Showing papers on "Stress corrosion cracking published in 2006"
TL;DR: In this paper, a mechanism of pitting corrosion caused by AIMn particles was proposed and the corrosion properties of AZ91D weld material were investigated, and the influence of metallurgical factors, such as alloying elements, microstructure and secondary phases, processing factors such as heat treatment and weld, and environmental factors including temperature, relative humidity, solution pH values and concentration on corrosion were discussed.
393 citations
TL;DR: In this paper, a review of the texture development in zirconium alloys (in the form of thin walled tube reduced extrusion or TREX, thin-walled tubing and sheets) of importance to light and heavy water nuclear reactor technology along with the resultant anisotropic mechanical properties is presented.
294 citations
15 Feb 2006-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, laser peening without protective coating (LPPC) has been applied to water-immersed SUS304 (Type 304) and SUS316L (Type 316L) austenitic stainless steels.
Abstract: Laser peening without protective coating (LPPC) has been applied to water-immersed SUS304 (Type 304) and SUS316L (Type 316L) austenitic stainless steels. The surface residual stress of both materials was converted from tensile to compressive of several hundreds of megapascals by LPPC with a Q-switched and frequency-doubled Nd:YAG laser. The depth of the compressive residual stresses after LPPC exceeded 1 mm from the surface. Accelerating stress corrosion cracking (SCC) tests in a high-temperature and corrosive-water environment showed that LPPC completely prevented the SCC initiation of sensitized SUS304. SCC tests of pre-cracked samples were also performed for SUS304, which indicated that LPPC inhibits the propagation of the small pre-cracks. Rotating bending tests demonstrated that the fatigue strength of SUS316L with LPPC is enhanced by 1.4–1.7 times compared to that of the reference material at 108 cycles.
281 citations
TL;DR: In this paper, Alloy 600 was tested in simulated pressurised water reactor (PWR) primary water, at 360 °C, under an hydrogen partial pressure of 30 kPa. These testing conditions correspond to the maximum sensitivity of alloy 600 to crack initiation.
165 citations
TL;DR: In this article, three dimensional X-ray tomographic images of intergranular stress corrosion crack nucleation and growth in sensitised austenitic stainless steel provide evidence for the development of crack bridging ligaments, caused by the resistance of non-sensitised special grain boundaries.
127 citations
TL;DR: Laser peening without coating (LPwC) is an innovative surface enhancement technology, which imparts compressive residual stress without any surface preparations as discussed by the authors, which significantly prolonged the fatigue lives despite the increase in surface roughness.
Abstract: Laser peening without coating (LPwC) is an innovative surface enhancement technology, which imparts compressive residual stress without any surface preparations. Materials were peened in aqueous environment with laser pulses of about 100 mJ from a Q-switched and frequency-doubled Nd:YAG laser. Surface roughness of the materials somewhat increased due to ablative interaction. Compressive residual stress nearly equal to the yield strength of the materials appeared at the surface after LPwC in spite of the possible heat effect by direct laser irradiation to the materials. The depth of the compression reaches 1 mm or more from the peened surface. High-cycle fatigue properties were evaluated through rotating-bending or push-pull type testing for an austenitic stainless steel (SUS316L), a titanium alloy (Ti-6Al-4V) and a cast aluminum alloy (AC4CH). LPwC significantly prolonged the fatigue lives despite the increase in surface roughness. Accelerating stress corrosion cracking (SCC) tests showed that LPwC completely eliminated SCC susceptibility of sensitized austenitic stainless steels, nickel-based alloys and their weld metals. LPwC has been utilized to prevent SCC in Japanese nuclear power reactors since 1999.
110 citations
TL;DR: In this article, the development and failure of crack bridging ligaments were studied in detail in three dimensions using high-resolution X-ray microtomography, and direct comparison of these features has been made with scanning electron microscopy fractography.
Abstract: Intergranular stress corrosion cracking in a sensitised type 302 stainless steel wire has been observed in situ using high resolution X-ray microtomography. Tomography enables the development and failure of crack bridging ligaments to be studied in detail in three dimensions. Direct comparison of these features has been made with scanning electron microscopy fractography. The crack bridges failed in a ductile manner, with a morphology that is consistent with non-sensitised low energy grain boundaries.
107 citations
TL;DR: In this paper, the effect of compressive stress on intergranular corrosion (IGC) of AA2024-T3 was studied using a constant load and simultaneous electrochemical measurement.
