Fig. 1. Metallographic microstructure of A7204 aluminum alloy

Fig. 2. Schematic of welding experimental setup

Fig. 3. Schematic of tensile specimen

Fig. 4. Macroscopic appearances of welds under three kinds of filler wires. (a) ER5087; (b) ER5356; (c) ER4047

Fig. 5. Microstructures at different positions of welds under different filler wires. (a) ER5087,upper part ; (b) ER5356, upper part; (c) ER4047, upper part; (d) ER5087, lower part; (e) ER5356, lower part; (f) ER4047, lower part

Fig. 6. (a) Tensile properties of joints welded with three kinds of filler wires and base metal after natural aging; (b) cross-sectional morphology of joint welded with ER5087 filler wire after natural aging

Fig. 7. Microhardness of joints welded with three kinds of filler wires

Fig. 8. Microhardness at different positions of joints welded with ER5356 filler wire. (a) Upper part; (b) lower part

Fig. 9. TEM images at different parts of joints welded with ER5356 filler wire and some diffraction spots. (a) Weld; (b) base metal; (c) heat-affected area near to weld; (d) heat-affected area far from weld