CMT Welding Process And Weld Joints Microstructure Analysis Between Aluminum Alloy And Steel Dissimilar Metals

Aluminum/steel as two kinds of wide range metals, has excellent performance, the aluminum alloy has low density, higher than strength, strong corrosion resistance and other excellent physical and chemical properties. And steel as the most mature industrial base material, has good mechanical performance, the steel can find easily, other metal cannot replace the importance of the steel. More and more field combined with the advantages of the two materials for the optimization and upgrading of products. Such as automobile manufacturing industry is experiencing the steel body becomes the aluminum/steel body, in order to guarantee the safety of the car at the same time, use some of the aluminum alloy to replace some steel parts, for the car weight could loss, so as to improve fuel economy and reduce carbon emissions.There are many kinds of technology for connect the aluminum/steel, but the CMT welding technology as the new welding technology has a unique advantage.This paper use the CMT welding technology to weld the aluminum/steel dissimilar metal sheet for the test, metallographic microscope, SEM, EDS and other methods for welded joint of tissue for analysis.Through a large number of trials, get the optimum process parameters for thickness of 2 mm 6061 aluminum alloy and galvanized steel Q235 in ER4043 filler metal welding wire condition: welding torch position in the middle, the welding speed 300 mm/min, wire feed speed 3.9m/min, the welding current 66 A, voltage 11.9V. Under the welding process parameters, obtained the good weld forming. Under the same parameters, guarantee the same heat input and change the welding wire into ER5183, the welded joint strength is very low.Through the thermodynamic analysis, combined with the interface reaction mechanism, get the intermetallic compounds of FeAl3 is most easily appear in the after of aluminum/steel weld reaction layer, theoretical analysis and actual measured intermetallic compound types are almost the same.Under the condition of the same heat input, respectively using ER4043 wire and ER5183 wire of thickness of 2 mm 5083 aluminum alloy/Q235 galvanized steel for the CMT welding. Use ER5183 wire the welding joint tensile test average maximum load(4.44kN) is much bigger than using ER4043 wire welding joint tensile test average maximum load(1.28kN). From the microscopic analysis because of ER5183 welding wire magnesium content is higher, the magnesium metallurgical combination between iron ability is very poor, but the welding process of magnesium aluminum generated between a large number of eutectic phase, the resulting increase in the number of types of intermetallic compound, leads to the formation of use ER5183 wire weld reaction layer thickness of intermetallic compounds in thickening, thus the forming of welding joint performance becomes poor.