Microstructure and Mechanical Properties of Laser Oscillated Welded DP780 Dual Phase Steel and 5083 Aluminium Alloy: Scanning Oscillations at the Same Energy Density

摘要

Steel and Al exhibit large differences in their physical properties and chemical compositions, making welding them together difficult. To obtain high quality steel-Al joints, three laser welding modes were used to perform lap joint experiments on two metals: DP780 dual phase steel; and 5083 Al alloy. The macroscopic morphology, microstructure and mechanical properties of the DP780 dual phase steel-5083 Al alloy joints formed with these different laser welding modes were investigated. The results show that laser oscillation welding can effectively improve the formation of the weld and reduce cracks, spatter and other defects. Laser oscillation welding through the stirring of the molten pool can distribute heat uniformly throughout the molten pool, reduce the content of ferrite in the welded joint and promote the mixing of liquid DP780 dual phase steel and 5083 Al alloy, effectively reducing the generation of an Al-rich intermetallic compound (IMC). After laser pendulum welding the microhardness of the DP780 dual phase steel-side joint was increased significantly by a factor of more than 1 1/2 times over that of the base material (BM). The maximum shear strength of the joint reached 114 N/mm, an increase of 56 compared to that achieved with conventional laser welding.