The Research Of CMT Brazing Of Aluminum Alloy And Steel

The composite structure of aluminum and steel has many comprehensive advantage, such as quality light,high strength and corrosion resisting. And it was wildly used in aerospace, automobile making and shipbuilding industry. However, the low solid solubility, the different thermos physical properties, easy to form brittle intermetallic compound makes the welding of aluminum and steel become a hard point in the area of welding. Now days, for the ability of convince and high efficiency, the CMT brazing has become a hot point of the research of the welding of Al and steel. How to improve the wetting spread ability and control the growth of brittle intermetallic compounds are the key to obtain a good joint of Al and steel.In this paper, using aluminum alloy of 5083 and 5052 and EH36 to do CMT brazing experiments to research the influence of different welding parameters to the microstructure and mechanical property of the joint. Besides, research the reaction mechanism of alloying element control the growth of interface layer. At last, gain the best welding parameters and understand the reaction mechanism of alloying element control the growth of interface layer.Results show that the welding of 5052 and EH36 can achieve a good joint with good macro morphology and mechanical properties, the stubble shaped IMCs of 3-5μm were evenly distributed in the interface under appropriate welding parameters. Using Nocolok flux with 30% Zn as flux, Al Si5 filler, both aluminum and steel open a 50° groove, filler speed is 4.3m/min, welding speed is 100mm/min.Results show that the welding of 5083 and EH36 can achieve a good joint with good macro morphology and mechanical properties under appropriate welding parameters. Using Nocolok flux with 30% Zn as flux, Al Si5 filler, open a 6mm wide molding groove on the back, filler speed is 4.3m/min, welding speed is 100mm/min.Analysis the action mechanism and infer IMC-growth model controlled by of alloying elements in the interface. It can be found that Si can improve the flexibility of filler and formed Fe8Al2 Si. It will formed large IMCs when the contents of Si increase to 12%. It will affect the property of joint. The contents of Zn can control the shape and thickness of IMCs, too high or too low will both formed large IMCs, affect the property of joints.