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通过试验测定汽车齿轮轴用钢SCM440H经淬火和高温回火后的扭转疲劳寿命,并采用扫描电镜(SEM)对疲劳断口进行观察、分析。结果表明,显微组织为回火索氏体的SCM440H齿轮轴用钢,在106的循环周次下,扭转疲劳强度约为253MPa;不同切应力幅下的扭转疲劳断口呈现韧性断裂特征,疲劳断口裂纹源处没有明显的析出物。
The torsional fatigue life of quenched and tempered steel SCM440H was measured through the test and the fatigue fracture was observed and analyzed by scanning electron microscopy (SEM). The results show that the microstructure is tempered sorbite of SCM440H gear shaft steel, and the torsional fatigue strength is about 253 MPa at the cycle of 106; the torsional fatigue fracture shows ductile fracture under different shear stress amplitude, the fatigue fracture There are no obvious precipitates at the crack source.