TIG Welding Stainless Steel: Gas Coverage<\/strong><\/h2>\n\n\n\nUsing the appropriate type and amount of shielding gas is an important way to prevent carbide precipitation when TIG welding stainless steel. Typically, pure argon provides the best results when welding thinner austenitic stainless steel, but the addition of small percentages of helium is not uncommon when better penetration and faster travel speeds are desired, especially on thicker pieces. <\/p>\n\n\n\n
The average flow rate required is between 15 to 20 psi, anything greater will cause turbulence in the gas flow and weld puddle and result in a poor weld. The use of a gas lens is really recommended when using TIG welding for stainless steel. A gas lens is a copper and brass component with layered stainless steel mesh screens that replace the collet body in a standard TIG torch. <\/p>\n\n\n\n
The gas lens helps distribute gas more evenly around the tungsten, arc, and weld puddle and provides good cooling action. Full penetration welds require back purging. Covering the back of the weld with shielding gas ensures that the underside of the weld is protected from atmospheric elements and can be done with commercial apparatuses or individually manufactured methods.<\/p>\n\n\n\n
The use of Chill Bars<\/strong>. The successful welding of stainless steel by various welding methods depends to a large extent on the type of backup bar or plate used. Experience has indicated that pure copper is the most satisfactory material for backing up a weld. The high heat conductivity of such a backup bar or plate will prevent its sticking to the weld metal, while its chill-mold effect will assure a clean smooth weld metal surface. Copper backup bars can be made by cutting pieces from a copper plate or sheet. Chill bars serve the best purpose by controlling distortion on light gauge material and also help to prevent excessive burn-through or melting of the base metal.<\/p>\n\n\n\nFinally, remember to maintain adequate post-flow<\/strong>. The best practice is to maintain one second of post-flow for every 10 amps of welding current used during welding.<\/p>\n\n\n\n