Stress Corrosion Cracking Resistance Research Articles

Improvement of sulfide stress corrosion cracking resistance of the Inconel 625/X80 weld overlay by post-weld heat treatment

Improvement of sulfide stress corrosion cracking resistance of the Inconel 625/X80 weld overlay by post-weld heat treatment

Effects of surface finishes, heat treatments and printing orientations on stress corrosion cracking behavior of laser powder bed fusion 316L stainless steel in high-temperature water

Stress corrosion cracking (SCC) of laser powder bed fusion 316 L stainless steel in oxygenated high-temperature water environments with chloride addition at 288 °C was studied. The influences of surface finishes (as-built, mechanically polished, Hirtisation® and shot peened), heat treatments (solution annealing at 1066 and 1150 °C and hot isostatic pressing) and the printing orientations on SCC were evaluated. Hirtisation resulted in a lower SCC susceptibility than as-built or polished surface while shot peening showed the lowest apparent SCC resistance. A high annealing temperature decreases SCC resistance. The effect of printing orientation is material and environment dependent.

Evaluation of Sensitization Behaviors on the Heat-Affected Zone of Austenitic Stainless Steel Weld by Thermal Cycles of Actual Multi-pass Welding

AbstractThe sensitization behavior of the welding heat affected zone (HAZ) in austenitic stainless steels (SSs) was investigated through simulated thermal cycles emulating actual multi-pass welding processes using the Gleeble simulator. The tests were performed with austenitic SSs, considering carbon contents, heat input, and distance from the fusion line to determine the thermal cycle conditions of the HAZ. Higher carbon content led to increased sensitization (degree of sensitization, DOS) values, while the influence of the thermal cycle in the final weld pass was that even though it was rapidly heated to over 1000 °C and cooled at a rapid rate, the DOS value decreased due to partial carbide dissolution and chromium diffusion. Therefore, effective management of the final thermal cycle in the HAZ contributes to improved intergranular stress corrosion cracking resistance. Even with prolonged exposure of the HAZ to the sensitization region, the discovery that corrosion resistance improves when the final heating cycle reaches 1000 °C underscores the importance of HAZ heat cycle management and provides valuable insights for materials engineering and industrial applications. Graphical abstract

The effect of inhomogeneous microstructures on strength and stress corrosion cracking of 7085 aluminum alloy thick plate

Inhomogeneous microstructures and alloy chemistry along the thickness direction can greatly affect the mechanical and corrosion properties of new generation 7xxx aluminum alloy thick plates. The inhomogeneous microstructure, stress corrosion cracking (SCC) resistance and strength of AA7085 thick plate (160 mm) at T/2, T/4, and surface position using mechanical tests, double cantilever beam (DCB) crack extension tests and electron microscopy experiments. The results show that the ultimate tensile strength, yield strength and elongation of the T/2 position are slightly lower than those of the surface position, but the SCC resistance of the T/2 position is significantly higher than that of the surface position. The reason is that larger discontinuously quench-induced grain boundary precipitates (Q-GBPs), and lower Zn and Mg elemental content of GBPs (including Q-GBPs and age-induced GBPs (A-GBPs)) and grain boundaries (GBs). Furthermore, it is newly found that the mechanical effects of larger-sized low aspect ratio unrecrystallized grains contribute significantly to the excellent SCC resistance of the T/2 position. The large size grain structure makes short-range SCC cracks along the large-angle GB more tortuous at T/2, improving the stress intensity required for sustained crack extension. In addition, the high GB triple junction deflection angle resulting from a low aspect ratio grain structure at T/2 improves the average driving force required for crack extension and drive force reduction after localized crack growth.

Stress corrosion behavior and mechanism of Ti6321 alloy with different microstructures in stimulated deep-sea environment

The stress corrosion cracking (SCC) behaviors of Ti-6Al-3Nb-2Zr-1Mo (Ti6321, in wt%) alloy samples with equiaxed microstructure (EM), bimodal microstructure (BM) and Widmanstätten microstructure (WM) in simulated 3000 m deep sea environment were investigated using electrochemical tests, electron backscattered diffraction (EBSD), and so on. WM exhibits the best SCC resistance, which is attributed to its best self-healing ability, and is beneficial for the re-passivation of fresh metal at the crack tip. Besides, there is no obvious micro-texture region in WM with higher β phase, and α phase colonies hinder the dislocation movement, resulting in the lowest crack growth rate.

