Welding galvanized steel to stainless steel

When hot dip galvanized steel and stainless steel are welded together, the zinc becomes molten and can penetrate the grain boundaries of the stainless steel resulting in a phenomenon called liquid metal cracking (LMC).

All types of zinc coatings including zinc rich paint, can cause LMC when they are heated until molten in the presence of stainless steel.

Removing the zinc from the area to be welded prior to welding will eliminate this problem. The most commonly used method is grinding the zinc away from the welded area and thoroughly cleaning the area prior to welding. However, this can still leave small zinc particles around the welded area maintaining the risk of LMC occurring. Another method used to remove the zinc is applying an acid to the surface and then thoroughly rinsing and drying the area prior to welding.

After welding has been completed the damaged areas should be repaired to restore the corrosion protection.