Metallurgical modifications and residual stress in a welded steel with medium carbon content (Modificazioni metallurgiche e tensioni residue in un acciaio saldato a medio contenuto di carbonio)

Welded joints on metal alloys are subject to residual stresses and metallurgical transformations, in particular in the Heat Affected Zone (HAZ) , with possible formation of brittle structures and loss of toughness, especially in the steels having an elevated carbon content. These facts favour cracks formation with consequent possible brittle fracture or fatigue crack propagation. Moreover residual stresses may cause premature failure on structural components, e.g. by contributing to buckling due to instability of compressed members. In the present work, referring to a specific case, the order of magnitude and the distribution of residual stresses are estimated through a theoretical-empirical approach, in order to focus on the portion of material more sensitive to the formation of cold cracks under the combined effect of residual stresses and microstructure brittleness.