An experimental study on the feature and behavior of impurity particles in a 220 °C low-temperature LBE loop pipeline

Graphene is an ideal reinforcement for enhancing the corrosion resistance of low-zinc epoxy coatings owing to its high specific surface area, excellent conductivity, and barrier properties. However, the low electron transfer efficiency in such coating often leads to uniform corrosion of zinc powder with corrosion products enveloping its surface, causing premature failure and low zinc utilization. Herein, amino-functionalized graphene (Gr-NH2) was synthesized to prepare Gr-NH2 reinforced low-zinc epoxy coatings (Gr-NH2/ZEC, 40 wt % zinc), where edge-grafted -NH2 groups were covalently bonded to graphene and C-N-Zn electron pathways were established between graphene and zinc fillers. The enhanced Gr-NH2/Zn interfaces promote interfacial electron transfer, redirecting zinc corrosion from uniform corrosion to preferential intergranular corrosion, which continually fractures zinc particles and exposes fresh active surfaces. As a result, Gr-NH2/ZEC shows a high initial |Z|f=0.01 value of 1.16 × 108 Ω at 6 h immersion, which is approximately 5.4 times that of GO/ZEC. After 28 days of immersion corrosion, the |Z|f=0.01 value remained 8.88 × 107 Ω, which is very close to its initial value and still higher than that of GO/ZEC. Meanwhile, the enhanced intergranular corrosion also enables multiple reactivations of cathodic protection, thereby leading to a remarkable increase of zinc utilization efficiency from 9% to 20.5%. This interfacial engineering strategy provides a promising route for enhancing the cathodic protection performance of low-zinc epoxy coatings.

The microstructure of high-strength martensitic steel specifically made for additive manufacturing was modified via in situ plasma arc remelting (PAR) to improve its surface properties. The results reveal that the microstructure is characterized by the intragranular martensite and intergranular eutectic structure of high-strength martensitic steel. The intragranular worm-like δ-ferrite embedding in the martensite matrix was clearly observed after PAR. Compared with the as-deposited part, the tensile strength of the PAR part reached 1753 MPa, and the ductility increased to 2.3%. The strength and elongation had increased by 20% and 229%, respectively. After in situ PAR, the wear loss decreased to 80% of the tailored high-strength martensitic steel, and the corrosion current density decreased to 17%. Both the as-deposited part and the PAR part exhibited significant intergranular corrosion morphological characteristics.

Discovery of novel phenomenon and mechanism revelation of an Al-Zn-Mg-Cu alloy without intergranular corrosion

Moisture-driven chlorination and exfoliation corrosion of Inconel 625 in NaCl–MgCl2 molten salt: Effect of salt purification and surface roughness

The mechanism of irradiation-assisted stress corrosion cracking (IASCC) in 321 stainless steel, an important reactor core material, remains unclear. IASCCs from slow strain rate tensile test in high-temperature and high-pressure water after heavy-ion irradiation were analysed. The irradiation damages are consistent with those from neutron irradiation at similar dose, confirming heavy ion is effective for IASCC study. IASCC susceptibility increases with dose, and local-deformation remains the primary driving factor. Radiation-induced segregation and oxidation under tensile stress synergistically initiate IASCCs. Pits induced by Si effect and the corrosion of γ-phase by Ni-Cr effect are important for the initiation of transgranular cracks. • Heavy-ion irradiation induces similar damage defects (dislocation loop and RIS) in SS as neutron irradiation at similar doses. • Local deformation, oxidation (including grain boundary oxidation and matrix oxidation) and radiation-induced segregation interacted synergistically to initiate stress corrosion cracking in heavy ion irradiated 321 SS. • Brittle Fe-Ni spinels and defect structures at grain boundaries directly contributes to the initiation of IGSCC when 321 SS is subjected to tensile stress, attributing to the radiation-induced segregation, oxidation and dissolution of Ni and Si at grain boundaries. • Intergranular stress corrosion cracks propagate in a periodic process of the migration of oxide tip along grain boundaries, the formation of new oxide forefront and cracking under tensile stress. • At the end of the heavy ion irradiation region, the irradiation can still promote the initiation of IASCC, but the effect diminish as the distance from the peak damage area increases. When IASCCs propagate from the irradiated to unirradiated region, wherein Ni oxide is transformed into Cr oxide at the crack tip, accompanied by a double-layer structure consisting of Cr oxide and (Ni, Cr) oxide as the transition zone. • Irradiation induces local enrichment of Si within intragranular. The defect structures formed by the dissolution of SiO x create pits under tensile stress and irradiation-electrochemical effect, with stress concentration at the bottom. In combination with the corrosion effect of CrO x on the γ-phase, TGSCC is initiated.

