Stress Corrosion Research Articles

Modeling the mechanical properties of rock at different pore and confining pressures using the grain-based stress corrosion model

Summary A grain-based stress corrosion model is built from 3DEC-GBM (i.e., a three-dimensional discrete element grain-based model). The model employs the effective stress law and stress corrosion theory to study the time-dependent and time-independent deformation at the mesoscale of the sandstone with varying confining and pore pressures. The simulations adequately explain complex macroscopic time-independent behavior in terms of the mesoscale interaction of grains, and tension cracks were the dominant crack propagation pattern in the simulation for different confining and pore pressures. The traditional creep behavior observed in laboratory brittle creep experiments could also be accurately reproduced by the proposed model. The simulations show that the percentage of tension cracks in rock fractures decreases with increasing confining pressure and pore pressures. Increasing the applied differential stress and reducing the effective pressure can shorten time-to-failure and increase the creep strain rate, respectively. We conclude that the proposed model is an appropriate tool to analyze the deformation behavior of sandstone under coupled hydro-mechanical loading in both the short and long term.

Predictions of the full-life pressurised water stress corrosion cracking behaviour of 690 weld joints

Predictions of the full-life pressurised water stress corrosion cracking behaviour of 690 weld joints

A comprehensive review of residual stresses in carbon steel welding: formation mechanisms, mitigation strategies, and advanced post-weld heat treatment techniques

Abstract Residual stresses are critical factors influencing the service performance, reliability, and durability of welded carbon steel joints. These stresses can affect the joint, susceptible to brittle fracture, fatigue failure, and stress corrosion cracking, particularly within the heat-affected zone (HAZ). These stresses result from uneven thermal expansion and contraction during welding, with thicker plates and constrained configurations being more susceptible. Post-weld heat treatment (PWHT) assumes a critical function in mitigating these stresses by tempering martensitic structures, refining microstructures, and enhancing mechanical properties such as toughness and ductility. This review examines the mechanisms driving residual stress formation, evaluates the effectiveness of PWHT techniques, and highlights advanced methodologies like neutron diffraction, computational modeling, and hybrid welding processes. While PWHT significantly alleviates residual stresses, complete stress elimination remains unattainable, emphasizing the need for innovative strategies such as hybrid welding methods, computational modeling, and advanced heat treatments. This work integrates metallurgical principles with experimental findings to provide a strategy for enhancing the performance and reliability of welded joints in critically demanding industrial applications.

Enhancing Stress Corrosion Cracking Resistance in a High Alloying Al–Zn–Mg–Cu Alloy by Controlling Recrystallization Morphology

Enhancing Stress Corrosion Cracking Resistance in a High Alloying Al–Zn–Mg–Cu Alloy by Controlling Recrystallization Morphology

Diode area melting of SS316L using low power 450 nm lasers

Abstract This study investigates the use of Diode Area Melting (DAM) to process 316L stainless steel (SS316L), an alternative to Laser Powder Bed Fusion (LPBF), utilising independently addressable, low-power (~ 3.5 W) 450 nm blue lasers to address key limitations of LPBF, including thermal control, scalability, and efficiency. A normalised energy density (NED) processing map was developed to ensure successful material melting. Results demonstrated that DAM can achieve a relative density of 99.99% in single-layer SS316L samples using multiple 450 nm blue diode lasers. Notably, DAM-processed SS316L exhibited a significantly higher delta-ferrite content than samples produced via traditional LPBF, which is attributed to the slower cooling rate in DAM (600 °C/s vs. 107 °C/s). This increased delta-ferrite content enhances resistance to stress corrosion cracking in austenitic steel welds. Moreover, sub-grain cellular structures in the DAM-processed SS316L showed a 100% increase in size (4 μm) compared to those produced by LPBF.

