Mechanical properties and structure of welded joints of the sheets of aluminum alloys of the Al-Ca-Zn-Mg system performed by automatic argon–arc welding

Abstract

We study the mechanical properties of welded joints of the sheets of aluminum alloys of the Al-Ca-Zn-Mg system additionally alloyed with zirconium and scandium. These joints are performed by the method of automatic argon-arc welding. We applied two versions of the procedure of automatic argon-arc welding, namely, without scanning and with scanning of the anode spot of the arc over the surface of the weld pool. It was established that the application of the procedure of scanning the anode spot of the arc over the surface of the weld pool contributes to a decrease in the volume of discontinuities appearing in the metal of the weld in the form of pores. The ultimate strength of welded joints of the sheets of Al-Ca-Zn-Mg alloys without internal defects in the welds is as large as 0.82–0.85 of the level of ultimate strength of the base metal. Moreover, the fracture of the specimens in the course of tensile tests occurs in the zone of fusion. In the presence of defects in the form of pores in the weld metal, the value of ultimate strength decreases down to 0.70–0.75 of the strength of base metal with breaking of the joints in the tests carried out in the weld metal. The bending angles of welded joints vary within the range 45–60°. It is shown that the compounds obtained by adding the Sv1575 filler wire exhibit higher values of the mechanical properties as compared with the SvAMg63 filler wire.