Abstract
Hot wire gas tungsten arc welding (HW-GTAW) process is the one where the filler wire is pre-heated close to its melting point before it is fed in to the arc. The effect of HW-GTAW parameters such as welding current, hot wire current and the wire feed rate during welding of super ASS 304H stainless steel tubes were evaluated in terms of heat input, voltage-current (V-I) characteristics and weld bead characteristics such as bead weight and geometry. The results obtained indicate that for a constant welding current, increasing the hot wire current and wire feed rate provides a stable V-I characteristics and higher bead weight. Further, increasing the hot wire current and wire feed rate also provides better or desired weld pool and hence the bead geometry was described in terms of width, penetration depth, area of fusion and toe angle. By utilising the above knowledge, the tube to tube butt welding of SS 304H material was carried out. It was observed that, the weld joint is qualified as per the quality requirement of ASME: Sec IX standard.
Highlights
Hot wire gas tungsten arc welding (HW-GTAW) process is a modified gas tungsten arc welding (GTAW) process in which the filler wire is pre-heated before entering the weld pool[1]
In case of HW-GTAW process, as the filler wire is resistance heated before entering the weld pool, the current used to heat the filler wire, referred as hot wire current influences the quality of welding
The effect of the aforementioned process variables of HW-GTAW of super 304H stainless steel tube used for boiler manufacturing has been evaluated by characterising the welding process and joint for (a) heat input (b) V-I characteristics (c) weight of the metal deposited and (5) bead geometry described in terms of bead width, depth of penetration, area of fusion and deposit, toe angle
Summary
Hot wire gas tungsten arc welding (HW-GTAW) process is a modified gas tungsten arc welding (GTAW) process in which the filler wire is pre-heated before entering the weld pool[1]. Though many research work has been carried out on evaluating the V-I characteristics and its influence on weld quality in conventional GTAW5,6, studies on HW-GTAW process are rather sparse[7]. The effect of the aforementioned process variables of HW-GTAW of super 304H stainless steel tube used for boiler manufacturing has been evaluated by characterising the welding process and joint for (a) heat input (b) V-I characteristics (c) weight of the metal deposited and (5) bead geometry described in terms of bead width, depth of penetration, area of fusion and deposit, toe angle.
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