a fully bladed wheel as shown in figure 21. The S/N 2-11
preform was then also successfully forged.
27
-------
Pratt & Whitney Oircraft
Figure 19. Initial Bladed Wheel Forging
FE 137261
FD 79237A
TIP
MIDSPAN
ROOT
CURRENT DESIGN
MODIFIED TOOLING
Figure 20. Modified Blade Cross-Section
FD 79246
28
-------
Pratt & Whitney Rircraft
Figure 21. Fully Bladed Wheel Forging
KFE 135874
FD 79238A
The bladed wheel forging trials established initial relationships between
blade shape and forgeability. The successful forging of the blades after slight
enlargement of the die insert cavities was attributed to the reduction of die sur-
face friction relative to the flow stress over the increased cross-sectional area.
It is expected that further refinement of the blade shape can be made to further
characterize blade shape and forgeability relationships.
7. Effect of Varying Forging Strain Rate
The S/N 2-9 wheel was successfully forged at the accelerated strain rate
from the preform forged at the same accelerated strain rate. This wheel was
given the baseline heat treatment, cut up and evaluated per Task 1 parameters.
The mechanical property test results are given in table VI. The properties
were typical of the baseline forgings. The grain size was ASTM 11. 5 to
ASTM 13. 5 which was also typical of the baseline forgings. Thus it was deter-
mined that varying the forging strain rate over the range studied, 0.25 to
0.38 cm/cm/min (0.10 to 0.15 in./in./min), did not adversely affect mechanical
properties or structure. The baseline strain rate did provide slightly better
forgeability and was therefore specified for the mass production processing
parameters.
29
-------
Table VI. Results of Task 2 Alternate Strain Rate Evaluation
co
o
Test
°C
RT
760
760
Temperature,
°F
RT
1400
1400
Test Temperature,
°C °F
927
927
927
927
1700
1700
1700
1700
Heat Treatment:
Wheel S/N:
Forge Temperature:
0.2% Yield
M^/m2 ksi
1090.8 158.2
1038.4 150.6
999.1 144.9
Stress Level Rupture
M^/m2 ksi hr
103.4 15 1.5
103.4 15 1.4
103.4 15
103.4 15
Baseline
2-9
1038°C/1093°C (1900°F/2000°F)
TENSILE
Ultimate Elongation,
Mj^/m2 ksi %
1389.3 201.5 11.3
1103.8 160.1 4.0
1069.4 155.1 7.3
CREEP RUPTURE
Life, Elongation, Red. of Area 1.0% Creep
% % hr
89.5 68.8 0.1
66.2 57.0 0.1
Red. of Area
12.4
8.4
11.4
V/N Rupture,
hr
4.4
4.5
STRAIN CONTROL LCF
Test
°C
927
927
Temperature,
°F
1700
1700
Total Strain,
0.5
0.5
Mean Strain,
% Total Cycles
0.25 3168
0.25 2884
Remarks
Failed
Failed
TJ
5
3
Co
CD
1 o
O5
Oi
-------
Pratt & Whitney Oircraft
8. Mechanical Property Response to Alternate Heat Treatments
The Task 2 alternate heat treatment study was aimed at establishing a
single wheel heat treatment which would achieve a compromise structure com-
bining the high tensile strengths typical of fine grain structure with the good
rupture life of large grained material, while maintaining an adequate LCF life.
Two heat treatments were determined from the gradient studies with this aim
in mind. The two remaining wheel forgings (S/N 2-10 and 2-11) were each given
one of these two heat treatments:
Solution: (1) 1177°C (2150°F)/2 hr/AC + 1121°C (2050°F)/2 hr/AC
(2) 1177°C (2150°F)/2 hr/AC + 1066°C (1950°F)/2 hr/AC
Both heat treatments included the following precipitation and age cycles:
871°C (1600°F)/40 min + 982°C (1800°F)/45 min +
649°C (1200°F)/24 hr + 760°C (1400°F)/4 hr
All cycles were air cooled.
These Task 2 wheels were cut up and evaluated. The grain size of the
wheel given the 1177°C (2150°F)/1121°C (2050°F) double solution (S/N 2-10) was
predominantly ASTM 3-4, with occasional ASTM 7-10. The S/N 2-11 wheel
which was solutioned at 1177°C (2150°F)/1066°C (1950°F) had a slightly smaller
grain size of predominantly ASTM 4-6, with occasional ASTM 7-8. The mechanical
property test data are presented in table VII.
It was felt that the differences in the mechanical properties could not be
adequately explained on the basis of grain size alone, so an Electron Microscopic
(EM) examination was conducted on material from both rotors. The EM review
showed differences in the secondary phases, probably due to the different double
solution cycles. Representative electron photomicrographs are shown in fig-
ure 22. Further study is needed to characterize the relation of these phases to
the heat treatments, and how they affect mechanical properties.