Effect of laser shock peening on stress corrosion cracking of TC4/2A14 dissimilar metal friction stir welding joints

Stress corrosion cracking (SCC) of welded joints is a significant issue that affects the widespread application of multimetal welded structures in aerospace, transportation, and other fields. This paper investigates the effect of laser shock peening (LSP) on the SCC of TC4/2A14 friction stir welded (FSW) joints with dissimilar metals. The microstructural evolution, mechanical properties, and corrosion behavior with and without LSP treatment were investigated using optical microscopy, transmission electron microscopy, X-ray analysis, electrochemical testing, and slow strain rate tensile testing (SSRT). The results showed that the LSP significantly refined the grains and induced work-hardening on the near-surface of the material. After LSP, the compressive residual stresses on the surface of the titanium and aluminium sides were −817.6 MPa and −153.6 MPa for the joint, respectively. Corrosion resistance was also improved, with the self-corrosion current density on the Al side of the joints reduced by 77% and the SCC susceptibility index (Issrt) reduced from 0.140 to 0.121. The enhanced SCC resistance of the LSP-treated TC4/2A14 dissimilar metal FSW joints is primarily due to grain refinement, work-hardening effect, and high-level compressive residual stress. These factors not only enhance the material strength and improve the pitting resistance of the joints but also prevent the initiation and propagation of SCC.

Influence of aging treatment on corrosion behavior of extruded 2195 Al−Li alloy

The 2195 Al-Li alloy was processed by under-aging (UA), peak-aging (PA), double-aging (DA) and retrogression re-aging (RRA) treatments, and the microstructure, intergranular corrosion (IGC), exfoliation corrosion (EXCO) and stress corrosion cracking (SCC) behaviors were observed and discussed. The results show that the sequence of IGC and EXCO resistance is: RRA > UA > DA > PA. The low corrosion resistance of PA and UA is mainly caused by the continuous precipitation of T1 phases at grain boundaries to form continuous corrosion channels, while the interruption of corrosion channels caused by coarse and discontinuous T1 phases and wider precipitate free zone is the reason for the best corrosion resistance of RRA. The RRA alloy exhibits the best SCC resistance, and the order of SCC resistance is: RRA > DA > UA > PA. The discontinuous precipitation of intergranular T1 phases promotes the propagation of corrosion cracks across grain boundaries, thereby improving the SCC resistance.

Nanostructuring of Ferritic Steel: A Review on Enhanced Surface Properties Using Ultrasonic Shot Peening

Nanostructuring of ferritic stainless steel refers to the process of intentionally reducing the grain size of the material at the nanoscale level. By manipulating the microstructure of the steel, it is possible to enhance its mechanical, physical, and chemical properties. Nanostructuring can significantly improve the strength, hardness, and wear resistance of ferritic stainless steel, while still maintaining its corrosion resistance. The increased density of grain boundaries and the complex dislocation network within the nanostructured material contribute to these improved properties. Moreover, the nanostructured ferritic stainless steel exhibits enhanced thermal stability, leading to better high-temperature performance and resistance to creep deformation. The small grain size also allows for increased precipitation of secondary phases, such as carbides, nitrides, or intermetallic compounds, which can further improve the material's properties. There are several methods to achieve nanostructuring in ferritic stainless steel, such as severe plastic deformation (SPD) techniques like high-pressure torsion, equal channel angular pressing, and accumulative roll bonding. These techniques impose extreme plastic deformation on the material. Leading to grain refinement below the micrometre range. Also, a novel method of surface nanostructuring ultrasonic shot peening (USP) is discussed in detail. Shot peening is a process in which small, spherical media, typically made of steel or ceramic, called "shots," are propelled onto the surface of a material at high velocities. Ultrasonic shot peening enhances the traditional shot peening process by introducing high-frequency vibrations to the shots. These vibrations are generated by an ultrasonic transducer, which is immersed in a bath of shots and liquid. The vibrations are transmitted through the liquid to the shots, causing them to collide with the surface of the ferritic steel at even higher velocities and energy levels than in traditional shot peening. In summary, nanostructuring of ferritic stainless steel offers great potential for tailoring the material's properties to meet specific application requirements, including improved strength, hardness, wear resistance, corrosion resistance, and high-temperature performance. USP is an effective surface treatment method for ferritic steel, offering advantages in terms of fatigue life, stress corrosion cracking resistance, surface hardness, and wear resistance.

