聚晶金刚石刀具加工钛合金热塑剪切失稳研究

Research on thermoplastic shear instability in PCD tools cutting titanium alloy

采用聚晶金刚石(PCD)刀具,以不同的切削速度对钛合金Ti-6Al-4V进行了切削实验.通过分析切屑的金相和扫描电子显微(SEM)照片,对PCD刀具加工钛合金Ti-6Al-4V的热塑剪切失稳现象进行了深入研究,分析表明发生热塑剪切失稳时锯齿形切屑齿尖角随切削速度先增大,后减小,并通过计算锯齿形切屑内的剪应变、测量剪切带内外的显微硬度和切屑内的X射线衍射分析证实了在发生热塑剪切失稳时钛合金的组织发生了相变.

With polycrystalline diamond（PCD） tools,Ti-6Al-4V alloy was machined at different cutting speeds.Optical microscope and scanning electron microscopy（SEM） micrographs of chip were analyzed in order to understand the thermoplastic shear instability in PCD tools cutting titanium alloy Ti-6Al-4V.Chip segment angle reduces after the first increase with the increasing of cutting speed when the thermoplastic shear instability happens.It is proved that phase transformation of titanium alloy happens when the thermoplastic shear instability takes place through calculating shear strain in the segment,measuring microhardness and X-ray diffraction analysis.