【摘要】 为精确预测Ti-6Al-2Zr-1Mo-1V板材热成形过程中的破裂现象,通过实验与有限元模拟相结合的方法建立基于C&L,R&T和Oyane的钛合金板材热成形韧性破裂准则。首先,进行不同温度及应变速率下的钛合金板材单轴等温拉伸实验,得到不同温度及应变速率下的破裂应变。随后,基于得到的破裂应变,利用有限元模拟及点追踪方法得到上述不同韧性破裂准则的损伤参数,通过引入Zener-Holloman参数lnZ,建立损伤参数随温度和应变速率变化的模型。最后,综合考虑变形历史、温度及应变速率对板材破裂的影响,建立基于C&L,R&T和Oyane准则的钛合金板材热成形韧性破裂准则,并将建立的韧性破裂准则应用到钛合金锥形件热旋成形破裂预测。研究结果表明:破裂应变随温度的升高和应变速率的降低而逐渐增大;不同韧性破裂准则的损伤参数随温度和应变速率的变化与破裂应变的相同;Oyane准则预测准确度最高。更多还原

【Abstract】 To accurately predict the fracture during the hot forming process of Ti-6Al-2Zr-1Mo-1V alloy sheets, ductile fracture criterions(DFCs) for the hot forming process of titanium alloy sheets was proposed based on C&L, R&T and Oyane criterions by the combination method of experiments with finite element(FE) simulation. Firstly, uniaxial isothermal tension tests were conducted at different temperatures under various strain rates and the fracture strains were obtained. Then, with the fracture strains, the damage parameters of different DFCs were obtained by FE method and point trace method. By introducing the Zener-Holloman parameter lnZ, the damage parameter model considering the effects of temperature and strain rate was established. Finally, the DFCs for hot forming process of titanium alloy sheets based on C&L, R&T and Oyane criterions were established by considering the deformation history, temperature and strain rate. The established criteria was applied in the hot shear spinning process of titanium alloy. The results show that fracture strains increase with the increase of temperature and decrease of strain rate; the changes of damage parameters of different DFCs are the same as that of fracture strains; Oyane criterion is the most accurate in predicting the fracture occurrence.更多还原