When welding stainless steel it is advisable to follow the general welding guidelines valid for each type of steel. Stainless steels have, due to their chemical compositions, a higher thermal expansion compared to mild steel, which may increase the risk for weld deformation. Dependent of weld metal microstructure, stainless steel might be more sensitive to hot cracking and to intermetallic precipitations that might influence corrosion resistance and mechanical properties, compared to mild steel.

Stainless steels can be welded with most common welding methods. A general rule is that stainless steels should be welded with somewhat lower heat input compared to mild steels. Welding with oxygen-acetylene shall, however, be avoided due to negative effects of carbon pick up.

A fundamental difference between weldments in stainless steel compared to weldments in mild steel is the need for post-weld cleaning of the stainless weldment. Stainless steel weldments exposed under wet corrosive conditions, normally require removal of weld oxides, weld slag and other surface contaminants in order to restore the passive film and to obtain optimal corrosion properties.

For further information about welding and post-weld cleaning, see the Outokumpu Welding Handbook. The handbook can be obtained from local Outokumpu Sales Offices.