Effect of Laser Power on Microstructure and Properties of Al/Cu Laser Welding-Brazing Joints
The welding test of 5052 aluminum alloy and T2 copper was carried out by laser welding-brazing.The effect of laser power(2 000,2 200,2 400,2 600,2 800 W)on the microstructure and mechanical properties of the joint was studied.The results show that under different laser powers,the microstructure of the brazing zone on the copper side of the joint was mainly columnar.With the increase of laser power,the dendrites in the weld zone changed from fine acicular shape to snowflake shape.The brazing zone on the copper side was composed of interfacial layer and intermetallic compound layer.The interfacial layer at 2 000 W and 2 600 W laser powers was mainly composed of AlCu phase,and the intermetallic compound layer was mainly composed of Al4 Cu9 phase.The interfacial layer at 2 400 W laser power was mainly composed of AlCu phase and CuZn phase,and the intermetallic compound layer was mainly composed of CuZn5 phase.The weld zone was composed of Al4.2 Cu3.2 Zn0.7 and Al0.71Zn0.29 phases.The thickness of intermetallic compound layer increased with the increase of laser power.The laser power had a great influence on the microhardness of the brazing zone on the copper side,and the maximum microhardness of each joint appeared in the brazing zone on the copper side.With the increase of laser power,the maximum hardness of the joint increased,and the tensile strength increased first and then decreased.When the laser power was 2 400 W,the tensile strength of the joint was the highest,reaching 92％of that of the aluminum alloy base metal.The joint welded at 2 400 W laser power fractured near the aluminum alloy base metal,while joints welded at other laser powers fractured at the copper side brazing zone and weld zone.
Al/Cu dissimilar metal jointlaser welding-brazinglaser powermicrostructuremechanical property
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