关键词: 弹簧钢, 轻量化, 高强韧性, 疲劳寿命

Abstract: In order to satisfy the demand for high load-bearing, lightweight and high fatigue resistance in automotive leaf springs, a novel medium carbon and medium silicon spring steel was designed, and the effects of quenching and tempering process on microstructure and mechanical properties of the steel were studied. The results show that both high strength and high toughness of the tested spring steel can be obtained after oil quenching at 850-880 ℃ for 15-30 min and tempering at 260-290 ℃ for 40-50 min. The tensile strength and yield strength reach 1850-1930 MPa and 1650-1710 MPa, respectively, the total extension at fracture is 10%-13%, the reduction of area is 55%-60%, and the impact absorbed energy at -50 ℃ is 45-50 J. The result of fatigue bench test of the leaf spring for a vehicle prepared by the tested spring steel and the heat treatment shows that it isn't failure after 456 000 cycles, meeting the high stress requirement of tensile stress of 1300 MPa and the life requirement of 100 000 cycles without breaking under the condition of 1P ± 53.6 mm amplitude, and achieves a weight reduction of 10%.

Key words: spring steel, lightweight, high strength and toughness, fatigue life