Ti6Al4V钛合金薄板退火畸变数值模拟及试验验证

Numerical simulation and experimental verification for distortion of Ti6Al4V titanium alloy sheet during annealing

对Ti6Al4V钛合金薄板在退火过程中发生的热处理畸变进行计算机模拟和试验研究,采用MSC.marc软件建立三种有限元模型,分析对比三种模型畸变模拟结果及试验结果,研究薄板热处理畸变规律。结果表明,残余应力引起的蠕变和弹性应变是畸变的主要原因,热粘塑性模型(Model 3)能较为准确地预测Ti6Al4V钛合金薄板退火畸变,热弹塑性模型(Model 1)模拟结果与试验结果差别较大,蠕变是预测畸变准确性的关键因素。残余应力导致薄板上下两部分X、Y方向应变,迫使薄板发生弯曲畸变,内部残余应力是薄板在退火过程中发生畸变的根本原因。重力改变弹性应变方向,总应变增大,从而使得薄板畸变量增大。

Heat treatment distortion of Ti6Al4 V sheets during annealing was investigated using numerical simulation and experiment methods.Three kinds of finite element model were built with MSC. marc software. The simulation results under the three models and experimental results were analyzed and compared to explore the law of heat treatment distortion. The results indicate that residual stress induced creep and elastic strain are responsible for heat treatment distortion. Thermal-viscoplastic model（ Model 3） is more accurate than thermal-elastic-plastic model（ Model 1） in predicting heat treatment distortion of Ti6Al4 V sheet during annealing. Meanwhile,creep is the key factor to accurately predict distortion. The internal residual stress,which changes strain distribution and forces the sheet to bend,is the fundamental reason of distortion. Gravity changes the direction of elastic strain,increases the total strain,and thereby increases the distortion of the sheet.