Experimental investigation of corrosion behaviour of selective laser melted maraging steel: a comparison with casting process

This study presents a comprehensive investigation into the corrosion behaviour of 18Ni300 maraging steel fabricated via selective laser melting (SLM) compared to its conventionally cast counterpart. The corrosion resistance of these materials was rigorously assessed through potentiodynamic polarisation testing in a 3.5% NaCl solution, complemented by microstructural characterisation techniques, including X-ray diffraction (XRD) and scanning electron microscopy (SEM-EDX). The findings reveal a significantly lower corrosion rate in SLM-produced maraging steel (1.40E-2 mm/year), representing a 61% improvement over cast steel. This enhanced performance is attributed to the rapid solidification process in SLM, which results in finer grain structures, increased crystallinity, and reduced porosity, thereby enhancing electrochemical stability. Furthermore, SEM analysis post-corrosion exposure confirmed that the SLM samples exhibited less-localised corrosion and a more uniform passive film, in contrast to the severe pitting observed in cast specimens. These results underscore the potential of SLM as a transformative manufacturing technique for producing corrosion-resistant components in aerospace, marine, and automotive applications. Future work should focus on optimising SLM processing parameters and post-treatment techniques to improve mechanical and electrochemical properties further.