【摘要】 应用超声疲劳试验技术,对三种不同微观组织状态的40CrNiMoA钢在超声振动载荷(f=20kHz,R=-1)下的疲劳性能进行测试分析。结果表明:在超声振动条件下,具有强韧配合的微观组织超声疲劳寿命得到显著提高;不同微观组织的40CrNiMoA具有两种类型的S-N曲线:持续下降型和阶梯下降型,试样在107以上仍会发生疲劳断裂。扫描电镜对疲劳断口的分析表明:在超声疲劳载荷循环下,疲劳裂纹起源于试样表面。初步探讨了超高周疲劳断裂机理。更多还原

【Abstract】 Fatigue lives of 40CrNiMoA steel with different microstructures were studied by the ultrasonic fatigue technique at 20kHz and R=-1.The results showed that the ultrasonic fatigue life of the specimen with microstructure of combined high strength and good toughness had higher fatigue life under ultrasonic vibration.Different microstructure of 40CrNiMoA had two types of S-N curves,stepwise and continually decreasing curves,and the specimen would be failing over 107 stress cycles.SEM fractograph of the fatigue specimens showed that,under ultrasonic vibration conditions,fatigue crack initiated at the surface of the specimens.The fracture mechanism of the super high cycle fatigue was discussed.更多还原