Microstructure and properties of repaired 5083-H112 aluminum alloy by laser direct energy deposited Al-Mg-Sc-Zr

Abstract

Laser repair technology has the advantages of short time, high efficiency, low cost and good mechanical properties, and has great development potential. Al-7.5Mg-0.3Sc-0.28Zr was used as the repair material to conduct laser repair experiments on 5083-H112 aluminum alloy used in rail transit, and a dense and defect-free repair sample was obtained. The microstructure and properties of the sample were studied, and the feasibility of laser repair of aluminum alloy was discussed. The results show that the transition zone near the fusion line can be divided into repair zone, partial melting zone, heat affected zone and base metal. The grains in the repaired area are completely equiaxed, consisting of a fine-grained band with an average grain size of 4.95 μm and a coarse-grained region of 18.34 μm respectively. In the transition area from the repair zone to the partial melting zone and then to the heat affected zone, the content of Al element gradually increases, the content of Mg element gradually decreases, and the hardness decreases gradually. The heat-affected zone and the base metal are not softened after the repair. Due to the rapid solidification of laser additive manufacturing technology, the fine-grain band near the fusion line has larger stress concentration, and the residual stress in the heat affected zone and partial melting zone is small due to the small heat input. The yield strength of the repaired sample of (152±2) MPa is 89.4% of the base metal, the tensile strength of (305±5) MPa is 100% of the base metal, and the elongation rate of (15.5±0.5)% is 85.2% of the base metal. Fracture occurs in the weaker base metal. Laser repair of aluminum alloys is feasible and has broad application prospects.

Keywords

• 5083-h112
• laser direct energy deposition
• laser repaired aluminum alloy
• transition zone
• microstructure
• tensile property