磨削白层特性及其与声发射信号的相关性  

Features of Grinding White Layer and Its Correlation with Acoustic Emission Signal

作　　者：毛聪[1] 孙鹏程 唐伟东 张明军[1] 罗源嫱 胡永乐[1] 张德嘉 唐昆[1] 管付如 MAO Cong;SUN Pengcheng;TANG Weidong;ZHANG Mingjun;LUO Yuanqiang;HU Yongle;ZHANG Dejia;TANG Kun;GUAN Furu(Hunan Provincial Key Laboratory of Intelligent Manufacturing Technology for High-performance Mechanical Equipment,Changsha University of Science and Technology,Changsha 410114;Hunan Wuxin Tunnel Intelligent Equipment Co.,Ltd.,Changsha 410100)

机构地区：[1]长沙理工大学机械装备高性能智能制造关键技术湖南省重点实验室,长沙410114 [2]湖南五新隧道智能装备股份有限公司,长沙410100

出　　处：《机械工程学报》2023年第9期349-359,共11页Journal of Mechanical Engineering

基　　金：国家自然科学基金(51875050,52275405);湖南省科技计划(2021GK2021,2022ZYC017)资助项目。

摘　　要：磨削白层严重影响零件的服役性能和寿命。为了研究磨削白层的物理本质,揭示磨削白层特性与声发射信号频谱幅值的相互关联,开展了淬硬GCr15轴承钢磨削实验,观测了磨削白层特性,揭示了磨削机械挤压和磨削热的耦合作用下声发射信号频谱规律。研究表明,白层组织更加致密,耐腐蚀性更强,显微硬度高于暗层与基体组织;磨削白层受到磨削温度与塑性形变的协同影响,当磨削温度低于工件材料名义相变温度时,在剧烈的塑性变形诱导下,磨削表面也会出现白层,当磨削温度超过名义相变温度时,白层厚度会突增;磨削时声发射信号受机械挤压应力和热应力效应协同影响,低频段幅值主要取决于机械挤压应力,高频段幅值主要受热应力效应影响,当磨削温度超过名义相变温度时,工件材料分/原子内能显著增大,进而产生无序高频振动,从而高频段幅值急剧增大。揭示了声发射信号高频段幅值与白层厚度之间关联关系,磨削过程中根据高频段幅值是否出现突变,可以判断磨削表面和亚表面是否出现相变及产生厚的白层。为白层厚度可控的磨削提供了在线监测方法。Grinding white layer seriously affects the service performance and life of the parts.To study the physical nature of grinding white layer and reveal the correlation between features of grinding white layer and spectrum amplitude of acoustic emission(AE)signal,grinding experiments of hardened GCr15 bearing steel are carried out to observe the characteristics of grinding white layer and reveal the frequency law of acoustic emission signal under the coupling effect of grinding mechanical extrusion and grinding heat.The results show that the microstructure of white layer is denser.The corrosion resistance and microhardness of white layer are superior to those of dark layer and matrix material.The grinding white layer is synergistically affected by grinding temperature and plastic deformation.When grinding temperature is lower than the nominal phase transition temperature of the workpiece material,the grinding white layer also appears under the induction of severe plastic deformation.The thickness of white layer increases suddenly when grinding temperature exceeds the nominal phase transition temperature.During grinding,the acoustic emission signal is synergistically affected by mechanical extrusion stress and thermal stress,the amplitude in low frequency band is mainly determined by mechanical extrusion stress,and the amplitude in high frequency is mainly affected by thermal stress.When grinding temperature exceeds the nominal phase transition temperature,the internal energy of molecules/atoms in workpiece increases significantly,resulting in disordered high-frequency vibration,and the high-frequency amplitude increases sharply.The correlation between the high-frequency amplitude of acoustic emission signal and the thickness of white layer is revealed.According to whether there is a mutation of high-frequency amplitude in grinding process,the appearance of phase transformation and thick white layer at surface and sub-surface can be judged.Online monitoring method is provided for grinding with controllable white layer

关 键 词：磨削 白层 声发射 频谱幅值 微观组织 

分 类 号：TG580[金属学及工艺—金属切削加工及机床]