In water applications, material selection is based on corrosion resistance, formability, and cost. While S30403A is a standard choice, where the fluid corrosiveness exceeds its tolerance, a superior alloy grade such as S31603A is required. To offer a more economical and environmental alternative, Aperam developed the new 316A grade. A comparative study—including localized, crevice, and uniform corrosion assessments using electrochemical methods and intergranular corrosion trials—confirms this grade achieves corrosion resistance similar to S31603 across different temperatures and media. Now registered in ASTM standards1 as S30416, 316A provides a cost-effective solution for demanding water environments without compromising performance.2

Mechanochemical and environmental factors in intergranular corrosion of additively manufactured AlSi10Mg

A comparative investigation of the corrosion behavior evolution of 15%SiCp/Al-Cu-Mg aluminum matrix composites (AMC) subjected to different heat treatments in a salt spray environment containing 5wt% NaCl was performed. Metallographic microscopy was used to observe the surface morphology of the corroded materials. Field-emission transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for microstructural evaluation and elemental analysis of the samples. Polarization curves and electrochemical impedance spectroscopy (EIS) were also employed to investigate the corrosion performance of the particle-reinforced aluminum matrix composites under different heat treatments. The test results indicate that, in addition to the influence of various grain boundary precipitates and electrochemical inhomogeneities between the precipitate-free zone (PFZ) and the aluminum matrix, differences in electrochemical properties between the SiC reinforcement particles and the aluminum alloy matrix are also a primary factor contributing to the corrosion of the aluminum-based composites in a 5wt% NaCl salt spray environment. Microstructural observations and electrochemical testing of AMC specimens at different corrosion stages indicate that under-aged samples exhibit relatively higher intergranular corrosion susceptibility. Under prolonged exposure to a salt spray environment, the over-aged specimen exhibited more pronounced galvanic corrosion phenomena, specifically, a significant decrease in Charge transfer resistance (Rct) values and an increase in CPE values. Rct results indicate that naturally aged AMC exhibits higher corrosion resistance than artificially aged AMC. With increased salt spray corrosion time, varying degrees of crevice corrosion occurred at the Al–SiC interface in all heat-treated samples.

Abstract The molten fluoride salts used in Molten Salt Reactors (MSRs) are known for being a challenging environment for construction materials. Nickel alloys are usually used in this application for their corrosion and temperature resistance. The goal of this work was to test MoNiCr alloy in a molten mixture of lithium fluoride and beryllium fluoride (FLiBe) and to evaluate the effect of laser shock peening (LSP) and hot isostatic pressing (HIP) methods of thermomechanical treatment on its corrosion resistance. The material was first processed by LSP, and then a HIP heat treatment followed. The aim is to create a modified surface layer through a combination of these processes. The corrosion test itself was performed by immersion of specimens in molten FLiBe at 700 °C for 1000 h. The results showed that both LSP and HIP have observable influence on corrosion of MoNiCr alloy. Although the depth of corrosion damage did not differ greatly, the mechanism varied considerably. Regardless of the treatment method, all samples showed chromium depletion to a depth of approximately 30 μm. A zone of finer grains was formed in the same area. Material processed with LSP alone was more susceptible to intergranular corrosion, while the combination of LSP and HIP suppressed it. The number of passes and type of ablation layer in LSP process have a big role. The best results were achieved with LSP processing with a higher number of repeated passes (10) and without ablation polymer tape. In combination with HIP, intergranular corrosion was completely suppressed.

This paper performs a bibliometric and critical review on the topic “corrosion of additively manufactured steel” using RStudio software and its tools. Data for analysis is collected from the Web of Science (WoS) database. The critical review reveals mechanical behavior, corrosion mechanisms, microstructural evolution, and additive manufacturing (AM) process development, highlighting that corrosion performance is strongly influenced by AM process selection, parameter settings, alloying elements, and post-treatment methods, all of which shape microstructure, surface morphology, and passive layer formation. Based on the reviewed literature, AM techniques produce stainless steels with material properties that promote the formation of a passive oxide film significantly thicker, more electrically resistive, and more uniform than in conventionally produced counterparts. Moreover, the repeated heating and cooling cycles in AM suppress chromium-carbide precipitation along twin boundaries, thereby significantly enhancing resistance to intergranular corrosion compared to wrought counterparts. By optimizingAM parameters, it may be possible to refine grain structure, reduce process-induced defects, enhance post-processing efficiency, and stabilize passive films, enabling AM stainless steels to possibly match or even exceed the corrosion resistance of wrought steels, thus accelerating the use of AM stainless steel in marine engineering applications.

