Download presentation

Presentation is loading. Please wait.

Published byHannah Flanagan Modified over 2 years ago

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

2
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
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 todays testing machines, and improve the reproducibility of tests.

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

5
5 Existing Speed of Testing When Determining Yield PropertiesUnless 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 Speed of Testing When Determining Yield PropertiesUnless 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%. Tinius Olsen - Changes to ASTM E8

6
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
7 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 10 6 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) Tinius Olsen -6 Pre-Yield Test Speeds

8
8 Sample ID Control TypeCTRL/SPDUltimate (ksi) 0.2 Offset (sec)Stress Rate Strain Rate Position Rate 1 Screw 5 kN1P Screw 50 kN1P Super L 300 kN1P MHT 150 kN1P Screw 5 kN2P Screw 50 kN2P Super L 300 kN2P MHT 150 kN2P Screw 5 kN3e Screw 50 kN3e Super L 300 kN3e MHT 150 kN3e Screw 5 kN4P Screw 50 kN4P Super L 300 kN4P MHT 150 kN4P Screw 5 kN5P Screw 50 kN5P Super L 300 kN5P MHT 150 kN5P Screw 5 kN6e Screw 50 kN6e Super L 300 kN6e MHT 150 kN6e

9
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
10 Tinius Olsen - Stress Rate vs. Strain Rate

11
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
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
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
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.

Similar presentations

© 2016 SlidePlayer.com Inc.

All rights reserved.

Ads by Google