中文摘要：

试验研究了硬态切削42CrMo（52HRC）中碳高强度合金结构钢锯齿形切屑形成过程。采用高速相机记录弹簧式快速落刀装置刀杆运动轨迹,计算落刀速度、加速度,定量分析该装置性能;在车床上直角自由切削盘状试样,以不同参数进行快速落刀试验,将获得的切屑根部制作成金相标本;考察“冻结”的切削区,着重考察剪切带上裂纹源、裂纹扩展以及绝热剪切带,分析锯齿形切屑形成过程。结果表明：裂纹源产生于自由表面,在切屑形成过程中向材料内部扩展,导致切屑分离的最终因素是裂纹扩展;硬态切削42CrMo切屑形成过程可划分为4个阶段。

英文摘要：

Saw-tooth chip formation process was trial researched herein, on hard cutting of medi um-carbon alloy structure 42CrMo（52HRC） high strength steel. Tool rod motion trajectory of QSD was recorded by a high-speed camera, the QSD＇s performance was quantitatively analyzed by calculating the velocity and acceleration. Orthogonal cutting QSD trial of disc sample was carried on lathe by cutting with different parameters, chip roots received were made into metallographic specimen; crack initiation, crack propagation and the adiabatic shear band at the stage of saw-tooth chip forming period were studied, saw-tooth chip forming process was also analyzed by observing the ＂breezed＂ cutting area. The results show that： crack initiation can be observed at the free surface, crack propagation expandes to cutting zone and eventually leads to the chip separation; the saw-tooth chip formation process of hard cutting high strength steel 42CrMo can be divided into four stages.