Effect of microstructure variation on the corrosion behavior of high-strength low-alloy steel in 3.5wt% NaCl solution

Abstract

The effect of microstructure variation on the corrosion behavior of high-strength low-alloy (HSLA) steel was investigated. The protective property of the corrosion product layer was also explored. Experimental results reveal that the type of microstructure has significant effect on the corrosion resistance of HSLA steel. The measurement results of weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy indicate that the steel with acicular ferrite microstructure exhibits the lowest corrosion rate. Martensite exhibits a reduced corrosion resistance compared with polygonal ferrite. It is found that the surface of the acicular ferrite specimen uniformly covered by corrosion products is seemingly denser and more compact than those of the other two microstructures, and can provide some amount of protection to the steel; thus, the charge transfer resistance and modulus values of the acicular ferrite specimen are the largest. However, corrosion products on martensite and polygonal ferrite are generally loose, porous, and defective, and can provide minor protectiveness; thus, the charge transfer resistance values for polygonal ferrite and martensite are lower.

Effect of Nd3+ Ion Concentration on the Corrosion Resistance of API X70 Steel in Chloride‐Rich Environments

“…It is known that depending on the manufacturing conditions and thermal treatments to which an X70 steel is subjected, its microstructure can be formed by the presence of different phases, the main being the polygonal ferrite, quasipolygonal ferrite, Widmanstätten ferrite, acicular ferrite, bainitic granular ferrite, bainite ferrite, martensite in addition to the presence of precipitates (Nb(CN), Fe 3 C, MnS, and SiO 2 ) [33][34][35]. is combination of phases can favor a galvanic effect between them, causing the corrosion of the electrochemically less stable phase, generally the ferrite [36], in addition to a nonuniform distribution of the local anodic/cathodic ratio that favors localized corrosion [37].…”

Investigation of Process Stability and Weld Quality of Underwater Wet Flux-Cored Arc Welding of Low-Alloy High-Strength Steel with Oxy-Rutile Wire

“…On the one hand, a number of dislocations in acicular ferrite may have become the nucleation sites of corrosion cavities, resulting in a great corrosion tendency of acicular ferrite [29]. On the other hand, the lowest corrosion rate of the acicular ferrite could be attributed to the uniform distribution of the phases in the welds [30]. For the base metal, pearlite with the lamellar structure of ferrite and cementite was considered to result from the cooperative growth of both ferrite and cementite.…”

The Effect of Chloride Ions on the Activity of Cerussite Surfaces

“…First, chloride ions added in pulp solutions can combine with lead on the cerussite surface to form PbCl + , which acts as the dominant species of lead chloride complexes in the pulp solution, and adsorbed onto the mineral surface and formed a lead-rich surface. Second, even the carbonate ions (CO3 2− ) with the inner cerussite can be exchanged by chloride ions [11][12][13]. All of these pathways result in increased lead concentrations on the mineral surface (i.e., increased number of active sites), which was revealed by the change of zeta potential.…”

“…In this case, it attaches more readily to the surface of cerussite through ligands than Pb 2+ , thereby increasing the number of active sites on the mineral surface and improving the subsequent sulfidization. Chloride ions also possess a small ionic radius, strong penetrability, and strong adsorption capacity onto metals; thus, chloride ions can combine with lead on the cerussite surface to form lead chloride complexes and even pass through the mineral surface to exchange carbonate ions (CO 3 2− ) with the inner cerussite, which can further increase the activity on the cerussite surface [11][12][13]. Adding chloride ions prior to sulfidization can activate the cerussite surface and reinforce the sulfidization of cerussite.…”