Single-pass full-penetration welding for thick stainless steel using high-current GMAW

This paper describes a high-current Gas Metal Arc Welding (GMAW) process using a constant voltage power source developed for high-efficiency welding of thick stainless steel plates. A short arc length as a welding condition is preferable to concentrate the arc and obtain a deep penetration for thick plate welding. However, it is easily found that an unstable arc derived from a short circuit happens irregularly by using a general purpose GMAW with constant voltage characteristic. A "low-frequency modulated voltage control" was applied for stabilizing a high-current arc that can maintain the short arc length without short circuiting. The welded joint using the developed welding process showed the similar corrosion resistance as that using the submerged arc welding, however, porosity was observed in the welded joints using the developed welding process in the current region of 400A or above. Consequently, a new current waveform control that changes the welding current dynamically and periodically has been developed, which realized reducing porosity and single-pass full-penetration welding of 9mm-thickness type 304 stainless steel plates with square groove. © 2021 Japan Welding Society. All rights reserved.