The influence of reheating temperature and direct-cooling rate after forging on microstructure and mechanical properties of V-microalloyed steel 38MnSiVS5

Abstract

Wiht the aim of replacing quenched and tempered forging parts and reducing by this way costly and time consuming operations; an industrial forging procedure was developed to evaluate the influence of thermo-mechanical processing parameters on the microstructure and mechanical properties of vanadium microalloyed steel. In order to study the influence of reheating temperature, after determining the dissolving temperature of vanadium carbonitrides precipitates, samples were heating in temperature rang 1 000 to 1 200°C. After austenitization at 1 100°C, the microalloyed steel billets were forged in a hydraulic press and then cooled with different cooling rates. The metallography and mechanical testing results indicated that by increasing the reheating temperature, the strength and toughness of V-microalloyed steel have not change significantly and so the temperature of 1 200°C was selected for forging. By increasing cooling rate, both strength and toughness improve. © 2006 ISIJ.