Effects of temperature and citric acid concentration on passive film and corrosion behavior of AISI 304L having different Mn and Cu contents – Dedicated to Gobboon Lothongkum

Abstract This research examines the passivation behavior of AISI 304L stainless steel containing various weight percentages of manganese and copper. Four specific alloy compositions were analyzed: 1.0%Mn-0.23%Cu, 1.2%Mn-0.40%Cu, 1.4%Mn-0.22%Cu, and 1.7%Mn-0.37%Cu. Potentiodynamic polarization tests were conducted in citric acid solutions (4, 6, 8, and 10 wt.%) at temperatures of 298, 323, and 343 K. The results demonstrate that higher temperatures and citric acid concentrations accelerate the corrosion rate while reducing both corrosion resistance and the stability of the passive region. It is found that the synergistic addition of manganese and copper enhanced the overall corrosion resistance of AISI 304L. Furthermore, an increase in temperature led to a positive shift in corrosion potential, while the transpassive potential shifted towards more active values.