Influence of heat treatment parameters on the microstructure and mechanical properties of boron-alloyed steels

Abstract

This paper focuses on the effect of heat treatment parameters on the microstructure and mechanical properties of quenchable 22MnB5 steel sheets with an Al-Si layer. Heat treatment parameters such as temperature and cooling rate from the solid solution temperature were investigated. For this purpose, the heat treatment was conducted within the temperature range from 700 degrees C to 950 degrees C, and two different cooling techniques were applied to the specimens: air cooling and water quenching. The microstructures of the specimens were then studied using optical microscopy. Additionally, tensile and hardness tests were performed at room temperature. The results show that the effects of heat treatment were obviously influenced by the original microstructure of the 22MnB5 sheet. With the increase of heat treatment temperature, the martensite proportions increased, and the hardness and tensile strength also increased, especially after the 850 degrees C quenching. Moreover, quenching after 900 degrees C has been reached was determined to be an ideal process for hot forming 22MnB5 steel sheets.