31
-------
Table VII. Results of Task 2 Mechanical Property Response to Heat Treat Evaluation
Heat Treatment:
Wheel S/N:
Forge Temperature:
TENSILE
2-10 & 2-11
1038°C (1900°F)
Test
°C
RT
RT
760
760
760
760
to Test
N °C
927
927
927
927
927
927
927
927
Temperature,
°F
RT
RT
1400
1400
1400
1400
Temperature,
°F
1700
1700
1700
1700
1700
1700
1700
1700
S/N
2-10
2-11
2-10
2-10
2-11
2-11
0.2% Yield
M^/m2 ksi
979.1
999.0
932.9
937.7
978.4
980.4
Stress Level,
S/N MN/m2 ksi
2-10
2-10
2-11
2-11
2-11
2-11
2-10
2-11
103.4 15
103.4 15
103.4 15
103.4 15
103.4 15
103.4 15
103.4 15
103.4 15
142.0
144.9
135.3
136.0
141.9
142.2
CREEP
Ultimate,
M^/m^ ksi
1094.9 158.8
1327.2 192.5
1115.6 161.8
1111.4 161.2
1143.1 165.8
1043.2 151.3
RUPTURE
Rupture Life, Elongation,
hr %
360.9
480.2
198.2
116.5
336.2
330.3
-
-
4.9
7.0
3.7
6.3
Discontinued**
Discontinued**
-
-
Elongation,
%
4.7
12.0
6.7
5.3
8.0
1.3
Red. of Area,
%
2.8
2.4
3.6
6.0
-
-
Red. of Area,
%
8.5
17.6
8.4
7.4
9.0
4.4
1. 0% Creep, V/N Rupture,
hr hr
164.8
236.0
93.5
34.3
159.7 Disconl
185. 1 Disconl
TJ
3
3
0>
hrj D
* 3
X 03
-------
Table VII. Results of Task 2 Mechanical Property Response to Heat Treat Evaluation (Continued)
STRAIN CONTROL LCF
Test Temperature, Total Strain, Mean Strain
°C °F S/N % % Total Cycles Remarks
927
927
927
927
1700
1700
1700
1700
2-10
2-10
2-11
2-11
0.5
0.5
0.5
0.47
0.25
0.25
0.25
0.235
2769
3109
5768
9313
Failed
Failed
Failed
Failed
*S/N 2-10 1177°C (2150°F) Solution,
Air Cool + 1121°C (2050°F)
Solution, Air Cool + Baseline
Precipitation and Age
co S/N 2-11 1177°C (2150°F) Solution,
00 Air Cool + 1066°C (1950°F)
Solution, Air Cool + Baseline
Precipitation and Age
**Equipment breakdown
3>"
CD
05
(0
o
-------
Pratt & Whitney Oircraft
1177°C/1121°C (2150°F/2050°F)
SOLUTION
1177°C/1066°C (2150°F/1950°F)
SOLUTION
MAG: 3000X
B678-5
MAG: 3000X
B677-28
CM
MAG: 10.000X
B678-6
MAG: 10,OOOX
B678-12
Figure 22. Task II Alternate Heat Treatment
Evaluation - Electron Photomicrographs
FD 84121
34
-------
Pratt & Whitney Rircraft
The mechanical property data points from these wheel forgings are
presented in figures 23, 24, and 25, along with data points from the base-
line evaluations and the Task 3 blade property characterization. The curves
are preform data from figure 28. These figures show that, while sacrificing
tensile strength (compared to baseline), one of the alternate heat treatments
(1177°C, 2150°F/1066°C, 1950°F) resulted in the highest LCF capability and
maintained close to the desired level of stress rupture strength. This heat
treatment was, therefore, selected for use in part 2 of Task 3.
C. TASK 3 - GENERATION OF DESIGN DATA
Task 3 was twofold as shown schematically in figure 26. The first part
involved selecting and evaluating heat treatments designed to enhance the high
temperature rupture properties of the blades. This part was conducted con-
currently with Task 2. The second part was the establishment of complete
design curves for the short time, long time and cyclic properties of the wheel.
A summary of the Task 3 evaluations is given in table VIII.
1. Blade Property Characterization
As mentioned previously, it was initially planned to preferentially heat
treat the blades of the finished wheel to enhance the rupture properties. In an
effort to determine a structure for the blades that would result in a good balance
of stress rupture life and ductility, solution heat treatment temperatures of
1163°C and 1177°C (2125°F and 2150°F) were selected from the gradient study.
These solution temperatures result in structures which are most likely to have
optimum 927°C - 982°C (1700°F - 1800°F) capabilities. The grain structures
resulting from the 1163°C and 1177°C (2125°F and 2150°F) solution are a compro-
mise between the fine grains in the material given the baseline heat treatment
(figure 11) and the excessively large grains resulting from solution heat treatment
temperatures above 1177°C (figure 13). The fine grains generally have poor
creep and rupture lives, while extremely coarse grained structures normally
exhibit poor rupture ductility and reduced low-cycle fatigue properties.
