Corrosion behaviour of ruthenium laser surface alloyed austenitic stainless steel in sulphuric acid and sodium chloride solutions

• Published in: Materials and corrosion 2017-08, Vol.68 (8), p.815-823
• Main Authors: van der Merwe, J. W., Moyo, F., Phetla, E. M.
• Format: Article
• Language: English
• Subjects: Alloy steels; austenitic stainless steel; Austenitic stainless steels; Chemical industry; Chloride; Chloride resistance; Continuous radiation; Corrosion currents; Corrosion inhibitors; Corrosion rate; Corrosion resistant alloys; Corrosion resistant steels; Current density; laser surface alloying; Passivity; Pitting (corrosion); Ruthenium; Semiconductor lasers; Sodium chloride; Sulfuric acid; YAG lasers
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.201609343

AISI 304L stainless steel was laser surface alloyed with ruthenium enriched 304L powder using a continuous wave Nd:YAG laser. Corrosion performance of the surface alloys was studied in 1 M sulphuric acid and 3.5 wt% sodium chloride at 25, 35 and 45 °C using potentiodynamic polarisation. The results showed that the presence of ruthenium decreased corrosion rates in both solutions and inhibited pitting in sodium chloride. High temperatures were particularly detrimental to the corrosion resistance of the alloys in sodium chloride, but were surprisingly beneficial in sulphuric acid; inducing spontaneous passivity and reducing corrosion current density from 129 μA/cm2 at 25 °C to about 0.5 μA/cm2 at 45 °C. At 25 and 45 °C 304L stainless steel enriched with 0.18 wt% ruthenium through laser surface alloying dramatically improves the corrosion and pitting resistance in 3.5 wt% sodium chloride.