A356铝合金半固态触变成形过程的有限元模拟

FEM Simulation on Thixo-forging of Aluminum Alloy A356

半固态成形技术是一种介于常规铸造和挤压成形之间的金属成形方法。针对高固相率半固态触变挤压成形,开发了一热力耦合半固态触变成形模拟模型。对触变挤压成形过程中温度场分布、最高/最低温度分布规律以及成形过程中模具运动速度对成形力的影响规律等进行了计算和分析。研究发现在半固态触变挤压成形过程中常伴有低于半固态温度的热加工想象出现,高成形速度会降低成形力,但也会导致成形坯料的液固相分离。试验验证中最大成形力与模拟得到的最大成形力相吻合表明,所开发的计算模型能较准确地预测触变挤压成形最大成形力。而成形过程中试验和模拟得到的成形力存在一定差异的事实表明计算模型还可进一步优化。本研究所开发的模拟模型为半固态触变成形提供了重要的理论和试验指导。

Semi-solid forming is a new metal forming technology between conventional die-casting and forging.With an aim to simulate thixo-forging with high solid fraction,a thermal-mechanical simulation modeling was developed.The distribution of temperature field,the highest / lowest temperature points in different forging steps and the effect of die running speed on the forming force were calculated and analyzed during thixo-forging.The calculation results showed that conventional hot-forging could also appear during thixo-forging and that the forming force was decreased with high forging speed,which could lead to negative effect of solid/liquid segregation.A comparison of the maximum forging force from experiment and that from simulation showed that the developed simulation modeling could predict the maximum forging force precisely.However,optimization of the modeling is needed owing to the that the forging force differs in the course of thixo-forging between simulation and experiment.