Alcoa Power and Propulsion

Effect of Testing Speed on Several Alloys

Susan MorfordAlcoa Howmet Research Center

susan.morford@alcoa.com231.894.7704

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Overview of Methodology and Analysis Approach

• Design of Experiment– Alloys– Strain rate / Crosshead speeds– Three specimens for each test condition

• Analysis methodology– Graphical results

• Ultimate Strength (KSI)• 0.2% Offset Yield Strength (KSI)• Percent Elongation (%)• Reduction of Area (%)

– ANOVA to evaluate statistical significance of results• Summary of results

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Design of Experiment

• Test Conditions (Full-factorial – all combinations were tested)– Strain rates

• A – 0.005 inch/inch/minute• B – 0.015 inch/inch/minute• C – 0.050 inch/inch/minute

– Crosshead rates• 1 – 0.05 inch/minute• 2 – 0.45 inch/minute

– Strain Rate / Crosshead rates tested• A1, A2, B1, B2, C1, C2

– Strain rate measured with an extensometer directly attached to the reduced section of specimen; removed at 0.4% offset

Alcoa Power and PropulsionAlcoa Power and Propulsion

Design of Experiment

• Equipment / Instrumentation– Tinius Olsen 60,000

pound load frame with Test Navigator version 7 software and 398 controller

– Extensometer – 1 inch gauge length attached to reduced section of specimen

Alcoa Power and PropulsionAlcoa Power and Propulsion

Design of Experiment

Alloy Base Alloy Alloy Type Specimen Configuration

17-4PH Iron Cast Machined

CMSX-4 ® Nickel Cast Machined

Alloy 718 Nickel/Iron Cast Cast to Size

Alloy 718 Nickel/Iron Wrought Machined

Stellite 31® Cobalt Cast Cast to Size

Ti-6-4 Titanium Cast Cast to Size

Alcoa Power and PropulsionAlcoa Power and Propulsion

Analysis Methodology - Graphical

17-4PH - Ultimate Tensile Strength (UTS)

166

168

170

172

174

176

A1 A2 B1 B2 C1 C2

Strain Rate / Crosshead Speed

KSI

Center Line: Mean of three (3) Specimens Spread: ± 1 Standard Deviation

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Analysis Methodology - ANOVA

• Summary of ANOVA table obtained from SAS software

• Interactions identified as significant are highlighted

Factor Degree of Freedom Percentiles of theF distribution

F* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.60 0.60 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 10.89 10.89 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.69 0.69 ≤ 3.89 Not Significant

Alcoa Power and PropulsionAlcoa Power and Propulsion

Ultimate Strength – 17-4PH

17-4PH - Ultimate Tensile Strength (UTS)

166

168

170

172

174

176

A1 A2 B1 B2 C1 C2

Strain Rate / Crosshead Speed

KS

I

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.60 0.60 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 10.89 10.89 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.69 0.69 ≤ 3.89 Not Significant

Alcoa Power and PropulsionAlcoa Power and Propulsion

0.2% Offset Yield Strength – 17-4PH

17-4PH - 0.2% Offset Yield Strength

125

127

129

131

133

135

A1 A2 B1 B2 C1 C2

Strain Rate / Crosshead Speed

KS

I

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 22.34 22.34 > 3.89 Significant

Crosshead 1 F(0.95,1,12) = 4.75 3.06 3.06 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 2.37 2.37≤ 3.89 Not Significant

Alcoa Power and PropulsionAlcoa Power and Propulsion

Percent Elongation – 17-4PH

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.24 0.24 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 4.57 4.57 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 1.68 1.68 ≤ 3.89 Not Significant

17-4PH - Elongation

11.5

12.0

12.5

13.0

A1 A2 B1 B2 C1 C2

Strain Rate / Crosshead Speed

Pe

rce

nt

Alcoa Power and PropulsionAlcoa Power and Propulsion

Percent Reduction of Area – 17-4PH

17-4PH - Reduction of Area

60

61

62

63

64

65

A1 A2 B1 B2 C1 C2

Strain Rate / Crosshead Speed

Pe

rce

nt

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.47 0.47 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 1.62 1.62 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 5.09 5.09 > 3.89 Significant

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Ultimate Strength – CMSX-4 ®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.10 0.10 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.00 0.00 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.06 0.06 ≤ 3.89 Not Significant

CMSX-4® - UTS

125

135

145

155

165

175

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

0.2% Offset Yield Strength – CMSX-4 ®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.03 0.03 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.47 0.47 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.16 0..16 ≤ 3.89 Not Significant

CMSX-4® - 0.2% Yield Strength

120

125

130

135

140

145

150

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

Elongation – CMSX-4 ®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.27 0.27 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 3.12 3.12 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.63 0.63 ≤ 3.89 Not Significant

CMSX-4® - Elongation

5

10

15

20

25

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Reduction of Area – CMSX-4 ®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.61 0.61≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.12 0.12 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 5.0 5.0 > 3.89 Significant

CMSX-4® - Reduction of Area

5

10

15

20

25

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Ultimate Strength – Cast Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.26 0.26 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 10.47 10.47 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.37 0.37 ≤ 3.89 Not Significant

Cast Alloy 718 - UTS

150

155

160

165

170

175

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

0.2% Offset Yield Strength – Cast Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 1.41 0.26 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.00 0.00 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 1.02 0.37 ≤ 3.89 Not Significant

Cast Alloy 718 - 0.2% Yield Strength

138

140

142

144

146

148

150

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

Elongation – Cast Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.89 0.89 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 1.92 1.92 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.58 0.58 ≤ 3.89 Not Significant

