Performance Analysis of Magnetic Field Assisted composite plate Multi - Position Laser Welding Joint

With the X65/DSS2205 composite plate as the research object, the bimetallic composite plate underwent a multi-position laser penetration welding control test, with and without magnetic field assistance. The forces acting on the molten pool in multiple positions were analyzed, the metallographic microstructure of the welded joint was examined, and the distribution and diffusion of characteristic elements were studied using scanning electron microscopy (EDS). The content of intermetallic compounds, grain size, and orientation distribution of the weld were analyzed using electron backscatter diffraction (EBSD), and the tensile properties and microhardness of the welded joint were evaluated. The polarization curve and AC impedance of the welded joint's clad layer in a 3.5% Cl environment were tested, and the influence of multi-position changes on the corrosion resistance of welded joints was investigated. The enhancement effect of magnetic field assistance on corrosion resistance in multi-position welding was assessed. The results indicate that as the welding angle changes in the absence of a magnetic field, the gravitational component in the direction of the weld decreases, causing a large number of clad layer components to flow upstream, affecting the weld's structure and performance. Due to the weld composition, the grain size and adjacent grain boundary angle of ferrite increase, and the angle between the texture and the crack expansion surface also increases, leading to reduced joint hardness but increased toughness. In magnetic field-assisted welding, the Lorentz force inhibits the upward flow of the melt, improves multilayer component retention, and refines and evenly distributes the grains. It also reduces or eliminates pore crack formation, reduces welding stress, changes the texture orientation of the welded joint, slows crack propagation, and improves the plasticity and toughness of the laser-welded joint. Magnetic field-assisted laser welding of composite materials significantly improves the corrosion resistance of welded joints and has a compensatory effect in multi-position welding, especially enhancing corrosion resistance at larger welding angles.