超声滚压强化对不同取向镍基单晶高温合金疲劳性能的影响机理研究

Tenon parts of aircraft engine turbine blades are often surface strengthened in order to improve their anti-fatigue performance. However, due to the orthotropic properties of single crystal superalloy, the surface strengthiening effect is very different in different orientations. Hence, Ni-based single crystal blades remain untreated. Ultrasonic surface rolling experiments will be carried out for single crystal in different orientations with different process parameters. The effect of the process variables, such as rolling force, rolling speed and rolling times, on the critical surface properties, such as surface roughness, residual stress and surface microstructure, will be studied to determine the relationship between process variables and surface variables. A series of fatigue tests will be carried out for single crystal in different orientations treated with different parameters surface ultrasonic rolling process to investigate the influence rules of surface rolling on the fatigue properties of single crystal. It is anticipated the relation between the surface variables and the fatigue properties will be determined to explain the surface strengthening mechanism of the single crystal in different crystal orientation. The results will be useful for the surface strengthening of aircraft engine turbine blades tenon to improve their anti-fatigue performance.

航空发动机涡轮叶片榫头部位需要进行表面强化以提高其抗疲劳能力，但目前单晶材料制备的涡轮叶片榫头还无法进行强化，主要原因是单晶具有正交各向异性材料性能，不同取向单晶材料的表面强化效果差异较大。本项目通过开展不同工艺参数下不同晶体取向单晶材料的超声滚压强化试验，研究滚压力、滚压速度、滚压次数等关键工艺参数对不同取向单晶材料表面粗糙度、残余应力、表层组织结构等关键材料表面性能参量的影响规律，确定工艺参数与表面性能参数之间的对应关系。进一步通过开展不同晶体取向单晶材料超声滚压后疲劳试验，明确超声滚压对不同晶体取向单晶材料疲劳性能的影响规律。在此基础上，建立材料表面性能参量与疲劳寿命间的关系，揭示不同取向单晶材料的超声滚压强化机理，为将表面强化工艺用于航空发动机单晶涡轮叶片榫头抗疲劳处理提供支撑。

本项目以目前我国先进航空发动机单晶涡轮叶片常用材料为研究对象，采用比喷丸强化具有更优表面粗糙度及表面残余应力分布的超声滚压强化为手段，重点研究不同超声滚压强化工艺参数对单晶材料表面粗糙度、表面层组织结构、残余应力等关键参量的影响规律，通过有限元软件建立不同晶体取向单晶材料超声滚压过程有限元模型，按试验条件设置不同的滚压静压力，求解获得不同静压力下单晶材料表面变形行为及残余应力分布，通过正交试验结果及有限元分析结果，获得超声滚压参数与不同晶体取向单晶材料表面粗糙度、表层组织结构及表面残余应力之间的关系，进而在优化后的工艺参数下研究超声滚压强化对不同取向镍基单晶材料疲劳性能的影响规律，最终揭示超声滚压强化对不同晶体取向单晶材料的强化机理；根据超声滚压强化后的疲劳试验揭示材料表面性能差异对不同取向下单晶材料疲劳性能的提高机理，为将表面强化工艺用于航空发动机单晶涡轮叶片榫头抗疲劳处理提供支撑。