Study on Stress Corrosion Cracking Mechanism of Steel Wires with Different Strength Levels

In civil engineering, stress corrosion cracking (SCC) is a common cause of premature failure in steel wires, and effective solutions are currently limited. Investigating the SCC behavior of steel wires with different strength levels is crucial for understanding its fracture mechanism and developing potential solutions. This study examines the SCC behavior of wire rods with three strength grades (Steel A, B, and C) through stress corrosion experiments. The results show that high-strength wire rods have smaller pearlite interlamellar spacing. Steel C has the highest tensile strength (2303 MPa), while Steel A has the lowest (1830 MPa). Regarding stress corrosion sensitivity, the SCC mechanism of Steel C is dominated by hydrogen embrittlement, while Steels A and B primarily exhibit anodic dissolution as the cracking mechanism. Although Steel C has the smallest pearlite interlamellar spacing and superior corrosion resistance, its SCC failure time is the shortest due to hydrogen embrittlement. In contrast, for the anodic dissolution cracking mechanism, Steel B has a smaller pearlite interlamellar spacing, which enhances its corrosion resistance, and exhibits higher local stress stability due to its higher strength, resulting in the best SCC resistance (failure time: 3.81 h). This study reveals the synergistic effects of microstructure and strength on the SCC behavior of wire rods, offering theoretical guidance for the application of high-strength wire rods.

Effect of post-heat treatments on the corrosion behaviour of additive manufactured M300 maraging steel

M300 maraging steel, with its exceptionally high strength, toughness and weldability, is widely employed in critical applications of space industry. In the present study, M300 alloy has been fabricated using laser powder bed fusion method and the effect of different post-heat treatments and build orientation on the corrosion and stress corrosion cracking (SCC) resistance have been examined using electrochemical polarisation and slow strain rate test methods. The results in general indicate that the fabricated alloy in the as-received condition exhibits fibrous texture in the 〈001〉 direction when compared to XY orientation. The microstructural heterogeneities have been partially improved after solution treatment and aging (STA) and significantly improved after hot isostatic processing (HIP) treatment at high temperature and pressure. As a result of this, the corrosion and SCC resistance of the alloy greatly improved wherein the SCC index value of the alloy was found to be 0.88 when compared to STA condition (0.52). With respect to the build orientation, corrosion resistance of XZ plane is high when compared to XY plane, which can be attributed to microstructural variations. In spite of the high SCC index of the alloy in the HIP condition, the alloy exhibits predominantly intergranular cracking morphology revealing that SCC problem could not be eliminated completely in M300 alloy. However, the high KISCC values of the alloy in HIP condition clearly reveal the improved SCC resistance, which was shown to be due to reduction in pores, texture and improved austenite content of the alloy.

Ab Initio Molecular Dynamics Insights into Stress Corrosion Cracking and Dissolution of Metal Oxides

Oxide phases such as α-Fe2O3 (hematite) and α-Al2O3 (corundum) are highly insoluble in water; however, subcritical crack growth has been observed in humidity nonetheless. Chemically induced bond breaking at the crack tip appears unlikely due to sterically hindered molecular transport. The molecular mechanics of a crack in corundum with a reactive force field reveal minimal lattice trapping, leading to bond breaking before sufficient space opens for water transport. To address this, we model a pre-built blunt crack with space for H2O molecule adsorption at the tip and show that it reduces fracture toughness by lowering the critical J-integral. Then, we explore stress-enhanced dissolution to understand the mechanism of crack tip blunting in the oxide/water system. Density functional theory combined with metadynamics was employed to describe atomic dissolution from flat hematite and corundum surfaces in pure water. Strain accelerates dissolution, stabilizing intermediate states with broken bonds before full atom detachment, while the free energy profile of unstrained surfaces is almost monotonic. The atomistic calculations provided input for a kinetic model, predicting the shape evolution of a blunt crack tip, which displays three distinct regimes: (i) dissolution primarily away from the tip, (ii) enhanced blunting near but not at the apex, and (iii) sharpening near the apex. The transition between regimes occurs at a low strain, highlighting the critical role of water in the subcritical crack growth of oxide scales, with dissolution as the fundamental microscopic mechanism behind this process.

