估算低温下金属材料应变疲劳寿命和疲劳极限的新方法

A New Method for Predicting Strain Cycling Fatigue Life and Endurance Limit of Metals at Low Temperatures

本文建立了估算低温下金属材料应变疲劳寿命的新方法,并首次提出了金属疲劳极限的热激活模型。该模型可定量地解释温度和频率对疲劳极限的影响。研究结果表明,提出的应变疲劳公式可很好地拟合低温下金属材料应变疲劳寿命的实验结果;疲劳极限可表示成非热激活分量σ_(ai)(ε_(apc))和热激活分量σ_a~*(T,ε_p)之和;σ_(ai)(ε_(apc))是与温度和频率(或应变速率)无关的材料常数;σ_a~*(T,ε_p)与流变应力的热激活分量近似相等。最后用文献中的实验数据对本文提出的低温下就应变疲劳寿命和疲劳极限的估算方法进行了验证。

It is well known that low temperature fatigue testing is expensive, especially when the testing temperature is below 77K and liquid helium has to be used as cryogen. The method proposed in this paper will greatly reduce the cost of experimenting. The authors establish a thermal activation model for endurance limit of metals. The endurance limit of metals can be accordingly considered as the sum of two parts: thermal component σ~* (T,e_p)and a thermal component σ_(a(?)) (ε_(apc)). The former is nearly the sa...