Laser welding-brazing joint for aluminum/steel dissimilar metals

Abstract

In order to suppress the formation of intermetallic compounds, the welding-brazing of aluminum to steel was realized by fiber laser. The interfacial microstructure of the joints was analyzed by OM, SEM, EDS and XRD. The results showed that two kinds of intermetallic compounds were formed along the interface. One is Fe2Al5, strip like, close to the steel side. The other is FeAl3, needle like, close to the aluminum base material. The thickness of the formed intermetallic compounds layer increased with heat input increasing and decreased with the defocus amount increasing. With the increase of heat input, the loading ability of the joints increased firstly and then decreased. Under the given welding heat input condition, a higher loading ability could be obtained at a larger defocus amount, the biggest value reached 58N/mm under the laser output power of 3500W, welding speed of 20mm/s and a defocus amount of 40mm.In order to suppress the formation of intermetallic compounds, the welding-brazing of aluminum to steel was realized by fiber laser. The interfacial microstructure of the joints was analyzed by OM, SEM, EDS and XRD. The results showed that two kinds of intermetallic compounds were formed along the interface. One is Fe2Al5, strip like, close to the steel side. The other is FeAl3, needle like, close to the aluminum base material. The thickness of the formed intermetallic compounds layer increased with heat input increasing and decreased with the defocus amount increasing. With the increase of heat input, the loading ability of the joints increased firstly and then decreased. Under the given welding heat input condition, a higher loading ability could be obtained at a larger defocus amount, the biggest value reached 58N/mm under the laser output power of 3500W, welding speed of 20mm/s and a defocus amount of 40mm.