INTERGRANULAR CORROSION OF WELDED JOINTS. FORMING CONDITIONS AND PROCEDURES FOR PREVENTION

Abstract

The paper describes structural changes in the welded joints, leading to the emergence of intergranular corrosion (IGC) during exploitation. The occurrence of intergranular corrosion in welded joints of austenitic, ferritic and duplex stainless steels and in welded joints of aluminium alloys and nickel alloys is analysed. Special attention was paid to austenitic stainless steels, due to their wide application in practice. In addition to sensitization in the weld heat-affected zone (HAZ), which results in degradation of the welded joint (“weld decay”), also considered is the sensitization that occurs close to the weld metal in the stabilized steel, which leads to a “knife line attack”. Considerable attention is devoted to describing the various procedures in order to prevent the sensitization of the welded joints.