切削深度对单晶γ-TiAl合金亚表面缺陷及残余应力的影响

Effect of Cutting Depth on Subsurface Defects and Residual Stress in Single Crystal γ-TiAl Alloy

本工作采用分子动力学方法模拟了单晶γ-TiAl合金在不同切削深度下的切削过程,分析了不同切削深度下微观缺陷演化及稳定切削后的内应力演变,研究了切削后残余应力和von Mises应力等在不同切削深度下的分布规律,讨论了不同切削深度下位错和层错等微观缺陷演化及内应力演变之间的关系。结果表明:位错反应及层错演化随着切削深度的增加越来越剧烈,位错反应对Lomer-Cottrell位错的形成影响较大;刀具挤压工件表面形成的残余压应力受层错演化及位错反应的影响,位错反应的剧烈程度影响内应力的大小,且残余压应力存在于亚表面下的一定深度内;同时发现切削深度的变化对von Mises应力的影响较小。

In this paper,the molecular dynamics method was used to simulate the cutting process of single crystal γ-TiAl alloy under different cutting depths.The evolution of microscopic defects and the evolution of internal stress after stable cutting at different depths of cutting was analyzed,and the distribution of residual stress and von Mises stress at different cutting depths were studied,the relationship between the evolution of microscopic defects and internal stress at different cutting depths was discussed.The results show that the dislocation reaction and the stacking fault evolution increase with the increase of cutting depth,and the dislocation reaction has a great influence on the formation of the Lomer-Cottrell dislocation.The residual compressive stress formed by the surface of the tool extrusion workpiece is affected by the stacking fault evolution and dislocation reaction,and the severity of the dislocation reaction affects the internal stress.The residual compressive stress exists on a certain depth of the subsurface.It is also found that the change of cutting depth had little effect on von Mises stress.