高温合金磨削热损伤的形成机理及对表面完整性的影响

Generation Mechanisms of Thermal Damages in Superalloy Grinding and Its Effect on Surface Integrity

高温合金磨削加工过程中易出现热损伤缺陷,严重降低零件的疲劳寿命,为解决该工程问题,采用锆刚玉砂轮与微晶刚玉砂轮对高温合金开展了深切缓进磨削试验.研究磨削工艺参数对磨削温度、磨削力,表面形貌与表面粗糙度的影响规律,揭示高温合金磨削热损伤的形成机理与有效抑制措施,对比分析磨削热损伤对表面完整性造成的影响.结果表明,加工弧区瞬时高温是引起高温合金磨削热损伤的本质原因,微晶刚玉砂轮因自锐性优势能有效抑制磨削热损伤,高温合金磨削热损伤表面呈现氧化变色、鱼鳞状涂覆纹理、硬度下降与残余拉应力等表面缺陷.实现高温合金无热损伤磨削的有效手段是降低磨削热量的产生与加工弧区的强化换热.

Thermal damage defects are prone to occur during the grinding process of superalloys,which seriously reduces the fatigue life of parts.To address this engineering issue,this paper uses zirconium corundum grinding wheels and microcrystalline corundum grinding wheels to carry out creep-deep grinding experiments on superalloys.The effects of grinding process parameters on grinding temperature,grinding force,surface morphology,and surface roughness were studied.The formation mechanisms and effective suppression measures of thermal damage in superalloy grinding were revealed.The influence of grinding thermal damages on surface integrity was compared and analyzed.The results indicate that the instantaneous high temperature in the processing arc zone is the essential cause of the thermal damage of superalloy grinding.Microcrystalline corundum grinder can suppress grinding thermal damages productively due to its self-sharpening advantage.The surface of superalloy alloy grinding with thermal damages exhibits oxidation discoloration,fish scale-like coating texture,decreased hardness,and residual tensile stress.An effective means to realize the thermal damage-free grinding of superalloys is to reduce the generation of grinding heat and strengthen the heat transfer in the machining arc region.