COMPORTAMIENTO CÍCLICO DE ACEROS SUPERFERRÍTICOS A TEMPERATURAS INTERMEDIAS

SILVINA HEREÑÚ; MARÍA GABRIELA MOSCATO; IRIS ALVAREZ-ARMAS; ALBERTO F. ARMAS

Buenos Aires

Congreso; Segundo Congreso Argentino de Microscopía; 2012

Asociación Argentina de Microscopía (SAMIC)

The low nickel content of superferritic stainless steel makes them cost- effective while maintaining good mechanical properties. These steels are widely used in applications where they are exposed at intermediate temperatures. Nevertheless, dynamic strain aging (DSA) or spinodal decomposition (SD) can take place at these temperatures affecting their mechanical properties.   This paper studies the influence of temperature on the cyclic behaviour of superferritic stainless steel UNS S 44600 with two thermal treatment conditions: as-received (unaged) and aged (100 hours at 475ºC). The specimens are tested under plastic strain control in air at 20 and 475ºC. A previous thermal treatment at 1100 ºC in the as received condition is carried out in order to produce precipitate’s dissolution. Scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) device is used to make a detalied study of the precipitates’s size and composition. The fatigue dislocation structures are analized using a Transmission Electron Microscope (TEM). DSA manifestation is observed in as-received samples tested at 475ºC whereas aged samples tested at 20 ºC exhibits a ductility decrease due to SD. These results are more pronounced in samples where the 1100 ºC thermal treatment is performed.