In this study, the critical condition of serrated chip formation of 42CrMo quenched and tempered steel considering thermal-mechanical coupled material behavior was studied. It was found that the balance of the strain strengthening and temperature softening of the materials dominated the mechanism of different types of chip formation. Thus, the material constitutive model of 42CrMo quenched and tempered steel considering the items of strain strengthening and temperature softening was established by the Split Hopkinson Pressure Bar (SHPB) tests. The initial condition and final condition for the tooth generation of serrated chips were derived by using the material constitutive model, combining with slip line theory which was used to calculate the local stress. It was found that the critical plastic strain of the serrated chip formation under the different cutting speeds was almost constant. The final strain of the serrated chip formation gradually increased with the increase of cutting speeds. Therefore, the chip types under different cutting conditions could be predicted according to the proposed mathematical model in this study.

在这项研究中，研究了考虑热力耦合材料行为的42CrMo调质钢锯齿状切屑形成的临界条件。发现材料的应变增强和温度软化之间的平衡支配了不同类型切屑形成的机理。因此，通过Split Hopkinson Pressure Bar（SHPB）试验建立了考虑了应变强化和温度软化项的42CrMo调质钢的材料本构模型。利用材料本构模型，结合滑移线理论推导了局部应力，得出了锯齿状切屑产生牙齿的初始条件和最终条件。发现在不同切削速度下锯齿状切屑形成的临界塑性应变几乎恒定。锯齿状切屑形成的最终应变随着切削速度的增加而逐渐增加。因此，根据本研究提出的数学模型，可以预测不同切削条件下的切屑类型。