一种镍基单晶和定向结晶合金的疲劳寿命模型

针对镍基单晶和定向结晶合金的高温低循环疲劳/蠕变寿命预测问题,用晶向函数修正总应变范围以考虑疲劳寿命的各向异性,并综合考虑了最大应力、平均应力、应力范围以及峰值保持等载荷因素对寿命的贡献,在循环损伤累积思想的基础上发展了一种低循环疲劳/蠕变寿命预测方法.利用定向结晶合金DZ125、单晶合金DD3和DD6在不同温度、不同取样方向和不同保载形式作用下的试验结果,对方法进行了验证,预测与试验寿命相比基本落在2倍分散带内,表明该方法能更好地适应叶片材料各向异性与低循环疲劳/蠕变载荷的情况. 

Fatigue life prediction model for nickel-based single crystal and directionally solidified superalloy

A lifing model was developed to predict the high temperature,low-cycle fatigue-creep(HTLCF-C) life behavior of nickel-based single crystal(SC) and directionally solidified(DS) superalloy.By modifying total strain range with a crystal orientation-dependent function,the mean and maximum stress and its range during a fatigue cycle,as well as dwell time at peak stress or strain level were incorporated into the lifing model using the idea of cyclic damage accumulation(CDA).The model was validated by correlating the fatigue data of DZ125,DD3 and DD6 superalloy under different temperatures,crystal orientations and holding times.Good agreements between predicted and experimental lives were yielded in these two factors for both DS and SC superalloy.The results show that the approach has better adaptability to model the anisotropic and HTLCF-C life behavior of turbine blade materials.