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Microstructure and Mechanical Properties of Laser Oscillated Welded DP780 Dual Phase Steel and 5083 Aluminium Alloy: Scanning Oscillations at the Same Laser Power
Y. Ba, W-Q. Shi, S-G. Han, J-Y. Huang, Y-P. Xie, J. Huang and K-F. He

To study the effect of laser swing welding on steel–Al welded joints, three different scanning paths were used to weld DP780 dual phase steel and 5083 Al thin plates with a fibre laser. The results show that the oscillating welded joint with the same power has a smaller depth-to-width ratio than the linear welded joint. Laser oscillating welding can refine the grain of the welded joint by disturbing the molten pool, promote uniform mixing of steel and Al reduce defects, and improve the mechanical properties of the welded joint. The microhardness test reveals that the microhardness of the weld zone (WZ) of the three scanning paths is higher than that of the base material (BM); the microhardness of the joint welded in the spiral mode is the highest, and that of the steel side joint and the Al side joint can reach 365 and 302 HV, respectively. The tensile strength of the joint welded in the zigzag mode is the best, and the shear strength per unit length can reach 137 N/mm.

Keywords: Disk laser, DP780 dual phase steel, 5083 Al, laser welding, laser oscillating welding, steel–Al dissimilar joints, macrostructure, microstructure, mechanical properties

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