GHTA Welding Experiments under Simulated Space Environment in Flying Laboratory

Abstract

GHTA (Gas Hollow Tungsten Arc) welding experiments were performed in a simulated space environment using aircraft. A vacuum chamber for GHTA welding test was placed in the cabin of the aircraft and the microgravity environment was produced by a parabolic flight of the aircraft.
Spot welding tests on stainless steel plates and girth welding tests of stainless steel pipes were performed in the vacuum chamber under microgravity condition.
The results are summarized as follows,
(1) GHTA method makes it possible 'to form a stable arc and weld stainless plates and pipes in the simulated space environment.
(2) Experimental results show that the arc configuration and the melting characteristics of GHTA are insensitive to the gravity.
(3) The weld bead formation is affected significantly by the gravity. The flat weld with full penetration, as is expected, is formed both in the spot welding and the girth welding under the microgravity condition.
(4) The butt joints of pipes welded by GHTA process in the simulated space environment have no defect good joint strength and the bead appearances is quite satisfactory.