A novel method to inhibit stress corrosion cracking of corrosion-resistant Ni-base alloy by N addition

Coupled mechanical and crystallographic analysis of intergranular stress corrosion cracking initiation in additively manufactured 316L stainless steels

Effects of rolling path-induced microstructure and dissolved oxygen on stress corrosion cracking of AISI 316 L stainless steel in high-temperature PWR primary water

Stress corrosion behavior and mechanism of anchor bars under multi-factor coupled corrosive environments

Abstract Stress corrosion cracking (SCC) of stainless-steel welds in chloride-containing environments remains a major concern in structural and process industries. Although Activated Tungsten Inert Gas (A-TIG) welding has been widely investigated for improving weld penetration and mechanical properties, comparative assessment of SCC behaviour of flux-assisted A-TIG welded AISI 304L stainless steel remains limited. This study investigates the SCC response of AISI 304L stainless steel welds fabricated using conventional TIG (C-TIG) and A-TIG welding employing SiO 2 , TiO 2 , and Cr 2 O 3 activating fluxes under chloride environments. SCC susceptibility was evaluated using Slow Strain Rate Testing (SSRT) in air and 3.5 wt.% NaCl solution. Mechanical degradation behaviour, time-to-failure response, fracture morphology, and localized compositional variations were comparatively assessed. Chloride exposure reduced the mechanical performance of all weld conditions. Among the investigated welds, TiO 2 -assisted A-TIG exhibited the most favourable SCC resistance, achieving a time-to-failure of 115 min compared with 98 min for the C-TIG weld. The SCC susceptibility indices further revealed lower degradation in strength and ductility for TiO 2 -assisted welds (Iσ ≈ 4.18% and Iε ≈ 10.82%) than for C-TIG welds (Iσ ≈ 15.96% and Iε ≈ 28.19%). Fractographic analysis also indicated comparatively reduced crack propagation in TiO 2 -assisted welds. The SCC resistance trend under the investigated conditions was established as TiO 2 A-TIG > Base Metal > Cr 2 O 3 A-TIG > SiO 2 A-TIG > C-TIG. The study provides a direct comparative assessment and performance-based ranking of activating fluxes with respect to SCC behaviour of AISI 304L stainless steel welds exposed to chloride environments.

ABSTRACT After one year of operation, S30408 heat exchange tubes in an economiser of an oil residue hydrogenation unit leaked. Examinations included macroscopy, chemical analysis, hardness testing, scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), micro-area X-ray diffraction (micro-XRD), metallography, and electron backscatter diffraction (EBSD). Severe work hardening at the elbow increased hardness from 165.3 to 332.7 HV10, raised geometrically necessary dislocation (GND) density from 0.75 × 10¹⁴ to 3.41 × 10¹⁴ m−², and reduced Σ3 twin boundaries from 42.0% to 27.1%. Corrosion products confirmed sulfuric acid dew point corrosion and upstream catalyst residue synergy. A quantitative environment–material–stress model yielded ηenv = 2.15, ηmaterial = 2.65, and φ = 0.37; ηenv × ηmaterial = 5.70 quantifies the combined acceleration by V/Mo residues and cold-worked microstructure. The measured average corrosion rate was 0.200 mm/a. The model predicted a failure time of 1.07 years, matching the actual service life. Sulfide stress corrosion cracking (SSC) dominated, reducing the failure time from ∼10.0 years to ∼1.2 years. Preventive measures include selecting duplex or stabilised austenitic stainless steel, controlling cold deformation, and solution heat treatment after cold forming.

Premature structural failure of biodegradable vascular stents (BVSs) induced by stress corrosion cracking (SCC) remains a critical challenge. Heterogeneous plaques compress the stent, leading to inadequate expansion and inducing stress concentration that exacerbates SCC. This study proposes variable-stiffness stents to improve radial support and mitigate non-uniform degradation. The stents were designed with shortened axial ring segments and selective strut widening at the stenotic regions for targeted stiffness enhancement. They were virtually deployed in arteries with non-calcified and calcified plaques to evaluate immediate performance, while long-term service behavior was assessed via degradation simulation under combined electrochemical corrosion and SCC effects. The results show that variable-stiffness stents exhibited comparable residual stenosis to uniform-stiffness stents with identical local structures at plaque regions. Dual-stiffness designs yielded a smoother luminal profile than uniform-stiffness counterparts, and gradient-stiffness designs achieved further improvements. Local strut widening extended full recoil time, with a more marked effect on high-stiffness segments, by 52.6% and 41.2% in non-calcified and calcified plaques, while simultaneously increasing volume loss to mitigate non-uniform degradation. In addition, widened gradient-stiffness designs further prolonged the stable support time by 9.7%. These findings show variable-stiffness stents with widened gradient-stiffness design exhibit a more favorable immediate and long-term performance.

