Electrochemical corrosion behavior of type 444 stainless steel in synthetic tap water at different temperatures

Abstract

Purpose The purpose of this paper is to investigate the electrochemical corrosion behavior of type 444 stainless steel (SS) in synthetic tap water from 25°C to 80°C, i.e. the operation environment of the electric water heater. Design/methodology/approach The corrosion behavior was studied by using electrochemical measurements such as electrochemical impedance spectroscopy and polarization curve. The specimen surfaces were observed with scanning electron microscopy. The passive films were characterized with X-ray photoelectron spectroscopy. Findings In the typical tap water, 444 SS passivates spontaneously under different temperatures. The passive films formed at higher temperatures contain relatively less Cr-species and more Cl− ions, resulting in lower polarization resistances. The stable pitting corrosion takes place in the potential region of oxygen evolution as the temperature increases to about 55°C. The critical Cl− concentration of pitting corrosion reduces from about 160 mg L−1 to 60 mg L−1 with changing temperature from 25°C to 80°C. Practical implications The pitting corrosion probability was assessed through the statistical analysis of tap water quality. The results are useful for the application of 444 SS as well as the design of electric water heater. Originality/value This paper shows the variation of polarization resistance, pitting potential, passive film composition and critical pitting chloride concentration with the temperature of tap water. It is of great significance for the development and application of SS in tap water environments.

Improvements of Corrosion Resistance and Antibacterial Properties of Hydroxyapatite/Cupric Oxide Doped Titania Composite Coatings on Degradable Magnesium Alloys

“…E pit is the potential matching with the position where the current density increases rapidly on the anodic polarization curve, that is, the position where the passivation zone (where current does not change with potential) ends . In other words, E pit is determined by the breakdown of the passivation coating . The higher the E pit , the larger the width of the passivation region, and the better the pitting resistance of alloys .…”

“…39 In other words, E pit is determined by the breakdown of the passivation coating. 40 The higher the E pit , the larger the width of the passivation region, and the better the pitting resistance of alloys. 41 The HTC2 coating had the lowest i corr and a passivation region of about 500 mV, indicating that with the appropriate amount of CuO doped TiO 2 coating Mg alloy corrosion could be effectually avoided.…”

Effect of Temperature and NaClO on the Corrosion Behavior of Copper in Synthetic Tap Water

“…This can be mainly attributed to the significant reduction in oxygen content in the solution. It is reported that the dissolved oxygen content linearly changes from about 8.0 to 3.5 mg L −1 with the increase in temperature from 25 to 80 • C [27], which is unfavorable for the cathodic reaction of the corrosion process.…”

Electrochemical Corrosion Behavior of 310S Stainless Steel in Hot Concentrated Tap Water

“…The pitting resistance becomes higher under higher HCO 3 − and SO 4 2− concentrations in the solution [16,17]. Zhang [18] and Niu [19] studied the effect of Cl − and SO 4 2− ions on the pitting corrosion behavior of stainless steel in synthetic tap water. They found that there was a critical Cl − concentration for the occurrence of pitting corrosion and the pitting potential decreased significantly with the increase of Cl − concentration.…”