Effect of surface treatment by sandblasting on the quality and electrochemical corrosion properties of a C-1020 carbon steel used by an Algerian oil company

Abstract

The purpose of the different operations under the term surface preparation is to get a clean surface able to be coated. It is essential to adapt this preparation in terms of the metallurgical nature of the substrate, cleanliness, its shape and roughness. Surface preparations especially the operations of sandblasting, polishing, or grinding prove of capital importance. It allows to modify the superficial properties of these materials, after these treatments the surface becomes very active. This paper evaluates the mechanical surface treatments effect by sandblasting (Sa 1.5 and Sa 2.5) on the electrochemical corrosion characteristics of C-1020 carbon steel in 3% NaCl solution electrolyte simulating aggressive sea atmosphere. Investigations are conducted using stationary (free potential "E-t, polarization curves "E-i", the Tafel rights and the Rp) and nonstationary electrochemical tools such as electrochemical impedance. The results obtained allowed us to highlight that sandblasted carbon steel degrades with immersion time because of the roughness of the surface. These results were confirmed by the plot of the electrochemical impedance diagrams, confirming that the process governing kinetics is under charge transfer control. Good protection against corrosion cannot be obtained only with a good surface preparation of the adapted steel.

The Influence of Different Type Materials of Grit Blasting on the Corrosion Resistance of S235JR Carbon Steel

“…A displacement of the potential towards more negative values (behavior indicating dissolution of the oxide layer) in the case of sandblasted surfaces was observed in the specialized literature also by other authors [25]. This behavior can be attributed to the increase in the roughness of a surface that causes an increase in corrosion processes because the roughness influences the corrosion potential favoring the appearance of corrosion pits [33].…”

“…The movement of the free potential towards more negative values indicates the inability of the material to form a protective oxide film on its surface, while the stationary state indicates that the surface has reached a state of equilibrium (it neither dissolves nor forms the oxide layer on the surface of the samples) [25]. If for S235JR-non-sandblasted (curve 1), the value of the free potential at immersion (Figure 3a) is E = −509.79 ± 24 mV vs. Ag/AgCl at the end of the first measurement period reaches E = −570.09 ± 32 mV vs. Ag/AgCl, the potential difference between the two values being 60.3 mV more negative than the free potential value from immersion.…”

“…In the specialized literature, there are very few studies that treat the effect of sandblasting on the corrosion resistance of different types of steels, and the results are contradictory [15,[20][21][22][23][24][25]. Some studies show that sandblasting decreases corrosion resistance [21,25], while others claim that sandblasting increases corrosion resistance [15,20,[22][23][24].…”

“…The importance of the study consists in the fact that sandblasting is one of the most effective methods of cleaning or finishing the surfaces of any type of solid material with the help of sandblasting grits. The metal surfaces that have been cleaned and from which the oxides have been removed can be covered with anti-corrosive protective films resistant to the action of aggressive environmental factors [25].…”

“…Because sandblasting also determines the appearance of deep grooves that can capture the corrosion products formed in the upper part of the surfaces, favoring the appearance of micro reactions, generating pitting corrosion, thus affecting the life of the anti-corrosion protections [25].…”