| With the rapid development of economy and technology, raw materials and energy consumption increased dramatically. Therefore reasonable use of raw materials and efficient use of resource have become particularly important.Lightweight structural materials have been getting more and more attention.The sandwich plates have become more widespread concern and attention. In recent years, more and more people have been involved in the research of sandwich plates. However they engaged the research on the sandwich panels of the same kind of metal, especially the steel sandwich panels, hardly about dissimilar metals.AZ31B magnesium alloy has a low density and high specific strength. 304 stainless steel has good plasticity, toughness, corrosion resistance and non magnetism. These two kinds of materials have a wide range of application.Magnesium alloy is easy to be corroded. Stainless steel has high density.Extensive use of stainless steel will greatly increase the quality of member. The sandwich plates structures with 304 stainless steel as panel and AZ31 B magnesium alloy as the core will largely solve the use of both defects and alsoplay to their respective advantages. It has great research values and potential applications. Through analyzing and summarizing the dissimilar metal magnesium and steel welding research results, a method with the use of laser welding, adding copper as sandwich method for welding magnesium alloy and steel T-joint is fine.In this paper, the technology and interface of AZ31B-304 stainless steel sandwich plate T-joints with copper foil as intermediate layer by laser welding were studied. The relationships between the formation, microstructures,mechanical properties and the energy of the T-joint were discussed. Then the interface bonding mechanism under different energy and the mechanical properties of the sandwich plate were studied.Through the experimental studies, optimal processing parameters were different when core board thickness of T-joints were not the same. When the thickness of core board d=3mm and the best forming welding parameters were P=1650W, v=0.014m/s. When d=4mm,The best forming welding parameters were P=1700W, v=0.014m/s. The weld penetration increased significantly with the increase of the linear energy. The connection width of AZ31 B and 304 stainless steel, neck width and the ratio of both showed a downward trend with the increase of the linear energy, which showed that when the linear energy was increased, neck width fell faster than the connection width of AZ31 B and 304 stainless steel, and the neck was more serious.With different parameters, the weld were made up of the continuous microstructure(?-Mg+Mg2Cu), ?-Mg and intermetallic compound Mg-Al-Cu located at the interface between the former two substances. There existed a layer of Fe-Cu-Mg-Al interface layer at the lower surface of the stainless steel. In copper completely melted zone, it is Mg-Al-Cu of intermetallic compound and?-Mg below the interface layer. When the energy gradually increased, the intermetallic compounds were fewer and fewer and ?-Mg were more and more,the morphology of Mg-Al-Cu intermetallic compounds became gradually with lamellar + granular, reticular + granular and reticular, and ?-Mg were distributed between Mg-Al-Cu. In copper incompletely melted zone, it were Mg-Al-Cu and incompletely melted copper mixed below the interface layer. Under different thickness of the core plate, in the minimum line energy when panel were welded perforated, the tensile performance of T-joint were best. When d=3mm was 17.6MPa, d=4mm was 13.9MPa, the joint were brittle fracture. Three point bending failure strength of AZ31 B magnesium alloy-304 stainless steel dissimilar metal sandwich plate was 1.3kN. The failure position was the Fe-Cu interface. |
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