1. Workshop on the Speed of Testing May 21, 2007 Norfolk, VA
ASTM E28.04 Workshop
Workshop on the
Speed of Testing
May 21, Norfolk, VA

2. Schedule of Presenters
Earl Ruth, Tinius Olsen
Jim Hartman, Honeywell
Carpenter Representative
Byron Skillings, Ladish
Len Manning, Dofasco
Sue Morford, Howmet
Rich Brazill, Alcoa

3. ASTM E28.04 Workshop Ballot Item:
Revise ASTM E 8 Standard Test Methods for Tension Testing of Metallic Materials by replacing existing section 7.6
Rationale:
For years the limitation on yield speed in E 8 has been in terms of rate of stressing. The wide range of acceptable test speeds currently in E 8 is another source of non reproducibility. This change to E 8 attempts to simplify the speed of testing section, make it more clear as to how to control today’s testing machines, and improve the reproducibility of tests.

4. Standard E8 Speed of Testing Section
ASTM E28.04 Workshop
Earl Ruth, Tinius Olsen
Proposed Change to
Standard E8 Speed of Testing Section

5. Tinius Olsen - Changes to ASTM E8
Existing
7.6.3 Speed of Testing When Determining Yield Properties—Unless otherwise specified, any convenient speed of testing may be used up to one half the specified yield strength or up to one quarter the specified tensile strength, whichever is smaller. The speed above this point shall be within the limits specified. If different speed limitations are required for use in determining yield strength, yield point elongation, tensile strength, elongation, and reduction of area, they should be stated in the product specifications. In the absence of any specified limitations on speed of testing, the following general rules shall apply:
 The speed of testing shall be such that the forces and strains used in obtaining the test results are accurately indicated.
 When performing a test to determine yield properties, the rate of stress application shall be between 1.15 and 11.5 MPa/s
( and psi/min).
Proposed
7.6.3 Speed of Testing When Determining Yield Properties—Unless otherwise specified, the following speeds shall apply. Any convenient speed of testing may be used up to one half the specified yield strength or up to one quarter of the specified tensile strength, whichever is smaller. The speed above this point shall be within the limits specified. If different speed limitations are required for use in determining yield strength, yield point elongation, tensile strength, elongation, and reduction of area, they should be stated in the product specifications. In the absence of any specified limitations on speed of testing, the following rules shall apply:
 The speed of testing shall be such that the forces and strains used in obtaining the test results are accurately indicated.
 When performing a test to determine yield properties, the strain rate or the crosshead speed shall be mm/mm/s (0.015 inches/inch/min) +/- 20%.

6. Tinius Olsen - Test Matrix
1 sheet steel specimen tested on
4 different testing machines at
6 different speed control settings
4 Machines
5kN single screw machine w/ wedge grips
50 kN twin screw machine w/ wedge grips
300 kN Hydraulic machine w/ wedge grips
150 kN twin screw machine w/ hydraulic grips

7. Tinius Olsen -6 Pre-Yield Test Speeds
1 – Existing E 8 Upper Limit using a position rate to achieve 100,000 psi/min
(Position rate required varied with machine stiffness from to inches/min)
2 – Existing E 8 Lower Limit using a position rate to achieve 10,000 psi/min
(Position rate required varied with machine stiffness from to inches/min)
3 – Existing E 8 Upper Limit using a strain rate of /min
(Strain Rate corresponding to a Stress Rate of 100,000 psi per minute for steel with a Modulus of Elasticity of 30X 106 psi)
4 – Existing A 370 Upper Limit using a position rate of inches/min
(ASTM A370 rate 1/16 of an inch per inch of reduced section per minute. Position rate of in/min = /min X 2.8 inches)
5 – Proposed new rate using position control
(Position rate of in/min = /min X 2.8 inches)
6 - Proposed new rate using strain rate control
(0.015 /min)

8. Sample ID
Control
Type
CTRL/SPD
Ultimate (ksi)
.2 (ksi)
0.2 Offset
(sec)
Stress Rate
Strain Rate
Position
Rate
1 Screw 5 kN 1
P 0.217
42.8 24
14.42
98000
0.0532
0.217
2 Screw 50 kN
P 0.140
42.2
23.3
27.3
107000
0.0399
0.1398
Super L 300 kN
P 0.16
42.7
23.4 21
109600
0.0431
0.1589
MHT 150 kN
P 0.039
42.1
22.8
23.9
96500
0.0388 2
P 0.025
42.5
22.3
117.9
10950
0.0251 P
40.8
21.2
227
9390
P 0.017
43.2
22.5
205
9940
P 0.004
41.9
21.6
222
12460 3 e 42
21.9
51.6
61600
43.3
53.6
143600
42.6
22.2
55.4
99100
50.9
66800
0.0097 4
P 0.175
42.9
23.7
19.42
77200
0.0445
0.1749
42.4
23.5
120500
0.0485
0.1751
19.11
121000
0.0475
0.1752
41.5
23.1
5.45
554000
0.0548
0.1772 5
P 0.042
42.3
69.6
18740
0.0421
43.1
22.9
81.7
28800
0.042
43.4 23
83.4
26000
41.8
22.6
106800
0.0415 6
e 0.015
13.55
162000
0.0168
0.0576
13.09
435000
0.0534
22.7
15.53
584000
0.0538
12.63
317000
0.0499

9. Tinius Olsen -Test Notes
The Stress Rate was determined in the elastic portion of the curve.
The strain and position rates were determined at the 0.2% Offset

10. Tinius Olsen - Stress Rate vs. Strain Rate

11. Tinius Olsen - Strain Rate vs. Test Type
1 – Existing E 8 Upper Limit using a position rate to achieve 100,000 psi/min
2 – Existing E 8 Lower Limit using a position rate to achieve 10,000 psi/min
3 – Existing E 8 Upper Limit using a strain rate of /min
4 – Existing A 370 Upper Limit using a position rate of inches/min
5 – Proposed new rate using position control at inches/min
6 - Proposed new rate using strain rate control at /min

12. Tinius Olsen - Effect on Yield Strength
1 – Existing E 8 Upper Limit using a position rate to achieve 100,000 psi/min
2 – Existing E 8 Lower Limit using a position rate to achieve 10,000 psi/min
3 – Existing E 8 Upper Limit using a strain rate of /min
4 – Existing A 370 Upper Limit using a position rate of inches/min
5 – Proposed new rate using position control at inches/min
6 - Proposed new rate using strain rate control at /min

13. Tinius Olsen – Production Considerations
1 – Existing E 8 Upper Limit using a position rate to achieve 100,000 psi/min
2 – Existing E 8 Lower Limit using a position rate to achieve 10,000 psi/min
3 – Existing E 8 Upper Limit using a strain rate of /min
4 – Existing A 370 Upper Limit using a position rate of inches/min
5 – Proposed new rate using position control at inches/min
6 - Proposed new rate using strain rate control at /min

14. Tinius Olsen - Conclusions
We should be able to reduce interlaboratory scatter by specifying the default ASTM E 8 speed in terms of Strain Rate instead of Stress Rate.
We can get comparable results by controlling the test in position rate or strain rate.
ASTM A370 speed of 1/16 of an inch per inch of reduced section is too fast for some machines.
Controlling position rate to achieve a /min strain rate (popular in many aerospace specifications) makes for a very long test time.
A strain rate of /min which allows both position control and strain rate control is reasonable because it can be achieved on machines without closed-loop strain rate control, there is good agreement between the position rate and the strain rate, and production testing is not harshly impacted.