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This paper presents the corrosion-induced cracking performance of reinforced concrete in a chloride condition. The meso-scale structures of concrete specimens were studied according to the X-ray micro-computed tomography test, including the corrosion propagation, the accumulation and transportation of corrosion products, the defects and cracking behaviors of concrete cover. The experimental results show that the defects could provide a reasonable space for the accommodation of corrosion products, which could significantly increase the corrosion process and postpone the cracking performance. The propagation of the cracking path initiating from the corrosion area of the reinforcement to the concrete cover was also captured based on the experimental images, which can make contribution to the recognition of corrosion-induced cracking behavior of the concrete cover.

Purpose This study aims to investigate the effect of galvanic corrosion on the sulfide stress corrosion cracking (SSCC) of X80/Inconel 625 weld overlay by altering the cathode/anode area ratios, Na2S2O3 concentrations and temperatures. Design/methodology/approach The effects of galvanic corrosion on X80/Inconel 625 weld overlay SSCC were investigated by immersion test, galvanic corrosion current test, electrochemical measurement, four-point bending experiment, hydrogen permeation experiment and scanning electron microscopy. Findings The anodic dissolution of the fusion boundary was enhanced as the cathode/anode area ratio increased, which is necessary for the SSCC of the X80/Inconel 625 weld overlay. However, severe galvanic corrosion reduced the SSCC susceptibility. The SSCC susceptibility showed a linear increase with Na2S2O3 concentration in the range of 10−4 ∼ 10−2 mol/L. However, further increasing the Na2S2O3 concentration to 10−1 mol/L resulted in the disappearance of SSCC. This is likely because sufficient hydrogen was required for SSCC initiation even under severe anodic dissolution conditions, which was further supported by the reduced SSCC susceptivity at elevated temperatures. Originality/value Limited studies aim to establish the relationship between the galvanic corrosion and SSCC of welded joints through altering the cathode/anode area ratios, Na2S2O3 concentrations and temperatures. This work will pave the way for understanding the effect of galvanic corrosion on the SSCC of dissimilar weld joints.

Stress corrosion cracking (SCC) of pipeline steels in near-neutral pH environments has remained a significant integrity risk for oil and gas pipelines. Although it has traditionally been termed “stress corrosion cracking,” crack growth has never been observed under a static loading condition. It was determined later that the cracking is driven by corrosion-fatigue mechanisms with some uniqueness. First, the loading frequencies typically vary over a wide range from 10−1 Hz to 10−6 Hz, which is usually beyond the scope of most fatigue investigations. Second, the rate of corrosion is typically well below 0.1 mm/y at which a premature failure solely by corrosion would occur much longer than that actually found in the field. Third, hydrogen, a by-product of corrosion, can be generated to a level at which hydrogen embrittlement may occur only under special conditions. Fourth, pipelines are operated under variable pressure fluctuations that may lead to enhanced crack growth resulting from load-interactions effects. All existing crack growth models were developed based on the results obtained from tests either under constant load for the case of SCC or under constant stress amplitude loading for the case of fatigue or corrosion fatigue. These models generally yield predictions that are deviated from the crack growth rates being measured because they fail to consider both the stress-dependent and the time-dependent load interactions during variable pressure fluctuations. This overview will discuss details on how these factors are synergistically interacted to cause failures of pipeline steels in the field. Based on the understanding of the cracking mechanisms, strategies to mitigate field crack initiation and propagation will be introduced.

Type 304 (UNS S30400) austenitic stainless steel was exposed for 6 months under elastic (0.1%) and elastic/plastic (0.2%) strain to MgCl2 and mixed MgCl2:FeCl3 droplets with varying chloride deposition densities (1.5 μg/cm2–1,500 μg/cm2) at 30% relative humidity (RH) and 50°C. The occurrence of pitting corrosion, crevice corrosion, atmospheric chloride-induced stress corrosion cracking (AISCC), and hydrogen embrittlement (HE) was observed, and the average crack growth rates estimated. Exposure to elastic/plastic strain resulted in longer and more severe cracks. AISCC was found at chloride deposition densities down to 14.5 μg/cm2, whereas no cracks were seen at lower deposition densities, with cracks developing at pit or crevice corrosion sites. More severe cracks were seen under MgCl2 droplets as contrasted to mixed MgCl2:FeCl3 salt droplets, which were seen to promote more localized corrosion sites with deeper penetration and in conjunction with shorter crack lengths. Differences in AISCC propagation rates and associated crack morphologies are discussed in relation to understanding long-term atmospheric corrosion exposures.

The history of dynamic straining in stress corrosion cracking studies and the evolution of the slow strain rate test (SSRT) are reviewed. Smooth and notched specimens; the importance of strain rate, electrode potential, and other environmental factors; the evaluation of test results; and comparisons to other techniques are addressed. The SSRT’s application in research for oil and gas sour service, buried natural gas pipelines, ethanol transportation, nuclear power, low pressure turbines, and mechanism studies is summarized and its usage by material, industry, and geographic region quantified. Standard test procedures are compared and improvements suggested. The more recent use of cyclic loading is discussed and areas for future study proposed.

