PCBN刀具材料的性能及切削20CrMnTi合金钢试验研究

以CBN为原料、TiCN和Al为结合剂, 在1550 ℃、5.5 GPa高温高压条件下合成了不同CBN含量的PCBN刀具材料。对PCBN刀具材料进行了显微结构观察、力学性能(磨耗比、硬度)以及高速精密切削20CrMnTi合金钢的切削性能检测。结果表明, PCBN刀具材料的结合剂均匀分布在CBN颗粒周围, 致密性良好;PCBN刀具材料的硬度、磨耗比与CBN含量成正比, CBN含量70%时, PCBN的硬度和磨耗比均最大, 分别为32.97 GPa和7400;高CBN含量的PCBN刀具使用寿命更长。切削试验结果表明, PCBN刀具高速切削20CrMnTi合金钢时的磨损是黏结磨损、氧化磨损、扩散磨损以及局部剥落等各种磨损机制综合作用的结果。

Experimental Study on Properties of PCBN Tool Material and Cutting of 20CrMnTi Alloy Steel

With CBN as raw material, TiCN and Al as binders, PCBN tool materials with different CBN content were synthesized at temperature of 1550 ℃ and pressure of 5.5 GPa. The mechanical properties (wear resistance ratio, hardness) and microstructure of the synthesized PCBN tool materials were tested, and the performance of PCBN tool for high-speed precision cutting of 20CrMnTi was also investigated. It is found that the binder is uniformly distributed around the CBN particles, leading to PCBN tool material with a good compactness. The hardness and wear resistance ratio of PCBN tool materials are directly proportional to the CBN content. With the CBN content of 70%, the hardness and wear resistance ratio of PCBN reach the highest, at 32.97 GPa and 7400, respectively, and PCBN tools with high CBN content have a longer service life. The cutting experiment shows that the wear mechanism of PCBN tool materials mainly includes adhesive wear, oxidative wear, diffusive wear and shell-like spalling at local region during the high-speed cutting of 20CrMnTi alloy.