Purpose The purpose of this paper is to investigate the synergistic effects of pH reduction and chloride ions (Cl−) on the corrosion behavior, passive film stability and corrosion-assisted mechanical degradation of Q235 steel in simulated concrete pore solutions, providing theoretical support for the durability design and corrosion prevention of reinforced concrete structures in marine environments. Design/methodology/approach Electrochemical measurements, slow strain rate tensile (SSRT) tests, scanning electron microscope and energy-dispersive X-ray spectroscopy were used to study Q235 steel in simulated concrete pore solutions with different pH values (12.5, 11.5 and 10.5) and Cl− concentrations (0–1.0 mol·L −¹). Findings The results show that decreasing pH and increasing Cl− concentration synergistically accelerate passive film destabilization, corrosion development and mechanical degradation of Q235 steel. pH 11.5 represents the onset condition for significant Cl−induced passive film destabilization rather than complete failure. MnS inclusions act as preferential sites for pitting initiation. SSRT results indicate reduced tensile strength and ductility under low-pH and high-Cl− conditions. Research limitations/implications This study clarifies the synergistic mechanism of pH reduction and Cl− attack on passive film stability and corrosion-assisted mechanical degradation of Q235 steel. The findings provide useful reference for corrosion prevention, durability design and maintenance of Q235 steel-reinforced concrete structures in marine environments. Practical implications This study provides critical parameters (pH = 11.5, Cl− = 0.5 mol·L−¹) for passive film breakdown and corrosion initiation of Q235 steel in carbonated and chloride-contaminated concrete. The findings offer a scientific basis for durability design, corrosion monitoring and maintenance strategy optimization of marine reinforced concrete structures, helping to extend service life and reduce lifecycle costs. Social implications By elucidating the corrosion failure mechanism in marine environments, this research provides support for the safety and sustainability of large-scale marine infrastructure such as cross-sea bridges, ports and tunnels. It helps mitigate economic losses caused by corrosion and enhances public safety by improving the integrity and reliability of concrete structures in harsh environments. Originality/value This study systematically reveals the synergistic degradation mechanism of pH and Cl− on the stability of the passive film and the stress corrosion behavior of Q235 steel, addressing key gaps in existing research. By linking microscopic initiation sites (MnS inclusions) to macroscopic failure, it provides new insights for corrosion prediction and protection in marine engineering.
Purpose This study aims to propose an embedded, structurally optimized electromagnetic sensor for quantitatively detecting local corrosive conditions in reinforced concrete by correlating its magnetic response with the corrosion-induced mass loss of the sensor steel shell. Design/methodology/approach A square hollow steel shell sensor integrating a permanent magnet and Hall elements was designed as an embedded detection component. The sensor forms a stable, short-range and repeatable magnetic response channel, allowing local corrosion severity to be quantified from magnetic-field variations caused by sensor steel shell corrosion. Two shell corrosion models were established to reveal the corrosion-response mechanism, and three sensor-structure models were compared to optimize the shell cavity and sensitive detection region. An equivalent magnetic circuit model was developed to relate magnetic flux density to shell mass loss, and accelerated corrosion tests were conducted for validation. Findings The proposed sensor showed strong correlations between magnetic response and the mass loss ratio of the sensor steel shell. The coefficients of determination were 0.9972 and 0.9932 under uniform and nonuniform corrosion, respectively, supporting quantitative assessment of local corrosion severity under controlled accelerated-corrosion conditions. Research limitations/implications This study was validated through modeling and accelerated corrosion tests. Further long-term field studies under different concrete environments and service conditions are needed to verify the sensor performance in practical reinforced concrete structures. Practical implications The proposed embedded electromagnetic sensor provides a feasible method for local and quantitative detection of corrosive conditions in reinforced concrete. It may support early warning of potential reinforcement-corrosion risks and durability assessment of reinforced concrete structures. Social implications Reliable detection of locally corrosive conditions can help improve the safety, durability and maintenance efficiency of reinforced concrete infrastructure by providing early warning of potential reinforcement-corrosion risks and helping extend service life. Originality/value This work introduces an embedded electromagnetic sensor for quantitative characterization of sensor steel shell corrosion. The sensor steel shell acts as a corrosion-sensitive element whose mass loss reflects local corrosive conditions in reinforced concrete.