35
-------
Pratt & Whitney fiircraft
BLADED WHEEL DATA
1038°C (1900°F)/1093°C (2000°F) FORGE TEMPERATURE
Ibl/ £.&)
1379 200
1241 180
1103 160
CM 965 140
-I
z JS
i t-
H 827 0 120
(5 Z
Z LU
LU GC
cc *~
H ">
£/>
689 100
552 80
414 60
276 40
138 20
n
o
V
• &
• :
V
Q £ BASELINE:
1121°C (2050°F) OIL QUENCH
A A 1163°C (2125°F) AIR COOL +
1121°C (2050°F) OIL QUENCH
Q • 1177°C (2150°F) AIR COOL +
1121°C (Z050°F) OIL QUENCH
^7 Tf 1177°C (2150°F) AIR COOL +
1121°C (2050°F) AIR COOL
<^> ^ 1177°C (2150°F) AIR COOL +
1066°C (1950°F) AIR COOL
NOTE:
ALL HhAI I nbA 1 IvlbIM 1 b rLUb
BASELINE PRECIPITATION AND
AGE CYCLES
^
QALJ W ULTIMATE STRENGTH
0AH V^ °-2% YIELD STRENGTH
D
1
A
^
z
ROOM 760°C
TEMP 1400°F
927°C 982°C
1700°F 1800°F
FORGE TEMPERATURE
Figure 23. Tensile Properties vs Heat Treatment
FD 79245A
36
-------
100
BLADED WHEEL DATA
1038°C (19000F)/1093°C(2000°F) FORGE TEMPERATURE
co
GO
V)
cc
00
10
HEAT TREATMENT
O - BASELINE: 1121°C (2050°F)
OIL QUENCH
A - 1177°C (2150°F) AIR COOL +
1121°C (2050°F) AIR COOL
\~\ - 1177°C (2150°F) AIR COOL +
1066°C (1950°F) AIR COOL
A - 1163°C (2125°F) AIR COOL •>-
1121°C (2050°F) OIL QUENCH
DESIGN POINT
NOTE: TYPICAL CURVES FROM PREFORM DATA,
FIGURE 28. ALL HEAT TREATMENTS
PLUS BASELINE PRECIPITATION AND
AGE CYCLES
TJ
3
42
43
44
45 46 47
PARAMETER = T(20 + LOG t ) x 10 3
48
49
Figure 24. Stress Rupture Capability vs Heat Treatment
50
FD 79241A
D
05
<
5
n
o
-------
w
00
BLADED WHEEL DATA CONSTANT STRAIN TESTING
(STRAIN RANGE 0.5%)
CYCLES TO FAILURE
1,000
5,000
10,000
I I
BASELINE:
1121°C (2050°F)
OIL QUENCH
1163°C (2125°F), AIR COOL
+ 1121°C (2050°F) OIL QUENCH
1177°C (2150°F), AIR COOL
+ 1121°C (2050°F) OIL QUENCH
1177°C (2150°F) AIR COOL
+ 1121°C (2050°F) AIR COOL
1177°C (2150°F) AIR COOL
+ 1066°C (1950°F) AIR COOL
DESIGN POINT
NOTE: ALL HEAT TREATMENTS PLUS
BASELINE PRECIPITATION AND
AGE CYCLES
00
o
o o
00
o
o
Figure 25. 927°C (1700°F) LCF Capability vs Heat Treatment
FD 79242A
QJ
3
Co
(D
o
5
-------
A. BLADE PROPERTY CHARACTERIZATION
B. DISK PROPERTY CHARACTERIZATION
FORGE TWO FLAT
PANCAKES
FORGE 5 TASK 2
WHEELS USING PARAMETERS
SELECTED FROM TASK 2
HEAT TREAT (OPTIMIZE
927°C(1700°F) 982°C(1800°F)
CAPABILITIES)
09
to
HEAT TREAT
VISUAL AND NDI
EVALUATION
MECHANICAL PROPERTY
AND STRUCTURAL EVALUATION
TENSILE
RT, 927°C(1700°F),
982°C(1800°F)
GENERATE DESIGN
DATA
CREEP-RUPTURE
871°C(1600°F),
982°C(1800°F)
LCF
MACROSTRUCTURE
AND
MICROSTRUCTURE
TENSILE
1.0% CREEP
STRESS RUPTURE
LCF
3
3
Co
Figure 26. Phase I - Feasibility Demonstration and Cost Analysis; Task 3 - Generation of Design Data
FD 72645A
o
3
-------
1517
1379
1241
CN 1103
.E
z
5
I 965
Z
LU
oc
rfk
o
827
689
552
414
276
z
UJ
IT
C/S
LLJ
220
200
180
160
140
120
100
80
60
40
\
\
1
}2 POINTS
a
m
A H 3 POINTS
- OAD • ULTIMATE STI
•AB • 0.2% YIELD SI
£)• • BASELINE HE/
1121°C (2050°
PRECIPITATIO
^A - 1163°C (2125°
QJB ' ' ' 1 1°^> (2lbO°
f
LENGTH
"RENGTH
^T TREAT
F) SOLUTION + BASELINE
N AND AGE
F) SOLUTION + BASELINE
F) SOLUTION + BASELINE
[
r
i
ROOM
TEMP
760°C
1400°F
927°C
1700°F
TEST TEMPERATURE
Figure 27. Tensile Properties vs Solution Temperature Preform Data 1038°C (1900° F) Forge Temperature
982°C
1800°F
FD 79239A
T
r+
0)
O
-------
PREFORM DATA
100
CO
CO
ill
cc
*> fc
10
o
OCX
o
A
D
I I I
SOLUTION TEMPERATURE
BASELINE - 1121°C (2050°F) +
BASELINE PRECIPITATION AND AGE
1163°C (2125°F) + BASELINE
1177°C (2150°F) + BASELINE
QD
NOTE:
POINTS DESIGNATE MULTIPLE
DATA POINTS
42
43
44
45 46 47
PARAMETER = T(20 + LOG t) x ID'3
Figure 28. Stress Rupture Capability vs Solution Temperature
48
49
50
FD 79240A
3
fio
3
(D
<
TJ
o
3
-------
Table VIII. Summary of Task 3 Evaluations
S/N
Forge Temperature
Preform Wheel
C °F °C °
Heat Treatment
Program Use
ASTM Grain Size
Predominate Occasional
2-2A 1038 1900
2-2B 1038 1900 -
2-6B 1038 1900
2-12A 1038 1900 1093 2000
2-12B 1038 1900 1093 2000
2-13
2-15
2-16
2-17
2-18
1038 1900 1093 2000
1163°C (2125°F) Solution,
Air Cool + Baseline
1177°C (2150°F) Solution,
Air Cool + Baseline
1177°C (2150°F) Solution,
Air Cool + Baseline
1163°C (2125°F) Solution,
Air Cool + Baseline
1177°C (2150°F) Solution,
Air Cool + Baseline
1177°C (2150°F) Solution,
Air Cool + 1066°C (1950°F)
Solution, Air Cool + Baseline
Precipitation and Age
Blade Property
Characteriz ation
Blade Property
Characterization
Blade Property
Characterization
Blade Property
Characteriz ation
Blade Property
Characterization
Disk Property
Characterization
4. 0 - 6.0 and
8.0 - 13.5
3.0 - 4.0
2.0 - 4.0
3.0-4.0
4.0-6.0
4.0 - 6.0
6.0 - 8.0
5.0 = 10.0
6.0 - 10.0
6.0 - 8.0
6.0 - 8.0
-------
Pratt & Whitney Pircraft
It was anticipated that the wheel would require a protective high tempera-
ture coating on the blades and platforms for erosion/corrosion resistance. The
application of the coating requires a 760°C (1400°F) pack coating application cycle
followed by a high temperature diffusion cycle. A coating study determined that
the coating diffusion cycle was compatible with and therefore could be achieved
during the 1121°C (2050°F) solution treatment portion of the baseline heat treat-
ment. The 760°C (1400°F) pack coating application cycle was therefore the only
additional operation required.
