Welding porosity and nitrogen content are considered significant factors affecting the mechanical properties of fusion-welding joints of high-nitrogen steel. In this study, a method of applying mechanical vibration in the welding process to reduce weld porosity and increase weld nitrogen content was investigated. The effects of mechanical vibration on porosity, tensile, and impact properties were analysed. The results indicated that the bubble floating speed in the vibrating weld pool is faster than that in the general welding mode. With the increase of mechanical vibration frequency, the porosity of the weld decreased at first and then rose. The tensile strength and impact energy increased first and then decreased, and the fracture surface indicated a ductile fracture.

In this paper, the electrochemical microcorrosion behavior of High-nitrogen steel hybrid weld joints with different wires addition were investigated. Polarization curves measurement was conducted to evaluate the corrosion feature in 3.5% NaCl solution. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to analyze the specific corrosion behavior and pitting deepening mechanism induced by precipitated ferrite-dendrites. The experimental results showed that the addition of nitrogen-containing welding wire improved the corrosion resistance of whole weld joint. As a transitional region, the HAZ exhibited relative weak pitting resistance and severe shedding behavior. The coherent dendrites and similar complex geometries led to the accumulation of continuous corrosion channels. The XPS spectra results indicated that the additional nitrogen in the welding wire optimized oxide composition of the surface passive film.

In order to investigate the microstructure of welded joint and corrosion resistance of the weld surface of high nitrogen steel, a laser-arc hybrid welding process was used for welding high nitrogen steel in this paper. The Ar+CO₂ mixed gas was used as the shielding gas above the weldment, N₂ was used as the shielding gas under the weldment. The microstructure of welded joint and corrosion resistance of the weld surface of high nitrogen steel were studied by changing the flow rate of N₂. The results showed that all of the welded joints have an excellent macroscopic appearance, weld nitrogen content increases with increasing N₂ flow, the microstructure of welded joints are austenite and a small amount of delta-ferrite, the higher the nitrogen flow, the tinier the dendrite of ferrite is. Compared with the weld arc zone, the dendrite of ferrite of the weld laser zone is finer. As the nitrogen flow rate increases, the pitting potential of L1-L4 increase, and the corrosion resistance become better. Nitrogen pores appear in the weld of the L5 group, and a large number of pitting pits appears around the nitrogen pores, which significantly reduce the corrosion resistance. Corrosion resistance of the weld arc zone is not affected by nitrogen flow, the dendrites of ferrite in the weld arc zone are peeled from the crystal structure. Compared with the surface of the weld laser zone, the corrosion resistance of the weld arc zone is worse.