Abstract:
As a final part of the steel production chain, continuous casting exposes its rollers to high process temperatures, thermal / mechanical fatigue, abrasive wear, and damage caused by corrosion processes. Collapses in casting rolls occur from the occurrence of failures as a result of nucleation / propagation of pits and cracks in reheated zones after welding or heat treatment processes. Pitting and cracking corrosion are the most frequent and the anodic dissolution of the metal is accelerated within the discontinuities promoted by the presence of hydrofluoric acid (HF), which will be formed from the reaction of calcium fluoride (CaF2), a component of the mold flow, material used as lubricant in the primary cooling stage, and water at high temperatures. The martensitic stainless steels have the properties required for the application and have good economic viability, which justifies their increasing use in applications that require high resistance to corrosion, mechanical, wear. Thus, the corrosion mechanisms of AISI 414 and AISI 415 steels were investigated using electrochemical techniques for the monitoring of open circuit potential and potentiodynamic polarization in order to study the influence of NaCl concentration on corrosive behavior. The results showed that for AISI 414, OCP values were more negative and the polarization curves tended to decrease potentials and increase current densities. As for AISI 415, the results showed increasing OCP values and polarization plots tending to more positive potentials and lower current densities. Thus, indicating that the AISI 415 presents greater resistance to corrosion when compared to AISI 414.