Investigation of the toughness behavior in cold-formed and welded high-strength steels using fracture mechanics concepts and notch impact test

High-strength steels are increasingly utilized across various industrial sectors, notably in statically loaded components such as crane constructions. These steels are frequently subjected to cold forming during production, followed by welding. However, welding in cold-formed regions of structural steels often results in embrittlement, thereby elevating the risk of brittle fracture. Current standards like Eurocode 3 address this phenomenon by prescribing a minimum distance of five times the plate thickness for welding in cold-formed areas of structural steels with a minimum yield strength of 700 MPa. Failure to meet this minimum distance necessitates costly heat treatment processes. This article investigates three steels with higher yield strengths ranging from 700 MPa to 1100 MPa, featuring diverse strengths and manufacturing variations, to elucidate the influence of embrittlement during cold forming and welding of high-strength steels utilizing concepts from fracture mechanics. The results indicate that embrittlement is not anticipated in the cold-formed and welded regions of high-strength steels. It is inferred that the absence of secondary recrystallization, attributed to the existing microstructure or fine grain size of the steels, mitigates the formation of coarse grains, thereby averting brittle fracture.