In vitro evaluation of stress corrosion cracking susceptibility of PEO-coated rare-earth magnesium alloy WE43

Controlling material degradation in complex mechanobiological environments is the current challenge in advancing biodegradable magnesium implants for orthopaedic applications. Understanding stress corrosion cracking (SCC) mechanisms of magnesium alloy-coating systems in physiological fluids facilitates the design of magnesium implants with excellent biomedical performance. In this study, we investigated the SCC behaviour of a medical grade PEO-coated magnesium alloy WE43 under different loading conditions. Constant loadings tests (CLT) and slow strain rate tests (SSRT) were conducted to evaluate the SCC susceptibility of this alloy-coating system under in vitro conditions. Fracture surfaces of the non-coated and PEO-coated specimens were characterised by scanning electron microscopy to reveal the SCC mechanisms under different loading configurations. The experimental results showed that the alloy-coating system exhibits a high SCC resistance in SSRT conditions. However, high stress levels and plastic deformations lead to a significant acceleration of the SCC process. Moreover, the fracture surface analysis demonstrated that the brittle nature of the PEO coating deteriorates the mechanical integrity of the alloy under critical mechanical loadings, which results in an increased susceptibility towards stress corrosion cracking of the coated WE43.

Dislocation channel broadening–A new mechanism to improve irradiation-assisted stress corrosion cracking resistance of additively manufactured 316 L stainless steel

Additively manufactured (AM) 316 L stainless steel (SS) after hot isostatic pressing (HIP) was found to exhibit superior resistance to irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water, as compared to wrought 316 L SS. The well-accepted IASCC factors of radiation-induced segregation (RIS) and radiation hardening are not accurate descriptions of IASCC susceptibility in this case. A decreased strain localization along grain boundaries, caused by dislocation channel broadening, was confirmed to suppress crack initiation. A unique distribution of irradiation-induced defects in HIP AM 316 L SS eased dislocation cross-slip compared to those in the wrought counterpart, thus increasing the channel width near the grain boundaries. For the first time, this study highlights the importance of dislocation channel broadening as a potential mechanism to further improve the IASCC resistance of 316 L SS and provides direct experimental evidence based on commercial-grade materials.

Understanding the Mechanism of Stress Corrosion Cracking Resistance in Stainless Steel Welds Subjected to Laser Shock Peening without Coating for Nuclear Canister Applications

Understanding the Mechanism of Stress Corrosion Cracking Resistance in Stainless Steel Welds Subjected to Laser Shock Peening without Coating for Nuclear Canister Applications

Development of a duplex stainless steel for dry storage canister with improved chloride-induced stress corrosion cracking resistance

The chloride-induced stress corrosion cracking (CISCC) is one of the major integrity concerns in dry storage canisters made of austenitic stainless steels (ASSs). In this study, an advanced duplex stainless steel (DSS) with a composition of Fe–19Cr–4Ni-2.5Mo-4.5Mn (ADCS) was developed and its performance was compared with that of commercial ASS and DSS alloys. The chemical composition of ADCS was determined to obtain greater pitting and CISCC resistance as well as a proper combination of strength and ductility. Then, the thermomechanical processing (TMP) condition was applied, which resulted in higher strength than ASSs (304L SS and 316L SS) and better ductility than DSSs (2101 LDSS and 2205 DSS). The potentiodynamic polarization and electrochemical impedance spectra (EIS) results represented the better pitting corrosion resistance of ADCS compared to 304L SS and 316L SS by forming a better passive layer. The CISCC tests using four-point loaded specimens showed that cracks were initiated at 24 h for 304L SS and 144 h for 316L SS, while crack was not found until 1008 h for ADCS. Overall, the developed alloy, ADCS, showed better combination of CISCC resistance and mechanical properties as dry storage canister materials than commercial alloys.

