Prediction of hardness distribution in steel heat affected zone

Abstract

A practical method to predict the heat affected zone (HAZ) hardness distribution was studied by considering the effects of prior austenite grain size and tempering on hardenability. For conventionally rolled and thermomechanically processed steels (400–490 MPa grade steels), the hardness distribution between the fusion and Ac₃ lines can be fairly well predicted by introducing the effect of grain size into the maximum HAZ hardness prediction method of Yurioka et al. For a quenched and tempered steel with boron addition (780 MPa grade steel), as the maximum hardness is obtained a small distance away from the fusion line, the present method cannot adequately predict its HAZ hardness. Hardness at the Ac₁ line for thermomechanically processed and quenched and tempered steels can be predicted with the present method, in which the parameter introduced by Inoue has been used to estimate the effect of tempering.