Showing papers on "Stress corrosion cracking published in 1973"
Patent•
13 Mar 1973
TL;DR: In this paper, a retrogression heat treatment for a short period of time at a temperature above the age-hardening temperature of the alloy but below the solution heat treatment temperature was proposed.
Abstract: A method is described of thermally treating the 7,000 series aluminum alloys that have been subjected to a solution heat treatment at a high temperature and then to an ageing treatment at a lower temperature, thereby hardening the alloy but likewise producing therein a susceptibility to stress-corrosion cracking. The novel method comprises the steps of (1) subjecting the alloy to a retrogression heat treatment for a short period of time at a temperature above the age-hardening temperature of the alloy but below the solution heat treatment temperature, and (2) subsequently subjecting the alloy to a re-ageing heat treatment for a substantially longer period of time at the age-hardening temperature of the alloy. This method substantially reduces the susceptibility of the alloy to stress-corrosion cracking while retaining its original strength.
118 citations
TL;DR: In this article, the correlation of the threshold stress for stress corrosion cracking (SCC) of plain specimens and of KISCC for precracked specimens in a Mg 7% Al alloy immersed in K2CrO4 was shown.
Abstract: It is shown that the correlation of the threshold stress for stress corrosion cracking (SCC) of plain specimens and of KISCC for precracked specimens in a Mg 7% Al alloy immersed in K2CrO4...
72 citations
01 Nov 1973
TL;DR: Second phases are used widely in the design of alloys and the state-of-the-art in their use is reviewed in this article, where an overview of the use of second phases in alloys is presented.
Abstract: Second phases are used widely in the design of alloys. The state of enlightenment in their use is reviewed. Attention is paid to a) processes to insert second phases, b) design of second phase morphology, and c) the use of second phases to control grain structure (size, orientation, shape) and dislocation networks. Optimization of design for strength, ductility and toughness, fatigue resistance, stress corrosion cracking resistance and fabricability is treated.
72 citations
TL;DR: In this article, the effects of stress, oxygen levels, and significant metallurgical parameters on intergranular SCC of AISI Type 304 are evaluated, e.g., austeno-ferritic duplex and stabilized austenitic stainless steels.
Abstract: Nonstabilized 300 series stainless steels stressed over yield are susceptible to intergranular stress corrosion cracking (SCC) when exposed in the heavily sensitized condition to 288 C (550 F), high purity water containing dissolved oxygen. The effects of stress, oxygen levels, and significant metallurgical parameters on intergranular SCC of AISI Type 304 are being evaluated. Several promising intergranular SCC resistant alternate alloys have been identified through preliminary investigations, e.g., austeno-ferritic duplex and stabilized austenitic stainless steels.
66 citations
TL;DR: In this paper, two thermomechanical treatments have been considered, one a high strength condition equivalent to the conventional T-6 treatment and the other an over-aged condition comparable to the T-73 treatment.
40 citations
TL;DR: In this article, it has been shown that at higher HCl concentrations, corrosion rates increase and uneven, general corrosion occurs instead of cracking, and the development of pitting and stress corrosion cracking under active conditions precludes the conclusion that active-passive cells always play a role in localized corrosion and, in particular, in stress-corrosion cracking.
37 citations
Patent•
14 Jun 1973TL;DR: An aluminum base alloy containing zinc, copper and magnesium together with zirconium or both ZIRconium and manganese and with specially controlled composition limits exhibits very high strength when thermally treated to a condition having high resistance to stress corrosion cracking as discussed by the authors.
Abstract: An aluminum base alloy containing zinc, copper and magnesium together with zirconium or both zirconium and manganese and with specially controlled composition limits exhibits very high strength when thermally treated to a condition having high resistance to stress corrosion cracking. Improved products of the alloy also exhibit low quench sensitivity and, accordingly, high strength even in very thick sections. A special aging treatment produces the optimum combination of strength and resistance to stress corrosion cracking properties.
35 citations
TL;DR: In this article, single phase, Cu-30 At % Zn specimens, which were anodically polarized at 0.24 V (SHE) (10−4 A cm−2) in acid Na2SO4 solution at 23 C (73 F), were found to undergo stress corrosion cracking (SCC) during elongation.
Abstract: Single phase, Cu-30 At % Zn specimens, which were anodically polarized at 0.24 V (SHE) ( 10−4 A cm−2) in acid Na2SO4 solution at 23 C (73 F), were found to undergo stress corrosion cracking (SCC) during elongation. The fracture path was mainly along grain boundaries, with some secondary cracking through the grains. The fracture surfaces exhibit metallic luster and deformation markings, indicating that fracture occurred in the absence of thick reaction product films. The results show that the ammonium ion and other complexing ions are not necessary for stress corrosion of α-brass. They support the idea that preferential anodic dissolution, which is enhanced at the crack tip by dislocation motion, may be important to the stress corrosion process.
