Ti6A14V 高效切削加工中绝热剪切带内微观组织演变及其形成机制

为了给钛合金的切削加工工艺制定提供参考，对Ti6A14V高效切削加工中绝热剪切带内微观组织演变及其形成机制进行研究。将Ti6Al4V看作切削材料，在不同情况下完成切削，选择有代表性的切屑当成制作金相的样本，给出切削实验工艺参数。选用蔡司金相显微镜对金相组织进行观察，通过Digimizer对锯齿金相的齿距、自由表面、带倾角和带宽进行测量，以体现锯齿化程度。针对金相样本，通过绝热剪切带内微观组织演变方法研究了切削速度和刀具前角对切屑的影响，以及进给速度对锯齿成形的影响，分析了Ti6Al4V切削形成机制。结果表明，在切削速度与进给速度逐渐增加，刀具前角从正值变化至负值的情况下，Ti6Al4V切削锯齿化程度增强；在切削速度、进给速度增加，刀具前角降低的情况下，绝热剪切程度增强；Ti6Al4V切削形成符合热（粘）塑性失稳机制。

Microstructure evolution and formation mechanism of adiabatic shear band in Ti6A14V high efficiency cutting process

In order to provide a reference for the formulation of cutting process for titanium alloy, the microstructure evolution and formation mechanism of adiabatic shear band in Ti6A14V high efficiency cutting were studied. Taking Ti6Al4V as cutting material, cutting was completed under different conditions, and representative chips were selected as metallographic samples. The cutting experimental parameters were given. Zeiss metallographic microscope was used to observe the metallographic structure. The tooth pitch, free surface, band inclination and bandwidth were measured by Digimizer to reflect the degree of sawtooth. For metallographic samples, the effect of cutting speed and tool rake angle on chip formation and feed rate on sawtooth forming were studied by means of microstructure evolution in adiabatic shear band. The cutting mechanism of Ti6Al4V was analyzed. The results show that the sawtooth degree of Ti6Al4V cutting increases with the increase of cutting speed and feed speed and the change of tool rake angle from positive value to negative value system.