The effect of different heat treatments on stress corrosion cracking of ZK60 magnesium alloy

Magnesium alloys used as degradable biomaterials often experience failure due to the combined effects of corrosive environments and stress. In this study, ZK60 magnesium alloy in three different states, i.e., solution treatment (T4), T4 followed by artificial aging (T6), and deep cryogenic treatment followed by T6 (DT6), were subjected to slow strain rate tensile tests in both air and phosphate-buffered saline environments. Comprehensive microstructural characterization revealed that the T4 specimen exhibited fewer blocky second-phase particles, whereas the volume fraction of the second phase significantly increased after T6 treatment. Moreover, noteworthy is that the introduction of deep cryogenic treatment before T6 treatment led to a significant increase in the length and quantity of rod-shaped precipitates β1′. Slow strain rate tensile tests in PBS revealed that the T4 specimen exhibited better stress corrosion cracking resistance due to the lesser amount of the second phase in the matrix, which mitigated localized corrosion. Conversely, the T6 and DT6 specimens, having a higher volume fraction of nanoscale second-phase precipitates within the matrix, exhibited improved strength compared to the T4 specimen but exacerbated micro-galvanic corrosion, resulting in a faster corrosion rate and consequently poorer stress corrosion cracking resistance. In summary, controlling the distribution of second-phase precipitates is paramount for enhancing the stress corrosion cracking resistance of ZK60 magnesium alloy.

Revealing the influence of solution and pre-deformation treatment on the corrosion resistance of Y-modified AZ91 magnesium alloy for lithium-ion battery shell

The usage of Mg–Al–Zn alloys for lithium-ion battery shell is able to achieve further lightweight of electric vehicles, and their corrosion resistance would highly determine the service life. In this work, therefore, a Y-modified AZ91 magnesium alloy (AZ91-0.5Y) was first prepared by conventional casting and following hot extrusion, and the influence of solution treatment (ST) and subsequent pre-deformation (SP) treatments on its electrochemical corrosion and stress corrosion cracking (SCC) resistance in 1 mol/L LiPF6 electrolyte were then investigated. The results indicated that the presence of large lamellar or rod-like β-Mg17Al12 phase in as-extruded AZ91-0.5Y alloy would lead to serious micro-galvanic corrosion and SCC. After solution treatment, the β-Mg17Al12 phase almost completely dissolved into Mg matrix, weakening the micro-galvanic corrosion and anodic dissolution (AD) and hydrogen embrittlement (HE) effect. Further, the subsequent pre-deformation treatment could introduce dislocation, more precipitation of Al2Y phase, massive twins and optimized texture, leading to the improved corrosion resistance and mechanical strength as well as the formation of well-integrated protective corrosion product film MgF2 with low porosity. As a result, the corrosion and SCC resistance of as-extruded, ST and SP specimens is ordered from low to high.

Effect of Zn addition on the stress corrosion cracking of as-cast BCC Mg-11Li based alloys

The stress corrosion cracking (SCC) of ultralight Mg-11Li alloys with different Zn content revealed the obvious SCC sensitivity of mechanical ductility, while the mechanical strength is minimal. The less Zn (1 wt. %) addition can improve SCC resistance, while none (1 wt. %) or massive Zn (3, 6 wt. %) addition presents the opposite effect. The lowest SCC sensitivity of Mg-11Li alloy with 1 wt. % Zn is determined by the excellent surface film and insignificant micro-galvanic effect, while elevating Zn will enhance SCC sensitivity due to the considerable micro-galvanic effect induced by cathodic second phase and anodic β-Li matrix.

Development of a Cr-Ni-Mo alloyed stress corrosion-resistant anchor bolt steel

PurposeThe purpose of this paper is to develop new types of anchor bolt materials by adding corrosion-resistant elements for alloying and microstructure regulation.Design/methodology/approachThree new anchor bolt materials were designed around the 1Ni system. The stress corrosion cracking resistance of the new materials was characterized by microstructure observation, electrochemical testing and slow strain rate tensile testing.FindingsThe strength of the new anchor bolt materials has been improved, and the stress corrosion sensitivity has been reduced. The addition of Nb makes the material exhibit excellent stress corrosion resistance under –1,200 mV conditions, but the expected results were not achieved when Nb and Sb were coupled.Originality/valueThe new anchor bolt materials designed around 1Ni have excellent stress corrosion resistance, which is the development direction of future materials. Nb allows the material to retain its ability to extend in hydrogen-evolution environments.

