Interface Characterization and Mechanical Properties of Dual Beam Laser Welded Steel/Al Joints
Y. Ba, X-H. Ren, J-Y. Huang and W-Q. Shi
The laser lap welding method using a disk laser with a dual beam laser welding (DBLW) configuration was used to join DP780 dual phase steel and 5083 Al alloy. The macrostructure and microstructure were observed and it was found that there were five different intermetallic compounds (IMCs) formed in the steel/Al interface. The mechanical properties of the laser welded joints were tested and the relationships between the mechanical properties, microstructure, welding parameters and the failure modes for the joints at different laser energy densities were established. At low and high welding speeds the steel/Al joint has two different fracture modes. The failures occurred in the heat affected zone (HAZ) of weld seam and the interface of steel/Al joint, respectively. These two failure modes were ductile fracture and brittle fracture, with cleavages occurring in fracture surfaces.
Keywords: Disk laser, DP780 dual phase steel, 5083 Al alloy, dual beam laser welding (DBLW), dissimilar joints, macrostructure, microstructure, mechanical properties, heat affected zone (HAZ), intermetallic compounds (IMCs)