# Effect of Strain Hardening on Yield Strength

1. Feb 14, 2012

1. The problem statement, all variables and given/known data

The strain hardening behavior of an annealed, low‐carbon steel is σ = 100,000ε0.2

If a bar of this material is initially cold worked 20%, followed by additional cold work of 30%, determine the probable yield strength of the final bar.

2. Relevant equations

σ=κεη

At ultimate strength η=ε (Dont think this is applicable here though?)

3. The attempt at a solution

σ=100000(0.5)0.2 = 87055 psi

Im not sure what to do with the percentages of cold work given. Can I use it as strain to find the yield strength at 50% cold work? Does the value of η need to be used as % cold work, or does σ = 100,000 ε0.2 represent a funtion of the yield strength?

Another attempt
I don't think that the % cold work is additive, so am I wrong to assume 50% cold work has taken place?

If 30% CW is with respect to the original 20%, then

A1/A0 = 0.2
A2/A1 = 0.3

A2/A0 = 0.26

so would σ=100000(.26)0.2 be correct?