装配间隙对铝合金激光-电弧复合焊接头成形及气孔的影响研究

Study on the Effect of Assembly Gap on the Formation and Porosity of Laser-Arc Hybrid Welded Joints in Aluminum Alloys

采用激光先导方式的激光-电弧复合焊对高速列车车体常用的6082-T6铝合金锁底接头进行焊接试验。通过改变水平间隙和竖直间隙的大小,研究其对焊缝成形、熔深熔宽和气孔率的影响,并结合Fluent数值模拟软件进行验证。结果表明,随着水平间隙的增加,焊接接头的熔深和熔宽都呈现逐渐增大的趋势,特别地,当水平间隙从0 mm增大到1.2 mm时,熔深和下部熔宽分别从5.91 mm和1.65 mm增加至6.45 mm和2.46 mm,这主要归因于激光焊接热输入的增大;另外,接头气孔率呈现先下降后上升的趋势,当水平间隙为0.7 mm时,气孔率达到最小,仅为9.21%,小于无间隙时的10.86%和间隙为1.2 mm时的12.61%,这说明一定的水平间隙尺寸有利于提高匙孔稳定性,而过大的水平间隙尺寸则会造成匙孔稳定性变差;另外,随着竖直间隙的增加,尽管接头的熔深熔宽无明显变化,但气孔率呈现不断增大的趋势,从10.86%增大到15.85%,说明竖直间隙的存在不利于维持熔池匙孔的稳定性。最佳装配间隙尺寸为:水平间隙0.7 mm和竖直间隙0 mm。本研究将为采用激光-电弧复合焊接技术来实现高速列车用铝型材的高质量焊接提供工艺指导,并扩大激光-电弧复合焊接在相关领域的应用范围。

Laser-arc hybrid welding with a laser leading method was employed to conduct welding tests on the 6082-T6 aluminum alloy lock-bottom joints commonly used in high-speed train bodies.By varying the size of the horizontal and vertical gaps,the effects on weld formation,penetration depth,weld width,and porosity were studied,and validated using the Fluent numerical simulation software.The results indicate that as the horizontal gap increases,both the penetration depth and weld width of the welded joint show a trend of gradual increase.In particular,when the horizontal gap increases from 0 mm to 1.2 mm,the penetration depth and the lower weld width increase from 5.91 mm and 1.65 mm to 6.45 mm and 2.46 mm,respectively,mainly due to the increase in laser welding heat input.Additionally,the joint porosity shows a trend of first decreasing and then increasing.When the horizontal gap is 0.7 mm,the porosity reaches a minimum of only 9.21%,which is lower than 10.86%with no gap and 12.61%with a 1.2 mm gap.This indicates that a certain horizontal gap size is beneficial for improving the stability of the keyhole,while an excessively large horizontal gap size may cause the keyhole stability to deteriorate.Moreover,with the increase of the vertical gap,although there is no significant change in the penetration depth and weld width of the joint,the porosity shows a continuous increasing trend,from 10.86%to 15.85%,indicating that the presence of a vertical gap is not conducive to maintaining the stability of the molten pool keyhole.The optimal assembly gap size is:0.7 mm horizontal gap and 0 mm vertical gap.This study will provide process guidance for achieving high-quality welding of aluminum profiles for high-speed trains using laser-arc hybrid welding technology,and expand the application range of laser-arc hybrid welding in related fields.