Applications and benefits of adaptive pulsed GMAW
Keywords:Adaptive Pulsed, GMAW, high energy, heat input, weld properties
The aim of this study was to investigate adaptive pulsed GMAW processes, considering possible benefits when welding thicker sections (> 3 mm) and structural steel. Adaptive pulsed GMAW processes are adaptive in that electrode feed speed is automatically adjusted and corrected to the mean pulsed current or voltage variation. In addition, current and voltage waveforms and welding parameters are modified to improve control of repeated peak and background values occurring during pulsed GMAW. The study experimentally tested the usability of adaptive welding processes and evaluated effects on weld properties, penetration and shape of the weld bead. The study first briefly reviewed adaptive GMAW to evaluate different approaches and their applications and to identify the benefits of adaptive pulsed GMAW. The literature shows that better control of current waveform and use of advanced power sources successfully improved welding quality of thin sheet metal. To assess applicability with thicker sheet metal (5 mm) experiments were then per-formed using Synergic GMAW, Synergic Pulsed GMAW and WiseFusionTM to weld a fillet weld (PB position). The air gap between the parts ranged from 0 to 2.5 mm. The base materials were structural steel grade S355MC, 5 mm thickness, and filler material G3Si1. The experiment inves-tigated heat input, mechanical properties and microstruc-ture of the welded joint.
The WiseFusionTM bead had the highest dilution of the processes tested, due to the weld bead shape, and the weld showed low defects such as porosity, undercut, and excessive or lack of reinforcement.
It was concluded that adaptive pulsed GMAW processes can be a favoured choice when welding struc-tures with many welded joints. The total heat reduction mitigates residual stresses and the bead shape allows a higher amperage limit. The stability of the arc during the process is virtually spatter free and allows an increase in welding speed.