Influence of Wire Configurations on Welding S355 Structural Steel with Tandem GMAW

Gas metal arc welding is a popular welding method and it has been widely used. A variant to gas metal arc welding, tandem gas metal arc welding utilises two-filler wires and each filler wire has a dedicated power source. The two filler wires are fixed into a single welding torch and work simultaneously when the welding starts. When fixing two wires into a single welding torch, the wire configuration may have a great influence on the welding quality. In this research, the purposed is to study how the wire configuration, i.e. the inter-wire distance influences the welding result. Three groups of inter-wire distances and welding speed are chosen to be the main variables in this work: the inter-wire distances chosen are 9 mm, 17 mm and 21 mm and welding speeds 1 m/min, 1.25 m/min and 1.5 m/min. The examination concentrates on the visual inspection of the welding, the amount of heat input, macro-picture analysis, micro-picture analysis, dilution analysis and hardness test to the weld zone. The result suggests that with the 17 mm inter-wire distance, the weld appearance is at its best and the weld penetration is the deepest with an average penetration of 2.94 mm. The results also indicate that the heat input decreases when increasing the welding speed. Better welding quality is achieved with 1.5 m/min welding speed.