Corrosion behavior of low carbon steel processed by ECAP in neutral and alkaline environment

Abstract

The purpose of this study was to evaluate the corrosion behavior of 1010 steel processed by Equal Channel Angular Pressing (ECAP), a technique that induces severe plastic deformation (SPD) in materials. The samples were processed by one and two passes of ECAP throught routes A and C. The corrosion behavior was evaluate using the potentiodynamic polarization and electrochemical impedance spectroscopy, using NaCl (pH= 6.5) and sodium hydroxide/sodium phosphate (pH= 10.5) solutions. The polarization tests showed better performance for the samples processed by ECAP than in the as cast samples both in alkaline and neutral solutions. The results showed that alkaline solution presented higher corrosion rate for the as cast and one ECAP pass materials. It is seen that samples processed throught routes A and C develop a film stabilization on the surface of these samples. In addition, the values of polarization resistance obtained from the electrochemical impedance spectroscopy in NaCl environment were higher for sample processed in route C.

An Overview on the Corrosion Behavior of Steels Processed by Severe Plastic Deformation

“…Several studies have also described the corrosion behavior of pure iron and steels with ultra-fine grains (26,65,70,71) . In these cases, the corrosion of UFG metals should be accelerated in active solutions (71,72,73) .…”

“…Low-carbon and alloyed steels have been processed mainly using Equal Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). Low-carbon steels consisting of less than 0.3% carbon (26,27,28) and low-alloy steels consisting of 0.05-0.25% carbon and other alloying elements, such as Fe-Cr-Ni-Mo(6), Fe-Ni-Cr (29) and Fe-Cr (30) , have been successfully processed using ECAP. For all the cases the refinement in the microstructure is produced, along with elongated grains with an apparent high dislocation density which affects the mechanical properties with increasing the number of ECAP passes.…”