激光定向能量沉积Al-Mg-Sc-Zr修复5083-H112铝合金的组织和性能

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

激光定向能量沉积增材修复技术具有时间短、效率高、成本低、力学性能好等优点,具有很大的发展潜力。采用Al-7.5Mg-0.3Sc-0.28Zr作为修复材料对轨道交通用5083-H112铝合金进行激光修复实验,得到了致密、无缺陷的修复试样,并对其组织和性能进行研究,探讨了激光修复铝合金的可行性。结果表明,熔合线附近过渡区可划分为修复区、部分熔化区、热影响区和母材。修复区为完全等轴晶,由平均晶粒尺寸为4.95μm的细晶带和18.34μm的粗晶区组成。从修复区到部分熔化区再到热影响区的过渡区域,Al元素含量逐渐升高,Mg元素含量逐渐下降,硬度逐渐下降,修复后母材未被软化。由于激光增材制造技术的快速凝固,在熔合线附近的细晶带有较大的应力集中,由于较小的热输入在部分熔化区、热影响区的残余应力较小。修复试样的屈服强度为(152±2)MPa,为母材的89.4%;抗拉强度为(305±5)MPa,为母材抗拉强度的100%;伸长率为(15.5±0.5)%,为母材的85.2%;断裂发生在强度较弱的母材。高性能的激光修复铝合金是可实现的,具有广泛的应用前景。

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 4.95μm and a coarse-grained region of 18.34μm 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.