This study aims to assess the performance of SAF 2205 duplex stainless steel against pure wear, tribo-corrosion, corrosion and the synergism between wear and corrosion. The effect of plasma nitriding conducted at low temperature (380°C) on SAF 2205 steel was analyzed.
Three systems were used for assessing the synergism between wear and corrosion: tribo-corrosion – wear tests conducted using the micro-scale abrasion test, performed under a slurry of alumina particles containing 3.5% NaCl; pure wear – tests conducted using the previous system but isolated in a glovebox with a 99% N2 atmosphere; and cyclic polarization under 3.5% NaCl solution. A hard nitrided layer of 3 µm thickness was characterized using X-ray diffraction, presenting expanded austenite.
The wear mode after micro-scale abrasion tests changed in the absence of an oxygen atmosphere. During pure wear, a mixed mode was identified (rolling + grooving), with the grooving mode more intense for the untreated steel. For tribo-corrosion tests, only rolling wear was identified. For all cases, the nitrided samples presented less wear. The corrosion results indicated a higher repassivation potential for the nitrided condition.
The synergism was more positive for the nitrided sample than for the untreated one, which can be considered for surface treatments of duplex stainless steels in practical applications.
A detailed description of wear mechanisms showed a significant change in the presence of oxygen atmosphere, a new approach for isolating pure wear.
The authors would like to thank funding given by National Council for Scientific and Technological Development (CNPq) (Process 443896/2014-3) and Fundação Araucãria (Process FA CP08/2017) for their financial support. The authors also thank the Multi-User Center for Materials Characterization (CMCM, Curitiba, Brazil) scanning electron microscopy analysis and Sandvik do Brasil S/A (São Paulo, Brazil) for supplying duplex stainless steel bars. One of authors, G. Pintaude, thanks to CNPq by the financial support through Process 308416/2017-1.
Núñez, Y., Mafra, M., Morales, R., Borges, P. and Pintaude, G. (2020), "The effect of plasma nitriding on the synergism between wear and corrosion of SAF 2205 duplex stainless steel", Industrial Lubrication and Tribology, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/ILT-08-2019-0302Download as .RIS
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