If high-alloyed Chromium-Nickel steels shall be processed by welding, it is advisable to do so with the aid of a forming gas device, for the corrosion-resistance of these materials already decrease significantly by moderate oxidation. For gas-sensitive materials, such as molybdenum, zirconium and titanium, the welding-related processing with forming gas is obligatory.
In the forming gas process, during welding the weld root and the heat-affected zone are continuously rinsed with shielding gases, such as argon, nitrogen, argon-hydrogen and nitrogen-hydrogen. This process introduces the elimination of the oxygen-containing atmosphere and therefore serves the protection of that part of the welding seam at opposite side of the welding electrode from oxidation and scaling. The controlled supply of the shielding-gas is one of the most important factors when forming; optimally, it is therefore laminar. This can be realized with a diffusor from porous sinter metal in the form of sheets, tubes or the like. Here, the supplied gas is distributed over the large surface of the porous material and flows laminarly from there.
If the forming process is performed correctly, a post-processing of the welding seams is not necessary.
For this application, following of our materials are suitable: SIPERM® R and SIPERM® B.