Corrosion fatigue characterisation of sintered multiphase stainless steels

Abstract

Multiphase stainless steels are produced for their attractive properties of mechanical strength and corrosion resistance relative to their austenite-ferrite structure. The manufacture of these steel by powder metallurgy technology presents some advantages in terms of low cost and formability of complex shapes. Mechanical and corrosion resistances are not at the level of the wrought steels due to their porous nature. In this work the fatigue and corrosion fatigue behaviour of some sintered steels obtained by sintering from 316L and 434L base powders has been studied for characterisation and comparison. The sintered steels were fatigue tested in two different environments: air and NaCl aqueous solution. The tests performed indicate that the chemical and microstructral composition has no great influence on fatigue behaviour in comparison with the manufacturing technology (sintering). This is most evident in the more aggressive environment, like seawater, in which these steels could be advantageously used. The analysis of fracture surfaces using SEM microscopy shows a peculiar crack propagation characterised by cleavage, stress intensification due to porosity, and features of localised ductility on sintering necks and base powder particles

Use of Fiber Optic Sensors for Monitoring Crack Growth in Fatigue and Corrosion-Fatigue Tests

“…In these last cases we usually refers to corrosion-fatigue. Many studies have been carried out on fatigue and corrosion-fatigue behaviour of metallic materials and test procedure are widely tested and standardized [1][2][3][4]. However new researches actually are conducted employing new test and measure techniques in order to study fatigue phenomena and to better understand the involved mechanisms.…”