Influence of Chromium Content and Stabilization on Tribocorrosion of Ferritic Stainless Steel

In recent years, the ferritic stainless steels have been proposed as a competitive alternative option for the bio-fuel and concrete mixer industries. The goal of the present work is to evaluate, using a recently proposed new methodology, the effect of chromium content with and without stabilization (Ti and Nb) on the tribocorrosion of ferritic stainless steels. For comparative purposes, a carbon steel (0.15 wt% C) was also studied. A reciprocating motion tribometer associated with a potentiostat assured that the potential scan during the tests was used under a constant load and sliding velocity. To this end, a recently introduced approach was applied. It consisted of performing sliding tribological tests to strictly evaluate the mechanical wear, potentiodynamic corrosion tests to determine the corrosion resistance in the absence of mechanical wear, and tribocorrosion tests, which combine both mechanical wear and corrosion degradation from chemical/electrochemical effects. Concerning the tribological performance, the 16% Cr steel showed a higher friction coefficient and lower wear rate than the 11% Cr steel. Carbon steel, in turn, presented the lowest friction coefficient and the highest wear rate among all materials. The corrosion tests showed that a higher chromium content was associated with a greater corrosion resistance. The similarities of the wear mechanism between the tribocorrosion and the tribological tests were verified and it can possibly explain the obtained synergy (S), which was slightly positive (11% Cr (S = 0.009 mg/min), 11% CrTi steel (S = 0.031 mg/min) and 16 % Cr steels (S = 0.005 mg/min)), as the tribocorrosion worsened the wear resistance of the materials, although insignificantly. The exception is the carbon steel, whose synergy effect was drastically higher than all other materials with chromium content (S = 2.674 mg/min).