Showing papers on "Stress corrosion cracking published in 2017"
TL;DR: In this article, the effects of two-sided simultaneous LSP on microstructure, residual stress, surface roughness and electrochemical property of AZ31B samples were investigated by using optical microscopy, X-ray diffraction (XRD) method, true color material confocal microscopy and transmission electron microscopy (TEM) experiments.
Abstract: Stress corrosion cracking (SCC) behavior of AZ31B Magnesium (Mg) alloy with and without Laser Shock Peening (LSP) was studied using slow strain rate tension (SSRT) method in a simulated body fluid (SBF) at 36.5 ± 0.5 °C. The effects of two-sided simultaneous LSP on microstructure, residual stress, surface roughness and electrochemical property of AZ31B samples were investigated by using optical microscopy, X-ray diffraction (XRD) method, true color material confocal microscopy, transmission electron microscopy (TEM) and electrochemical polarization experiment. The experimental results show that based on the optimal laser processing parameters, surface nanocrystallization could be induced in the AZ31B surface layer. Comparing with the original samples, the corrosion potential increased 131 mV, the corrosion current density decreased by 85.4% and the SCC susceptibility index (ISCC) decreased by 47.5% after LSP. Based on the experimental observations, the improvement mechanism of SCC resistance for AZ31B with LSP was also analysed and revealed.
88 citations
TL;DR: In this article, a comprehensive study of the stress corrosion crack growth behavior of laser additively-manufactured (AM) 316L stainless steel in high temperature water was performed and a wide range of parameters and their effects were evaluated, including microstructure, heat treatment, stress intensity factor, cold work, crack orientation, oxidizing vs. reducing conditions, and porosity.
81 citations
30 Jan 2017
TL;DR: In this paper, the effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS) are reviewed.
Abstract: The effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS) are reviewed. Austenitic stainless steel (ASS) is welded using low-heat inputs. However, owing to differences in the physical metallurgy between ASS and DSS, low-heat inputs should be avoided for DSS. This review highlights the differences in solidification mode and transformation characteristics between ASS and DSS with regard to the heat input in welding processes. Specifically, many studies about the effects of heat energy input in welding process on the pitting corrosion, intergranular stress, stresscorrosion cracking, and mechanical properties of weldments of DSS are reviewed.
79 citations
TL;DR: In this article, a phase field model for simulating the stress corrosion cracking (SCC) phenomenon in metallic materials is presented, where the effect of mechanical stresses is incorporated by relating the interface kinetics parameter to the stress intensity factor and stress field near the crack tip.
76 citations
TL;DR: EIS analysis show that although the majority of cracking occurred during the apparent plastic straining, cracking initiation occurs already in the elastic region at ∼50% of the ultimate tensile strength (UTS), which shows the potential for electrochemical methods to be used for in situ monitoring crack formation of implants in more applied studies.
66 citations
TL;DR: In this article, an industrial case history of the failure of the evaporator (water wall) tubes of a water-tube boiler is presented, and the failure mechanism of the tubes was identified as stress corrosion cracking (SCC).
64 citations
TL;DR: The martensitic stainless steel EN 1.4418 grade exhibits a clear protective passive behavior with no sulfide stress corrosion cracking when exposed to sour environments of pH ≥ 4, but undergoes a steep decrease in its corrosion resistance at lower pH conditions.
64 citations
08 Feb 2017-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the stress corrosion cracking behavior of X70 steel in simulated shallow and deep sea environments was studied using potentiodynamic polarization measurement, a slow strain rate tensile (SSRT) test and scanning electron microscopy (SEM).
Abstract: The stress corrosion cracking (SCC) behavior of X70 steel in simulated shallow and deep sea environments was studied using potentiodynamic polarization measurement, a slow strain rate tensile (SSRT) test and scanning electron microscopy (SEM). The results indicate that the predominant cathodic reaction changes from an oxygen reduction reaction to the hydrogen evolution reaction as the dissolved oxygen (DO) content decreases. In the simulated deep sea environment, the SCC susceptibility of X70 steel decreased first, reached its lowest point at 15 MPa and then increased as the simulated sea hydrostatic pressure (HP) further increased. This is consistent with the regularity for the change of the cathodic hydrogen evolution reaction current density i H at E corr , which indicates that the HP may influence the SCC susceptibility of X70 steel by changing the permeated hydrogen concentration.
