预腐蚀疲劳退化加速因子研究

Investigation of acceleration factor for pre-corrosion fatigue degradation:model and analysis

考虑预腐蚀对材料疲劳性能的影响,以疲劳强度作为腐蚀量,给出了考虑预腐蚀疲劳退化的加速腐蚀因子的定义和表达式,并结合疲劳分析方法,以细节疲劳额定值(DFR)作为疲劳强度的衡量,给出了预腐蚀条件下的DFR确定方法,通过加速环境和实际服役环境下DFR随预腐蚀时间退化规律的对比分析,建立基于DFR的加速腐蚀因子,并进行参数估计,最后,给出了LY12CZ铝合金试件在典型环境下的加速腐蚀因子取值.

The acceleration corrosion factor （ACF） for accelerated corrosion test under service or natural exposed environment is the most important parameter in the accelerated corrosion test （ACT）. The material property was degraded seriously in pre-corrosion environment, and the corrosion damage was characterized by fatigue strength. So, the acceleration factor was defined as the ratio of fatigue strength in different environments, and the ex pression was proposed in consideration of the degradation process of fatigue strength with corrosion time. To evaluate the fatigue property, the pre corrosion fatigue life was assumed to follow the two parameter Weibull distribution, the detail fatigue rating （DFR） method in pre-corrosion environment was proposed, and the relationship between the DFR and the corrosion time was expressed as an exponential function. The acceleration corrosion factor based on the DFR was proposed by comparing the degradation process in accelerated corrosive environment and the natural exposed environment, and was proved to be a constant regardless of corrosion time. Finally, the typical ACF of LY12CZ Aluminum alloy specimen was calculat ed.