一种镍基单晶合金高温低周疲劳寿命预测方法

LOW CYCLE FATIGUE LIFE PREDICTION METHOD FOR SINGLE CRYSTAL NICKEL-BASE SUPERALLOYS AT HIGH TEMPERATURE

提出一种考虑平均应力、应变比和晶体取向的镍基单晶合金低周疲劳寿命预测方法。首先建立镍基单晶合金在[001]和[111]晶体取向下的疲劳寿命预测模型,该模型考虑了平均应力和应变比对疲劳寿命的影响。然后,通过引入晶体取向函数建立不同晶体取向与[001]和[111]晶体取向下寿命预测模型中疲劳参数的关系,从而考虑镍基单晶合金晶体取向对疲劳寿命的影响。最后,提出通过[001]和[111]晶体取向下的模型来预测任意晶体取向下疲劳寿命的方法。提出的方法用DD3和PWA1840镍基单晶合金高温低周疲劳寿命试验数据进行验证,结果表明提出的方法是可接受的。

A low cycle fatigue life prediction method for single crystal nickel-base superalloys at high temperature is presented, and the method can consider the effect of average stress, strain ratio and crystal orientation on fatigue life. Firstly, a fatigue life prediction model is established to predict fatigue life of single crystal nickel-base superalloys in the [ 001 ] and [ 111 ] crystal orientations. The model considers the effect of mean stress and strain ratio on fatigue life. Then, to consider the effect of crystal orientation of single crystal nickel based superalloys on fatigue life, the relationships of fatigue parameters between [001 ]. [ 111 ] and other different crystal orientations are given by an orientation function. Finally, the fatigue life prediction method of single crystal nickel based superalloys for other crystal orientations is proposed by using fatigue parameters of the [001 ] and [ 111 ] crystal orientations. The method is validated using low cycle fatigue test data of DD3 and PWA1840 nickel- base single crystal superalloy at high temperature, and the results show that the proposed method is acceptable.