1996 Volume 14 Issue 4 Pages 633-640
The characteristics of the GHTA (Gas Hollow Tungsten Arc) welding of aluminum alloy in a vacuum are shown in the present paper. The results are summarized as follows,
(1) There is a shifting phenomenon of arc discharge in which transient arc discharge shifts via the transitional arc discharge to the stationary arc discharge under GHTA welding in a vacuum, and the characteristics of current and voltage of these discharges are shown.
(2) The period of transient arc discharge could be shortened by increasing the flow rate of argon, using the 2%La2O3-W electrode and/or by decreasing the initial current.
(3) The surface of electrode and collet body is eroded by the vaporization of the material during the transient arc discharge. The amount of vaporized material increases linearly with increase of the period of transient arc discharge.
(4) Taking account of the repair of the space station and space structures which may be made of an aluminum alloy with a thickness about 3-4 mm, the arc current at 50-70 A may be enough to weld aluminum alloy of plate thickness 3-4 mm by the GHTA method in a vacuum.
(5) The characteristics of hardness distribution and strength of joints of aluminum alloy by GHTA welding in a vacuum are clarified.
