Thanks for your comment. It is about the pipe line and not computer. Three tensile samples have been tested. The values for elongation, yield strength at 0,5% and ultimate tensile strength are all acceptable but the young's modulus measured (calculated) by automatic system was 130 to 165 GPa. are the values valid or other samples have to be re-tested regarding the low values for young's modulus?
The yield strength is supposed to be tested at .2% offset, in my experience.
Where did you get .5% offset? That is probably the issue.
milo
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The yield strength could be measured at 0,2% offset or for elongation of 0,5% and they are called Rp 0,2% and Rt 0,5% (for API and DNV the 2nd parameter will be checked).
The Young's modulus reported in texts is actually an average value of the actual modulus and depends upon the crystallographic orientation. It is not ucommon to see a fairly large range of values for this factor. Automated tensile machines use an algorythym to measure the value of the modulus. It is typically given a starting and ending value and then determines the slope of the curve between these points. If your curve is not appropriate due to slippage of the grippers or the extensometer, then your value of Young's modulus will be off.
The yield strength can be measured in two ways per ASTM standards. The more traditional is preferred for use in testing steels, where the elastic limit is easily determined, is the 0.2% offset method. The other acceptable method is a total elongation of 0.5%. This method is applied to soft materials like aluminum that do not exhibit a clear elastic limit.
Young's Modulus
Re: Young's Modulus
