A Study on the plasma Welding of Stainless Steel plate

On the welding conditions and its effects on Welding mechanism

Abstract

Recently, plasma process has been applied to such industrial uses as cutting and spraying. Arc plasma is constricted by the gas flow and/or metallic wall of nozzle in a plasma process. The temperature and the thermal energy intensity of the constricted arc plasma are much higher than those of ordinary open arc. In the cutting and welding applications, it will be expected that the plasma stream has a property of line heat source similar to the one as observed in Electrlon Beam Welding.
In this report the experimental results on the plasma welding of stainless steel plate are described briefly. The electric capacity of plasma welding torch used in these experiments is about 8 KW. The plasma welding is capable of producing a narrow and deep weld bead by the action of "Key Hole". And a sound weld is obtained by one pass of torch even for a 15 mm thick plate. With the above welding energy source, optimum welding conditions are established for various thickness of plate. Welding speed in plasma process is much higher than that in TIG welding and others at the same welding energy.
Various tests on the microstructure, mechanical property and the deformation of weld specimen are carried out with satisfactory results.
It was confirmed that the formation of key hole in crater of bead had much influence upon the welding results. When the key hole is not formed, porosity is contained in most weld beads. The formation of key hole is sensitive to the travelling speed.