Effects of austenite conditioning and hardenability on mechanical properties of B-containing high strength steels

Abstract

Direct quenching(DQ) has become widespread instead of conventional reheat quenching in order to obtain good mechanical balance of high strength steels in addition to productivity, energy savings, alloy savings, and weldability. It is well known that mechanical properties of DQ steel can be changed by varying slab reheating temperature, finish rolling temperature, and cooling rate in addition to alloy composition. The effect of pancaking by controlled rolling at low temperatures on mechanical properties was investigated. The effect of pancaking depends on hardenability determined by alloy contents. Pancaking increased strength or toughness when alloy-determined hardenability is high. But pancaking decreased strength when alloy-determined hardenablity is low. © 2000 ISIJ.