63 citations
TL;DR: This study investigates the deformation behaviour of a newly developed high-strength low-alloy Mg alloy, MgZn1Ca0.3 (ZX10), processed at two different extrusion temperatures of 325 and 400°C (named E325 and E400, respectively), under slow strain tensile and cyclic tension-compression loadings in air and modified simulated body fluid (m-SBF).
Abstract: Magnesium (Mg) alloys have attracted great attention as potential materials for biodegradable implants. It is essential that an implant material possesses adequate resistance to cracking/fracture under the simultaneous actions of corrosion and mechanical stresses, i.e., stress corrosion cracking (SCC) and/or corrosion fatigue (CF). This study investigates the deformation behaviour of a newly developed high-strength low-alloy Mg alloy, MgZn1Ca0.3 (ZX10), processed at two different extrusion temperatures of 325 and 400°C (named E325 and E400, respectively), under slow strain tensile and cyclic tension-compression loadings in air and modified simulated body fluid (m-SBF). Extrusion resulted in a bimodal grain size distribution with recrystallised grain sizes of 1.2 μm ± 0.8 μm and 7 ± 5 μm for E325 and E400, respectively. E325 possessed superior tensile and fatigue properties to E400 when tested in air. This is mainly attributed to a grain-boundary strengthening mechanism. However, both E325 and E400 were found to be susceptible to SCC at a strain rate of 3.1×10-7s-1 in m-SBF. Moreover, both E325 and E400 showed similar fatigue strength when tested in m-SBF. This is explained on the basis of crack initiation from localised corrosion following tests in m-SBF.
60 citations
TL;DR: Both the mechanical data and fractographic evidence have confirmed susceptibility of the alloy to SCC, however, in the presence of BSA, the alloy suffered greater SCC which was attributed to its increased susceptibility towards localized corrosion.
58 citations
TL;DR: In this article, the phase transition model for material dissolution is coupled with the mechanical problem in a robust manner, providing an efficient tool for studying the competition between electrochemical and mechanical contributions to fracture.
TL;DR: In this paper, an accelerated technique was developed for evaluation of intergranular stress corrosion cracking (IGSCC) initiation behavior of non-sensitized materials in pressure water reactor environment by means of the implementation of hollowed cylindrical specimens under slow strain rate tensile.
TL;DR: In this paper, the impact of an increased dislocation density, due to cold rolling, on β phase precipitation as well as the effect of misorientation on growth and kinetics was investigated.
TL;DR: Different artificial two-stage ageing behaviors and their effect on stress corrosion cracking (SCC) susceptibility of Al-Zn-Mg alloy have been investigated in this paper, where the experimental results show that two hardness peaks present on the second stage ageing-hardening curve when the first stage ageing is dealt with comparatively lower temperature than the conventional one.
TL;DR: In this article, the authors investigated the stress corrosion cracking behavior of ZK60 magnesium alloy under different conditions, i.e. thin electrolyte layer (TEL) and solution, by slow strain rate tensile tests, electrochemical techniques, Auger electron spectroscopy, scanning electron microscopy coupled with electron backscattered diffraction, and time of flight secondary ion mass spectrometry.
TL;DR: In this article, the authors investigated the corrosion and stress corrosion cracking susceptibility of 316L stainless steel exposed to 550°C and 600°C supercritical water and found that increasing the test temperature reduced the corrosion resistance.
TL;DR: In this article, the authors present an experimental study to determine the impacts of environmental factors on SCC in high-carbon steel cable bolts used in ground support system and demonstrate that the presence of hydrogen sulphide is more critical than its concentration in SCC.
TL;DR: In this paper, the mechanical, metallurgical and corrosion properties of Alloy 625 produced using the laser powder bed fusion (L-PBF) manufacturing process were investigated and compared with typical performance of the alloy produced using conventional forging processes.
