Prediction of the work-hardening exponent for ultrafine-grained steels

The work-hardening exponent is used to quantify the work-hardening of ultrafine-grained steels. The exponent for the types of steel with the carbon content below 0.22 wt% is proposed to be directly predicted by either yield strength or ferrite grain size. The exponentʹs value linearly decreases with increasing yield strength or D−1/2 (where D is the ferrite grain size), and becomes zero when yield strength is higher than 620 MPa (or D is less than 1 μm).