1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. Shenzhen Institute of Central South University, Shenzhen 518057, China; 3. CRRC Industrial Research Institute, Beijing 100073, China
Abstract：Laser additive repair technologyis of great strategic significance to save cost and improve service performance of materials. In this paper, laser directional energy deposition method was used to study the laser repair of Al-Zn-Mg-Cu aluminum alloy substrate in preset slots. After repairing, the microstructure evolution, metallurgical defects and mechanical properties of Al-Zn-Mg-Cu aluminum alloy were studied by means of scanning electron microscopy, electron backscatter diffraction and universal mechanical testing machine. The results show that the crack is easy to occur when the laser scanning distance increases in repair zone. With the increase of laser energy input, the number of holes in the repair zone increases, and the formation of holes is related to the evaporation of Mg. The Al3(Sc,Zr) particles precipitate in the partial melting zone and the boundary of the molten pool in the repaired zone .The Al3(Sc,Zr) particles play a role of grain refinement. The grain orientation of the zone between the interior and boundary of repair zone is different obviously. The grain orientation of the repaired zone is random while that of the boundary of repair zoneis consistent. Most of the tensile samples fracture in the substrate region that is thermally cycled by the laser. When the scanning rate is 600 mm/min and the scanning spacing is 0.8 mm, the tensile samples fracture in the repaired zone, and there are a certain number of holes in the fracture of the sample.
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2022, Vol. 27 
