Research On Fiber Laser Wire Fusion-brazing Welding Of Steel-aluminum Dissimilar Butt Joints

The fiber laser wire fusion brazing welding of6013aluminum alloy andgalvanized low carbon steel with ER4043Al-Si wire was mainly discussed inthis paper. The appearance of welds and thickness of intermetalliccompounds as well as the mechanical properties of melt brazed joints wasresearched.According to the research in laser wire fusion brazing process, theformation of weld surface is affected by the power of laser, the speed offeeding wire and offsets collaboratively. In addition, a conclusion was drawnthat when the power of laser is3.05kW, the aluminum alloy base material isfully penetrated; when the speed of feeding wire is6m/min, the formation ofweld is in good condition; when the offset parameter is0.55, the weld iswell-formed.After the analysis of the microstructure of the fusion brazing weldedjoints using optical microscope, scanning electron microscope (SEM) andenergy dispersive spectroscope (EDS), the composition and microstructureand morphology of typical laser wire fusion brazing welded butt jointindicates that a2-6μm thick layered intermetallic compounds withhierarchical structure is generated on the steel side of braze interface.Specifically, the main component of the intermetallic compound on the steel side is FeAl2, and the main component on the aluminum alloy side is FeAl3.In addition, the intermetallic compound on the steel side has a flat edge whileit has a jagged edge on the aluminum alloy, which indicates that theintermetallic compound is grew from brazed interface to the aluminum weld.The influence of heat input on the thickness on the intermetalliccompound was also studied; three impact factors were illustrated in the paper:the power of laser, the offset parameters and the speed of feeding wire. As thepower of laser increases, the thickness of the intermetallic compoundincreases correspondingly; as the offset parameter increases, the intermetalliccompound decreases (when the offset parameter is1mm, no effectiveconnection would be formed); as the speed of feeding wire increases, thethickness of intermetallic compound decreases. When comes to the fusionratio, the intermetallic compound will increases as the ratio increase.In the end, the relationship between the three factors–the power of laser,the offset parameter and the speed of feeding wire–and the tensile strengthof the joint was researched. All others remain constant, as the power of laserincreases, the tensile strength of the join decrease when using the depth ofpenetration to calculate it. With the increase in the offset parameter, thetensile strength increases limitedly and it is also limited by the requirement offorming the joint, which is no effect connection with1.0mm offset parameter.As the speed of feeding wire increases, the tensile strength increases whencalculating it by the depth of penetration. Besides, the tensile strength is alsoaffected by bevel angle and the thickness of galvanized layer.