Radiation-induced segregation (RIS) poses a significant challenge for ferritic Fe–Cr alloys under irradiation, as it can compromise mechanical integrity and increase susceptibility to intergranular corrosion. Yet, the mechanisms governing Cr segregation remain incompletely understood. In this study, we present a physics-based rate-theory model parameterized using self-consistent mean field theory-based Onsager transport coefficients to investigate RIS at the grain boundary in dilute Fe-(0.1 at. %) Cr. Under equal production rates of vacancies and self-interstitial atoms (SIA), and their equal absorption rates by bulk dislocations, the model simulates the experimentally observed transition from Cr enrichment at low temperatures to depletion at higher temperatures. Under these unbiased conditions, systematic investigation reveals that while temperature-dependent transport properties dictate the segregation direction, dose rate, grain size, and dislocation density only influence the magnitude and spatial extent of Cr segregation. However, under more realistic conditions of preferential vacancy production within damage cascade and/or preferential SIA absorption by bulk dislocations, the enrichment-to-depletion transition shifts to lower temperatures. Our findings demonstrate that RIS predictions based solely on transport coefficients are valid only under symmetric point defect flux conditions, and that biases in defect production and absorption must be considered for accurate predictions. This work provides a mechanistic framework for understanding RIS in ferritic alloys and informs alloy design for advanced nuclear systems.

As a key component in oil drilling, drill pipes are prone to failure in harsh operating service environments. Multiple severe cracks were identified in the S135 drill pipes following field service, with partial crack extensions of ~1 mm detected at the thread roots penetrating into the pipe wall, posing critical threats to structural integrity. This study investigated the failure mechanisms of the drill pipes and examined the potential effects of dynamic rotation on corrosion-assisted cracking. The results showed that this failure was close to the combined results of corrosion and torque. Cl- and S2- in the drilling fluid were the main sources of corrosive substances. Cl- preferentially accumulated on the drill pipe surface, initiating localized pitting corrosion. Under applied stress, these surface pits exacerbated local stress concentration. The synergistic action of S2- then promoted the transition from pitting to stress corrosion cracking. Regarding the corrosion stage, the rotational state of the drill pipe will affect the drilling fluid's corrosion results. The mud deposition during rotation leads to severe intergranular corrosion, which further causes material peeling. Dynamic rotation at 60 r·min-1 increased the corrosion rate to 0.55 mm·a-1 after 216 h of immersion, 41% higher than under static conditions, while maximum corrosion depth increased from 8.43 μm to 13.86 μm. These results indicate that rotational motion accelerates corrosion-assisted cracking.

Metal Fatigue Fracture After Revision Total Knee Arthroplasty: A Retrieval Analysis.

Effects of Cu content and Ga addition on suppressing intergranular corrosion of copper substrate in stainless steel/copper vacuum brazed joints

Abstract Induction heat treatment is a promising alternative to conventional furnace-based processes for martensitic stainless steels due to its fast-processing capability and lower energy demand. In this study, induction heating combined with thermal cyclic treatment was applied to improve the microstructural homogeneity and mechanical performance of the material. The results showed a refined and stable microstructure, reduced wear loss, improved intergranular corrosion resistance, and a more uniform hardness distribution. These improvements were supported by statistical reliability analyses of hardness measurements.

Intergranular corrosion (IGC) and exfoliation corrosion (EXCO) limit the durability of 2219 Al–Cu in chloride-rich, cyclic-humidity aerospace environments, and conventional thermal stress relief can worsen grain boundary precipitates and grain boundary non-precipitation zones (PFZs), motivating evaluation of low-temperature resonant vibration stress relief. Using polarization tests and microstructural analysis, we show that RRV lowers corrosion current, strengthens passivation, and reduces IGC and EXCO susceptibility. Alternating tensile–compressive stresses build dislocation networks that convert continuous or semi-continuous grain boundary precipitates into discrete distributions, increasing corrosion path tortuosity and slowing intergranular attack. A more discrete cathodic phase, a narrowed solute-enriched anodic band, and reduced PFZs disrupt corrosion channel continuity, weaken microgalvanic driving forces via a more uniform θ′ distribution, and limit corrosion product wedging, while homogenized precipitates suppress local galvanic coupling in EXCO-like media. Overall, RRV synergistically optimizes dislocation configuration and precipitate redistribution to intrinsically enhance corrosion resistance and offers a practical, low-temperature, scalable route to improve the durability of high-strength aluminum alloy structures in aerospace service.

Abstract 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.

Effect of salt purity on the corrosion of 316 L SS: Long-term studies in molten FLiNaK and ThF4 - LiF

Effect of Mg + Si content on the mechanical properties and intergranular corrosion behaviors of Al–Mg–Si alloys