Cast Alloy 718 - Elongation

0

2

4

6

8

10

12

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Reduction of Area – Cast Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.84 0.84 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 3.17 3.17 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.35 0.35 ≤ 3.89 Not Significant

Cast Alloy 718 - Reduction of Area

0

5

10

15

20

25

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Ultimate Strength – Wrought Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.78 0.78 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.00 0.00 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 3.21 3.21 ≤ 3.89 Not Significant

Wrought Alloy 718 - UTS

203204205206207208209210211

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

0.2% Offset Yield Strength – Wrought Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 3.64 3.64 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.11 0.11 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 2.89 2.89 ≤ 3.89 Not Significant

Wrought Alloy 718 - 0.2% Yield Strength

168

170

172

174

176

178

180

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

Elongation – Wrought Alloy 718

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.16 0.16 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 373.48 373.48 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 1.11 1.11 ≤ 3.89 Not Significant

Wrought Alloy 718 - Elongation

16.0

17.0

18.0

19.0

20.0

21.0

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Reduction of Area – Wrought Alloy 718

Factor Degree of FreedomPercentiles of theF distribution

F* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.16 0.16 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 13.21 13.21 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.26 0.26 ≤ 3.89 Not Significant

Wrought Alloy 718 - Reduction of Area

38.5

39.0

39.5

40.0

40.5

41.0

41.5

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Ultimate Strength – Stellite 31®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.03 0.03 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 3.58 3.58 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 1.25 1.25 ≤ 3.89 Not Significant

Stellite 31® - UTS

110

115

120

125

130

135

140

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

0.2% Offset Yield Strength – Stellite 31®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 2.79 2.79 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.07 0.07 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.52 0.52 ≤ 3.89 Not Significant

Stellite 31® - 0.2% Yield Strengh

75

80

85

90

95

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

Elongation – Stellite 31®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.02 0.02 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.37 0.37 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.82 0.82 ≤ 3.89 Not Significant

Stellite 31® - Elongation

4

5

6

7

8

9

10

11

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Reduction of Area – Stellite 31®

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.51 0.51 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 2.53 2.53 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.06 0.06 ≤ 3.89 Not Significant

Stellite 31® - Reduction of Area

4

6

8

10

12

14

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Alcoa Power and PropulsionAlcoa Power and Propulsion

Ultimate Strength – Ti-6-4

Ti-6-4 - UTS

134

136

138

140

142

144

146

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.30 0.30 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 9.78 9.78 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.59 0.59 ≤ 3.89 Not Significant

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0.2% Offset Yield Strength – Ti-6-4

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 13.20 13.20 > 3.89 Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.03 0.03 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 0.67 0.67 ≤ 3.89 Not Significant

Ti-6-4 - 0.2% Yield Strength

120

122

124

126

128

130

132

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

KS

I

Alcoa Power and PropulsionAlcoa Power and Propulsion

Elongation – Ti-6-4

Ti-6-4 - Elongation

6

8

10

12

14

16

18

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 0.00 0.00 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 0.61 0.61 ≤ 4.75 Not Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 2.68 2.68 ≤ 3.89 Not Significant

Alcoa Power and PropulsionAlcoa Power and Propulsion

Reduction of Area – Ti-6-4

Ti-6-4 - Reduction of Area

6

11

16

21

26

31

36

A1 A2 B1 B2 C1 C2

Strain Rate / Cross Head Speed

Perc

en

t

Factor Degree of FreedomPercentiles of the

F distributionF* Conclusion Result

Strain 2 F(0.95,2,12) = 3.89 2.24 2.24 ≤ 3.89 Not Significant

Crosshead 1 F(0.95,1,12) = 4.75 15.0 15.0 > 4.75 Significant

Strain * Crosshead 2 F(0.95,2,12) = 3.89 2.00 2.00 ≤ 3.89 Not Significant

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ANOVA Summary for Significant Relationships

Strain Crosshead Strain*Crosshead

17-4PH 0.2% YS UTS ROA

CMSX-4® ROA

Alloy 718 - Cast UTS

Alloy 718 - Wrought% Elongation, ROA

Stellite 31 ®

Ti-6-4 0.2% YS UTS, ROA

Alcoa Power and PropulsionAlcoa Power and Propulsion

Variation in Time to Fracture

Time to Fracture

012345678

A1 A2 B1 B2 C1 C2

Strain Rate / Crosshead Speed

Tim

e in

Min

ute

s

17-4PH

CMSX-4®

Alloy 718 - Cast

Alloy 718 - Wrought

Stellite 31®

Ti-6-4

Alcoa Power and PropulsionAlcoa Power and Propulsion

Conclusions

• Five of the six alloys evaluated at room temperature had at least one tensile property that is dependent on the speed of testing

• ASTM E21-05 Standard Test Methods for Elevated Tension Test of Metallic Materials– Section 9.6 addresses “Strain Measurement and Strain Rate”

• Tensile properties of materials at elevated temperature are affected by the rate of deformation

• A similar statement should be included in ASTM E8

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Recommendations

• Allow use of ASTM E-21-05 9.6.1.1 as an option or as a recommendation for room temperature testing– “During yield strength determination, maintain the stain rate in

the uniform section of the specimen at 0.005 ± 0.002 /min. After yield strength determination, increase the crosshead motion to 0.05 ± 0.01 times the adjusted length of the reduced section of the specimen per minute.”

• Add an Appendix to ASTM E8 and E21 addressing speed of testing