Processing,microstructure and corrosion behaviour of multi-axially forged low carbon steels

Abstract

Increasing attention is being paid to processing bulk ultrafine grained (UFG) materials for structural applications. Along with mechanical properties, study of corrosion behaviour of these materials is important for them to find wider applications. In this work, low carbon steels that are extensively used for general purpose structural applications are studied. Low carbon steels were processed by using multi-axial forging, a technique of severe plastic deformation. Steel specimens were processed using six passes of warm multi-axial forging operations, to produce UFG structures. The present work further investigated the corrosion behaviour of these severely deformed UFG steels. Potentiodynamic tests, immersion tests, and salt spray tests were performed in chloride environments. In most environments employed in this study, UFG steels showed improved uniform corrosion behaviour compared to their coarse grained counterparts. The improvement in corrosion properties is explained based on microstructural evolution with respect to grain size, dislocation population and substructure development.