基于临界平面法的镍基单晶高温合金高周疲劳寿命模型

High cycle fatigue life model of nickel-based single crystal superalloys based on critical plane approach

由于目前,国外已经基于八面体滑移系,采用临界平面法对镍基单晶高温合金〈001〉取向的高周疲劳寿命进行预测.然而,该方法未考虑〈111〉取向受载时滑移系参量的特点,所以不能较准确地预测镍基单晶高温合金〈111〉取向的高周疲劳寿命.为此,选取临界平面时综合考虑六面体、八面体滑移系,选定疲劳参量最大的滑移面作为临界平面,采用SSR(shear stress range),CCB(Chu-Conle-Bonnen),Walls寿命模型进行镍基单晶高温合金高周疲劳寿命预测,并根据800℃下DD6镍基单晶高温合金〈001〉,〈011〉,〈111〉3个取向的高周疲劳试验结果,对寿命模型的预测精度进行验证.结果表明:当基于两种滑移系预测镍基单晶高温合金的高周疲劳寿命时,寿命模型的拟合系数可达到0.913 4.

The high cycle fatigue life predication of the （001） orientation of nickel-based single crystal superalloys was studied by foreign scholars with critical plane approach based on octahedral slip system currently. However, without considering the characteristics of slip system parameters when the （111） orientation was loaded, the predication of high cycle fa- tigue life of the （111） orientation was inaccurate. Therefore hexahedral and octahedral slip systems was considered comprehensively when choosing the critical plane. Slid planes of maximum fatigue parameter could determine the position of critical plane, and the life models of the SSR （shear stress rang）, CCB （Chu-Conle-Bonnen） and Walls were used for high cycle fatigue life prediction of single crystal superalloys. According to the results of high cycle fatigue test under 800℃ along （001）, （011） and （111） orientations of DD6 nickel-based single crystal superalloys, the prediction accura dicate that the fitting coefficient of life model life of single crystal superalloys is predicted cy of the life model was verified. The results in- can reach to 0. 9134 when the high cycle fatigue based on two slip systems.