钛合金激光熔丝增材制造的温度场与应力场模拟

Temperature Field and Stress Field Simulation of Titanium Alloy Laser Fuse Additive Manufacturing

激光熔丝增材成形过程中复杂热循环和残余应力分布会使沉积层产生较大的变形甚至开裂.利用ABAQUS软件建立其完全热力耦合有限元模型,采用移动热源子程序模拟激光加载,生死单元技术模拟材料的添加.综合考虑了材料的熔化潜热、对流/辐射换热边界条件、随温度变化的材料非线性等问题,研究Ti-6Al-4V钛合金单道多层薄壁件沉积过程中的热循环特性和残余应力分布.结果表明:沉积成形经历了快速加热、快速冷却的过程,随着层数的增加,热累积效应增强;沉积层整体呈拉应力状态,易产生裂纹等缺陷.

Complex thermal cycling and residual stress distribution during the laser fuse additive forming can cause large deformation or even cracking of the deposited layer.ABAQUS software was used to establish a fully thermo-mechanical coupled finite element model.The mobile heat source subroutine was used to simulate laser loading,and the life-and-death unit technology was used to simulate the addition of materials.The thermal cycle characteristics and residual stress distribution of Ti-6Al-4V titanium alloy’s single-channel multi-layer thin-walled parts during the deposition were studied by considering the latent heat of fusion,convective/radiation heat transfer boundary conditions and material nonlinearity with temperature.The results showed that the deposition process has experienced the rapid heating and rapid cooling.With the increase of the number of layers,the thermal accumulation effect is enhanced.The sedimentary layer is in the tensile stress state and is prone to cracks and other defects.