Chip morphology is one of the evaluation indexes of cutting performance of cutting tools, and chip forming process has a direct and important influence on chip morphology. High-strength steel 40CrMnMo is one of typical oil country tubular goods (OCTG) and difficult-to-cut materials, and its chip morphology represents the machining quality of OCTG. The chip forming process of a new independent-developed microgroove turning tool for turning oil country tubular goods 40CrMnMo is researched, combining machining experiments with theoretical analysis. Research results show that with the increase of cutting speed, the initial radius of curvature of the chip fluctuates slightly, but the overall trend is upward. However, the ultimate radius of curvature decreases and the chip’s radius ratio also decreases. The relative ideal chip can be obtained if the proper cutting velocity and feed rate are given. Chip morphology results from the comprehensive effect of the two processes: The fracture and separation process of the workpiece during passing through the shear deformation zone and the process of curling and breaking away of the chip after passing through the rake face of the tool. The research results have a certain guiding significance for controlling the cutting process of machining the other material with similar performance.

切屑形态是切削刀具切削性能的评价指标之一，切屑形成过程对切屑形态有着直接而重要的影响。高强钢40CrMnMo是典型的油井管材和难切削材料之一，其切屑形貌代表着油井管材的加工质量。将加工实验与理论分析相结合，对自主研发的新型油田管材40CrMnMo微槽车刀的切屑形成过程进行了研究。研究结果表明，随着切削速度的增加，切屑的初始曲率半径略有波动，但总体趋势是向上的。然而，极限曲率半径减小，切屑半径比也减小。如果给定适当的切削速度和进给量，可以获得相对理想的切屑。切屑形态是工件通过剪切变形区时的断裂分离过程和切屑通过刀具前刀面后的卷曲脱离过程这两个过程综合作用的结果。研究成果对于控制加工其他性能相似材料的切削过程具有一定的指导意义。