High-strength steel welding with consumable double-electrode gas metal arc welding

Low heat input is typically desired for welding high-strength steels to ensure that the mechanical behavior of material in the HAZ would not change significantly after welding. However, a high current, and thus a high heat input, is required to melt more wire to achieve a goal of increased productivity through increased deposition rate. A novel process referred to as Consumable Double-Electrode GMAW or DE-GMAW has been developed to increase the deposition rate without increasing the heat input. This work studies the characteristics of the heat-affected zone (HAZ) including the HAZ size, microstructure, and the hardness of high-strength steel ASTM A514 welded by DE-GMAW. It is found that, to obtain the same deposition rate, the DEGMAW process can significantly decrease the heat input using a low base metal current, in comparison with conventional GMAW, to achieve a small HAZ and low joint penetration. The low heat input caused a fast cooling rate and high hardness in the HAZ.