Flow stress and microstructure of the cold-rolled IF-steel

The dependence of flow stress (measured by tensile experiment) on the microstructure is discussed based on the Hall–Petch (H–P) relationship in interstitial-free steel cold-rolled to different reductions of 10–90%. The microstructure was characterized by TEM with semi-automated Kikuchi pattern analysis method. The significant effect of misorientation on the flow stress was found experimentally. The linear dependence of the slope of H–P relation on the average sub(grain) boundary misorientation is derived based on the work hardening dislocation mechanism. The modified H–P relation, i.e. σf=σ0+KH((θav/15)/dsubgrain)0.5 is proposed to describe the effect of average misorientation on flow stress.