Abstract: Secondary heating quenching and low temperature tempering processes were used to improve the performance of ø120 mm forged wear-resistant steel balls, and the effects of heating rates and cooling time in secondary heating quenching process on the hardness distribution, impact property and microstructure of the steel balls were studied. The optimized heat treatment process of the steel ball is as follows: heating to 840 ℃ with the rate of 2.8 ℃/min and holding for 1 h, air cooling to 800 ℃, quenching into 35 ℃ water for 350-400 s, and then air cooling to below 80 ℃; tempering at 200 ℃ for 4 h, furnace cooling to below 80 ℃, and then air cooling. After treating by the optimized process, the hardness from surface to core of the wear-resistant steel ball is all in the range of 58-60 HRC, the impact absorbed energy at core of the ball at room temperature is ≥15 J, and the number of single falling test is more than 5000 times, which proves that this process can improve the quality and life of large-diameter forged wear-resistant steel balls.

Key words: forged wear-resistant steel ball, heat treatment, mechanical properties, microstructure