104 citations
TL;DR: In this paper, two forms of high-resolution X-ray tomographic experiments (i.e., synchrotron based Xray micro-tomography and desktop microfocus computed Xray tomography) are demonstrated to illustrate the wide application of these techniques for qualitative and quantitative studies of localised corrosion and environmentally assisted cracking.
Abstract: Two forms of high resolution X-ray tomographic experiments (i.e. synchrotron based X-ray microtomography and desktop microfocus computed X-ray tomography) are demonstrated in the present paper to illustrate the wide application of these techniques for qualitative and quantitative studies of localised corrosion and environmentally assisted cracking. Specifically, synchrotron based X-ray tomography was used to investigate the localised corrosion morphology within aluminium specimens when exposed in situ to a chloride environment while microfocus computed X-ray tomography was used to investigate the morphology and quantify the transition from localised corrosion to stress corrosion cracking in steel specimens exposed ex situ to a simulated corrosive condensate environment.
92 citations
TL;DR: In this article, the IGC and SCC susceptibility of AA5182 (Al-4.5 wt% Mg) was found to depend strongly on sensitisation heat treatments.
Abstract: AA5182 (Al-4.5 wt% Mg) can become susceptible to intergranular corrosion (IGC) with time at moderately elevated service temperatures owing to precipitation of Mg-rich β-phase at grain boundaries, which can lead to stress corrosion cracking (SCC). The IGC and SCC susceptibility of AA5182 was found to depend strongly on sensitisation heat treatments. AFM and TEM studies demonstrated that the degree of precipitation and thus susceptibility to attack for a boundary can be related to its crystallographic misorientation. Low angle boundaries (
86 citations
TL;DR: In this paper, the role of hydrogen embrittlement (hydrogen-induced cracking) in pipeline safety and reliability is examined. But the authors do not consider the impact of carbon steels on pipeline performance.
01 Jan 2006
TL;DR: In this paper, the IGC and SCC susceptibility of AA5182 (Al-4.5 wt% Mg) was found to depend strongly on sensitisation heat treatments.
Abstract: AA5182 (Al-4.5 wt% Mg) can become susceptible to intergranular corrosion (IGC) with time at moderately elevated service temperatures owing to precipitation of Mg-rich β-phase at grain boundaries, which can lead to stress corrosion cracking (SCC). The IGC and SCC susceptibility of AA5182 was found to depend strongly on sensitisation heat treatments. AFM and TEM studies demonstrated that the degree of precipitation and thus susceptibility to attack for a boundary can be related to its crystallographic misorientation. Low angle boundaries (<20°) are most resistant to attack as they do not show β-phase precipitation. However, higher angle boundaries show highly variable precipitation and corrosion susceptibility: critical factors are the grain boundary plane and precipitate/matrix crystallographic relationship.
TL;DR: In this article, the effect of hydrogen embrittlement on notched tensile strength and fracture characteristics of two ultra-high strength steels (PH 13-8 Mo stainless steel and T-200 maraging steel) was determined by an electrochemical permeation method.
TL;DR: In this article, the role of sulfate-reducing bacteria in hydrogen-assisted cracking of carbon steel was investigated in both biotic and abiotic environments, with and without the microbiological cultures.
TL;DR: In this article, the authors present the results of a study on the effects of water, acetic acid (CH3COOH), oxygen, corrosion inhibitor, chloride, methanol, denaturant, and corrosion product on the stress corrosion cracking (SCC) of steel in ethanol (C2H5OH).
Abstract: This paper presents the results of a study on the effects of water, acetic acid (CH3COOH), oxygen, corrosion inhibitor, chloride, methanol (CH3OH), denaturant, and corrosion product on the stress corrosion cracking (SCC) of steel in ethanol (C2H5OH). The factor that was found to have the greatest effect on causing SCC was corrosion potential, as influenced by oxygen. The lower critical potential for SCC ranges from 25 mV vs. saturated calomel electrode (SCE) to 300 mVSCE, depending on the presence of chloride and methanol as impurities. Galvanic contact with precorroded steel appeared to exacerbate SCC by increasing the corrosion potential. Within the fuel ethanol specification limits, chloride had a less significant effect than oxygen. SCC was intergranular when the chloride concentration in ethanol (both laboratory and field samples) was low (less than 1 ppm) and it was transgranular when the chloride concentration was high (32 mg/L). A denaturant, a corrosion inhibitor, and acidity, within the...
TL;DR: In this article, the intergranular stress corrosion cracking (IGSCC) growth behavior of austenitic stainless steels in hydrogenated high-temperature water was studied using compact tension specimens.
Abstract: The intergranular stress corrosion cracking (IGSCC) growth behavior of austenitic stainless steels (SS) in hydrogenated high-temperature water were studied using compact tension specimens ...
