The Research Of Welding Process Of Marine 5083 Aluminum Alloy

With its low specific gravity,high specific strength and corrosion resistance,5083aluminum alloy has become the main force of ship lightweight.The traditional welding technology has a large heat input amount and the welding process is difficult to control,which may cause problems such as large deformation after welding and poor performance of welded joints.Pulse welding technology achieves the same welding effect at a lower heat input.The pulse also has a good agitation bath,which makes the grain more refined.The deformation caused by welding stress can be significantly reduced,and the performance of the welded joint is improved.At the same time,the weld seam will form a well-formed fish scale weld under the action of the pulse.In this paper,pulsed laser welding and pulsed TIG welding are used to study the weld formation of 5083 aluminum alloy.In the first part,the 3 mm thickness of 5083 aluminum alloy was butt welded by Nd:YAG pulsed laser.The effect of the technology on the quality,tensile properties and microstructure of the welded joint was studied.The results show that the most serious weld defects in pulsed laser welding 5083aluminum alloy are air holes.Choosing the right combination of power and pulse width laser pulses can effectively reduce the generation of pores.The proper amount of defocusing ensures that the energy of each plane of the aluminum alloy is balanced and the welding quality is better.In the second part,the pulsed TIG welding technology was used to investigate the weld formation of 3 mm thickness of 5083 aluminum alloy by means of non-filling and filling.And the effect of the process on the quality and microstructure of the welded joint was studied.At the same time,elemental composition analysis is performed on the weld zone,the fusion zone and the base metal.After the non-filled wire welding process of 5083 aluminum alloy,it is found that the welding current,welding speed,pulse frequency and heat source height will affect the forming quality of the joint.The final determination is that the welding current is about 160A and the welding speed is 38cm/min.The welding frequency is controlled to 100Hz.The heat source height is kept at 4mm and the preheating current is selected to be 80A,which can achieve better weld quality.Tensile strength is up to 296MPa and the elongation is 7.8%.However,due to the high thermal conductivity of the aluminum alloy during the welding process,the heat loss of the welding is fast.The molten metal at the bottom is rapidly solidified,and the bottom of the welded test piece without the filler wire is mostly fused.After filling the 5356 welding wire,when the wire filling speed is 120cm/min,the tensile strength reaches 315MPa and the elongation is 8.5%.The welded joint performance is further improved.The problem of poor bottom fusion during the non-filled welding is solved.The distribution of Mg element in the weld zone,fusion line zone of 5083 aluminum alloy was investigated.Combined with Al-Mg phase diagram analysis,Mg and Al will form?-Al₃Mg₂ phase with strong solid solution strengthening effect.The content of Mg in the non-filled weld zone is 4.9%,and the content of Mg in the weld zone of the filler wire is 5.4%.It is considered that the increase of Mg content is beneficial to improve the performance of welded joints.