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. sigma(f) = sigma(0) + K-H((theta(av)/15)/d(subgrain))(0.5) is proposed to describe the effect of average misorientation on flow stress. (C) 2002 Elsevier Science B.V. All rights reserved.