Research Of Process On CMT Of Aluminum/steel

The aluminum and aluminum alloy/low carbon steel composite structure has the advantages of light weight,high strength,good thermal conductivity,and a wide range of industrial applications.The arc welding cold metal transition?CMT?technology effectively controls the droplet transfer and heat input,and has the characteristics of low welding heat input,no-spatter,etc,making direct arc welding of dissimilar metals of steel and aluminum possible.The use of CMT fusion-brazing technology for the welding of dissimilar metals of steel and aluminum is mostly welded between thin aluminum/aluminum alloys plates and steel plates and the welding is often used in overlapping mode.There is almost no institution about welding between thick steel plates and aluminum plates.The use of CMT fusion-brazing technique for the butt welding experiment of thick steel plates and aluminum plates and the study of the formation mechanism of dissimilar metal welding joints of steel and aluminum have engineering application value and theoretical significance.In this paper,6-mm-thick Q235 steel plate and 1-mm-thick 1060 aluminum soft tape were used for CMT fusion-brazing experiments.The impact of welding process parameters for CMT arc brazing were studied in terms of the solderability,macroscopic morphology of welds,mechanical properties of welded joints and the microstructure.The formation mechanism of steel-aluminum CMT fusion-brazing and steel-aluminum explosion welding joints were analyzed,and a good steel-aluminum CMT fusion-brazing welding effect was obtained,and trials were started on aluminum electrolytic tanks.The results showed that when welding 6mm thick Q235 steel plate and 4 pieces of1mmthick1060aluminumsofttape,applymodifiedflux?Noclock:K₂Si F₆:Sn:Zn=11:1:4:4?to the surface of the steel plate,ER4043 welding wire,welding current 80A,arc length correction value 0,welding speed 600mm/min,the solder wettability is appropriate,the forming and mechanical properties of the welding joint was good,its tensile strength can reach 79.38MPa.The iron-aluminum intermetallic compounds formed at the steel-aluminum interface are Fe Al₃,FeAl₂,Fe₂Al₅,etc,and its thickness is between 3 and 7?m.The tensile strength of steel-aluminum CMT fusion-brazing welded joints meets the established target requirements of pure aluminum tensile strength of 60%or more at normal temperature and 300°C.When they are used under conditions where the force is not applied or the stress is small,steel-aluminum CMT fusion-brazing welded joints are safe.There is no significant difference in the resistance test results of steel-aluminum CMT fusion-brazing and steel-aluminum explosion-welded joints.When CMT melting-brazing is used to directly weld cathode steel bars and aluminum flexible belts on electrolytic cells,the total resistance is as equivalent as using explosive welding block transition welding method.The use of CMT fusion-brazing to directly weld cathode steel bars and aluminum flexible tapes instead of explosive welding block transition welding will reduce manufacturing costs and be expected to bring considerable benefits.