TL;DR: In this article, a mathematical model has been applied to simulate the evolution of stress corrosion cracks from corrosion pits in the short and long crack domains, and some unique features of pit and crack profiles reproduced.
25 Jun 2006-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a 3-kW Nd:YAG laser and different filler powders were used to butt weld a 6013 sheet, and the weld region exhibited a dendritic cellular structure in the fusion zone and a partially melted zone adjacent to the fusion boundaries.
Abstract: Aluminium alloy 6013 sheet was butt welded using a 3 kW Nd:YAG laser and different filler powders. Two kinds of filler metals were used: gas atomised powders of the aluminium alloys AlMg5, AlSi12, AlSi12Mg5 and AlSi10Mg, as well as mixtures of powders of the elements Al and Si and the binary alloys Al–5Mg, Al–5Zr, Al–5Cr and Al–10Mn. Microstructure, hardness, tensile properties and corrosion behaviour of the welds were investigated in the as-welded T4 and T6 conditions and after a post-weld heat treatment to the T6 temper. The weld region exhibited a dendritic cellular structure in the fusion zone and a partially melted zone adjacent to the fusion boundaries. The hardness of the fusion zone depended upon the filler metals used. Post-weld artificial aging to the T6 temper improved the hardness, being associated with precipitation of strengthening phases, as confirmed by transmission electron microscopy. Joint efficiencies achieved for post-weld heat treated joints ranged from 80 to 90%. Strengths of welds in the as-welded T6 condition were lower due to the softened fusion zone and heat affected zone, being between 70 and 75% of the ultimate tensile strength of the base alloy 6013–T6. Optimum tensile properties were obtained with joints made with the filler powder AlSi12. Reasonable tensile properties were achieved for welds made with mixtures of elemental and binary alloy powders, but they did not reach those of joints made with aluminium alloy powders. The dispersoid forming elements Zr, Cr and Mn added to a mixed Al–7Si powder did not prove beneficial effects on weld quality. When exposed to an intermittent acidified salt spray fog, joints in the as-welded T4 and post-weld heat treated T6 conditions exhibited corrosion behaviour similar to that of the base sheet in the tempers T4 and T6. As-welded 6013–T4 joints were susceptible to stress corrosion cracking when immersed in an aqueous solution of 0.6 M NaCl + 0.06 M NaHCO 3 . Sensitivity to environmentally assisted cracking was associated with grain boundary precipitates in the heat affected zone.
TL;DR: In this paper, a new equation for the diffusion coefficient of hydrogen (H) in magnesium (Mg) has been proposed, which indicates that there can be significant H transport ahead of a stress corrosion crack in Mg at ambient temperature and that H may be involved in the mechanism of stress corrosion cracking in mg.
Abstract: Evaluation of recent data for hydrogen (H) diffusion in magnesium (Mg) yielded a new equation for the diffusion coefficient of H in Mg. This indicates that there can be significant H transport ahead of a stress corrosion crack in Mg at ambient temperature and that H may be involved in the mechanism of stress corrosion cracking in Mg.
TL;DR: The influence of material factors on the intergranular stress corrosion cracking (IGSCC) susceptibility of austenitic stainless steels under hydrogenated high-temperature water were studied in this paper.
Abstract: The influence of material factors on the intergranular stress corrosion cracking (IGSCC) susceptibility of austenitic stainless steels under hydrogenated high-temperature water were studie...
TL;DR: In this article, the authors evaluated the ground surface quality improvements of the austenitic stainless steel AISI 304 resulting from the application of cryogenic cooling and found that a reduction of more than 40% of the surface roughness could be realized, a higher level of work hardening occurred, a lower level of tensile residual stress was measured and better resistances to stress corrosion cracking and pitting corrosion were noticed.
Abstract: Grinding fluid selection is becoming increasingly constrained by environmental considerations, thus requiring the substitution of the conventionally used oil-based coolants. The work presented in this paper aims at evaluating the ground surface quality improvements of the austenitic stainless steel AISI 304 resulting from the application of cryogenic cooling. The evaluation is based on criteria related to grindability, surface integrity and corrosion resistance characterisation. Grinding experiments at an almost constant stock removal rate were conducted under three different environments: dry, soluble oil and cryogenic cooling. The grindability results have shown that while the cryogenic cooling generates the lowest grinding temperature, no significant differences over the specific grinding force components were observed. As for the ground surface integrity, however, substantial improvements were realized. Indeed, by using the cryogenic cooling, a reduction of more than 40% of the surface roughness could be realized, a higher level of work hardening occurred, a lower level of tensile residual stress was measured and better resistances to stress corrosion cracking and pitting corrosion were noticed. These improvements in grindability and in surface integrity are particularly favoured by grinding conditions using high work speed and low depth of cut values. It is also shown that these improvements are essentially due to the reduction of the grinding temperature, which lowers the tensile residual stress and to the cryo-temperature, which favours the material removal by shearing and limits the ground surface damage.
