Effect of nanograin–boundary networks generation on corrosion of carburized martensitic stainless steel

Abstract

Martensitic stainless steel parts used in carbonaceous atmosphere at high temperature are subject to corrosion which results in a large amount of lost energy and high repair and maintenance costs. This work therefore proposes a model for surface development and corrosion mechanism as a solution to reduce corrosion costs. The morphology, phase, and corrosion behavior of steel are investigated using GIXRD, XANES, and EIS. The results show formation of nanograin–boundary networks in the protective layer of martensitic stainless steel. This Cr2O3–Cr7C3 nanograin mixture on the FeCr2O4 layer causes ion transport which is the main reason for the corrosion reaction during carburizing of the steel. The results reveal the rate determining steps in the corrosion mechanism during carburizing of steel. These steps are the diffusion of uncharged active gases in the stagnant–gas layer over the steel surface followed by the conversion of C into C4− and O into O2− at the gas–oxide interface simultaneously with the migration of Cr3+ from the metal-oxide interface to the gas-oxide interface. It is proposed that previous research on Al2O3 coatings may be the solution to producing effective coatings that overcome the corrosion challenges discussed in this work.

Effect of nano-grain carbide formation on electrochemical behavior of 316L stainless steel

“…In redox reaction, metal atoms are oxidized and converted to metal ions and electrons. O atoms dissociated from O 2 gas molecules (in electrolyte) adsorbing onto the surface are reduced by these electrons which results in generation of O 2− 7 , 49 . In the testing environment of electrolyte with no carbon potential, Cr 3 C 2 was less thermodynamically stable than Cr 7 C 3 and underwent a larger amount of decomposition.…”

“…The rising of redox reaction resulted in reduction of R ct of the steel treated for 20 min when compared to 10 min. The uncharged diffusion process associates with O 2 diffusion (perpendicular to the surface) in a stagnant gas layer that establishes an O 2 concentration gradient (producing diffusion impedance) over the surface 7 , 50 . As active species, O 2 diffused down the concentration gradient which arisen between the material surface and the location from material surface where the O 2 concentration equal to a bulk solution.…”

“…In operation, the components such as CO 2 -cooled nuclear reactor, furnace tube, and reformer or pyrolysis tubes 4 – 6 are not only subjected to dry corrosion during in-service period but also wet corrosion in out-of-service one. Failure of the parts can lead to a leakage of chemicals which produces pollution problems and approximately 137 quadrillion joules of lost energy 2 , 7 . Austenitic stainless steels are extensively used in such carbonaceous atmosphere due to possession of higher carburizing resistance (resulted from lower diffusion coefficient of carbon) than ferritic stainless steels.…”

Corrosion Susceptibility and Allergy Potential of Austenitic Stainless Steels

“…Corrosion represents an important factor in the design and selection of metals and alloys for different purposes, as various corrosion mechanisms can lead to failure [ 1 , 2 ]. Corrosion resistance is an important criterion for selecting materials used, because the cost of their degradation due to corrosion and the associated environmental impact are quite substantial [ 3 ]. Like all metals, stainless steels can undergo chemical corrosion over time [ 4 , 5 , 6 ].…”

Corrosion behavior of metastable AISI 321 austenitic stainless steel: Investigating the effect of grain size and prior plastic deformation on its degradation pattern in saline media

“…Corrosion resistance is an important criterion for selecting materials used in the fabrication of chemical and nuclear plants. This is because the cost of materials degradation due to corrosion and the associated environmental impact are quite substantial 1 . Generally, the composition of austenitic stainless steels (e.g.…”