Relationship between silicon, phosphorus content and grain number in mild steels and its corrosion resistance in pickling hydrochloric acid

• Published in: International journal of industrial chemistry Vol. 11; no. 2; pp. 111 - 122
• Main Authors: El Kacimi, Y., Touir, R., Galai, M., Alaoui, K., Dkhireche, N., Touhami, M. Ebn
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2020; Springer Nature B.V
• Subjects: Acid resistance; Carbon steels; Cementite; Chemistry; Chemistry and Materials Science; Corrosion effects; Corrosion rate; Corrosion resistance; Corrosion resistant steels; Electrochemical impedance spectroscopy; Environmental Chemistry; Galvanic corrosion; Galvanizing; Hydrochloric acid; Industrial Chemistry/Chemical Engineering; Iron carbides; Low carbon steels; Nanochemistry; Optical microscopes; Phosphorus; Phosphorus content; Pickling; Polymer Sciences; Scanning electron microscopy; Silicon; Silicon steels; Structural analysis; Corrosion resistance; Hydrochloric acid; Mild steels classes; Microstructure
• ISSN: 2228-5970; 2228-5547
• DOI: 10.1007/s40090-020-00206-0

The micro-structural effects on the corrosion resistance of three classes of mild steels (A, B and C) suitable for galvanizing industry, according to their silicon, phosphorus content, grain number and size of carbides (Fe 3 C) in concentrated hydrochloride acid solution was investigated by a series of known techniques, such as potentiodynamic polarization curves, electrochemical impedance spectroscopy measurements, optical microscope and scanning electron microscopy. Results showed that the corrosion rate of the three classes of mild steel depends on their silicon and silicon/phosphorus combinations contents. It is found also that the corrosion rate depends on grain number and size of carbide content in mild steels. These findings were confirmed by micro-structural characterization and scanning electron microscopy techniques. They indicated that the severe corrosion cavities formed on the carbon steel surfaces and their sizes depended to silicon and silicon/phosphorus combinations contents. These results explained by micro-galvanic corrosion process between cementites and ferrites which became more serious with silicon and silicon/phosphorus combinations contents.