The coating application cycle 760°C (1400°F) was not included in the heat
treatment of wheels or preforms for mechanical property testing since it is
followed by a high temperature solution cycle which would negate any structural
effects from the lower temperature cycle. In conducting the coating study, it
was found that there were no adverse effects on the coating from the oil quench
used in the baseline heat treatment. Thus the coating of wheels could easily be
included in any of the heat treatments studied in the program.
Two forging mults were machined from the extruded stock. These were
boron nitride coated and forged into the preform configuration at the baseline
parameters. One preform (S/N 2-12) was subsequently forged into a bladed
wheel at 1093°C (2000°F). Both the preform (S/N 2-2) and the bladed wheel were
cut in half. One half from each part was given the 1163°C (2125°F) solution cycle
for 2 hours, and the other half of each disk was given the 1177°C (2150°F) solu-
tion for 2 hours. A segment of S/N 2-6 was also used in this evaluation. All
pieces were air cooled. The disk halves subsequently received the baseline
heat treat and were cut up for mechanical property testing.
Evaluation of these disk halves included room temperature, 927°C and
982°C (1700°F and 1800°F) tensile properties, 871°C and 982°C (1600°F and 1800°F)
creep rupture properties, 927°C (1700°F) low cycle fatigue properties, and a micro-
structural evaluation. The mechanical property test results are listed in table DC,
and the preform data are plotted in figures 27 and 28. Baseline preform data are
also shown. For comparison with the Task 1 and 2 results, Task 3 wheel results
are also included in figures 23, 24, and 25, as mentioned previously. The micro-
structural evaluation showed a grain size of predominantly duplexed ASTM 3-6
and ASTM 8-13. 5 from the 1163°C (2125°F) solution and predominantly ASTM 3-6
from the 1177°C (2150°F) solution.
43
-------
Table IX. Results of Task 3 Blade Property Characterization Evaluation
Heat Treatment:
Preform S/N:
Forge Temperature:
Wheel S/N:
Forge Temperature:
2-2A & B, 2-6B
1038°C (1900°F)
2-12A & B
1038°C/1093°C (1900°F/2000°F)
TENSILE
Test
°C
RT
RT
760
760
760
760
927
927
982
982
Temperature,
°F
RT
RT
1400
1400
1400
1400
1700
1700
1800
1800
0.2% Yield,
S/N
2-2A
2-2B
2-6A
2-6A
2-6B
2-6B
2-6B
2-12B
2-6B
2-12B
MN/m^
1047.3
1020.4
946.6
966.0
923.2
898.4
535.7
464.7
358.5
276.5
ksi
151.
148.
137.
140.
133.
130.
77.
67.
52.
40.
9
0
3
1
9
3
7
4
0
1
CREEP
Test
°C
871
871
871
871
871
871
982
982
982
982
Temperature,
°F
1600
1600
1600
1600
1600
1600
1800
1800
1800
1800
Stress Level,
Rupture
S/N MN/m2 ksi
2-2B 224
2-2A 224
2-12A 224
2-6B 138
2-2A 345
2-6B 345
2-2A 103
2-2B 103
2-6B 68
2-12A 103
32.
32.
32.
20
50
50
.4 15
.4 15
.9 10
.4 15
5
5
5
hr
165.
22.
14.
657.
-
-
3.
42.
86.
2.
Ultimate,
Mj^/m2 ksi
1336.9 193.9
1221.8 177.2
1097.6 159.5
1116.9 162.0
1114.9 161.7
1083.9 157.2
633.6 91.9
584.7 84.8
429.2 62.2
410.2 59.5
RUPTURE
Life, Elongation,
3
1
5
8
0
7
8
2
7o
2.5
7.4
6.5
Discontinued**
-
-
14.1
5.9
9.6
16.8
Elongation,
%
11.3
10.0
18.0
9.3
24.0
5.3
4.7
3.3
2.7
2.7
Red. of Area
%
4.8
7.2
8.3
-
-
-
24.1
3.6
18.1
15.0
Red.
Time to
1.0% Creep
hr
49.0
5.5
4.4
643.5
-
-
0.4
13.7
23.5
0.2
of
%
13.
11.
19.
11.
21.
6.
7.
6.
3.
2.
»
Area,
6
6
4
0
2
5
4
7
3
2
V/N Rupture,
hr
-
—
—
—
3.7
21.2
-
—
—
—
0)
D
0)
^ ¥
7 O
§ s
to -*
o '-f
-------
Table IX. Results of Task 3 Blade Property Characterization Evaluation (Continued)
Test Temperature,
°C °F
927 1700
927 1700
927 1700
S/N
2-12A
2-12B
2-12B
STRAIN
Total Strain,
%
0.5
0.5
0.5
CONTROL LCF
Mean Strain,
%
0.25
0.25
0.25
Total Cycles
2382
5069
3859
Remarks
Failed
Failed
Failed
*S/N 2-2A, 2-12A
1163°C (2125°F) Solution,
Air Cool + Baseline
S/N 2-2B, 2-6B, 2-12B 1177°C (2150°F) Solution,
Air Cool + Baseline
**Equipment Failure
TJ
CD
0>
s
o
-------
Pratt & Whitney Pircraft
2. Disk Property Characterization
Processing parameters selected from Task 2 which provided optimum
wheel properties were used for forging five preforms and subsequently five
wheels. The preform forging temperature was 1038°C (1900°F), the wheel forging
temperature was 1093°C (2000°F), and the strain rate was 0.25 cm/cm/min
(0.1 in./in./min). These wheels were heat treated to the Task 2 alternate heat
treat utilizing the 1177°C (2150°F) + 1066°C (1950°F) double solution cycles.
