基于Oyane准则的三通阀体横向法兰热成形起裂分析

Crack analysis in hot forming process of tee-joint valve’s horizontal flange based on Oyane criterion

针对石油管道中关键的AISI-5140三通阀体多向加载过程中起裂问题,建立了多向加载成形的热力耦合刚粘塑性三维有限元模型,通过改变多组凸模加载顺序,选择合适的三通阀体多向模锻的加载路径,确定了上凸模先工作、水平凸模后工作的加载工艺。针对三通阀体成形缺陷中突出的横向法兰热锻起裂缺陷现象,采用体积成形Oyane断裂准则,设计虚拟正交试验,对阀体成形过程中的开裂进行预测,研究成形过程中加载速度、加载温度、摩擦因子等因素对缺陷形成影响。模拟结果表明,成形末期阀体横向法兰端下缘是材料起裂危险区域,法兰端起裂趋势随着摩擦因子的增大而增大,随着凸模加载速度和坯料初锻温度的增大而减小。试验结果表明,合理的加载顺序和工艺参数可以有效提高三通阀体的成形质量。

Aiming at the crack initiation in the key AISI-5140 petroleum pipeline tee-joint valve during multi-way loading forming,the thermo coupled rigid viscoplastic three-dimensional finite element model with the multi-way loading constraint condition was built up.Through changing the sequence of the multi punches loading and selecting appropriate loading path of multi-way die forging for the tee-joint valve,the loading process that the upper punch working first,and then the horizontal punch working afterward was determined. Aiming at the serious crack initiation defect around the horizontal tee-joint valve flange during hot forging forming,during the virtual orthogonal test based on Oyane criterion was used to predict the crack initiation during the forming process of valve,and the influence of loading velocity,temperature and friction factor on the crack initiation was obtained. The simulation result shows that the lower edge on the horizontal teejoint valve flange is the dangerous area of crack initiation,and the trend of crack initiation decreases with the punch working velocity and initial temperature of forging increase,and increases with the increasing friction factor. The experimental result shows that the optimized loading sequence and process parameters can improve the forming quality of petroleum pipeline tee-joint valve effectively.