High-Efficiency and Low-Heat-Input CO_2 Arc-Welding Technology for Butt Joint of Thick Steel Plate Using Hot Wire

摘要

The purpose of this study was to develop a high-efficiency and low-heat-input CO_2 arc-welding process using hot-wire feeding. The optimization of welding conditions using only two welding passes on the butt joint of 20-mm thickness steel plates was investigated using several combinations of hot-wire feeding speed and welding current. Stable welding phenomena, such as molten pool formation and hot-wire feeding during welding, were observed for all tested conditions. A sound joint without any defects could be obtained in only two welding passes using the optimized conditions. The proposed hot-wire CO_2 arc-welding process has potential to simultaneously achieve both high efficiency and low heat input. Use of a higher hot-wire feeding speed with a lower welding current enabled a lower dilution ratio, narrower width of the heat-affected zone, and higher weld metal hardness owing to the resultant lower molten pool temperature and higher cooling speed. The proposed hotwire CO_2 arc-welding process also achieved about 50% reductions in the power consumption and arc time compared with those of the conventional CO_2 arc-welding process on the butt joint of 20-mm thickness steel plates.