Abstract: 42CrMo-R test steel was designed and smelted and rolled into a tyre. Effect of heat treatment process on microstructure and mechanical properties of the 42CrMo-R steel tyre were studied by means of metallographic microscope, scanning electron microscope, tensile testing machine, hardness tester and other methods. The results show that after quenching in the range of 830-980 ℃, the matrix of the 42CrMo-R steel tyre is lath martensite, when the quenching temperature exceeds 890 ℃, the proportion of lath martensite increases significantly, and when quenched at 860 ℃, the original austenite grain size distribution is uniform and the strength is the highest, so it is the optimal quenching temperature. Tempered in the range of 520-600 ℃, the tyre matrix microstructure are all tempered martensite. With the increase of tempering temperature, the hardness, tensile strength and yield strength all show a downward trend, while the elongation and percentage reducation of area basically show an upward trend. After quenching at 860 ℃and tempering at 560-580 ℃, the 42CrMo-R steel tyre has a relatively high proportion of tempered martensite, a small amount of undissolved ferrite and there is a large margin of R_m, R_p0.2, hardness and elongation compared with customer requirements, and it has good microstructure and comprehensive mechanical properties.

Key words: heat treatment, 42CrMo-R steel, tyre, microstructure, mechanical properties