镍基单晶高温合金磨削表面白层的形成规律

Formation of White Layer on the Grinding Surface of Ni Based Single Crystal Superalloy

表面完整性对零件的服役性能和寿命影响至关重要,但是目前仍缺乏关于单晶高温合金加工过程中微观组织演化机制的研究.本文对单晶高温合金磨削过程中的磨削力与温度进行采集,同时对亚表面微观组织以及显微硬度进行表征,研究了表面白层特性.结果表明,在试验参数范围内磨削力和温度随着磨削深度的增加呈现显著上升的趋势,白层和塑性变形层厚度随着磨削深度和进给速度的增加而增大.白层与塑性变形层之间发生元素扩散现象,导致白层富含Al和Ta元素.磨削之后表面显微硬度有所提高,其硬化程度随着磨削深度和进给速度的增加而提高.

Surface integrity is very important to the service performance and lifespan of parts,but research of the microstructure evolution mechanism of single crystal superalloy during machining is still lacking.The grinding force and temperature of single crystal superalloy were collected,and the microstructure changes and microhardness on the grinding subsurface were characterized.The characteristics of the white layer were studied as well.The results showed that in the range of test parameters,the grinding force and temperature increase remarkably with the grinding depth increasing,and the thickness of the white layer and the plastic deformation layer increases with the increase of grinding depth and feed speed.The element diffusion is found between the white layer and the plastic deformation layer,resulting in rich Al and Ta elements in the white layer.The surface microhardness increases after grinding,and the hardening degree rises with the increase of grinding depth and feed speed.