converting yield strength

[MATE45]

Hi all,

I have an Material Test Report for a material that has a Y.S of 30000 psi @ .2% offset. Heres the question, the spec the previous guy wrote say 35000 psi @ 1% offset. Is there a conversion for this to compare apples to apples.

 

[metengr]

MATE45;
No. There is no direct conversion to equate % offset with YS. You can attempt to calculate what the expected YS or flow stress would be for this material based on using a strain hardening equation. However, I would not risk acceptance or rejection of material for an application using the above equation.

Go back and re-review the specification. I would suspect that there was a typo and the offset was probably at 0.1% versus 1% for reporting yield stregnth from tension tests for MTR's.

 

[CoryPad]

No, there is no conversion.

Can you get a stress strain curve?

Or, can you get the strain hardening exponent? Then you could calculate stress at 1% strain.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MATE45]

hey thanks guys for the quick response. Ill have to go back to purchasing and request some different information from the mill.

 

[TubeSled]

Also, if the mill is pretty current in their testing equipment, they may be able to go back into their system and change the offset of what the test was performed at, but caution: it may not be able give you results on this extreme difference.

Also, 1% offset does not make sense. It is not a common practice for testing of metals.

 

[EdStainless]

It may be 0.1% offset.
Take a second look.

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[MATE45]

it definitely says 1.0 percent on the spec sheet, however in ASTM 511 the material would fall under all austenic stainless steels, and says yield of 30000 psi, no reference with regards to what method. Im leaning more towards 0.2% offset and going with what the STD says.