Abstract: The mechanical, metallurgical and corrosion properties of Alloy 625 produced using the laser powder bed fusion (L-PBF) manufacturing process were investigated and compared with typical performance of the alloy produced using conventional forging processes. Test specimens were produced near net shape along with several demonstration pieces that were produced to examine the geometric complexity that could be achieved with the process. The additively manufactured specimens exhibited strength, fracture toughness and impact toughness that was equal to or better than properties typically achieved for wrought product. There was no evidence of stress corrosion cracking susceptibility in 3.5% NaCl solution at stress intensities up to 70 ksi-in1/2 after 700 h exposure. The microstructure was equiaxed in the plane of the powder bed build platform (X–Y) and exhibited a columnar shape in the Z direction although there was not any significant evidence of anisotropy in the mechanical properties.
TL;DR: The results demonstrate that both zinc alloys can be considered as potential candidates for biodegradable implants, with a relative advantage to the Zn-1%Mg alloy in terms of its corrosion resistance and SCC performance.
Abstract: Increasing interest in biodegradable metals (Mg, Fe, and Zn) as structural materials for orthopedic and cardiovascular applications mainly relates to their promising biocompatibility, mechanical properties and ability to self-remove. However, Mg alloys suffer from excessive corrosion rates associated with premature loss of mechanical integrity and gas embolism risks. Fe based alloys produce voluminous corrosion products that have a detrimental effect on neighboring cells and extracellular matrix. In contrast, Zn does not appear to exhibit a harmful mode of corrosion. Unfortunately, pure zinc possesses insufficient mechanical strength for biomedical structural applications. The present study aimed at examining the potential of two new zinc based alloys, Zn-1%Mg and Zn-1%Mg-0.5%Ca to serve as structural materials for biodegradable implants. This examination was carried out under in vitro conditions, including immersion testing, potentiodynamic polarization analysis, electrochemical impedance spectroscopy (EIS), and stress corrosion cracking (SCC) assessments in terms of slow strain rate testing (SSRT). In order to assess the cytotoxicity of the tested alloys, cell viability was evaluated indirectly using Saos-2 cells. The results demonstrate that both zinc alloys can be considered as potential candidates for biodegradable implants, with a relative advantage to the Zn-1%Mg alloy in terms of its corrosion resistance and SCC performance.
TL;DR: In this article, the effect of Sc content on microstructure and stress corrosion cracking behavior of medium strength Al-Zn-Mg alloy has been investigated by optical microscopy, scanning electron microscopy and electron backscatter diffraction.
TL;DR: In this paper, the authors investigated the PbSCC of Alloy 690TT exposed to a caustic solution at 320°C and found that lead is involved in the formation of oxides and evenly distributed in the films.
TL;DR: In this paper, the authors investigated the correlation of microstructure and stress corrosion cracking (SCC) initiation behavior of the fusion boundary (FB) region in a SA508 Cl. 3-Alloy 52M weld joint in primary pressurized water reactor environment.
13 Jan 2017-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, two mechanistically different modes of EIC were identified using high-resolution X-ray computed tomography and scanning electron microscopy (SEM) in sensitized AA5083-H131 that had been pre-exposed to 0.6m NaCl prior to interrupted slow strain rate testing (SSRT) in the short transverse direction while exposed to laboratory air (50% RH).
Abstract: Two mechanistically different modes of EIC have been identified using high-resolution X-ray computed tomography and scanning electron microscopy (SEM) in sensitized AA5083-H131 that had been pre-exposed to 0.6 M NaCl prior to interrupted slow strain rate testing (SSRT) in the short transverse direction while exposed to laboratory air (50% RH). One mode, shown to propagate when local stress intensity factors are in the range of 4–12 MNm‐3/2, is the well-known ‘classic’ form of intergranular stress corrosion cracking, Type-1 cracking, which would not initiate and propagate in dry air, irrespective of pre-exposure or sensitization. The second mode of cracking, identified presently as Type-2 cracking, is associated with sudden load-drops occurring after the UTS during SSRT. Type-2 cracking propagates at higher local stress intensity factors (above 12–15 MNm-3/2) with significantly higher average growth rates than Type-1 cracking, involves the sudden simultaneous mechanical linkage of multiple fully-isolated regions of damage, pre-determined during pre-exposure to NaCl solution and generated during straining in laboratory air. Differences in the extent of Type-2 cracking for pre-exposed samples tested in ‘dry’ air compared to laboratory air (50% RH) were marked, with that in dry air being limited to isolated patches. High-resolution 3D tomography and detailed SEM has been used to distinguish these two mechanistically different modes of EIC. Implications for a role of hydrogen embrittlement during EIC are discussed.
