The corrosion resistance of low concentration ruthenium laser alloyed 304L stainless steel exposed to sulphuric acid at 25°C

Purpose: This paper aims to study the effect of small ruthenium additions through laser surface alloying of 304L stainless steel on the corrosion resistance when exposed to a 1 M sulphuric acid solution at 25°C. Design/methodology/approach: In this study, the characteristics of laser-alloyed surface layers enriched with low concentrations of ruthenium, less than 0.3 Wt.%, were evaluated. Samples were manufactured by performing laser surface alloying on a 304L stainless steel and using a 304 stainless steel powder enriched with ruthenium. The welded surfaces were cross-sectioned and the microstructure and chemical composition were analysed; in addition, the depth of penetration was determined. The corrosion characteristics of these surface welds were investigated through electrochemical analysis such as open circuit potential measurements and potentiodynamic scans. Findings: It was found that with the addition of ruthenium levels of more than 0.2 Wt.%, the corrosion characteristics when exposed to 1 M sulphuric acid improved in the enriched welded zone. Research limitations/implications: This study investigated the improvement of the surface layer of the 304L stainless steel because of the cost involved when ruthenium is alloyed in the bulk and showed that an improved corrosion resistance can be achieved in sulphuric acid at room temperature. Practical implications: The hardness of the laser alloying was not significantly affected by the ruthenium, but more by the laser parameters. Originality/value: This paper considers the improvement of 304L stainless steel through laser alloying with ruthenium.