The five wheels were visually inspected and evaluated by nondestructive
inspection techniques. All were within dimensional tolerances and no internal or
external defects were detected. The wheels were cut up and machined into test
specimens. A variety of testing parameters were used to establish design curves.
The testing parameters and test results are listed in table X. The design curves
are presented in figures 29, 30, 31, 32, and 33. These curves are discussed
in Task 4.
D. TASK 4 - DEFINITION OF MANUFACTURING PROCESS
The Task 4 manufacturing process definition consists of detailed process
sheets for the manufacture of the finished wheel and a. description of the capa-
bilities and limitations of the forging process.
1. Manufacturing Flow Sheet
Table XI is a detailed list of the operations required in the processing
sequence designed for the mass production of GATORIZED automotive gas
turbine wheels.
2. Capabilities and Limitations of Forging Process
The GATORIZING forging process has the capability to forge complex,
contoured shaped parts to extremely close tolerances (±0.051 mm (0.002 in.))
with no surface cracking. Parts can be forged to near finished shape with very
minimal machining to obtain finish dimensions. Finish machining will only be
required to deburr, tip blades to length, turn bearing surfaces, and remove
metal for balancing.
46
-------
Table X. Results of Task 3 Disk Property Characterization Evaluation
Heat Treatment:
Wheel S/N:
Forge Temperature:
1177°C (2150°F) Solution, Air Cool +
1066°C (1950°F) Solution, Air Cool +
Baseline Precipitation and Age
2-13, 2-15, 2-16, 2-17 and 2-18
1038°C/1093°C (1900°F/2000°F)
TENSILE
Test Temperature,
°C °F
RT
316
316
316
649
649
649
760
871
871
871
982
982
982
RT
600
600
600
1200
1200
1200
1400
1600
1600
1600
1800
1800
1800
S/N
2-16
2-15
2-16
2-17
2-13
2-15
2-18
2-15
2-13
2-17
2-18
2-16
2-17
2-18
0.2% Yield
M^/m2 ksi
989.4
958.4
954.9
981.1
996.3
998.4
1000.4
960.4
646.0
618.5
626.0
315.8
299.9
314.4
143.5
139.0
138.5
142.3
144.5
144.8
145.1
139.3
93.7
89.7
90.8
45.7
43.5
45.6
Ultimate,
MN/m2 ksi
1279.0
1202.4
1245.2
1244.5
1168.7
1226.6
1273.5
1105.2
715.0
763.9
765.3
405.4
346.1
402.7
185.5
174.4
180.6
180.5
169.5
177.9
184.7
160.3
103.8
110.8
111.0
58.8
50.2
58.4
Elongation,
%
10.7
8.0
10.7
11.3
5.3
7.3
13.3
6.7
2.7
6.7
3.3
3.3
2.7
3.3
Red. of Area,
%
13.8
11.4
14.4
14.7
10.5
12.6
15.3
8.9
5.9
8.5
5.4
2.2
4.4
1.6
0)
3
BO
0>
'
Oi
05
§
o
-------
Table X. Results of Task 3 Disk Property Characterization Evaluation (Continued)
