Quantifying Amount of Cold Working through Change in Tensile Strength?

[g_hal77]

Hi, I have a project I'm working on that requires an analysis of 1018 steel samples.

The samples given were strain hardened (Ultimate Tensile strength (TS) of ~90ksi as opposed to the published data of ~64ksi), and I have to figure out the percentage of cold working (CW) that was done on the parts.
The textbooks, and other sources I've visited, didn't give too much detail other than the normal % CW = area reduction, which was of no use for this particular project. However, I did come across a chart that gives some insight onto how CW effects the TS, which I've extrapolated to determine that the samples are roughly 36% CW.

I'm just wondering if there's an analytical way (and if there's a source) of determining the %CW from %change in TS?

Thank you.

 

[EdStainless]

No, only empirical correlations for this.
What are you missing, area reduction is cold work percentage.
As you can see from your figure the curves all flatten out after about 20%, so anything beyond that is a pure guess.
You also don't know what the properties were before it was worked, so you really don't know how much stronger it is. In the wire business they do this a lot, heat treat wire and then re-draw it afterward, you can get interesting properties.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

Using graphs or graph for steel to establish an approximation regarding percent cold work on UTS increase is acceptable.