40Cr钢超高周疲劳性能及疲劳断口分析  

Study on the Gigacycle Fatigue Behaviors and Fracture Surface of 40Cr Steel

作　　者：王弘[1] 高庆[1] 

机构地区：[1]西南交通大学应用力学与工程系,四川成都610031

出　　处：《中国铁道科学》2003年第6期93-98,共6页China Railway Science

基　　金：四川省重点实验室开放基金资助项目[XJJQZ(2002)1号];四川省应用基础研究基金资助项目[02GY029 028]

摘　　要：采用超声疲劳试验方法研究40Cr钢在105周次～1010周次范围内的疲劳性能,其载荷频率为20kHz。用扫描电子显微镜分析了疲劳断口形貌特征。结果表明,40Cr钢的S N曲线始终保持下降趋势,且随疲劳循环数的增加,在106周次处并没有传统意义上的水平段;107周次疲劳强度为443MPa,1010周次疲劳强度为235MPa,二者存在明显差别;超声疲劳断口的扫描电子显微分析结果表明,40Cr钢超声疲劳断口显微形貌与常规疲劳载荷下的疲劳断口形貌无明显差异,疲劳裂纹在光滑试样表面或近表面材料缺陷处萌生,扩展区断口显微形貌观察到明显的疲劳辉纹。The fatigue behavior of 40Cr steel between 10~5-10~10 cycles was studied with the ultrasonic fatigue testing technique, with a loading frequency of about 20 kHz. The fracture surfaces of specimens were investigated with scanning electron microscopy (SEM). The experimental results show that the S-N curve of 40Cr steel continues to decrease with the increase of the number of cycles between 10~5 and 10~10 cycles and does not generally exhibit a plateau beyond 10~6 cycles. The fatigue strength at 10~7 cycles is found to be 443 MPa and at 10~10 cycles is 235 MPa. The difference between them is very large. The observation of fracture surface shows that the mechanism of fatigue failure is similar in both cases of ultrasonic fatigue and conventional fatigue in long life regime. Cracks initiate from a mass defect of specimen surface or beneath the surface. The fatigue striation areas have been found in the fracture surface of specimens.

关 键 词：钢材 超声疲劳试验 疲劳寿命 疲劳断口 试验分析 

分 类 号：TG142.15[一般工业技术—材料科学与工程]