A basic study on reliability of axles for high-speed railway

(1)提出了一种将超声掠射SH波检测系统与SH波形成方法相结合的超声新技术。应用该技术，对新干线列车轮对轴的微动疲劳裂纹进行检测成为可能。(2)对混合表面改性轴进行了疲劳试验和超声试验。结果表明：轴的疲劳极限有所提高，但由于残余压应力较大，裂纹检测难度加大；(3)对轴承用高碳铬钢JIS SUJ2进行了恒幅和变幅土地序列下的旋转弯曲、高周疲劳试验。在重复两步着陆的情况下，由于载荷的变化，疲劳裂纹的起始点由试件表面向地下发生变化。讨论了变幅荷载序列下线性损伤累积规律的有效性。(4)渗碳与木塑复合可以在近表面附近产生较高的残余压应力，保持了渗碳形成的较深的残余压应力层，复合改性的缺口试样的疲劳强度明显高于单纯渗碳改性的缺口试样。

(1) A new ultrasonic technique in combination of ultrasonic grazing SH wave inspection system and a wave forming method were proposed. Applying this technique, it became possible to detect the fretting fatigue cracks in wheel set axle of shinkansen train.(2) Fatigue test and ultrasonic test were performed for the hybrid surface improved axles. The results show that the fatigue limit of the axle increases but the detection of cracks becomes more difficult because of large compressive residual stresses.(3) Rotating bending, high-cycle fatigue tests under constant amplitude and variable amplitude land sequences were carried out on a high carbon chromium steel for bearings, JIS SUJ2. In the case of repeated two-step landing, fatigue crack origin sites change from the specimen surface to the subsurface due to the load variation. The usefulness of linear damage accumulation law under variable amplitude load sequences was discussed.(4) By combining the carburizing and the WPC process, it is possible to generate a high compressive residual stress near the near the surface, maintaining a deep layer of compressive residual stress formed by the carburizing The notched specimens modified by combined show a significantly higher fatigue strength compared to those modified by only carburizing.