CREEP RUPTURE
Test Temperature,
°C °F
760
760
760
760
760
871
871
871
871
£ 871
00 927
927
927
927
871
871
871
760
760
871
871
927
927
982
982
1400
1400
1400
1400
1400
1600
1600
1600
1600
1600
1700
1700
1700
1700
1800
1800
1800
1400
1400
1600
1600
1700
1700
1800
1800
S/N
2-15
2-16
2-17
2-13
2-18
2-13
2-17
2-18
2-16
2-18
2-16
2-17
2-15
2-18
2-17
2-15
2-16
2-15
2-16
2-18
2-13
2-18
2-17
2-16
2-17
Stress Level,
Mj^/m^ ksi
344.7
488.2
488.2
551.6
551.6
344.7
448.2
448.2
551.6
551.6
206.8
206.8
103.4
103.4
68.9
103.4
103.4
551.6
551.6
448.2
448.2
344.7
344.7
103.4
103.4
50
65
65
80
80
50
65
65
80
80
30
30
15
15
10
15
15
80
80
65
65
50
50
15
15
Rupture Life,
hr
321.4 Disc.
334.7
301.0
76.2
84.1
5.4
1.4
0.9
0.2
0.2
8.9
7.3
74.3
225.1
67.8
10.3
25.3
-
-
-
-
-
-
-
-
Elongation,
5.64
5.2
11.1
12.4
5.2
3.8
2.4
4.8
3.9
1.8
3.5
7.0
7.2
20.9
9.3
7.4
-
-
-
-
-
-
-
-
Time to
Red. of Area, 1. 0% Creep,
% hr
_
6.9
8.7
11.2
12.1
3.3
6.8
3.2
3.6
4.4
3.6
3.6
17.6
6.5
17.6
9.2
8.0
-
-
-
-
-
-
-
-
-
160.2
117.4
26.1
29.1
2.4
0.5
0.5
<0. 1
<0. 1
3.8
2.6
15.1
84.2
16.4
2.9
7.6
-
-
-
-
-
-
-
-
V/N Rupture,
hr
_
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
231
144.3
4.6
3.3
1.1
1.3
85.2
91.9
TJ
3
Co
05
m
<£>
O
-------
Table X. Results of Task 3 Disk Property Characterization Evaluation (Continued)
STRAIN CONTROL LCF
Test Temperature,
°C
927
927
927
927
927
927
927
927
927
927
°F
1700
1700
1700
1700
1700
1700
1700
1700
1700
1700
S/N
2-13
2-13
2-15
2-15
2-16
2-16
2-17
2-17
2-18
2-18
Total Strain,
%
0.5
0.3
0.7
0.5
0.5
0.7
0.4
0.5
0.4
0.7
Mean Strain,
%
0.25
0.15
0.35
0.25
0.25
0.35
0.20
0.25
0.20
0.35
Total Cycles
3,537
52,255
861
1,595
4,865
951
38,391
2,315
82,645
496
Remarks
Failed
DNF
Failed
Failed
Failed
Failed
Failed
Failed
DNF
Failed
TJ
s
3
Co
0>
g
<=>
q
3
-------
Pratt & Whitney fiircraft
FR-6690
Table XI. Manufacturing Flow Sheet
Operation Description
5 Cast Master Melt Ingots
10 Prepare Ingot for Remelting
15 Produce Remelt Ingot
20 Prep Ingot for Canning
25 Can Ingot
30 Extrude Ingot to 6. 35 cm (2. 5 in.) Dia.
35 Remove Can from Extrusion
40 Inspect Extrusion
45 Store for Manufacturing
50 Cut Extrusion into Multiples
55 Degrease Mults
60 Lubricate with Boron Nitride
65 Preheat Mult
70 Load into Preform Press
75 Gatorize Preform Disk
80 Eject Preform and Cool
85 Trim Flash and Turn OD Concentric to Hub
90 Degrease Preform
95 Lubricate with Boron Nitride
100 Assemble Ring of Inserts and Preform Disk
Package
105 Preheat Package
110 Load Package into Press
115 Gatorize Final Form Wheel
120 Eject Package and Cool to Room Temperature
125 Disassemble Package
130 Inspect, Relubricate, and Return Inserts to
Load Station
135 Barrel Finish Wheel
140 Solution Heat Treat Wheel
145 Plunge Grind Blade Tips to Correct Dia.
150 Apply Aluminide Coating
155 Stabilization and Age Heat Treat Wheel
160 Dimensional Check with Sigma Test
165 Finish Machine Wheel Hubs
170 Deburr and Polish Wheel
175 Final Inspect
180 Degrease
185 Identify and Store
190 Ship Parts
50
-------
Pratt & Whitney aircraft
FR-6690
The primary limitation on the shape of parts which can be forged is the
development of laps during forging. Lapping is a condition that results from
metal flow from two directions after the outside diameter of the forging is in
contact with the die walls. Lapping may be prevented by using a two-step forging
with ID entrance angles as low as 2 deg, if required. The only limitations are
that during the first forging step, lapping be prevented, and during the second
forging step the surface area of the forging is always increasing. A decreasing
surface area would create a lap.
The advantages of a two-step forging operation are a savings in material
input weight and a savings in the cost of machining away the excess metal. The
advantages of a one-step operation are in the elimination of the need for a second
set of forging dies and the saving of one forging operation on every part. The
lubrication requirements are less severe on a two-step forging operation in that
the preform can be lubricated prior to the final forging operation.
Certain special considerations have to be made in designing the airfoil
for successful forging of integrally bladed wheels. Airfoil cross-sectional
areas should have the following characteristics to enhance forging:
1. Near constant to constant airfoil thickness
2. Minimum chord taper
3. Maximum permissible leading and trailing edge radii
4. Minimum airfoil twist
5. Airfoil solidity ratio not more than 4 blades/2. 54 cm (1. 00 in.)
of disk rim.
3. Design Data Sheets
The design data sheets were generated in the Task 3 disk property char-
acterization. Typical tensile vs temperature data and 927°C (1700°F) low cycle
fatigue life data are shown in figures 29 and 30 respectively. Typical creep
and stress rupture data are shown on the Larson-Miller plots of figures 31
and 32. Figure 33 is a trade-off curve demonstrating graphically how a change
in grain size affects rupture and LCF lives. These curves all represent typical
properties and are based on the limited testing that was done during Phase I.
51
-------
1379
1241
1103
cs 965
Z
Ol
to
0
V)
LU
827
689
414
276
138
200
180
160
140
X
I-
0
z
LU
cc
V)
LU
-J
v>
120
O
0
80
60
20
0.2% YIELD STRENGTH
LEGEND
TYPICAL
ULTIMATE STRENGTH
POINTS
400 800 1200
TEMPERATURE - °F
1600 2000 0
400
800 1200
TEMPERATURE - °F
1600
204 427 649
TEMPERATURE - °C
871
1093
204 427 649
TEMPERATURE - °C
871
1093
Figure 29. Automotive Turbine Wheel Design Data Tensile Properties of Wrought INIOO
FD
TJ
3
tney
o
3
a
-------
Pratt & Whitney fiircraft
LIFE CYCLES
Figure 30. EPA Automotive Turbine Wheel Design
Data LCF 927°C (1700°F) IN100
FD 84123
53
-------
1000
100
O
x
01
10
— 1000
— 100
V)
CO
Ul
cc
7
899°C
1650°F
1 7
871°C
1600°F
7
732°C
1350°F
r?—i—7
760°F 788°C
1400°F 1450°F
71
816°C
1500°F
982°C
1800°F
982°C(1800°F) 3 POINTS
927°C(1700°F) 4 POINTS
871°C (1600°F) 3 POINTS
760°C (1400°F) 4 POINTS
/
45
46
50 51 52 53 54 55
LARSON-MILLER PARAMETER, C = 23.0
Figure 31. EPA Automotive Turbine Wheel Design Data INIOO Larson-Miller Plot of 1. 0% Creep Life
FD 84124
Co
|
r+
0>
O
-------
1000
co 100
cc
D
O
I
LU
01
10
1000
100
co
CO
111
cc
CO
7 1
954°C 982°C
1750°F 1800°F
1
899°C
1650°F
7
732°C
1350°F
n i
760°F 788°C
1400°F 1450°F
927°C
1700°F
982°C (1800°F) 3 POINTS
927°C (1700°F) 4 POINTS
871°C (1600°F) 5 POINTS
760°C (1400°F) 4 POINTS
z
V NOTCH FAILURES
52 53 54 55 56 57 58
45 46 47 48 49 50
LARSON-MILLER PARAMETER, C = 23.0
59 60
Figure 32. EPA Automotive Turbine Wheel Design Data INIOO Larson-Miller Plot of Stress Rupture Life FD 84125
3
Co
I
I)
-------
Pratt & Whitney Rircraft
20-
V)
V)
at
cc
D
o.
