Aluminum alloys have been used widely in constructing various space structures including the International Space Station (ISS) and launch vehicles. For space applications, welding experiments on aluminum alloy were performed using the GHTA (Gas Hollow Tungsten Arc) welding process using a filler wire feeder in a vacuum. We investigated the melting phenomenon of the base metal and filler wire, bead formation, and the effects of wire feed speed on melting characteristics. The melting mechanism in the base metal during the bead on a plate with wire feed was similar to that for the melt run without wire feed. We clarified the effects of wire feed speed on bead sizes and configurations. Furthermore, the butt welded joint welded using the optimum wire feed speed, and the joint tensile strengths were evaluated. The tensile strength of the square butt joint welded by the pulsed DC GHTA welding with wire feed in a vacuum is nearly equal to that of the same joint welded by conventional GTA (Gas Tungsten Arc) welding in air.

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Aluminum alloys have been widely used in the constructing various space structures including the International Space Station (ISS) and launch vehicles. For space application, welding experiments of an aluminum alloy were conducted by the GHTA (Gas Hollow Tungsten Arc) welding processes using a filler wire feeder in vacuum. We investigated the melting phenomena of a base metal and a filler wire, bead formation phenomena and effects of wire feeding speed on melting characteristics. The melting phenomenon of melt-run welding with a filler wire was basically the same as that of without a filler wire. It was clarified that the effects of wire feeding speed on bead sizes and configurations. Furthermore the butt welding joints were welded by the optimum wire feeding speed and the tensile strengths of those joints were evaluated. The mean value of tensile strengths of butt welding joints that were made using d.c.-pulsed GHTA welding with filler wire in vacuum was almost same value as that was welded by GTA (Gas Tungsten Arc) welding in air.