Understanding the effect of galvanic corrosion on the sulfide stress corrosion cracking of X80/Inconel 625 weld overlay

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 of 316L Stainless Steel in Concentrated Ammonium Chloride Solution with Very Low Dissolved Oxygen Levels

ABSTRACT Slow strain rate testing has been used to investigate the susceptibility of 316L stainless steel to SCC in high chloride and low dissolved oxygen brines. Tests have been carried out for various temperatures and ammonium chloride (NH4Cl) concentrations. The susceptibility to SCC was assessed in terms of ductility loss, detailed fractography and cross-sectional inspections to identify the damage mechanisms. It is challenging to maintain long-term SCC experiments with very low DO levels. In this work, we showed that 3 hours of sparging with high purity nitrogen at a flow rate of 0.2 L/min was sufficient to reduce the DO in a 0.6 L test solution to ~ 10 ppb. However, over the full test duration of 7 or 8 days with continuous nitrogen purging of the solution, the mean and maximum DO values were 17.4 and 34.4 ppb in 40 wt.% NH4Cl, and 16.5 ppb and 41.8 ppb in 30 wt.% NH4Cl solutions at 95 °C. For 316L stainless steel at open circuit in ≥ 30 wt % (i.e. 6.1M) ammonium chloride solutions with these very low DO levels, pitting corrosion was not seen at 60 °C, became evident at 80 °C and was severe at 95 °C and above, while SCC was not seen at 60 or 80 °C, was possibly initiating at 80 °C without propagating significantly, and was severe at 95 °C.

Peening Techniques for Mitigating Chlorine-Induced Stress Corrosion Cracking of Dry Storage Canisters for Nuclear Applications.

Fusion-welded austenitic stainless steel (ASS) was predominantly employed to manufacture dry storage canisters (DSCs) for the storage applications of spent nuclear fuel (SNF). However, the ASS weld joints are prone to chloride-induced stress corrosion cracking (CISCC), a critical safety issue in the nuclear industry. DSCs were exposed to a chloride-rich environment during storage, creating CISCC precursors. The CISCC failure leads to nuclear radiation leakage. Therefore, there is a critical need to enhance the CISCC resistance of DSC weld joints using promising repair techniques. This review article encapsulates the current state-of-the-art of peening techniques for mitigating the CISCC in DSCs. More specifically, conventional shot peening (CSP), ultrasonic impact peening (UIP), and laser shock peening (LSP) were elucidated with a focus on CISCC mitigation. The underlying mechanism of CISCC mitigation in each process was summarized. Finally, this review provides recent advances in surface modification techniques, repair techniques, and developments in welding techniques for CISCC mitigation in DSCs.

The Damage Evolution of a Cr2O3-TiO2 Coating Subjected to Cyclic Impact and Corrosive Environments and the Influence of a Nickel Intermediate Layer

Cyclic impacts in corrosive environments significantly affect the service life of ceramic coatings, greatly increasing their susceptibility to cracking and delamination. This study investigated the damage evolution behavior of Cr2O3-TiO2 (CT) coatings under cyclic stress in a corrosive medium, and analyzed the effects of the nickel layer on coating stress, corrosion current, and crack propagation. The variations in corrosion potential and current were analyzed, and the formation patterns of interfacial corrosion cracks were observed. Pre-cracks were introduced on the ceramic coating surface using a Micro-Nano mechanical testing system, and cyclic impacts were applied to the samples in 5% diluted hydrochloric acid using SiC balls to induce damage evolution. The results indicate that the presence of the nickel interlayer reduced the corrosion current density from 9.197 × 10−6 A/cm2 to 8.088 × 10−6 A/cm2 and significantly decreased the stress between the coating and the substrate. The surface cracks gradually extended toward the interface under the coupling effect of corrosion and SiC ball impact. When cracks reached the interface, they provided channels for corrosive media, leading to stress corrosion cracking at the interface. The Ni intermediate layer suppressed the formation of interface cracks and greatly enhanced the impact damage resistance of the CT coating–substrate system in corrosive media.

