Welding Stainless Steel With the Gas Metal Arc Process

Problem: I’ve had trouble welding stainless steel plate in the past. Are there any tips that would help?

Solution: Stainless steel may be welded by the gas metal arc process (GMAP) using short-circuiting, spray arc or pulsed arc transfer. Copper back-up is helpful when welding thicker sections of plate from one side only.

No air must be permitted to reach the underside of the weld while the weld puddle is solidifying. Oxygen and nitrogen picked up by the molten metal may reduce the corrosion resistance and ductility of the stainless steel as it cools. To prevent this, the underside of the weld should be shielded by an inert gas such as argon.

Special gases for the GMAW process contain argon, helium and precise amounts of CO2 for this purpose. As a result, butt, lap and single fillet welds in material ranging from 0.060 in. to 0.125 in. in 304, 310, 316, 321, 347, 410 and similar stainless steels can be welded successfully.

Mr. O thanks David Westbrook, a BOC welding specialist in Ontario for this tip. Further information is available from local BOC branches (toll free 1-888-256-7359 or e-mail info@ca.gases.boc.com). BOC offers Stainshield gases for the GMAW process. For more information, visit www.bocgases.ca.

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