Rate of stress for Yield detremination of HR M.S.

[mohanmohit]

We find that while testing samples of hot rolled mild steel sheets the value of yield strength is dependent on the rate of stress applied. We have conducted trials in the range of 6 to 30 N/mm2 sec(-1) on samples of cross-sectional area of about 75 mm2 (3mm thick). The yield strength values of samples drawn from the same coil, varies in the range of about 210 to 260 N/mm2 and is inversely propotional to rate of stress applied. All tips on the correct rate of stressing for yield strength determination shall be appriciated.

 

[Carburize]

ASTM E 8 "Tension Testing of Metallic Material"
Section 7.2.7.1 "During the conduct of the test to determine yield strength or yield point the rate of stress application shall not exceed 100,000 psi/min"

 

[TVP]

For those using SI units, ASTM E 8M specifies a rate of 1.15-11.5 MPa/s when determining yield properties. I strongly recommend you obtain a copy of ASTM E 8 or E 8M. The latest revision level is 2004 and you can purchase an electronic copy from either Global Engineering Documents or directly from ASTM:

http://global.ihs.com

http://www.astm.org