HighlightsStrain rate and relative humidity strongly influence SCC susceptibility.Pre-soaking localized attacks are necessary for SCC initiation.Strain rates below 10−5 s−1 markedly increase SCC damage.IGC susceptibility drives predominant intergranular fracture.Critical environmental–mechanical window for SCC testing was identified.The aim of this study is to comprehensively investigate and quantify the effect of strain rate (SR) and environmental parameters on the stress corrosion cracking (SCC) behavior of a high-strength, aluminum–copper alloy. Slow strain rate (SSR) tests were carried out in air at 25 °C, over a SR range from 10−4 to 10−7 s−1 and controlled relative humidity (RH) between 40% and 80%. The influence of the pre-soaking period in 3.5 wt.% NaCl solution was also assessed. A major effect of pre-soaking was identified, as it was necessary for the onset of SCC. Increasing RH over 40% and decreasing SR below 10−5 s−1 significantly intensified SCC susceptibility, leading to ductility loss up to 84%. SSR test results were supported by microstructural investigations, with particular emphasis on the role of second phases. Their electrochemical activity was examined by scanning Kelvin probe force microscopy (SKPFM), while intergranular corrosion (IGC) susceptibility was evaluated according to the ISO 11846 standard. The pronounced IGC susceptibility of the alloy led to predominantly intergranular fracture morphologies in cross-section peripheral areas after SSR testing. The results confirmed the synergistic effect among microstructure, IGC susceptibility and SCC behavior, identifying a critical window of mechanical and environmental parameters governing SCC.

Influence of ECO coating thickness and microstructural defects on corrosion, corrosion fatigue, and stress corrosion cracking in biomedical Mg alloys

Synergistic anodic dissolution and hydrogen embrittlement in stress corrosion cracking of high-strength steels: Mechanisms and multiscale dynamics

A Review of Stress Corrosion Cracking Behavior of Stainless Steel

The article deals with the study of stress corrosion cracking (SCC) of X70 steel using corrosion-mechanical testing that simulates the operating conditions of underground pipelines. The tests were carried out under cyclic four-point bending at stresses close to the yield point, in electrolytes with various hydrogen charging capacities. The following model environments were used: NS4 solution and citrate buffer (pH 5.5). Hydrogen charging was controlled by the addition of thiourea and by varying the potential. It was shown that microcracks initiated at corrosion defects (pits) and then emerged at the surface to form narrow cracks. The incubation period depends on the environment: under corrosive conditions it is approximately two times shorter than in the air. The size and nature of stress concentrators play a significant role: natural pits (~hundreds of μm) lead to crack formation within 24–28 days, whereas artificial holes (0.6–1 mm) lead to crack formation within 5–7 days. The effect of hydrogen was established: the acceleration is insignificant under moderate hydrogen charging, whereas the incubation period decreases sharply at high hydrogen charging. Critical hydrogen concentrations where its effect becomes significant were determined. Methods for inhibiting stress corrosion cracking by means of organosilicon films (vinyl- and aminosilanes, as well as their mixtures with inhibitors—benzotriazole and amines) were considered. The most effective composition is vinylsilane + benzotriazole: the time to crack initiation increases from 5 to 36 days, and the crack growth rate decreases.

This study examined the stress corrosion of Alloy 625 in Cl− + S2O32− solutions using digital holography in combination with electrochemical methods. Without elastic tensile stress, intergranular corrosion (IGC) occurred, due to the higher activity of grain boundaries compared to the grain interior and to preferential adsorption of sulfur (produced by S2O32− decomposition) at these boundaries. Digital holography observations showed that IGC initiated at certain grain boundaries and propagated to adjacent boundaries, even in the absence of elastic tensile deformation. Applying elastic tensile stress (260 MPa, ~46% σy) increased the defect density within the oxide film, thereby enhancing corrosion and anodic currents, and inducing river-like cracks. Although elastic tensile stress suppressed IGC, it simultaneously promoted stress corrosion cracking (SCC), as the stress exerted a stronger accelerating effect on corrosion than the grain-boundary did. Digital holography allowed in situ monitoring of the stress corrosion process in Alloy 625, demonstrating that cracks initiated via localized corrosion/IGC and subsequently propagated along the direction of the applied stress.

