The Gas Hollow Tungsten Arc (GHTA) welding experiments on aluminum pipe were carried out in a simulated space environment and a ground 1G vacuum environment. The square butt welding joints with non root gap on aluminum pipe were made by orbital welding with filler metal using DC-pulsed power supply in the vacuum chamber under the 10-2G and 1G gravity conditions. The butt welding phenomenon during the aluminum DC-pulsed GHTA welding with filler metal recorded in the high-speed video image were analyzed and also the macrostructure and mechanical properties of the butt weld joints were investigated. As the result, it was clarified that the arc discharge and melting-solidifying process during DC-pulsed GHTA welding were insensitive to the gravity condition, because the welding phenomenon greatly receives the effect of the impulsive arc pressure in pulsed current. And also, the GHTA welding experiments under simulated space environment proved that the DC-pulsed GHTA welding process with filler metal could produce the defect-free aluminum butt welding joints with the enough strength safely.