Effects of Matrix and Dendrite Boundary Composition on Stress Corrosion Cracking Performance of Alloy 52M Buttering Layer in Simulated Pressurized Water Reactor Primary Water

The oxidation and stress corrosion cracking (SCC) behaviors of Alloy 52M buttering (52Mb) layer were studied in simulated pressurized water reactor (PWR) primary water after microstructure characterization. The 52Mb layer was first postweld heat treatment (1st-PWHT) and follow-up PWHT (FU-PWHT). Two dilution zones (DZs) were found in both the 1st-PWHT and FU-PWHT 52Mb samples. FU-PWHT decreased the Cr content in the first DZ, enhancing the oxidation rate and accelerating the formation of the local oxidation penetration zone at the oxide/substrate interface. Lower Cr content and high Fe content in the DZ were detrimental to the SCC resistance of the 52Mb in PWR primary water.

Microstructure and properties of intercritically reheated coarse-grained heat affected zone in X65 pipeline steel with pre-strain

The properties of the intercritically reheated coarse-grained heat affected zone (ICCGHAZ) in X65 pipeline steel with large deformation are studied. The ICCGHAZ is composed of acicular ferrite, granular bainite and lath bainite. With the increasing t8/5 (the time for specimens to cool from 800 °C to 500 °C), the sulfide stress corrosion cracking (SSCC) resistance with and without pre-strain both increases, and the secondary cracks propagate along the necklace-type martensite-austenite (M-A)/matrix interface or near the M-A constituents, and the fracture toughness decrease. When t8/5 = 30 s, ICCGHAZ has the most ideal performance on fracture toughness and stress corrosion resistance.

Effect of non-isothermal creep aging on the microstructure, mechanical properties and stress corrosion cracking resistance of 7075 alloy

The effect of non-isothermal creep aging (NICA) on the microstructure, mechanical properties, and stress corrosion cracking (SCC) resistance of 7075 alloy was investigated. The results showed that the tensile strength of the alloy increased to 565 MPa when the alloy was heated to 210 °C (CH210) and reached 580 MPa when it was subsequently cooled to 120 °C (CC120). Simultaneously, the SCC susceptibility of rtf increased from 50.8 % to 98.4 %. As compared with traditional creep aging process [1], a large strength increment with excellent stress corrosion resistance have been obtained by NICA. The microstructure revealed that a lot of dislocations have been introduced by creep during the heating stage which could improve the precipitates volume fraction and accelerate the diffusion of solutes; while during the cooling stage, η′ was greatly refined, and GPI and GPⅡ were re-precipitated from the matrix due to the decreased solid solubility and increased critical radius R*; both of them are responsible for the continuous strength increase during NICA. Moreover, the width of the precipitate free zone (PFZ) was narrowed from 46.1 nm (CH210) to 28.6 nm (CC120). The microchemical analysis reveals that solutes were more homogenously distributed in grain boundary precipitates (GB-ppts), matrix precipitates, the PFZ, and the matrix with the help of creep. The narrower PFZ and homogeneous solute distribution are responsible for improving the SCC susceptibility in the CC120 alloy.

Determining SCC resistance of stainless steel claddings in high- temperature water by constant load crack growth tests and slow strain rate tests

Stress corrosion cracking (SCC) behaviors of 309 L and 308 L weld overlays are characterized in oxygen-free and oxygen-bearing high-temperature water using slow strain rate tests (SSRTs) and crack growth rate (CGR) tests with compact tension specimens. There is no apparent SCC indication on 308 L, while local SCC is observed on 309 L after SSRT in oxygen-free water. The SCC sensitivities of 308 L and 309 L increase with the increase of dissolved oxygen (DO) content, while 308 L shows relatively higher SCC resistance than 309 L in water with 200 ppb and 8000 ppb DO. SSRT and CGR test results show a similar effect of DO concentration on SCC of 309 L and 308 L. The fracture surface of 309 L exhibits extensive intergranular SCC, while 308 L shows only local interdendritic SCC after CGR tests. The crack tip blunting decreased the CGR in the low alloy steel. The highly island-shaped δ-ferrites and moderate strain hardening in 308 L contribute to its SCC resistance over 309 L.