Tension-induced rock masses at steep slope fronts undergo progressive failure under self-weight tensile stress, characterized by deep rear-edge fractures that propagate subcritically over decades before catastrophic collapse. Conventional monitoring systems frequently fail to provide adequate warning because the measurable deformation phase typically lasts only hours to days, despite decades-long crack incubation. We develop an integrated framework combining physical similarity modeling, smoothed particle hydrodynamics (SPH) simulation, and field validation to systematically investigate failure evolution. High-frequency MEMS accelerometers (1000Hz) capture dynamic tilt progression through spatial vector analysis of gravitational acceleration components. Water-induced weakening at fracture tips simulates natural stress corrosion, accelerating time-dependent deformation under controlled conditions. Results reveal distinct two-stage evolution: prolonged quasi-static deformation followed by rapid acceleration, where reciprocal tilt rate exhibits linear decay toward zero before failure, enabling quantitative prediction. SPH simulations with an elastoplastic-mixed damage model demonstrate that fracture geometry significantly influences prediction window duration, with central horizontal fractures providing optimal early warning conditions. Field validation confirms method robustness: reciprocal tilt rate approached zero linearly across all scenarios, with prediction accuracy within 0.9% and a 38-hour acceleration phase in prototype scale, providing practical lead time for risk mitigation. This integrated physical-numerical approach advances understanding of brittle rock mass failure mechanisms and provides reliable tools for implementing effective early warning systems in rockfall-prone regions.

Magnesium (Mg) alloys are promising for automotive lightweighting and the low-altitude economy, yet their reliability is challenged by stress corrosion cracking (SCC). To realize a quantitative and physics-based evaluation of SCC resistance, this study develops a mesoscale simulation framework coupling dislocation density-based crystal plasticity with an anodic dissolution phase-field model. A 2D representative volume element is constructed for randomly textured polycrystalline Mg to investigate the synergistic acceleration of corrosion by dislocation slip and hydrostatic stress. Results show that heterogeneous dislocation multiplication induced by pre-deformation is the decisive factor in corrosion path selection. In soft-oriented grains, high dislocation densities elevate the interface kinetic coefficient to levels substantially higher than those in hard-oriented regions. Notably, within such soft grains, the contribution of dislocation density to the interface kinetic coefficient can be up to 7.7 times that of hydrostatic stress, establishing dislocation-induced lattice disorder as the primary accelerator for transgranular corrosion. Hard-oriented grains effectively impede corrosion propagation due to restricted dislocation proliferation. This study elucidates how grain orientation-dependent dislocation evolution regulates corrosion morphology, revealing that the random texture delays overall structural failure based on a “weakest-link” mechanism.

Electrochemical and stress corrosion behaviors of low-alloy high-strength steel in the soil environment of Western China

This study clarifies the mechano-chemical role of surface treatments on the SCC of sensitized Alloy 600. We compared 400-grit grinding, Scotch-Brite polishing, and CWJP under “bend-then-treat” CBB testing. While grinding caused severe cracking, CWJP provided complete immunity during a 500 h CBB testing. This occurred despite the CWJP surface having the highest GND density and roughness. The dominant protective mechanism was a relatively deeper, higher-magnitude CRS field induced by CWJP. This CRS mechanically counteracts applied loads and electrochemically stabilizes the surface by retarding DO diffusion, as confirmed by DFT. Engineering deep CRS is thus paramount for mitigating SCC. The investigation evaluates how different post-bending surface treatments modify the near-surface mechanical state of Alloy 600 and subsequently affect stress corrosion cracking (SCC) behavior in high-temperature boiling water reactor (BWR). Each treatment produces a characteristic combination of roughness, residual stress, and work hardening, resulting in distinct crack initiation and propagation patterns. Results demonstrate that the durability of the induced compressive stress and microstructural strengthening, rather than their initial levels, plays the decisive role in SCC mitigation. • CWJP on pre-strained Alloy 600 provides considerable immunity to SCC initiation during 500 h exposure • Deep compressive residual stress (CRS) is the dominant factor for SCC mitigation • Protective CRS overrides detrimental effects of high GND density and surface roughness • DFT confirms compressive strain slows down dissolved oxygen diffusion, hindering SCC

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.

Mechanistic study of electrochemical corrosion and stress corrosion cracking in welded Ti-6321 alloy structures

Review on stress corrosion cracking in additively manufactured alloys: Experimental and computational modeling aspects