Purpose This study aims to investigate the corrosion and hydrogen permeation behaviors of SM, T95 and 8028 steels in a simulated oilfield transportation environment by electrochemical methods. Design/methodology/approach Specimens of SM, T95 and 8028 steels were prepared. The polarization curves, EIS and hydrogen permeation curves of the materials were tested in the simulated solution for oilfield transportation service. The surface morphology was characterized by SEM, XPS and EBSD. Finally, DFT method was applied for cross verification. Findings In the simulated oilfield transportation environment, both 8028 and T95 steels form passive films and demonstrate excellent corrosion resistance, whereas SM steel exhibits inferior corrosion resistance. Both hydrogen permeation curves and TDS data demonstrate that the barrier effect of passive films significantly inhibits hydrogen permeation. DFT calculation results further confirm that the surface passive films on T95 and 8028 steels are the primary factors responsible for their extremely low hydrogen permeation current. Originality/value This work systematically evaluates the corrosion resistance and hydrogen permeation performance of SM, T95 and 8028 steels under simulated oilfield transportation conditions. It provides theoretical support and technical references for rational material selection and in-depth research on hydrogen embrittlement mechanisms.
Purpose - This study aims to elucidate the role of graphite nodules in the corrosion behavior of ductile iron in molten aluminum and to provide references for the design of Al alloy die-casting molds. Design/methodology/approach - Ductile irons with different graphite nodule counts were fabricated and immersed in molten aluminum for various durations. The corrosion behavior of ductile iron in molten Al was evaluated by characterizing the morphology, phase constituents and thickness of intermetallic compound (IMC) layers formed at the interface. Findings - The IMC layer is primarily composed of FeAl3, Fe(2)Al(5)and Fe-Al-Si phases, with Fe(2)Al(5)governing the overall layer thickness. As the number density of graphite particles increases, the thickness of IMC layer formed in ductile iron decreases. When graphite nodule count exceeds 600/mm(2), the corrosion resistance of the ductile iron surpasses that of H13 steel. Originality/value - Reduced internodular graphite spacing significantly enhances the resistance of ductile cast iron to molten aluminum corrosion, while graphite nodule size should also be comprehensively considered. This finding provides a reliable reference for the design of aluminum alloy die-casting molds. The present finding provides reference for aluminum alloy die-casting die design.
Purpose This study aims to review methods for stabilizing sheet architectures in two-dimensional (2D)-based hybrid anticorrosion coatings and analyze their effects on the retention of barrier performance and long-term protection. Design/methodology/approach Starting from corrosive-species transport and structural failure, the review considers effective aspect ratio, sheet orientation, filler loading, internal component ratio, interfacial continuity and electrical percolation. It compares in situ growth and deposition, surface engineering, self-assembly and interfacial assembly and field-assisted alignment and evaluates durability using coating morphology, permeability, water uptake, adhesion, electrochemical impedance spectroscopy (EIS) and evidence from scratched coatings. Findings The barrier advantage of 2D sheets can be realized only when their effective architecture is retained during dispersion, curing and service. Auxiliary units can suppress restacking, restrict relative motion, improve filler-resin interfaces and regulate electrical contacts. Excessive loading, open pores, hydrophilic surfaces and inadequate resin infiltration may, however, introduce new transport pathways. Durable protection therefore requires a formulation-specific balance among sheet morphology and orientation, component ratio, interfacial state and electrical percolation. In active systems, performance further depends on trigger timing, the effective concentration at defects and the post-release integrity of carriers and interfaces. Originality/value Using structural stability as the central theme, this review connects structural destabilization, stabilization-oriented fabrication and protection in service and derives structure-performance relationships and design implications from representative quantitative evidence.
