硬质合金基体对涂层刀具高速切削镍基高温合金切削性能的影响

Effects of cemented carbide substrates on tool cutting performance in high-speed machining nickel-based superalloy

采用热常数仪和高温维氏硬度计对Co含量(质量分数)分别为6%和10%的硬质合金进行热学性能与高温力学性能检测,然后用以这2种硬质合金为基体的涂层刀片对镍基高温合金GH4133进行高速车削,采用扫描电镜(SEM)和能谱(EDS)对车削后刀片的磨损区域进行观察和成分分析,研究刀片基体的Co含量对刀具切削性能的影响。研究结果表明,硬质合金中的Co含量由10%降低到6%时,热导率由62.78(W.m)/K升高到84.57(W.m)/K,与此同时同一温度下的高温维氏硬度提高10%左右;YBG202刀片(基体中Co含量为10%)的切削刃与后刀面的磨损均较迅速,而YBG102(基体中的Co含量为6%)刀片后刀面的磨损相对均匀,磨损速率低;基体中的Co含量由10%降低到6%时,刀片的切削寿命提高约3倍。故高速连续切削镍基高温合金时应当尽量选用低Co硬质合金作为刀片的基体。

Two kinds of coated cemented carbide tools with different cobalt contents （mass fraction）of WC-Co substrate, 6% and 10% respectively, were used to investigate the effects of cemented carbide substrate components on the cutting performance of the coated cemented carbide tools for high-speed-turning nickel based superalloy GH4133.The thermal property and high temperature Vickers hardness of the cemented carbide substrates were detected. The morphology and element distribution of the wear region of the cemented carbide tools after high-speed turning GH4133 were observed by scanning electron microscope （SEM） and energy dispersive X-ray spectroscopy （EDS）, respectively. The investigation results show that with the substrate cobalt content decreasing from 10% to 6%, the thermal conductivity of the substrate increas from 62.75 to 84.57 （W.m）/K, and the high temperature Vickers hardness elevates by about 10% at the same temperature. The cutting edge and flank face of the YBG202 insert （containing 10% cobalt in substrate） wear seriously, while YBG102 insert wear steadily and slowly, and the cutting life of the tool increases about 3 times when the cobalt content of substrate decreased from 10 % to 6%. Therefore, the optimized tool selection for continuous high-speed cutting Ni-based superalloy should be coated cemented carbide tools with low cobalt substrate, for example the cobalt content does not exceed 6%.