| Al-12.7Si-0.7Mg alloy, a novel wrought Al-Si alloy with excellent mechanical properties, is expecting to be used as a substitute for the more commonly used6063aluminum alloy. Therefore, the research related to the welding parameters and properties of this new developed wrought Al-Si alloy is the most pressing issue for the promotion of its application. In this study, Al-12.7Si-0.7Mg alloy plates were used as base materials and automatic MIG straight seam welding was employed. The influence of MIG welding parameters on appearance, microstructures and mechanical properties of welded joints were systematically investigated. In addition, the corrosion resistance of welded joints was preliminary evaluated by means of electrochemical corrosion measurement and immersion corrosion test. The conclusions drawn from this study are summarized as follows:1. The welded joints with best mechanical property can be produced using welding parameters as80Hz pulse frequency,90A, welding current,17.5V welding voltage,4.1m/min wire feeding speed and550mm/min welding speed. Under the above welding conditions, a minimum number of gas pore existed in weld zone (WZ) of the joint.The tensile strength of joints is180.33MPa (equivalent to98.4%that of base metal) and the elongation rate is9.6%;2. The application of Synergic Pulse Welding refined the solidified structure and lowered the porosity of the WZ. The number of gas pore in WZ reduced visibly with increasing the low frequency pulse(1Hz～5Hz);3. Compared with the use of ER4047filler metal, joint strength welded with ER4043is slightly lower. The strength of the joints welded with ER4047and ER4043can reach the strength of90%or more to that of the base material;4. According to the results of electrochemical corrosion and immersion corrosion test, the corrosion resistance for the joints and base material is in the following sequence:joint welded with ER4043> BM> joint welded with ER4047. |
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