The microstructure and weldability in welded joints for AA 5356 aluminum alloy after adding modified trace amounts of Sc and Zr

Abstract

Abstract Different AA5356 alloy filler metals containing various amounts of Sc and Zr are obtained and applied to join the 5083 aluminium plate with 2.8 mm thickness. A significant grain refinement can be observed in the fusion zone (FZ) of welded joints after the additions of Sc and Zr. The filler metal modified with 0.2 wt.% Zr+0.1 wt.% Sc obtained the smallest grain size with 29 μm, and the filler metal with 0.2 wt.% Sc+0.1 wt.% Zr additions got the similar grain size with 30 μm. The 0.2 wt.% Sc addition can effectively modify the microstructure of filler metal and improve the mechanical properties. The grain size of fusion zone for AA5356 + 0.2 wt.% Sc+0.1 wt.% Zr filler metal decreased by 75.8 % and the highest ultimate tensile strength (UTS) increases by 15 % compared with the unmodified alloy joints. However, individual 0.2 wt.% Zr addition cannot effectively modify the filler metal. The improvement of mechanical properties can attribute to the presence of refined grains.