CO
111
cc
W-t
5-
Q 100 hr STRESS
RUPTURE STRENGTH
r] 3000 LCF CYCLES
(TYPICAL VALUES)
^ 5000 LCF CYCLES
(CURVE EXTRAPOLATED
BY SIMILAR SLOPE)
-0.6
-O.BUJ
o
z
cc
-0.41
cc
-0.30
-0.2
-0.1
8-10 4-6
ASTM GRAIN SIZE
2-4
Figure 33. Trade-Off Curve: LCF and Rupture vs
Grain Size
FD 84127
The use of these curves for actual design would be dependent on design
philosophy. For example, in a growth limited application (yield or creep), a
design might be based on typical properties in that the part grows based on the
average properties. On the other hand, a burst or rupture limited criteria
would probably dictate the use of a minimum curve, which minimum would
depend on the desired confidence level.
E. TASK 5 - MANUFACTURING COST STUDY
1. Background
For the purposes of this study, a projected manufacturing process, and
a complete facility, shown in figure 34, suitable for volume production of auto-
motive turbine wheels was developed based on the manufacturing flow sheet
generated in Task 4. This process includes the physical manufacturing cost
elements and all other significant cost elements necessary to project a mean-
ingful unit cost for automotive turbine wheels.
56
-------
01
EMPLOYEE
PARKING
ISO CARS)
I-
I- --- J
TRUCK
DOCKS
]_ H
.^
HIPPING
D n n 03 tJd DsD DRiD D D D
B-nnnnnnnnnn:
ELECTRONIC
GAGING LJ LI
GRIT BLAST
ABRASIVE SAWS
AND
—*
RECEIVING
OPFICES
ION PRESS
OVERHEAD CONVEYORS
BARREL FINISHERS
~~1 FTT n n ra^iSDODffi&mFn^r
1—' M-1 U UF LJLU u DODDDOOi!vr'aw°"
ASSYSASSY LATHE GmNDER BARREL VERT Q Q Q 0 0 Q D 0 LJ R PI H^
BROACH BENCHES [J M
LATHES
n n
PREFORM GATOR PRESSES
DECREASE
CONTINUOUS FURNACE HEAT TREAT ' A"
FINAL FORM GATOR PRESSES
MACHINE MAINTENANCE
ELECTRICAL
SHOP
f—"—^ FINAL FORM GATOR PRESSES PLUNGE
n ^ 'n n n D n D n1 T&.«
SMALL
TOOL
CRIB
CENTRAL
OPFICES
D n
nnnnnnnnn
nnnnnnnan
nnnnnnnnn
nnnnnnnnn
nnnnnnnnn
nnnnnnnnn_
nnnnnnnnnn
a
nnnnnnnnnn
n n n
n n n a
n n n a
n n n a
n n n n «
n n
n
CONDIT
ION ING
n n
n n n n n
n
n
n n
n n
n n
BATCH
FURNACES
MANUAL
LOAD
AND
UNLOAD
'C' THRU
G"
ELECTRONIC
GAGING
CONTROL CONSOLES
n en m en
SPECIAL HORZONTAL LATHES
CONTROL CONSOLES
cn CD cu mi
en CD
OVERHEAD CONVEYOR
n
I 1 I 1 BOROMATICS I 1
nnn
en
n a a n a n
EMPLOYEE
PARKING
(35 CARS)
Figure 34. Plant Layout EPA Rotor Production 191, 000 sq ft
FD 84126
TI
3
3
CD
D
o
-------
Pratt & Whitney fiircrafi
For purposes of comparison, this cost study was patterned after that
conducted by Williams Research Corporation for the EPA under Contract EPA-
460/9-73-001. With one exception, Williams' assumptions were used to estab-
lish a baseline for this cost study. This exception is that the wheel produced in
the "P&WA" facility is complete with gas path coating and ready for final assembly
and balancing, whereas, the wheel produced in the Williams' facility is a raw
casting requiring finish machining and coating before assembly.
2. Manufacturing Assumptions
The following assumptions were made to generate the manufacturing facility
and cost to produce automotive turbine wheels:
1. The manufacturing facility will be a complete production
operation in that raw materials are received in the form of
alloy constituents to make up the master melts, and finished
wheels ready for assembly are shipped out.
2. The facility is designed to eliminate labor where possible by
use of automated production techniques.
3. The production facility will operate 249 days, two 8-hour shifts,
5 days per week. Additional upkeep is planned for furnace over-
haul and system maintenance.
4. Capital depreciation on all facilities except the building were
carried over 8 years. The building was carried over 40 years.
5. Labor floor/floor prime was estimated assuming all opera-
tions are automated where possible.
6. Tooling life was estimated to be 25 thousand forging cycles
with 25 resinks and insert tooling to have a 100 forging cycle
life.
7. Performance variation of 1. 333 was used for determination
of manpower requirements.