TL;DR: In this paper, the effect of retrogression and re-aging (RRA) heat treatment on the microstructure and mechanical properties of a low frequency electromagnetic casting alloy as Al-9.99%Zn-1.13%Zr was investigated by tensile properties test, Vickers hardness, electrical conductivity test, DSC analysis, SEM and TEM observation.
TL;DR: Nd-YAG laser surface treatment on 7075-T651 aluminum alloy with the aim of improving the stress corrosion cracking resistance of the alloy was performed under two different gas environments, air and nitrogen.
TL;DR: In this article, the authors determined the stress corrosion cracking behavior of austenitic alloys in pure supercritical water (SCW) and to gain a better understanding of the stress co...
Abstract: The purpose of this study was to determine the stress corrosion cracking behavior of austenitic alloys in pure supercritical water (SCW) and to gain a better understanding of the stress co...
TL;DR: In this article, a crack initiation mechanism was proposed to explain crack initiation and propagation in INCONEL alloy 600 along the grain boundaries, where Cr2O3 has formed from the leaching of Cr from the matrix, leaving behind a porous Ni-rich region.
Abstract: In this work, thermodynamic arguments for the stability of Ni and Cr compounds developed under pressurized water reactor environments (\(P_{H_2 O} \) and\(P_{H_2 } \)) were experimentally tested. A mechanism is proposed to explain crack initiation and propagation alloy 600 along the grain boundaries, where Cr2O3 has formed from the leaching of Cr from the matrix, leaving behind a porous Ni-rich region. The mechanism is based on the thermodynamic potential for the transformation of a protective NiO surface layer into an amorphous nonprotective Ni(OH)2 gel. This gel would also form along the grain boundaries and when hydrogenated steam reaches the porous Ni-rich regions. Crack initiation is then favored by tensile stressing of the grain boundary regions, which can easily rupture the gelatinous film. The leaching of matrix Cr to form nonprotective CrOOH gel at the crack tip followed by the exposure of fresh porous Ni to the environment could explain crack propagation in INCONEL alloy 600. The proposed crack initiation mechanism is not expected to occur in alloy 690 where a protective Cr2O3 film covers the entire metal surface. However, crack propagation along the grain boundaries in alloy 600 and precracked alloy 690 is expected to be active as hydroxide-forming reactions weaken the boundaries.
TL;DR: In this paper, a three-dimensional mechanical model for intergranular crack propagation is presented, which uses a regular representation of the material's microstructure and a categorisation of grain boundaries as beneficial and detrimental to fracture.
TL;DR: In this article, the relationship between pH stress corrosion cracking (SCC) resistance and yield strength of pipeline steels was investigated and an attempt was made to make an attempt to...
Abstract: In this paper the relationship between the near-neutral pH stress corrosion cracking (SCC) resistance and the yield strength of pipeline steels was investigated and an attempt was made to ...
TL;DR: In this paper, the authors investigated the energy-assisted crack propagation behavior of a bulk amorphous metal, Zr41.2Ti13.8Cu12.5Ni10Be22.5.
TL;DR: In this article, slow strain rate testing was carried out on over aged 7010 Al-alloy in laboratory air, glycerin and 3.5 wt.% NaCl solution with and without cathodic charging to study the hydrogen embrittlement susceptibility of the alloy in over aged condition.
Abstract: Slow strain rate testing (SSRT) was carried out on over aged 7010 Al-alloy in laboratory air, glycerin and 3.5 wt.% NaCl solution with and without cathodic charging to study the hydrogen embrittlement susceptibility of the alloy in over aged condition. It was found that the over aged alloy exhibited high resistance to stress corrosion cracking (SCC) than hydrogen embrittlement (HE). The high SCC resistance is due to the modification in the grain boundary precipitate morphology and chemistry due to over aging, however it is suggested that the dislocations in the alloy are not completed annealed during over aging to arrest HE.
TL;DR: In this paper, various oxide dispersion strengthened (ODS) steels which have high Cr concentrations with and without Al addition were made by mechanical alloying method and the susceptibility to stress corrosion cracking (SCC) was evaluated by slow strain rate test (SSRT).