Papers by Author: Gemma Fargas

Abstract: Duplex stainless steels contain similar amounts of austenite  and ferrite α. This two-phase microstructure leads to an excellent combination of mechanical properties and corrosion resistance. However, there are few works dealing with the wear behaviour of these steels. This paper aims to determine the sliding wear mechanisms of a duplex stainless steel type 2205. In order to do it, three different sliding velocities (0.2, 0.7 and 1.2 m/s) and six sliding distances (500, 1000, 2000, 3000, 4000 and 5000 m) were selected. The results show that wear rate depends on both sliding velocity and sliding distance. The wear mechanisms detected were plowing, microcracking and microcutting (typical mechanisms of fatigue wear). These mechanisms evolve according to sliding velocity and sliding distance, highlighting a transition zone in which wear rate is reduced.

Abstract: The martensitic transformation in austenitic stainless steels can be induced by plastic deformation at room temperature. The benefit of this transformation is commonly used to strengthen stainless steels grades, i.e. their yield and tensile resistance can be adjusted according to the requirement by cold rolling. In this paper, the martensitic transformation was induced by means of torsion deformation. Several torsion angles were selected to achieve different percentages of martensite at the surface of the specimens and then the effect on the fatigue life of the steel was studied. Fatigue testing results showed dissimilar behavior depending on the stress ratio (R) applied during the test. As a conclusion, the presence of martensite in the surface increases the fatigue life for high stress ratios (R=0.8), while at low R values martensitic transformation has no positive effect.