EFECTO DE LA FRAGILIZACIÓN DE LOS 475ºC SOBRE LA VIDA EN FATIGA DE UN ACERO INOXIDABLE DÚPLEX

MARÍA CECILIA MARINELLI ; MARÍA GABRIELA MOSCATO ; SILVINA NOEMÍ HEREÑÚ; IRIS ÁLVAREZ-ARMAS; ULRICH KRUPP

Rosario

Conferencia; 6ta Conferencia sobre Usos del Acero IAS; 2012

Instituto Argentino de Siderurgia

Duplex stainless steels (DSS) have found widespread use in the chemical and petrochemical industries. This is mainly due to their relatively high strength and toughness as well as high resistance to corrosion and stress corrosion. These remarkable properties enhance the use of DSS. However, these steels embrittled when they are exposed in the temperature range of 280-500ºC limiting their applications. Many applications imply cyclic loading and thus the prediction of the fatigue life or the residual fatigue life as well as the knowledge of fatigue limit is essential. The present work studies the effect of 475ºC embrittlement on fatigue life of a standard duplex stainless steel. Rotating bending fatigue tests, low cycle fatigue (LCF) and high cycle fatigue (HCF) tests were performed. Moreover, in grains where short cracks nucleate and grow, the slip systems and their associated Schmid factor are analyzed by automated electron backscattered diffraction technique (EBSD). The fatigue dislocation structures are analyzed using a Transmission Electron Microscope (TEM). In HCF regime the embrittled ferritic phase improved the fatigue life of DSS. However, in LCF regime aged DSS shows a similar or shorter fatigue life than the as-received material.