Avaliação da influência do hidrogênio na tenacidade à fratura de juntas soldadas do aço inoxidável superduplex UNS S32750 com diferentes aportes térmicos

Abstract

The superduplex stainless steels (SDSS) have a microstructure composed by two phases, ferrite (α) and austenite (γ). This dual microstructure improves simultaneously the mechanical and corrosion resistance properties. However, the welding of these steels is often a critical operation. This work aims to evaluate the fracture toughness of welded joints, with two different heat input 1.1 kJ/mm and 2.0 kJ/mm, of one superduplex stainless steel (UNS S32750) in presence of hydrogen. The unloading compliance tests (according ASTM E1820 standard) were performed in the air and after different times of hydrogenation (15, 30 and 60 days). The partial results showed strong evidence that the reductions on CTOD values of air and hydrogenated tests are associated with different γ2 morphologies. Were also discussed aspects concerning the application of the unloading compliance methos for high fracture toughness materials that exhibit considerable amount of plastic deformation during the crack propagation.