Heat Tints on Stainless Steels can cause Corrosion Problems (14050)
By A.H. Tuthill and R.E. Avery, reprinted from Materials Performance February 1999. The dark heat tint formed alongside welds during welding of stainless steel (SS) the heat-affected zone (HAZ) is a thicker chromium oxide scale with a mixture of iron, nickel, and other oxides. This thin layer is lower in chromium, the primary constituent that gives SS its good corrosion resistance. Corrosion that would not occur elsewhere can initiate in the HAZ unless the heat tint scale and the thin chromium-depleted layer just beneath are removed. Removal by rotating fiber brush, pickling, or electropolishing readily restores this area to base-metal resistance.