高速切削淬硬钢切屑变质层微结构及形成机理.PDF

第20卷摇 第3期 材摇 料摇 科摇 学摇 与摇 工摇 艺 Vol.20 No.3 摇 摇 20 12年6月 MATERIALS SCIENCE TECHNOLOGY Jun. ,2012 摇 摇 摇 摇 摇 摇 高速切削淬硬钢切屑变质层微结构及形成机理 段春争,王敏杰,于海洋 (大连理工大学 机械工程学院模具研究所,辽宁 大连 116024) 摘摇 要:为了揭示高速切削过程中切屑形成以及刀具-切屑界面摩擦机理,对剪切区内剪切带及白层进行了 微观观察和分析.利用光学显微镜,SEM,电子探针,TEM 和X 射线衍射等方法对高速切削淬硬钢锯齿状切 屑剪切变形区内变质层的微细组织进行了观察,对变质层的微结构本质及其形成机理进行了分析.研究表 明:在锯齿状切屑锯齿之间的第一变形区存在绝热剪切带,由切屑基体到剪切带中心依次出现马氏体板条、 沿剪切方向拉长并被位错分割的板条和等轴晶粒等不同的微结构特征;在切屑底部的第二变形区存在白层, 其微结构显示了非晶组织特征.剪切带形成过程中没有相变发生,其形成是基于一种旋转式动态再结晶机 制,白层的形成过程中发生了非晶转变和马氏体相变,形成机理属于相变机制. 关键词:高速切削;变质层;绝热剪切带;再结晶,相变 中图分类号:TG506.1 文献标志码:A 文章编号:1005-0299(2012)03-0127-05 Microstructure and formation mechanism of deterioration layer in hardened steel chips during high speed machining DUAN Chun鄄zheng,WANG Min鄄jie,YU Hai鄄yang (Molded Products Engineering Research Center of the Ministry of Education,School of Mechanical Engineering, Dalian University of Technology,Dalian116024,China ) Abstract:To reveal the mechanism of chipformation and tool鄄chip interfacefriction during high speed machi鄄 ning,the microstructure observation by optical microscope,SEM,electron probe and TEM,and the analysis of shear band and white layer in shear deformation were carried out.The investigation shows that there are adia鄄 batic shear bandsinprimary shearzonesbetweenthesaw teeth.Thedifferentmicrostructures,suchasmartens鄄 ite lath,elongated martensite laths divided by dislocations and equiaxed grains,appear in turn from the chip matrix to the center of shear band.There are white layers,which have amorphous microstructure,in second shear zones on the bottom of chips.N