"Alan Baker" wrote in message
...
In article ,
"Dick" wrote:

okay, got pounds per Square Inch and elongation differences and the
failure
sequence in my noodle.

For simplicity, let's use 120,000 and 80,000 psi numbers.

So if the 120,000 # piece is .667 square inches
and the 80,000# piece is 1.0 square inch,,,are the elongations the
same???

Thanks, Dick

Ummm...

Think about it for a moment. To be different strengths, the two steels
must differ in chemical composition, right? Do you think that that
wouldn't also lead to different elongation under the same load?

--
Alan Baker

No it wouldn't lead to a different elongation under the same load. The
alloy materials are such a small percentage of the metal that generally the
bulk metal overrides and different alloys have, for all practical purposes,
the same youngs modulus. In this case, both alloys were 4130 so there isn't
even a difference in the alloy. If they have the same cross section area
and the same load they will have the same elongation. The heat treatment
doesn't change the slope of the stress strain curve. It merely moves the
yield point closer to the ultimate rupture point.

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