Forged components of ferritic steel are protected by a welded austenitic stainless steel clad. Intergranular cracking can take place in the ferritic phase close to the ferritic austenitic interface. Sulphur segregations embrittle the grain boundaries which are cracked by residual and thermal stresses during the postweld heat treatment. The intergranular brittleness and fracture at low temperature is characterised by a lower toughness than for transgranular fracture. On the other hand, the crack ligament length ratio is small. The toughness transition temperature is decreased by the shallow crack effect.
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