Stainless steel welding requires a bit more finesse than welding mild steel or aluminum, because heat is an enemy in this process. There are three methods of stainless steel welding which are preferred over the rest by many welders: Metal Inert Gas (MIG) welding, Tungsten Inert Gas (TIG) welding, and Shielded Metal Arc Welding (SMAW) or stick welding. The fumes made from any of these processes are very harmful, and great care must be taken to avoid breathing them.
MIG welding uses a wire containing a flux core along with a shielding gas to make the weld. The shielding gas is commonly 100 percent carbon dioxide or a carbon dioxide and argon mix. This gas prevents oxidation and promotes a stable arc while the flux core of the wire allows stainless steel welding to be performed in all positions. A mixture of 20 to 25 percent of argon with the carbon dioxide will allow a lower heat setting to be used when MIG welding, resulting in a weld with less distortion and discoloration.
TIG welding utilizes a tungsten welding electrode, a filler metal rod and an inert gas to shield the weld. This welding method requires little or no post-weld finishing. The tungsten tip in the welding torch is touched to the material to be welded. This creates an arc that the welder dips the filler metal rod into and allows it to melt into the welding puddle. The shielding gas prevents contamination from entering the weld and allows the weld to flow out smoothly. Heat is controlled through a foot switch.
SMAW welding uses an electrode, or welding rod, coated with chemicals commonly referred to as flux. This coating burns off as the welding rod is melted into the weld joint and shields the weld from contaminates. This method of welding utilizes equipment, which is typically the least expensive. The SMAW weld will require the welder to remove the slag residue from the cooled weld by chipping it away with a hammer and cleaning it with a wire brush.
Stainless steel welding is used in food preparation tables and fixtures, as well as many medical equipment applications. Exhaust fans and special smoke suction tips, which are attached to the welding torch are used when welding to keep the harmful smoke away from the welder. Stainless steel also scratches very easily so great care must be taken to keep debris off of the welding table.