To study the corrosion cracking process of reinforced concrete under the combined effects of chloride and fatigue loading, the constan-current and dry-wet cycle accelerated corrosion method was used to corrosion the specimens under different stress levels for different time. The quality loss of reinforcement, the composition of corrosion products and the cracking of concrete are analyzed from the macro, micro and micro scales, and to obtain the spatial distribution as well as microscopic characteristics of corrosion products of the reinforcement bar under coupling conditions. Additionally, a model of steel rust cracking under the coupled action of chloride and fatigue loading is established. The results show that: under the same corrosion time, the concrete cracking and steel corrosion degree become more serious with the increase of stress level. The greater the stress level, the earlier corrosion occurs and the more corrosion products are, Moreover, due to the fatigue load, the concrete on the upper side of the steel bar has rust expansion cracks earlier than the lower side.

The corrosion of additively manufactured (AM) metallic materials, such as stainless steels (SS), is a critical factor for their qualification and reliable use. This review assesses the emerging knowledgebase of powder-based laser AM SS corrosion and environmentally assisted cracking (EAC). The origins of AM-unique material features and their hierarchal impact on corrosion and EAC are addressed relative to conventionally processed SS. The effects of starting material, heat treatment, and surface finishing are substantively discussed. An assessment of the current status of AM corrosion research, scientific gaps, and research needs with greatest impact for AM SS advancement and qualification is provided.

The presence of water greatly influences time-dependent rock deformation. An understanding of how water can affect the time-dependent mechanical behavior of rock is important when assessing the long-term stability of geotechnical projects. While the previous studies have performed brittle creep experiments on oven-dry or fully-saturated rocks, we report here on a study designed to better understand brittle creep at different levels of saturation. We performed brittle creep experiments on oven-dry samples of red sandstone (Hunan province, China) and samples of the sandstone pre-immersed in water for different durations (from 2 to 8 days). These samples were deformed at a constant stress in one of either two conditions: dry or submerged in water. Before performing creep experiments, we first performed a series of water absorption and constant stress rate experiments to guide the stresses required for our creep tests and to assist with their interpretation. Our creep experiments show that immersion in water greatly increased the minimum creep strain rate and greatly shortened the time-to-failure when compared to the dry state. In detail, the minimum creep strain rate and time-to-failure increased and decreased, respectively, as pre-immersion duration increased from 4 to 6 days, but did not change as the duration was further increased to 8 days. We attribute this to the saturation of microcracks between 4 and 6 days (i.e., water imbibition was complete, or close to completion, following 6 days). We also show that oven-dry samples deformed at a constant stress underwater fail at stresses much lower than oven-dry samples deformed under dry conditions, due to the imbibition of water during deformation. Samples pre-immersed in water, but deformed in the dry condition were characterized by lower strain rates and longer time-to-failure than those pre-immersed in water and deformed underwater. Our explanation for this is that, due to the availability of water, crack tips can remain hydrated when the sample is deformed underwater, thus increasing the efficacy of stress corrosion cracking. The relationships and data provided herein inform on the long-term stability of engineering structures.

This study investigates the influence of chloride ion concentration and thermal-mechanical treatments on intergranular corrosion (IGC) and stress corrosion cracking (SCC) in austenitic stainless steel 201. Heat treatment involved annealing at 1000°C for 60 minutes, followed by sensitization at 700°C with varied holding times (90, 120, and 150 minutes). Mechanical deformation was introduced through bending tests at 0°, 90°, and 180° angles. Electrochemical corrosion behavior was analyzed using open-circuit potential (OCP) and Tafel polarization curves in 3.5 wt% NaCl solution, while microstructural changes were characterized using optical microscopy and Scanning Electron Microscopy (SEM). Results showed that both increased holding time and bending angle led to greater chromium-carbide precipitation along grain boundaries, thereby intensifying IGC and promoting deeper, longer SCC cracks. The corrosion potential (Ecorr) became more negative, and corrosion current density (Icorr) increased, confirming a rise in corrosion rate. This comprehensive approach provides insights into the mechanisms of material degradation in chloride-rich environments and guides industrial strategies to mitigate corrosion in piping systems.

Thiosulfate salts have been known to be dangerous corrosion promoters for over 30 y, when present under typical service conditions. This paper reviews the role of thiosulfate anion in causing localized corrosion and/or stress corrosion cracking of steels. Electrochemical and mechanical aspects associated with the pitting and stress corrosion cracking of steels in thiosulfate-containing environments are thoroughly discussed and reviewed. In particular, results from the research studies relevant to pulp and paper, oil and gas, and nuclear industries, where thiosulfate ion is known to be present advertently or inadvertently, have been analyzed.