MECHANISMS AND FACTORS THAT INFLUENCE POSTWELD INTERGRANULAR UNDERCLAD CRACKING

— Forged components of ferritic steel can be protected by a welded austenitic stainless steel clad. Intergranular cracking can take place in the ferritic phase close to the ferritic austenitic interface. After developing a technique for fabrication of these cracks, the formation conditions are studied. Auger electron spectroscopy investigations of specimens containing a real crack opened inside the vacuum chamber are used for interpretation. Sulphur segregations embrittle the grain boundaries which are cracked by residual and thermal stresses during the postweld heat treatment.