转向架用SMA490BW钢的疲劳性能研究

Study on Fatigue Properties of SMA490BW Steel for Bogie

基于高速列车转向架在运行进程中常因承受各种交变载荷而导致的疲劳断裂问题,对CRH2高速列车转向架用SMA490BW钢试样进行拉伸试验。为确保SMA490BW钢的力学性能符合标准要求,对此种钢材在不同取样方向及不同应力比下开展疲劳性能及断裂机理研究。结果表明:T-L取样方向试样的疲劳极限应力较L-T取样方向高出5.4%。在相同的最大循环应力下,应力比R越大,疲劳强度越大。SMA490BW钢的疲劳裂纹基本萌生于基体表面。裂纹扩展区以海滩波纹状解理断裂为主,且在内部出现少量的二次裂纹和疲劳台阶,瞬断区断面主要为韧窝状形貌,且伴随有大量的撕裂棱。

Due to various alternating loads that the high-speed train bogies during the operation process often suffer from,the fatigue fracture occurs. To ensure that the mechanical properties of SMA490 BW steel meet the standard requirements, a tensile test was conducted on SMA490 BW steel specimen for CRH2 high-speed train bogies. For this type of steel, the fatigue performance was studied under different sampling directions and different stress ratios, and the fracture analysis was performed by SEM. The results show that the ultimate fatigue stress of the T-L sampling direction specimen is 5.4% higher than that of the L-T sampling direction. Under the same maximum cyclic stress, the greater the stress ratio R, the greater the fatigue strength.The fatigue cracks of SMA490 BW steel basically originate from the surface of the substrate. The crack propagation area is dominated by beach corrugated cleavage faults, and a small amount of secondary cracks and fatigue steps occur in the interior. The section of the instantaneous fracture zone is mainly a dimple-like morphology with a large number of torn edges.