Effect of Quenching and Tempering Treatment on Microstructure and Mechanical Properties of CSS-42L Bearing Steel

By means of microstructure observation, phase analysis and mechanical property tests, the effect of the quenching and tempering treatment on microstructure and mechanical properties of CSS-42L bearing steel were studied. Results show that with the increase in solution temperature, the content of undissolved carbides decreased, and the grain size increased. However, when the solution temperature was higher than 1080°C, the content of undissolved carbides did not change obviously, but the grain size increased sharply. Therefore, 1080°C was chosen as the optimal solid solution temperature. As the tempering temperature increased, the hardness, the yield strength and the tensile strength of the steel increased, which reached the maximum values of 44.7 HRC, 1433.8 and 1811.9 MPa at 580°C, respectively. The elongation increased with the decrease in the tempering temperature, which reached the largest of 14.62% at 500°C, and the impact absorption energy was the highest of 38.72 J at this temperature. The changes in the microstructure and mechanical properties of CSS-42L steel are closely related to the transformation of retained austenite and carbide precipitation behavior in the steel caused by different heat treatment regimes.