腐蚀疲劳裂纹扩展的断裂模型

将修正的疲劳裂纹扩展静态断裂模型和裂尖腐蚀溶解相结合,提出了腐蚀疲劳裂纹扩展(CFCP)的腐蚀-钝化-断裂模型.根据该模型和断裂力学原理,导出了CFCP速率的定量表达式,它揭示了CFCP速率与力学条件,裂尖表面腐蚀率、加载频率、假设的裂尖材料元临界断裂应力之间的定量关系,并能说明氢脆对CFCP率的影响规律。实验结果表明,应用所提出的模型可很好地描述铝合金在35％NaCI中CFCP的一般规律。

A FRACTURE MODEL FOR CORROSION FATIGUE CRACK PROPAGATION PROCESS

Taking into simultaneous consideration of the modified static fracture model for fatigue crack propagation and the corrosion dissolution of the bare metal surface at a crack tip, a corrosion-bluntening-fracture model for corrosion fatigue crack propagation (CFCP) was proposed. According to the new model and linear elastic fracture mechanics, an expression for CFCP rate, which revealed the quantitative correlation among CFCP rate, stress intensity factor amplitude, the CFCP threshold, the corrosion rate of the bare metal at the crack tip, loading frequency and the critical fracture stress of the hypothetical material elements along the crack path, was derived. The expression could interpret the effect of hydrogen embrit-tlement on the CFCP process. The experimental results showed that the expression gave a good fit to the CFCP rates of two commercial aluminum alloys in 3.5% NaCl solution at loading frequency 10Hz.