58
-------
Pratt & Wh itney fi ire raft
8. General and administrative costs were set to be 10%; same
as Williams Research Corp. report.
9. Corporate profit was set at 25%; same as Williams Research
Corp. report.
3. General Process Description
In the effort to produce wrought turbine wheels at low cost, the proposed
manufacturing process utilizes current technology casting methods, conventional
superalloy extrusion, P&WA's patented forging technique (known as GATORIZING),
and typical high volume, automated production.
Melting is carried out in two steps; the first, to alloy master heat ingots,
and the second, to produce remelt ingots. The material is then conditioned to
a superplastic state by extruding the remelt ingots. The wheels are then forged
to final dimensions utilizing the GATORIZING process to maintain the material
in a superplastic condition. The desired mechanical properties of the wheels
are then restored utilizing production heat treat techniques.
The finishing operations, such as cleaning, deburring, blade tipping,
lathe turning the hubs and applying blade coatings, use either current or modi-
fications of current production practices.
4. Cost Summary
The cost summary was developed analyzing all cost elements that would
normally be associated with a manufacturing operation of this type.
The major cost centers within this study were:
1. Materials
2. Manpower
3. Capitalization.
The first cost center considered raw material production, extrusion cans,
forging die material, expendable tools, scrap factors, freight and other pertinent
items to this category.
Manpower was established by analyzing the manufacturing operation for
direct labor, indirect supporting labor, and indirect salaried requirements. A
plant manpower description broken down on a per shift basis is shown in table XII.
Table XIII is a summary of general and administrative costs incurred in the opera-
tion of this facility.
59
-------
Pratt & Whitney Pircraft
The final cost center considered a complete manufacturing facility including
operation equipment, building, grounds, support equipment, etc. A summary of
the major facilities cost is listed in table XIV.
From these three major cost centers overhead rates were established.
The general and administrative fees and profit were computed to establish a
final selling price of $51.77 per turbine wheel. A condensed cost summary is
given in table XV.
Table XII. Manpower Requirement Summary Automotive Turbine
Wheel Manufacturing Facility
Description
Direct Hourly
Indirect Hourly
Indirect Salary
G&A Personnel
Totals
Shift
123
73
12
38
16
139
71
10
16
2 1
99 1
Total
144
22
54
19
239
Table XIII. Summary of General and Administrative
Estimated Cost
Item
A
B
C
D
E
F
Description
Salaries & Benefits (Insurance, Pensions, etc.)
IR&D Monies
Expenses (Insurance, Office Supplies,
Utilities, etc.)
Total
Table XIV. Estimated Cost Summary of
Description
Ingot Production and Extrusion Facilities
Wheel Production Facilities
Tool Build and Maintenance Facility
Equipment Maintenance Facilities
Support Facilities
Building and Grounds
Total
Total
$ 348,000
2,632,000
855,000
$3,835,000
Facilities
Est. Cost Total
$ 4,792,000
13,286,000
1,889,000
940,000
2,177,000
6,845,000
$29,929,000
60
-------
Pratt & Whitney Rircraft
FR-6690
II
Table XV. Cost Summary
(GATORIZED Automotive Turbine Wheel)
I Raw
A.
B.
C.
D.
E.
F.
G.
H.
Material
Metal per pound (as converted ingot)
Die Material (per pound of wheel)
Freight and Expendable Tools (per pound of wheel)
Initial Die Material (3 sets)
Scrap Cost @ 5%
Subtotal
15% Contingency
Cost per pound of wheel
Cost per rotor @ 2. 7 lb/ wheel
$ 5.76
2.29
0.47
0.60
0.30
$ 9.42
$ 1.41
$10.83
$29.25
Labor & Overhead
A. Direct Labor/Wheel
B. Overhead/Wheel
1. Depreciation
2. Wages, fringes and
benefits, Indirect
3. Fringes and benefits for
direct labor
4. Indirect expenses
5. TOTAL
C. Labor Plus Overhead/Wheel
HI Totals
A. Raw Materials/Wheel
B. Labor plus Overhead/Wheel
$3.05
$1.17
$ .52
$2.86-
Overhead
is 508%
Subtotal
C. Plus G&A and Profit
$ 1.50
Total Cost Per Wheel
$ 7.60
$ 9.10
$29.25
9.10
$38.35
13.42
$51.77
61
-------
Pratt & Whitney Rircraft
FR-6690
SECTION III
SUMMARY OF RESULTS
This study provides adequate evidence that volume production of automotive
turbine wheels utilizing the GATORIZING process is within the current state-of-
the-art. Integrally bladed turbine wheels were successfully forged and it was
demonstrated that control of the LCF-stress-rupture life tradeoff can be
achieved with heat treat variations.
The selling price of a mass-produced turbine wheel, based upon a material/
labor ratio of 75%/25% and an overhead of 508% at the projected study level of
one million parts per year could be less than $55. 00. The capitalization of a
complete facility to manufacture 1, 000, 000 turbine wheels per year would cost
$29, 930, 000. The impact of alternate production rates of 100, 000 and 10, 000, 000
rotors per year will be studied in more detail in Phase II of this contract.
62
-------
Pratt & Whitney fiircraft
FR-6690
SECTION IV
RECOMMENDATIONS
Based on the findings of Phase I, it is recommended that Phase II consist
primarily of: a detailed design analysis to produce a turbine wheel design more
compatible with the forging technique and still compatible with the performance
characteristics of the Chrysler Baseline Gas Turbine Engine; and the production
of several integrally-bladed turbine wheels for engine verification and other
qualification testing. After initial wheel forgings of IN 100 are produced, a
second Ni-base alloy, modified IN 792, will be introduced into the program.
The modified IN 792 is reported to have superior hot corrosion resistance and
mechanical properties consistent with the Upgraded Engine Requirements.
63
------- |