不同后处理对MT-TiCN涂层刀具组织与切削性能的影响

目的研究不同后处理工艺(包括热处理、湿喷砂和刃口处理)对MT-TiCN涂层组织与刀片切削性能的影响。方法采用中温化学气相沉积技术在硬质合金刀片上制备TiCN涂层;利用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪分析MT-TiCN涂层的组织形貌、相结构、硬度和弹性模量;在AISI 4340合金钢上进行车削试验。结果 MT-TiCN涂层呈柱状晶结构,涂层沿(422)晶面方向择优生长,且织构系数达5.5;涂层表面和断口平均硬度分别为26.6 GPa和30.7~31.8 GPa,平均弹性模量分别为528.6 GPa和467.7~494.4 GPa;在连续车削条件下,经湿喷砂处理的涂层刀片切削性能最佳;在低切深、低进给断续车削工况下,湿喷砂后又经热处理和刃口处理的涂层刀片使用寿命最长;湿喷砂后再进行热处理,对刀具的切削性能影响较小。结论湿喷砂和热处理对MT-TiCN涂层组织的影响较小;不同后处理工艺对涂层刀具切削性能的影响较大,这主要是因为刃口处理会减小涂层厚度同时提高涂层韧性。

Influences of Different Post-treatments on Microstructure and Cutting Performance of MT-TiCN Coated Cutting Tool

The paper aims to elucidate influences of different post treatments (heat treatment, wet blasting and brushing) on microstructure and cutting performance of MT-TiCN coating. The MTCVD was adopted to prepare TiCN coatings on the carbide blade; optical microscope (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), nano-indentation tester were used for the characterization of microstructure, phase structure, hardness and elastic modulus; turning tests were applied on alloyed steel AISI 4340. MT-TiCN coating had a columnar microstructure and highly oriented at (422) plane with a texture coefficient up to 5.5; the average hardness of the surface and the cross section were 26.6 GPa and 528.6 Gpa, respectively; and the average elastic modulus were 30.7~31.8 GPa and 467.7~494.4 Gpa, respectively; the coated blade after wet blasting treatment had the best cutting performance under continuous cutting; the coated blade treated by the combination of heat treatment, wet blasting and brushing had the longest service life during interrupted turning under dry conditions with small depth of cut and feed rate. The heat treatment after wet blasting had few influences on cutting performance of cutting tools. Wet blasting and heat treatment have few influences on the MT-TiCN coating. Different post treatment processes have great influences on cutting performance of coated cutting tools, because the brushing reduces the thickness and improves the toughness of t coating.