Estudio del envejecimiento por deformación dinámico en un acero inoxidable dúplex a través de mediciones de dureza

S HEREÑÚ; I. ALVAREZ- ARMAS; A .F. ARMAS

San Nicolás, Argentina

Conferencia; 15 CONF DE LAM / 2 CONF SOBRE USOS DEL ACERO DEL IAS; 2004

As a result of the exceptional combination of mechanical and corrosion properties duplex stainless steels (DSSs) have recently attracted considerable interest. Among the different mechanical properties of these steels one of the less studied is its fatigue behaviour. Some of the applications for which DSS is potentially considered imply operation at temperatures of about 573 K where this material is susceptible to aging embrittlement. This phenomenon is sometimes ascribed to the spinodal decomposition of the ferritic phase. It is also known that single-phase austenitic and ferritic steels exhibit a strong influence of Dynamic Strain Ageing (DSA) in their cyclic behaviour. New investigations have studied this theme in DSS. In this respect, manifestations of DSA in the form of a pronounced hardening and an inverse strain rate dependence at intermediate temperatures have been observed in DSS. Moreover, something worthy to note is that a high dislocation density is developed in the ferritic phase in comparison with austenitic phase within the DSA range of temperature. This dislocation structure is associated with a strong interaction between dislocation and interstitial atoms. Therefore, a thorough study on the contribution of each phase to the cyclic hardening in the DSA range is needed.   Thus, this paper attempt to elucidate through the correlation between hardness measurement and transmission electron microscopy observations which is the role of each phase in the pronounced cyclic hardening within the DSA regime. It is inferred from this analysis that the ferritic phase shows evidences of a preponderant role in the cyclic hardening of the material during the DSA stage.