6061铝合金激光焊温度场与应力场数值模拟研究

Numerical Simulation Study on Temperature Field and Stress-Strain Field of 6061 Aluminum Alloy in Laser Beam Welding

为了解决激光焊接铝合金对接接头的质量问题,本文采用热-结构耦合有限元技术,建立了在移动高斯热源作用下的三维激光焊接温度场和应力应变场的计算模型。首先,利用有限元软件MSC.Marc模拟焊接过程中试片级试样的温度和应力的变化及其变形情况;其次,研究试样瞬态温度场和应力应变场的变化规律及其分布特征;最后,探讨激光功率和焊接速度对接头质量的影响规律。试验中所选取的激光功率和焊接速度等工艺参数均通过数值模拟进行优化,并根据优化后的工艺参数完成激光焊接4 mm厚6061-T6铝合金平板对接试验。通过对焊接接头形貌的观察及分析进行热源校核,结果表明:仿真计算得到的焊接熔池边界温度达到6061铝合金熔点以上,且其形状分布与实际试验所得焊缝边界基本吻合,从而验证了模拟结果的准确性和可靠性。

To solve the quality problem of laser beam welded 6061 aluminum alloy butt joints,a thermalstructural coupling finite element(FE)technique is used to establish a calculation model for simulating the temperature field and the stress-strain field during the laser beam welding process under the action of 3 D moving Gaussian heat source. Firstly,the FE software MSC.Marc is adopted to calculate the variation of temperature field and stress field and the deformation of the specimens in the welding process. Secondly,the variation law and distribution characteristics of the samples’ transient temperature field and strain field are studied. Finally,the influences of laser power and welding speed on the joint quality are discussed. These welding process parameters selected in the test are optimized by numerical simulation. According to the optimized process parameters,a laser welding 4 mm thick 6061-T6 aluminum alloy plate butt joint test is completed. The heat source is checked by observing and analyzing the microstructure of the weld seam. The results show that the temperature of the boundary molten pool obtained by the simulation reaches the melting point 6061 aluminum alloy. Its shape distribution is consistent with the weld seam boundary obtained in the actual test,which verifies the simulation results’ accuracy and reliability.