intergranular corrosion causes
Among the metals affected by this type of corrosion are stainless steel, certain magnesium alloys, and the copper-bearing aluminum alloys. Intergranular corrosion occurs in certain grades of stainless steel when the steel is heated, as in welding. Brittleness results, causing the metal to crack near the weld. For this reason, a post-weld heat treatment is needed before reinstalling stainless steel parts that have been welded.