Austenite grain coarsening behavior in V-Ti microalloyed steels during reheating process

High strength microalloyed steels have been widely used for structural applications. For applications with restrict toughness requirements, it is essential to control the former austenite grain size. This paper investigated the austenite grain coarsening behavior in low carbon alloyed steels with vanadium and titanium additions during the reheating process in a wide temperature range of 900°C to 1400°C. Below a critical temperature, the V and Ti addition is effective impeding austenite grain growth leading to a fine and uniform grain size. For an intermediate temperature regime, abnormal grain growth was triggered by the dissolution of V and Ti precipitates. Above the dissolution temperature of V and Ti precipitates, normal grain growth resumed. The austenite grain growth in the sample with Ti addition is much faster than that in the sample containing V after the abnormal grain growth. These findings can guide the set-up of industrial hot strip mill furnace reheating temperature before rolling.