镍基粉末高温合金切削加工表面白层形成热-力耦合作用机理  

Thermo-mechanical Coupling Mechanisms for White Layer Formation on Machined Surface of Powder Metallurgical Nickel-based Superalloy

作　　者：刘战强[1,2] 吕绍瑜 

机构地区：[1]山东大学机械工程学院,济南250061 [2]山东大学高效洁净机械制造教育部重点实验室,济南250061

出　　处：《机械工程学报》2014年第17期186-193,共8页Journal of Mechanical Engineering

基　　金：国家重点基础研究发展计划(973计划;2009CB724401);国家自然科学基金(51375272;U1201245)资助项目

摘　　要：对镍基粉末高温合金FGH95进行高速铣削加工试验,研究切削速度对FGH95切削表面白层厚度的影响规律,利用有限元对FGH95高速铣削过程进行二维仿真,获得已加工表面的温度场、应变场和应变率场。研究结果表明:FGH95已加工表面白层厚度随着切削速度的提高呈现先增大后减少的趋势;已加工表面温度、应变和应变率的综合作用使表面材料发生相变和晶粒细化,相变和晶粒细化的耦合作用促进白层的产生;切削过程中FGH95塑性变形导致白层形成的临界温度降低,促进白层的产生;切削表面的高应变率导致FGH95白层形成的临界温度升高,阻碍白层的产生。Through investigations of high-speed milling experiments of PM nickel-based superalloy FGH95, the influence of the cutting speed on white layer formation is investigated. 2D finite element simulation of high-speed milling process is carded out. The distribution of temperature field, strain field and strain-rate field at different cutting speeds are obtained. Research results show that the white layer thickness increases with the cutting speed. However, the thickness of white layer decreases while the cutting speed increases a step further. The Combined influences of temperature, strain and strain-rate at machined subsurface layer results to the onsets of phase transformation and grain refinement, which in turn promote the formation of white layer. Severe plastic deformation decreases the critical temperature for white layer formation, while high strain-rate increases the critical temperature of white layer formation.

关 键 词：粉末镍基高温合金 高速切削 白层 相变 塑性变形 

分 类 号：TG54[金属学及工艺—金属切削加工及机床]