材料强化因素对切削过程中尺寸效应的影响

摘要

Finite element-based orthogonal cutting simulations were performed with titanium alloy TiAl6V4.The orthogonal cutting experiments were used to validate the numerical model.Based on the systemic simulation results,the dependences of strain,strain rate and temperature in the primary and secondary shear zone on the uncut chip thickness were investigated.The influences of material strengthening factors,including strain,strain rate and temperature effects,on the ＂size effect＂ in specific cutting energy were further discussed.The results show that,the strain and strain rate dependences of material flow stress have no effect on ＂size effect＂,while the thermal-softening effect plays a dominant role in causing ＂size effect＂.In addition,the ＂size effect＂ can be attributed to a drop in the primary shear zone temperature and an increase in the tool-chip contact length.%针对航天航空常用材料TiAl6V4的正交切削过程开展了一系列的有限元模拟,进行了相应的切削实验用以验证模拟的可靠性。基于系统的数值仿真,考察了切削过程中主次剪切区的平均应变、应变率、温度随切削厚度的变化规律,集中研究了材料应变、应变率强化及热软化因素对切削过程中＂尺寸效应＂现象的影响。研究结果表明,材料应变和应变率强化因素对＂尺寸效应＂没有太大影响,而材料热软化作用是导致＂尺寸效应＂形成的重要因素。另外,随着切削厚度的减小,主剪切区温度降低以及刀具和切屑间单位接触长度非线性增加是造成＂尺寸效应＂的主要原因。