TC4合金焊接熔池微观组织演变的数值模拟与分析

Numerical simulation and analysis of microstructure evolution of TC4 Alloy weld pool

在MATLAB模拟平台上基于CA-FE法(元胞自动机-有限元)结合晶粒的形核与生长理论,建立了TC4钛合金瞬态焊接温度场下熔池内微观组织演变的数值计算模型,基于该模型对焊接瞬态温度场及其作用下的微观组织演变进行了模拟。结果表明:温度场的计算结果符合焊接热过程局部热量集中且高度动态变化的特点,熔池边缘先形核,在温度梯度作用下晶粒以柱状晶的形式向熔池中心生长,最后形成粗大的柱状晶组织,固态相变阶段,熔池内组织迅速转变为α'马氏体。对模拟结果进行验证性实验,模拟结果与实验结果吻合性良好,显示所建数值计算模型可靠性较高。

Based on the CA-FE method(cell automaton-finite element)combined with grain nucleation and growth theory,a numerical calculation model for microstructure evolution in TC4 titanium alloy molten pool under transient welding temperature field was established on MATLAB simulation platform.Based on the model,the welding transient temperature field and the microstructure evolution under its influence were simulated.The results show that,the calculation results of the temperature field are consistent with the characteristics of local heat concentration and high dynamic changes in the welding heat process.The edge of the molten pool is first nucleated,and under the action of the temperature gradient,the crystal grains grow in the form of columnar crystals to the center of the molten pool and finally form a coarse columnar crystal structure.The microstructure in the molten pool rapidly transforms intoα'martensite in the solid phase transformation stage.The verification experiment was carried out on the simulation results,and the simulation results are in good agreement with the experimental results,indicating that the model is highly reliable.