晶体取向对镍基单晶DD6合金蠕变性能的影响

Effect of Crystal Orientation on Creep Properties of DD6 Single Crystal Superalloy

摘要:

针对航空发动机镍基单晶涡轮叶片高温服役下蠕变寿命的取向敏感性难题，开展了DD6单晶合金［001］、［011］与［111］3种典型取向在980^oC下的蠕变试验，获得了服役温度下单晶合金的蠕变寿命、伸长率，均为［111］取向>［001］取向>［011］取向；通过对蠕变过程中微观组织演化以及蠕变断裂后断口形貌进行分析，揭示了不同取向下单晶合金的蠕变失效机理；基于晶体塑性理论，建立了DD6单晶考虑取向敏感性的粘塑性本构及损伤方程，能够较好地拟合不同晶体取向单晶的蠕变过程，为单晶叶片的强度分析与寿命预测提供参考。

Abstract:

In order to study the orientation sensitivity for creep life of aero-engine nickel-based single crystal turbine blades serving under high temperature， creep tests of DD6 single crystal superalloy were carried out with three typical orientations ［001］， ［011］ and ［111］ at 980^oC， indicated that the creep life and elongation of the single crystal alloy are both ［111］ > ［001］ > ［011］. By analyzing the microstructure evolution during the creep process and the fracture morphology after creep fracture， the creep failure mechanism of single crystal alloy with different orientations is revealed. Based on the crystal plasticity theory， the viscoplastic constitutive equation and damage equation considering the orientation sensitivity of DD6 single crystal were established， which could well fit the strain-time curve of single crystal with different crystal orientations， and provided a reference for the strength analysis and life prediction of single crystal blade.