Effect of electrode wire surface integrity and surface oxides on the stability of gas metal arc welding

ER70S-6 gas metal arc welding (GMAW) wire electrodes are widely used in various market segments. Stability of GMAW process is vital for obtaining desired welding performance. The random variations in voltage transients can represent welding consumable quality. In the present study, wire electrodes from three sources were analysed in standard synergic and pulse synergic GMAW using digital storage oscilloscope (DSO) and high-speed camera setup. The recorded voltage data were analysed using time domain and probability density distribution (PDD) analysis. High speed camera images were used to understand abnormal voltage variations observed in voltage oscillograms and PDD patterns. Results confirmed the presence of signatures of wire quality in the variations of analysed voltage transients along with high speed camera images. Microscopic examination confirmed damaged wire surface and presence of remnant oxide layer post manufacturing on the wire surface/sub surface as the main reasons for poor product performance and arc instability. The method adopted in this work can help end users in selecting appropriate welding wire to enhance productivity and can also help wire manufacturers to improve their product quality.