Consequences of Cold Drawing and Hot Rolling Processes on Microstructure, Microhardness and Electrochemical Corrosion of Structural Steels in 0.1 M Na ₂ SO ₄ , 0.1 M NaCl and Simulated Concrete Pore Solutions

ABSTRACT In this work, the electrochemical corrosion of four structural steels, in the form of round bars coming from two thermo‐mechanical treatments (cold drawing or hot rolling), was investigated separately in 0.1 M Na 2 SO 4 , 0.1 M NaCl, simulated concrete pore solution (SCPS) made of saturated 0.1 M Ca(OH) 2 , 0.1 M NaOH and 0.2 M KOH, and SCP solution with 0.1 M NaCl. Specimens were labeled as follows: TRA S235, LAM S275, LAM S355, and TRA S355, where TRA and LAM stand for cold‐drawn and hot‐rolled, respectively. An evaluation of the electrochemical corrosion properties was carried out through open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and anodic cyclic polarization (ACP) techniques. Furthermore, the surface or cross‐section hardening and softening effects caused by cold drawing and hot rolling processes were monitored by Vicker's microhardness testing. Moreover, the structural and microstructural changes in steels due to thermo‐mechanical treatments were characterized by means of XRD, OM and SEM‐EDX analyses. Results obtained allowed to confirm the significant correlations between structural, microstructural, electrochemical, and microhardness changes with respect to the nature of the plastic deformation manufacturing process.