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Purpose: The purpose of this paper is to study the corrosion behavior of Q235 steel in the bentonite-based resistance-reducing agent (RRA) with different infiltration rates of underground water. Design/methodology/approach: The corrosion behavior of the steel in underground water was assessed by weight loss experiment, electrochemical impedance spectroscopy and polarization curve. Findings: The results showed that the corrosion rate of the steel in the RRA pastes was much lower than that in the original acidic soil. The underground water infiltration slightly accelerated the corrosion rate of the steel in the RRA pastes, but the acceleration role is weak. The bentonite-based RRA can be compatibly applied in the acidic soil. Originality/value: The bentonite-based RRA can significantly reduce the corrosion rate of the steel and is suitable to compatibly apply in the acidic soil. [ABSTRACT FROM AUTHOR]

Purpose: High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions. Design/methodology/approach: The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer. Findings: The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process. Originality/value: The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to clarify the influence of the cathodic polarized potential on the stress corrosion cracking (SCC) susceptibility of X120 steel in a simulated acidic soil solution and the different SCC mechanisms at different cathodic polarized potentials. Design/methodology/approach – The SCC behaviors of X120 pipe steels at various potentials were investigated in a simulated acidic soil solution by slow strain rate tensile tests, electrochemical impedance spectroscopy and surface analysis techniques. Findings – The fracture surface of X120 steel stretched in air showed a ductile fracture. Both elongation and tensile strength of X120 steel in the simulated acidic soil solution decreased compared to that obtained in air. A slight cathodic polarization increased the elongation and tensile strength of X120 steel; therefore, the SCC susceptibility was lower at -0.65 VSCE than that at OCP, anodic dissolution dominates the corrosion process. However, a strong cathodic polarization induced hydrogen embrittlement, decreasing elongation and tensile strength, therefore, the SCC susceptibility was highest at -1.1 VSCE, and hydrogen embrittlement became the dominant process. Originality/value – The paper provides an essential insight into the mechanism of pipeline SCC for X120 steel in acidic soil environments. [ABSTRACT FROM AUTHOR]