Lower hardness but same YS
Lower hardness but same YS
(OP)
Can someone explain me the possible reasons why after homogenization of an austenitic steel, I obtain smaller hardness (about 100HV smaller) but the same yield strength? For me it's not logical... Lower hardness is probably conencted with recrystallization and grain growth, but shouldn't it be connected with lower YS?





RE: Lower hardness but same YS
RE: Lower hardness but same YS
If not in this case, what can be a general explanation of this phenomenon?
RE: Lower hardness but same YS
Of course they don't agree, they are in very different conditions.
Strain hardening, especially if it was from warm work can result in interesting (seemingly inconsistent) properties.
Now if you have multiple annealed samples that differ from each other that would be different.
I have generated many samples of the same SS alloy that have
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Plymouth Tube
RE: Lower hardness but same YS
RE: Lower hardness but same YS
RE: Lower hardness but same YS
RE: Lower hardness but same YS
In wire it is common to add just a little more work in the form of flexing the wire by running it looped around a roller.
The slight bending back and forth causes redistribution of residual stresses and can greatly lower the measured yield strength.
The should be no correlation between the properties of cold or warm worked part and the same material after annealing other than the reduction of UTS. Everything else depends on conditions.
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Plymouth Tube
RE: Lower hardness but same YS
The twin spacing does not affect the proof stress because the stacking fault energy, which controls the work-hardening rate, has little or no effect at the
low strains at which the proof stress is measured. The twin spacing is much more important than the grain size in controlling the tensile strength because the effect of stacking fault energy on the work-hardening rate, and hence on the tensile strength, is quite significant. However, in high stacking fault energy austenites, in which there are relatively few twins, the tensile strength will depend on the grain size, following a Hall-Petch type of relationship.
See my previous post regarding how hardness correlates better to ultimate tensile strength. You could have more closely spaced twins in the higher hardness/UTS material and more widely spaced twins in the low hardness/UTS material. Just one possibility for your case.