铝合金不等厚板的CO2激光拼焊及数值模拟

采用CO2激光器,在填加和不填加合金粉末两种条件下,进行了不等厚铝合金(5A02,5A06)薄板的激光拼焊,研究了影响焊接过程稳定性和焊缝成形性能的主要因素,并用有限元方法(FEA)对焊接过程的温度场和应力场进行数值模拟,分析了拼焊板的残余应力分布和变形特点.试验结果表明,镁含量较高的铝合金对激光束的吸收率高,因此达到稳定深熔焊的临界功率密度较低,容易获得稳定的深熔焊过程;填粉能提高铝合金对激光的吸收率,使激光焊接中等离子体更加稳定,使焊接过程更趋稳定,更易得到成形优良的焊缝.模拟结果表明,不等厚铝合金板激光拼焊的温度场不对称,不等厚板的残余应力场和应变场也分布不对称,薄板上残余拉应力范围比厚板大.薄板整体变形大于厚板且比厚板复杂.

CO2 Laser Welding of Tailored Aluminum Alloy Sheets with Different Thickness and Numerical Simulation

CO2 Laser welding of 5A02 and 5A06 aluminum alloys sheet with different thickness is performed with or without the addition of filler metal powder.The main factors affecting welding process stability and formability of weld are investigated.Meanwhile,based on the finite element analysis(FEA),temperature field and the stress-strain field of aluminum alloy with different thickness on laser welding are simulated.The residual stresses distribution and deformation features of tailored welded blanks(TWB) are analyzed.The results indicate that with the increasing of magnesium in aluminum alloys,the absorptivity is also improved,so a stable welding process can be obtained for a higher content of magnesium in aluminum alloys.The addition of the metal powder can enhance the energy coupling efficiency during laser welding of aluminum alloys sheet with different thickness,and the weld formation and process stability can be improved greatly.The simulated results indicate that temperature field distribution is unsymmetrical.The distributions of the stress-strain are also asymmetric.The distributions of pulling stress field in the thinner plate are larger than that in the thicker one and the deformations in thinner plate are more serious than that in thicker one.