Discontinuous yielding induced by the addition of nickel to interstitial-free steel

Interstitial-free steels containing 1–3% Ni were tensile tested. A clear yield point and yield point elongation were observed in each steel, even though they contained no solute carbon or nitrogen in the ferrite matrix. The mechanism could be explained by grain refinement strengthening enhanced by the addition of Ni, which is derived from the increase in Hall–Petch coefficient caused by grain boundary segregation.