中文摘要：

对TC4钛合金外圆切削加工过程锯齿形切屑材料组织演变的影响因素及其规律进行了阐述。使用金相显微镜、显微硬度测试仪和扫描电子显微镜对其形态、组织进行观察和测试;使用红外测温仪测量切屑形成温度。研究表明：锯齿形切屑的组织变化主要表现为剪切带的变化。随着切削速度增加,切削温度上升,剪切带的结构为：形变带→形变带＋转变带→转变带,转变带的宽度逐渐变宽,显微硬度值增加。刀具前角、进给量的改变也影响剪切带的组织变化。TC4钛合金的锯齿形切屑的形成机理为热塑性失稳。

英文摘要：

We present the factors and laws of material structure changes of chips in the turning and cutting process of titanium alloy TC4.Shapes and structures of the saw-toothed chips obtained under various conditions were observed and tested by optical microscope,scanning electron microscope（SEM） and microhardness tester.The cutting temperatures were measured by infrared thermo detector.The investigation shows that structure changes of the saw-toothed chips mainly occur inside shear band.As the cutting speed increases and the cutting temperature rises,structures inside the shear bands change from deformed band to deformed band plus transformed band and finally to transformed band.The transformed band becomes wider,and the microhardness value increases.Rake angle and feeding speed are the other two factors that influence structure changes of shear bands.Saw-toothed chip formation mechanism of titanium alloy TC4 is thermoplastic instability.