Research On BC-DSAW Process Of Marine Aluminum Alloy And Numerical Simulation

In recent years, Aluminum alloy is more and more widely used in the filed of ship construction in our country. Due to its light weight, high corrosion resistance and excellent mechanical properties, aluminum structure can greatly improve the flexibility of the ship,navigation speed and the service life. The traditional aluminum alloy welding methods are tungsten/metal inert-gas welding (TIG/MIG), which have some limitations in welding quality and efficiency. Therefore, It is significant to develop new aluminum alloy welding process to strengththeship-construction.In this paper, the low heat input and high efficiency welding process of bypass-current MIG-TIG double-sided welding (BC-DASW) was applied. Compared with any of TIG, MIG or bypass-current MIG-TIG single-sided welding process, BC-DSAW can greatly improve penetration and heat melting efficiency, while reducing the welding production cost. The different welding parameters on influence of mechanical properties of BC-DASW was investigated, The microstructure of joints and morphology of aluminum joints were researched. Meanwhile, considering of vessels long-term sailing in the sea, the corrosion property of joint was tested, including cyclic polarization curves and nyquist diagram, in order to compare the corrosion resistance of the weld zone and the base metal region.The results showed that BC-DSAW welding technology could obtain stable process and good welding appearance for joining marine aluminum alloy. "1 + 1 >2" synergy effect occurred in the molten pool under double-side heat source, which showed medium X-shape.Which made both hardness and tensile properties are higher than the base metal. The corrosion test showed that intermetallic compounds grain, and primary silicon particle sizes not only improve the corrosion properties of the weld zone, but also higher than the base metal in the field of corrosion degree and resistance, which met the requirements of strength and corrosion of aluminum alloy vessels during the navigation process. Considering that the characteristic coupled arc attract each other in the process of BC-MIG, we found attraction also existed in BC-DSAW process through making the main torch and other side torch offset in the vertical direction of the butt weld. Meanwhile, according to the accuracy problem in the construction of vessels and the preheating on the welding efficiency of aluminum alloy,the adaption of BC-DSAW process to tandem arc welding was studied.The ANSYS finite element method was used based on the conclusion of experiments and double ellipsoid heat source distribution model was adopted in the numerical simulation.We analyzed the temperature field and displacement field between different welding processes, which indicated that the temperature field distribution of the double side welding is similar to the appearance of the weld pool. Meanwhile, double side heat sources played a positive role in the control of welding deformation.Comprehensive results show that BC-DSAW can significantly improve the welding efficiency of aluminum alloy construction, and owns high practicability and considerable application prospect.