Fundamental understanding of corrosion performances of laser-melted metallic alloys Available to Purchase

It is generally accepted that laser surface melting (LSM) can be used for the improving corrosion resistance of metallic alloys as a result of homogenization/refinement of microstructure, dissolution/redistribution of precipitates or inclusions and phase transformation. However, some studies have shown that laser-treated surfaces do not always exhibit enhanced corrosion performance. To date, no satisfactory explanation has been given for the findings, in particular concerning the relationship between microstructure and electrochemical responses. This paper summarises the results of the investigation, carried out at UMIST, into the corrosion performances of various laser-melted metallic alloys, including AA2014-T6 and AA2024-T351 alloys, 304L austenitic stainless steel and 3Cr12 dual-phase steel, to enhance the knowledge of important, but poorly understood relationships between corrosion and microstructural characteristics of surfaces following laser treatment. It has been found that apart from the refinement/homogenization of microstructure, other factors, such as the electrochemical nature of various intermetallics with respect to the solid solution matrix and heat-affected zones produced by overlapping, and optimised cooling rate, play key roles in determining the corrosion behaviour after the laser treatment.