中文摘要：

随着切削速度进一步提高，带有绝热剪切带（Adiabatic shear band, ASB）的锯齿形切屑会不可避免地发生绝热剪切局部化断裂（Adiabatic shear localization fracture, ASLF），使锯齿彼此完全分离。以淬硬45钢（45HRC）为例，采用前角-10°的PCBN刀具进行进给0．2-0．4mm、切削速度高达l400m／min的高速正交车削试验，获得ASLF发生时的切屑形貌、切削条件以及剪切带内能量变化规律。结合梯度塑性理论，建立高速切削过程热塑性剪切波的传播模型，推导绝热剪切饱和极限（Adiabatic shear saturation limit, ASSL） 及饱和度（Adiabatic shear saturation degree, ASSD）的表达式，提出ASLF判据，并与试验结果进行对比验证，分析讨论剪切带与材料属性、加载条件对ASSD的影响规律。由热塑性剪切波的传播理论推导的ASSL可有效描述剪切带中能量随切削条件的汇聚情况，为今后高速切削领域对锯齿形切屑发生ALSF的预报研究奠定了理论与试验基础。

英文摘要：

As the cutting speed increases further, adiabatic shear localization fracture （ASLF） which is a fracture of adiabatic shear band （ASB） in serrated chip and makes segments separated completely inevitably. High speed machining experiment of hardened 45 steel （45 HRC） is carried out by using PCBN cutter with rake angle -10° at various speed up to 1 400 rrdmin and various feeds from 0.2 mm to 0.4 mm. The chip morphology, the cutting conditions and the corresponding changing regularity of energy in band are obtained. Combining gradient plasticity theory, the propagation model of thermo-plastic shear wave in serrated chip in high speed machining is established. Based on this theory, the expressions of adiabatic shear saturation limit （ASSL） and saturation degree （ASSD） are derived out, the fracture criterion of adiabatic shear localization is proposed and compare with the experimental results. The influences of shear band properties, material properties and loading conditions on ASLF are investigated. The shear band energy with cutting conditions can be described effectively by using ASSL derived from the propagation theory of thermo-plastic shear wave, which lays a theatrical and experimental foundation for the further study of predicting the occurrence of ASLF in serrated chip in the field of high speed machining.