中温回火温度对22MnB5钢扭力梁疲劳性能的影响

Effect of Medium Tempering Temperature on Fatigue Properties of 22MnB5 Steel Torsion Beam

对冷成形22MnB5钢管状扭力梁进行960℃感应淬火和中温回火,研究了回火温度(220,350,400,450,500℃)对扭力梁拉伸性能、冲击性能和疲劳寿命的影响。结果表明:随着回火温度从350℃升至500℃,22MnB5钢扭力梁的抗拉强度降低,断后伸长率增加,强塑积先增大后减小,450℃回火后最大,达到12.3 GPa·%;随着回火温度从220℃升至450℃,22MnB5钢扭力梁显微硬度减小,冲击吸收力增加;回火后扭力梁表面残余应力下降,且回火温度越高,下降程度越大;随回火温度升高,扭力梁疲劳寿命呈先下降后增再降的变化趋势,450℃回火疲劳寿命最长,达(15.8±2.4)万次;22MnB5钢扭力梁的最佳回火温度为450℃。

The cold formed 22MnB5 steel tubular torsion beam was treated by induction quenching at 960℃and tempering at medium temperature.The effect of tempering temperatures(220,350,400,450,500℃)on tensile properties,impact properties and fatigue life of the torsion beam was studied.The results show that with the tempering temperature rising from 350℃to 500℃,the tensile strength of 22MnB5 steel torsion beam decreased,the elongation percentage after fracture increased,and the product of tensile strength and elongation increased first and then decreased,and reached maximum of 12.3 GPa·%after tempering at 450℃.With increasing tempering temperature,the microhardness of 22MnB5 steel torsion beam decreased and the impact strength increased.After tempering,the residual stress on the surface of torsion beam decreased,and the higher the tempering temperature,the greater the reduction degree.With increasing tempering temperature,the fatigue life of the torsion beam decreased first,then increased and then decreased.When the tempering temperature was 450℃,the fatigue life was the longest,reaching(15.8±2.4)×104 cycles.The optimal tempering temperature of 22MnB5 steel torsion beam was 450℃.