在980 ℃温度下, 对不同取向镍基单晶高温合金DD6在不同低周疲劳条件下的循环变形行为进行了研究。结果表明: ［001］取向的合金在高总应变幅下表现出循环硬化特征, 在低总应变幅下表现为基本循环稳定; ［011］和［001］取向合金具有大致相同的特征。应变速率会对合金的循环硬化曲线产生影响, 在低应变速率的条件下, 硬化曲线整体上是向下移动, 循环应力峰值下降; 施加的总应变幅越大, 循环应力下降越明显; 高应变速率使得两种取向合金在相同的总应变幅下硬化曲线的初始硬化速率上升, 这种现象对于［111］取向的尤为明显。

Low cycle fatigue tests were conducted on different oriented single crystals of nickel base superalloy DD6 at 980 ℃ to study their cyclic deformation. Results show that at 980 ℃, the alloy with orientation of ［001］ exhibited cyclic hardening under higher total strain amplitude and cyclic stability under lower total strain amplitude, the same trend occurred in the specimens with ［011］ and ［111］ orientations. Strain rate could affect the cyclic hardening curve of the alloy. Under condition of low strain rate, the hardening curve moved upwards and the cyclic stress amplitude decreased. The higher the applied total strain amplitude, the more obviously the cyclic stress amplitude decreased. The higher strain rate made the initial hardening rate of the hardening curves increase under the same total strain amplitudes for both ［001］ and ［111］ oriented specimens, especially for the ［111］ oriented one.