Phase Transformation upon Dissimilar Laser Welding of Al5083 and SS304

The welding of dissimilar metalsMetals is desirable for light-weighting applications in many industries. The brittle intermetallic compoundsIntermetallic compound present in the dissimilar joints of aluminum alloysAluminum alloys and stainless steelStainless steel affect the joint mechanical propertiesMechanical properties adversely. To improve the dissimilar joint properties, phases including intermetallics in the joints must be identified. Dissimilar joints of Al5083 and SS304 are fabricated with different laser power, ranging from 1 to 2 kW. These joints were subjected to characterizationCharacterization for phase identification and microhardness testing. Phases were predicted by Thermo-Calc software and validated through XRD results and relevant literature. At the dissimilar interface, the first phase Fe2Al5 is experimentally observed from the aluminumAluminum/steelSteel chemical reaction. Phases were also predicted through Thermo-Calc software. It predicted Fe2Al5 and FeAl3 at the interface, while XRD results showed only Fe2Al5 at the interface. High heating and cooling rateCooling rate in laser weldingLaser welding leadsLead to non-equilibrium conditions, and it suppresses certain phases. The high hardnessHardness at the interface of AlAl/steelSteel butt joint is attributed to the brittle intermetallics.