Effect of Medium Tempering Temperature on Fatigue Properties of 22MnB5 Steel Torsion Beam
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 ℃.
high strength steelmedium temperature temperingtorsion beamresidual stressfatigue property
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