Question

If you had tensile tested a specimen to about half way between where it yielded and when you expected the ultimate stress to be reached, then stopped the test, removed the sample, and later decided to test it again, what would the yield strength be during the second test?

Answer 1

After crossing the yield point, the material will not regain its initial position completely, because it has now entered to the plastic deformation region where there is the partial recovery of strain after removing stress, this happens because the material has now suffered through breking of bonds between inside material.

in this case, if we now loaded the test specimen its yield strength will increase due to the strain hardening concept. where there are lots of deformation present inside material which creates strain field in the material, so we have to apply more force to overcome such strain field generated, and ultimately the result will be increased in yield strength.

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