Pretreatment mechanism and experiment of 6061 aluminum
alloy by nanosecond laser before welding
1. School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003, China; 3. Key Laboratory of Surface Engineering Technology for Water Resources and Hydropower Equipment in Zhejiang Province, Hangzhou, Zhejiang 310012, China)
Abstract：The nondestructive and environmentally friendly laser cleaning technology with high efficiency was used for pretreatment before welding. The mechanism of laser pretreatment for the oxide layer of 6061 aluminum alloy was theoretically analyzed by partial differential equation of heat conduction. The simulation results show that the surface temperature is increased rapidly by laser irradiation. The temperature peak of Al2O3 is approximately 4 times value of that of aluminum alloy matrix after absorbing the same laser energy, and the thermal effect becomes more obvious under wider pulse width. The mechanism of laser pretreatment for oxidation layer is gasification. The characteristic analyses of surface morphology and oxygen content by nanosecond pulse laser show that the pretreatment process can cause secondary oxidation due to thermal effect of high laser energy. The pit depth tends to be stable with the increasing of laser energy. The oxidation layer can be effectively removed for the laser energy from 15 W to 25 W. The oxide layer still exist on the surface when the laser power is less than 15 W.
2019, Vol. 40 
