The effect of Austenitizing temperature and time on the Austenite grain size, microstructure and hardness of 1045 steel
Grain growth during heat treatment in medium carbon is object of interest because it has a significant effect on mechanical properties such as strength and ductility. In this work, the effect of Austenizing temperatures and holding times on Austenite grain size, microstructure and hardness was experimentally investigated. Samples of 1045 steel were Austenized at 900 °C,1000 °C and 1100 °C and held for 1, 4 and 9 hours. After Austenizing, samples were cooled down in the furnace to 850 °C followed by quenching in agitated water. Rockwell and Vickers hardness measurements were taken to each sample. The microstructures of all heat-treated samples was investigated with optical microscopy. Measurements for the Austenite grain size were performed according to ASTM E112-10. It was found that the Austenite average grain size increased with an increase in Austenizing temperature and time. It was also found that the as-quenched hardness decreased with increasing grain size.