Corrosion resistance of laser cladded 304L stainless steel enriched with Ru in hydrochloric acid

Abstract

The corrosion behaviour of laser surface cladding made from 304L stainless steel alloyed with varying concentrations of ruthenium in 1M HCl at 25°C was evaluated, fresh and after 12 hours, by electrochemical tests including open circuit potential and potentiodynamic polarisation scans. The ruthenium concentration in the 800 µm cladded layer varied from 0.82 wt-% to 4.67 wt-% ruthenium. The ruthenium doped samples were compared against a 304L stainless steel laser surface cladding with no ruthenium, 304L stainless steel samples with no laser cladding, 316L stainless steel, SAF2205 duplex stainless steel and Hastelloy C276®. Initial passivation was not observed in the 1M HCl but after 12 hours the addition of ruthenium led to reduced corrosion rates and improved passivation characteristics compared to the surface cladding without ruthenium. An optimum ruthenium range was observed between 3 wt-% and 5 wt-%. It was shown that at this optimum concentration, the ruthenium containing stainless steel clad on 304L stainless steel can compete commercially with the SAF2205 and Hastelloy C276® as long as the clad is 200 µm or less.

Keywords:

• Corrosion protection
• Ruthenium
• Laser cladding
• 304L Stainless steel
• Hydrochloric acid

Acknowledgements

The authors would like to thank the National Laser Centre of South Africa at the CSIR for the sample preparation, the DST-NRF Centre of Excellence in Strong Materials for financial support.