A Novel, Automated Measurement and Analysis Technique forBonding Energy of Fusion and Hybrid Wafer to Wafer Bonding

Wafer bond quality is determined through Dual Cantilever Beam (DCB, Mazara method) testing. However, DCB is influenced by environmental and human factors and prone to large measurement error (>20%). Here, we demonstrate novel, automated measurement and analysis to remove these factors delivering industry leading accuracy (<5% error) and throughput (>100x). Bonding Energy (BE) is a crucial parameter for evaluating wafer bonding quality and determining whether bonded wafers can survive downstream processes in next generation 3D integration. There are several methods to measure bonding energy, but the dual cantilever beam (DCB) method is widely used due to its simplicity and cost-effectiveness. In DCB, a razor blade is inserted between two bonded wafers and the bonding energy is calculated from the length of the resulting crack. However, due to human and environmental factors, the error in DCB is often too large to make accurate and consistent measurements. The main environmental factor is stress corrosion where ambient water reacts with stressed siloxane bonds to prematurely break bonds causing BE to decrease over time. This means the bonding energy over time is proportional to the ambient humidity. Humidity can be removed using a glovebox, but this significantly reduces throughput due to purge/pump times and increases measurement complexity and cost. Here, we automate the crack length measurement in DCB to remove human measurement error and develop a novel method to remove the impact of stress corrosion without a glovebox. This technique also allows us to detect residual water in the bonding interface. Using our new technique, the bonding energy of fusion and hybrid bonded wafers are measured with <5% error. From these findings, we propose a new industry standard for measuring and reporting bonding energy in wafer-to-wafer bonding.

Creep model of bond-degradation in deep granite based on variable radius particle clump

The creep failure of rocks is related to its microstructure, external loading and time. A nonlinear yield model was introduced to describe the variation in the cohesion and friction angle with plastic strain and intergranular stress. The mechanical properties and creep characteristics of deep granite were obtained by indoor tests, and a variable radius particle clump model was constructed based on the particle flow method. The bond-weakening-friction-strengthening model was combined with the parallel bond stress corrosion method to establish the bond-degradation creep model of granite. The creep failure time, creep rate and tension and shear fractures number of the parallel bond stress corrosion model and the bond-degradation creep model were compared and analyzed to verify the applicability of the model. The fracture evolution law of deep roadway surrounding rock was studied based on the bond-degradation creep model. The results show that the rock failure characteristics and tension-compression ratio obtained by the variable radius particle clump modeling method are closer to the actual situation. Compared with the parallel bond stress corrosion model, the creep failure time of the bond-degradation creep model is shorter, more microfractures are generated during the failure process, and the numerical creep curves are more consistent with the test curves. The deep roadway vault shear failure and sidewall plate crack failure characteristics calculated based on the bond-degradation creep model are basically similar to the actual project situation. The bond-degradation creep model can better simulate the creep damage process of rocks under high stress, and is more suitable for analyzing the fracture evolution law of surrounding rock in deep hard rock cavern.

Development of a Neuroevolution Machine Learning Potential of Al-Cu-Li Alloys

Al-Li alloys are widely used in aerospace applications due to their high strength, high fracture toughness, and strong resistance to stress corrosion. However, the lack of interatomic potentials has hindered systematic investigations of the relationship between structures and properties. To address this issue, we apply a neural network-based neuroevolutionary machine learning potential (NEP) and use evolutionary strategies to train it for large-scale molecular dynamics (MD) simulations. The results obtained from this potential function are compared with those from Density Functional Theory (DFT) calculations, with training errors of 2.1 meV/atom for energy, 47.4 meV/Å for force, and 14.8 meV/atom for virial, demonstrating high training accuracy. Using this potential, we simulate cluster formation and the high-temperature stability of the T1 phase, with results consistent with previous experimental findings, confirming the accurate predictive capability of this potential. This approach provides a simple and efficient method for predicting atomic motion, offering a promising tool for the thermal treatment of Al-Li alloys.

