A study on the influence of austenitization temperature on the mechanical, thermal, and structural properties of 51CrV4 steel

Abstract

In this paper, emphasis is placed on studying the influence of quenching temperature (austenitization) on the mechanical, thermal, and structural properties of 51CrV4 chrome-vanadium steel. Generally, 51CrV4 steel is often categorized as spring steel; however, in recent years, it has been increasingly used in the production of different types of tools, so it can also be categorized as tool steel. To obtain better-quality tools, this steel is subjected to various types of heat treatment, which usually include normalizing, quenching, and medium-temperature tempering. In this investigation, the samples were austenitized at different temperatures, ranging from 780 °C to 920 °C, and subsequently quenched in oil. After quenching, the samples were tempered at a temperature of 350 °C for 2 hours. The goal was to monitor the influence of austenitizing temperature on hardness, thermal conductivity, and microstructure by subjecting the samples to characterization after the applied heat treatment. The results showed that with an increase in the austenitization temperature, the hardness values gradually increase, reach a maximum, and then decrease, regardless of the type of heat treatment. On the other hand, thermal conductivity values show the opposite trend. After the characterization, it was concluded that by choosing a low austenitization temperature (770 °C), samples would be cooled from the two-phase region (a+g), which produces lower hardness values. However, choosing a high austenitization temperature (920 °C) would lead to austenite grain growth and surface decarburization, again lowering hardness values.