Investigation On The Preparation Of ER5356 Welding Wire For Al-Mg Alloy And The Microstructure And Properties Of Welded Joint

Because of the trend of the light weight and high speed of the ship,Al-Mg alloy has become a promising material for the shipbuilding industry.Part of steel is replaced by Al-Mg alloy welding component as the superstructure and ship outfitting,weight can be reduced to reach more than 50%,it can also make up for the loss of steel due to corrosion during service.At the same time,the choice of welding wire directly affects the performance of welded structural materials.However,the quality of welding wire developed by our country cannot be compared with the quality of foreign welding wire because of the problem of welding wire production technology.Based on this,a kind of ER5356 aluminum alloy welding wire was prepared by continuous extrusion—drawing—scraping lighting technology,and was also welded with 5083 aluminum magnesium alloy plate used in ship by Metal Inert-Gas Arc Welding(MIG welding).According to the requirements for evaluating the welding process of marine aluminum alloy,the microstructure and properties of welded joint of 5083 aluminum magnesium alloy were investigated by such as microstructural observation methods of metallography,scanning electron microscopy,electron backscatter diffraction(EBSD)and transmission and also combining with such as properties test methods of micro-hardness testing,tensile mechanical properties test,bending test and penetration test,etc.,so as comprehensive to assess the quality of self-made alloy welding wire and the welding effect.The subject has completed the following two aspects:(1)ER5356 aluminum alloy wire billet with a diameter of 3.2mm with good surface quality can be prepared when the extrusion speed is set between 9~16r/min,the extrusion temperature is set between 400~450 ?through repeated continuous extrusion tests and the parameters adjustment.Through multiple water tank pullout tests and parameters adjustment,it is found that the fatigue layer and oxide layer of the wire surface can be scraped away completely when the drawing speed is between 10cm/s~14cm/s and the drawing die exhibits good lubrication degree,ER5356 aluminum alloy finished wire with a diameter of 1.6mm is obtained.(2)Using self-made ER5356 welding wire to weld the annealed 5083 aluminum magnesium alloy sheet by MIG welding,and then the macroscopic morphology,tensile mechanical properties,flexural properties and permeability properties of the welded joints were tested.The test results show that the tensile strength of the welded joint of the 5083 aluminum magnesium alloy sheet is 287 MPa,and the strength coefficient is 84%.The quality of bending and penetration tests is all in line with the relevant standard requirements of the shipbuilding industry.The welding structure has fully met the requirements of the actual welding and the use of the ship.