Stress corrosion behavior and microstructure analysis of Al-Zn-Mg-Cu alloys fabricated by CMT wire arc additive manufacturing with different post-treatments

In this study, Al-Zn-Mg-Cu alloys components were fabricated by cold metal transfer (CMT) wire arc additive manufacturing (WAAM), and the stress corrosion cracking (SCC) behavior of the alloys with different post-treatments was studied by combining in-situ electrochemical impedance spectroscopy (EIS) with slow strain rate tensile. The hot-rolling process was employed to close the internal pores of the WAAM products, following by single-stage aging (T6) to further improve the mechanical properties of the products. The elongation loss and SCC susceptibility index of T6 sample are 38.0% and 43.0%, respectively, which exceed those of the hot-rolled sample at 35.5% and 37.0%. Furthermore, the corrosion fracture of the T6 sample exhibits intensive secondary cracks, indicating an increased SCC susceptibility. The stress corrosion process is classified into four stages based on the trend of the EIS: (Ⅰ) Initial stage of corrosion; (Ⅱ) Corrosion products accumulation stage; (Ⅲ) Corrosion products coverage stage; (Ⅳ) Approaching fracture stage. The hot-rolled samples have reduced SCC susceptibility due to the presence of coarse grain boundary precipitates (GBPs) which can act as the irreversible traps to capture hydrogen. The ultimate tensile strength and elongation of T6 sample reached 568.3 ± 11.5MPa and 9.1 ± 0.7%, respectively. However, the small-sized GBPs and wider precipitates-free zone reduced its SCC resistance. This study found that the hot-rolling process can fully exploit the mechanical property potential of Al-Zn-Mg-Cu alloys and improve their SCC resistance, which is an important guiding significance for the practical application of WAAM technology in Al-Zn-Mg-Cu alloys.

Optical microscopic study of the stress induced corrosion of brass and aluminium in dilute electrolyte, and the inhibition effect of Cedrus Atantica and Ocimum Basilicum

Optical microscopic analysis of the stress induced (85% calculated stress) corrosion of brass in 1M ammonium sulfate [(NH4)2SO4] + 1M copper (II) sulfate (CuSO4) solution, and aluminium in 0.5M, 1M and 2M sulfuric (H2SO4) solution at 10% and 20% addition of Cedrus Atlantica and Ocimum basilicum Linn. essential oil extracts were documented. The optical images obtained showed the effect of both extracts on the alloys. Optical images of aluminium in the presence of Cedrus Atlantica showed increased susceptibility of the alloy to localized and general corrosion compared to Ocimum basilicum Linn which enhanced the corrosion resistance of aluminium. Cedrus Atlantica increased the susceptibility of alpha brass to corrosion compared to the solution without it. In the absence of Cedrus Atlantica, general surface deterioration was observed without any localized corrosion. However, at 10% Cedrus Atlantica concentration superficial crack was observed. The crack further increased to visible intergranular crack (fracture) at 20% Cedrus Atlantica concentration. Ocimum basilicum Linn performed effectively at 10% concentration, sustaining the corrosion resistance of brass in 1M (NH4)2SO4 + 1M CuSO4 solution. At 20% Ocimum basilicum Linn concentration superficial cracking appeared.

ANODIZING PROCESS FOR ENHANCING CORROSION RESISTANCE OF ALUMINIUM ANODES IN 1M NaOH ALKALINE SOLUTION

Corrosion electrochemical behaviour of aluminium anodes coated with various coating processes, such as nickel electroplating, nickel and copper electroplating, zinc flake coating, and anodizing, in 1M NaOH alkaline solution were studied by electrochemical impedance spectroscopy (EIS) in Aluminium air batteries. The impedance spectra of the four coating samples of aluminium anode during immersion in alkaline solution were analysed and their surface morphology was studied using SEM. The findings from the experiments showed that the Ni-Cu plated aluminium anode sample had the highest protection characteristics in the four coating samples in 1M NaOH alkaline solution. Ni-Cu plated aluminium shows outstanding resistance to stress corrosion cracking, is more uncomplicated and efficient, and increases the mechanical strength of the aluminium alloy sample in an alkaline solution for an aluminium air battery.

Insight into the stress corrosion cracking mechanism of N80 carbon steel under different crevice opening dimensions in a CO2-saturated NaCl solution

Insight into the stress corrosion cracking mechanism of N80 carbon steel under different crevice opening dimensions in a CO2-saturated NaCl solution

Role of residual stress and ultrafine grain layer at the surface introduced by water jet cavitation peening in stress corrosion cracking of alloy 600 in high temperature water

Role of residual stress and ultrafine grain layer at the surface introduced by water jet cavitation peening in stress corrosion cracking of alloy 600 in high temperature water