Effect of different thermal treatment temperatures on dimensional stability and mechanical properties of M50 steel

Abstract

By using field-emission scanning electron microscopy, X-ray diffraction, impact and tensile-property tests, the effect of thermal treatment temperatures in stabilization treatment on the microstructure, dimensional stability and mechanical properties of M50 bearing steel was studied. Results show that the size of M50 steel decreases due to carbide precipitation at 400 °C, 420 °C, 440 °C and 480 °C, and increases due to martensite transformation at 460 °C. In the thermal treatment temperature range of 400–480 °C, the amount of secondary carbide precipitation in M50 steel increases first and then decreases with the increase of thermal treatment temperature, and the amount of carbide precipitation in the steel reaches the maximum at 460 °C. During the thermal treatment temperature range of 400–460 °C, the residual austenite gradually decomposes and decreases in quantity. However, at 480 °C, the residual austenite has relatively higher carbon content to make it more stable and less likely to decompose. At the same time, the tensile properties are slightly improved, the impact toughness decreases at 460 °C and improved under other conditions.