取向相关的单晶高温合金低周疲劳寿命评估方法

为研究单晶(SC)高温合金低周疲劳（LCF）性能各向异性规律，收集了SC7-14-6、DD3、PWA1480、Rene N4与DD6共5种单晶合金的低周疲劳试验数据，校验了文献中单晶合金不同晶体取向的弹性模量计算方法，利用不同取向的弹性模量对总应变幅进行修正，提出了一种简单的适用于单晶合金不同取向的低周疲劳损伤参量，进而形成了取向相关的单晶合金低周疲劳寿命评估方法，利用上述5种合金的试验数据对方法进行了验证。结果表明:弹性模量是单晶合金LCF性能各向异性的重要影响因素；文献中的不同晶体取向弹性模量换算方法较为可靠；所提低周疲劳寿命评估方法的预测结果大多在2倍分散带内。此方法形式简单、效果显著，较为适合工程应用。 

Orientation-dependent low-cycle fatigue life evaluation method for single crystal superalloys

In order to investigate the anisotropy of low-cycle fatigue （LCF） properties of single crystal （SC） superalloys，the LCF experimental data of SC7-14-6，DD3，PWA1480，Rene N4 and DD6 were collected from literatures.The calculation method of elastic modulus of SC superalloys was verified.The elastic modulus of different orientations was introduced to modify the total strain amplitude.A simple expression of LCF damage parameter was proposed，which was suitable for different crystallographic orientations of single crystal superalloys.Furthermore，an orientation-dependent LCF life evaluation method was formed.The experimental data of the above five alloys were used to validate this method.The results showed that:the elastic modulus was an important factor influencing the anisotropy of SC superalloys' LCF performance；the elastic modulus conversion method among different orientations in literature was reliable；most prediction results of the proposed method were within a factor of two.The proposed method is quite simple and effective，and it is suitable for engineering applications.