Properties Research Of 5A06 TIG Welding Joint And Development Of High Strength And High Toughness Welding Wires

With the continuous progress of Chinese vehicle industry production technology,5A06 aluminum alloy is used widely. Vehicle fuel tank made of aluminum alloy can reduce vehicle weight and improve vehicle performance. But welded aluminum fuel tank in a vehicle often occur fatigue crack because of the vibration of vehicle. Also, aluminum alloy welded structure in other applications requires good fatigue performance. Therefore, improving the fatigue performance of aluminum alloy welded joints become inevitable. Research of high strength and high toughness aluminum alloy wire can meet the demand and widen the application of aluminum connection.This article studied properties of welded joints used four kinds of welding wire (ER4043,5A06,1#:5A06-0.2Cr-0.15Zr-0.05B,2#:5A06-0.20Cr-0.15-Zr-0.05B-0.20-V) and two kinds of welding parameter through metallographic examination, fatigue test, tensile test, microhardness test, SEM, potentiodynamic polarization et al. testing methods. The main conclusions of the present study are below:(1) Developed two kinds of high strength and high toughness aluminum alloy wire.(1):5A06-0.2Cr-0.15Zr-0.05B,2#:5A06-0.20Cr-0.15-Zr-0.05B-0.20V)(2) The welded joint tensile strength with ER4043 was 257MPa and its elongation percentage was 3.7%. Welded joint tensile strength with 5A06 was 313MPa and its elongation percentage was 10.3%. Welded joint tensile strength of 1# wire was 327MPa and its elongation percentage was 12%. Welded joint tensile strength with 2#wire was 341MPa and its elongation percentage was 14.9%. The biggest increase of tensile strength and elongation percentage was 28MPa and 4.6%.(3) Under the condition of 2×106 cycles and 95% livability, the welded joint fatigue strength with 1# wire and 2# wire was 41MPa and 44MPa. Compared with the welded joint fatigue strength with 5A06 wire, it increased 7MPa and lOMPa.(4) Compared with the welded joint with 5A06 wire, The maximum microhardness of welded joint with 1# wire and 2# wire increased 4HV and 11HV and the microhardness of soften zone increased 1HV and 9HV.(5) In the 0.5M NaCl solution, the corrosion resistance of welded joint with ER4043 was better than welded joint with 5A06 wire, but it had a lower Epit. Pitting corrosion was easier. And compared welded joint with 5A06 wire, the welded joint with 2# wire improve the corrosion resistance.