TL;DR: In this paper, the sensitivity of nonlinear ultrasound to the presence of sensitization was determined by using nonlinear Rayleigh waves to quantitatively track the sensitization of 304 and 304L stainless steels as a function of holding time at 675°C.
Abstract: Austenitic stainless steels have a wide range of applications in the energy industry, but the corrosion resistance of these stainless steels can be reduced by sensitization, particularly in the heat affected zones in welds. Sensitization is the formation of chromium carbide precipitates along the grain boundaries, causing the formation of a zone of chromium depletion around the grain boundary. Since chromium is the primary alloying element that makes stainless steel corrosion resistant, this chromium depleted zone is susceptible to intergranular stress corrosion cracking (IGSCC). Sensitization occurs when a stainless steel is exposed to a high temperature for an extended time period, such as during welding. The objective of this research is to determine the sensitivity of nonlinear ultrasound to the presence of sensitization by using nonlinear Rayleigh waves to quantitatively track the sensitization of 304 and 304L stainless steels as a function of holding time at 675 °C. The effect of the carbon content of the alloys (304 versus 304L) to the sensitization process and the measured nonlinearity parameter, β are investigated. Annealing of these specimens isolates the effect of just sensitization, removing the presence of cold work which can also affect the material nonlinearity. Complementary electrochemical potentiodynamic reactivation (EPR) measurements and microscopy are used to confirm the absence or presence of sensitization. The results show that the acoustic nonlinearity parameter is sensitive to the presence of chromium carbide precipitates in sensitized austenitic stainless steels.
TL;DR: In this article, the effects of dissolved hydrogen (DH) and inner surface finish condition of the hollowed specimen on stress corrosion crack initiation and small crack growth behaviors of 316 stainless steel were investigated in high temperature water with various DH levels.
TL;DR: In this article, the intergranular stress corrosion cracking (IGSCC) susceptibility of SA508-52M-316L dissimilar metal weld joint in primary water was investigated by the interrupted slow strain rate tension test following a microstructure characterization.
TL;DR: In this article, a maraging steel, an ultra high strength steel, is welded using FSW process and it was observed that FSW joints demonstrated higher resistance to stress corrosion cracking (SCC) compared to both, base metal and gas tungsten arc weldments.
TL;DR: In this paper, a multiphysics model for crack propagation under the effect of stress corrosion cracking is proposed, which is based upon a phase field method, based on a variational formulation of brittle fracture with regularized approximation of discontinuities, and a robust algorithm capable to prescribe the displacements (over the boundary of a small subvolume) and crack onset obtained by image processing based on digital image correlation in the sample during the numerical simulations.
TL;DR: In this article, the authors investigated the stress corrosion cracking (SCC) properties of X70 pipeline steel in simulated deep-sea environments and showed that the HP promoted pitting propagation and linkage, which then initiated microcracks in SCC.
TL;DR: In this paper, the authors investigated stress corrosion crack initiation of two thermally-treated, cold-worked Alloy 690 (UNS N06690) materials in 360°C simulated pressurized water reactor primary water using constant load tensile (CLT) and blunt notch compact tension (BNCT) tests equipped with direct current potential drop (DCPD) for in situ detection of cracking.
Abstract: Stress corrosion crack initiation of two thermally-treated, cold-worked (CW) Alloy 690 (UNS N06690) materials was investigated in 360°C simulated pressurized water reactor primary water using constant load tensile (CLT) and blunt notch compact tension (BNCT) tests equipped with direct current potential drop (DCPD) for in situ detection of cracking Stress corrosion cracking initiation was not detected by DCPD for either the 21% or 31% CW CLT specimens loaded at their yield stress for ∼9,220 h; however, intergranular (IG) precursor damage and isolated surface cracks were observed on the specimens The two 31% CW BNCT specimens loaded at constant stress intensity after several cyclic loading ramps showed DCPD-indicated crack initiation after 10,400 h of exposure, which resulted from significant growth of IG cracks The 21% CW BNCT specimens only exhibited isolated small IG surface cracks and showed no apparent DCPD change throughout the test Post-test cross-section examinations revealed many grain boundary