Growth behavior of ultrafine austenite grains in microalloyed steel

Ultrafine austenite grains (UFAGs) with size of 1-5 μm were prepared through repetitive treatment, four times, of rapid heating and quenching, and the growth behaviors of these UFAGs during both the reheating and cooling stages were investigated. The results indicated that UFAGs without pinning particles appeared with significant coarsening when the reheating temperature reached 1000 °C. Although coarsening still occurred in the cooling stage, the growth was obscured during the isothermal holding process at temperatures between 900 °C and Ar3.