取向偏离度对镍基单晶高温合金DD10低周疲劳行为的影响

Orientation Dependence of Low Cycle Fatigue Properties of a Ni-based Single Crystal Superalloy DD10

摘要:

本文研究了特定试验条件下,镍基单晶DD10取向偏离[001]的程度对其低周疲劳行为的影响。结果表明：取向偏离度对DD10合金的低周疲劳行为影响明显。疲劳寿命随取向偏离度的增加而明显降低,在同等偏离度下,晶体取向靠近[001]-[011]的合金低周寿命优于取向靠近[001]-[11]的合金；分析发现：不同取向偏离度合金DD10低周疲劳寿命的差异源于其每循环周次的可累计塑性变形的差异。另一方面,取向偏离度对疲劳总应力幅和塑性应变幅的影响却截然相反,但对疲劳裂纹萌生和扩展方式影响不大。

Abstract:

Low cycle fatigue (LCF) properties of a nickel-based single crystal (SX) superalloy DD10 with different orientation deviation angles from the [001] axis was investigated at 760 °C and with invariable total strain amplitude of 1.4%. Results reveal that the LCF behavior of DD10 exhibited a strong orientation-dependence. The fatigue life decreased apparently with the increment of the orientation deviation angle. For specimens with the same orientation deviation angle from the [001] axis, those on the [001]-[011] boundary exhibited a longer fatigue life than ones on the [001]-[11] boundary. It was found that the orientation-dependence of fatigue life stems from the difference of accumulated plastic deformation per cycle. On the other hand, both of total stress amplitude and plastic strain amplitude showed a reverse orientation-dependence compared with the fatigue life. However, the orientation deviation showed no influence on the model of fatigue crack initiation and subsequently propagation.