车轮铸钢热疲劳裂纹损伤行为研究

Study on Characteristic of Thermal Fatigue Cracking Damage of Wheel Casting Steel

确定了车轮铸钢循环温度范围与循环次数间幂指数关系。其热疲劳损伤有两种主要形式；在低循环上限温度，表面氧化轻微，形成少量表面氧化腐蚀坑；在高循环上限温度，表面氧化严重，厚氧化膜剥落，大量的氧化腐蚀坑及微裂纹形成，并连接成细长主裂纹。表面氧化对热疲劳裂纹扩展有重要作用。

The relationship between the cycling temperature ranges and the cycling numbers is expressed by a regressive power law equation. Under lower maximum cycling temperature,while the surface was oxidized lightly,the oxidation corrosion pits were the main damage mode. Under higher maximum cycling temperature,while the surface was oxidized severely and thicker oxide film was stripped,a number of oxidation corrosion pits and crack linking to each other were the main damage mode. The oxidation of the surface contributed to the cracking propagating,which led to severe damage of the wheel casting steel.