29 citations
TL;DR: The stress corrosion cracking behavior of sensitized Type 304 stainless steel has been studied in 288 C (550 F) primary water as a function of oxygen and fluoride contents of the water.
Abstract: The stress corrosion cracking (SCC) behavior of sensitized Type 304 stainless steel has been studied in 288 C (550 F) primary water as a function of oxygen and fluoride contents of the wat...
27 citations
TL;DR: In this paper, the authors demonstrate that the crack initiation process may be controlled by the presence of non-metallic inclusions rather than grain boundaries, which helps to explain the existence of fractures in the segregated regions of turbine discs, the initiation of cracks in high purity steam and the unusual occurrence of transgranular cracking in ferritic alloys.
Abstract: Most instances of stress corrosion cracking in both mild and low alloy steels occur in an intergranular mode. Consequently, effects upon the stress corrosion susceptibility of a steel have often been explained in terms of their influence upon the grain boundary regions. The results presented in this paper, however, clearly demonstrate that in the system under investigation the crack initiation process may be controlled by the presence of non-metallic inclusions rather than grain boundaries. This helps to explain the presence of fractures in the segregated regions of turbine discs, the initiation of cracks in high purity steam and the unusual occurrence of transgranular cracking in ferritic alloys.
26 citations
TL;DR: In this article, an experimental program was carried out to further determine the range of applicability of the superposition model, proposed by Wei and Landes, for estimating the effects of cyclic loading variables and chemical environment on fatigue crack growth.
Abstract: An experimental program was carried out to further determine the range of applicability of the superposition model, proposed by Wei and Landes, for estimating the effects of cyclic loading variables and chemical environment on fatigue crack growth. AISI 4340 steel, tempered at 200 deg F and 500 deg F, and RQ360A steel were used in this investigation. The influences of frequency, stress ratio, and cyclic-load waveform were examined. The results showed that the superposition model provides correct estimates of the trend and the order of magnitude for the influences of these variables within the applicable range provided that steady-state crack growth data are used. Data on the AISI 4340 steel suggest the presence of some synergistic effect of fatigue and environmental attack. Modification of this model will be needed to incorporate this effect and to improve the accuracy of predictions. Environment can affect fatigue-crack growth at K levels below the K level for stress corrosion cracking. Data obtined on the RQ360A steel indicate that the environmental effect can depend on frequency and cyclic-load waveform. These results are in agreement with published results on highly alloyed steels. Further basic studies will be needed to clarify these effects and to develop viable prediction procedures. Nonsteady-state crack growth in fatigue was observed. This state of carck growth would occur at the start of testing and following test interruptions. This phenomenon must be recongnized, and be taken into consideration in data acquisition and subsequent utilization. /Author/
TL;DR: In this article, the effect of total carbon content on susceptibility of iron to stress corrosion cracking (SCC), on the depth of intergranular corrosion without stresses, anodic polarization curves, and the general corrosion rate was examined on decarburized Armco iron and its ferritic or martensitic alloys with carbon up to 1.4% in 5N NH4NO3 and 5N Ca(NO3)2, pH 5.0, at 75 and 100 C (167 and 212 F).
Abstract: The effect of total carbon content on susceptibility of iron to stress corrosion cracking (SCC), on the depth of intergranular corrosion without stresses, anodic polarization curves, and the general corrosion rate was examined on decarburized Armco iron and its ferritic or martensitic alloys with carbon up to 1.4% in 5N NH4NO3 and 5N Ca(NO3)2, pH 5.0, at 75 and 100 C (167 and 212 F). The susceptibility to SCC and intergranular corrosion increased with the carbon content increasing up to about 0.009% or above, and it diminished with further increase in the carbon content. Carbon decreased the ability of iron to passivate (depassivating action), but it also promoted deposition of magnetite and enhanced its protective properties (impeding action). It is suggested that the observed effect of carbon on SCC and intergranular corrosion results from the predominance of the depassivating action at low carbon contents, and the predominance of the impeding action at higher carbon contents.
TL;DR: Stress corrosion cracking of iron and nickel base alloys in aqueous solutions at 289 C (552 F) was studied using a straining electrode apparatus in this article, where the authors showed that SCC susceptibility decreas...
Abstract: Stress corrosion cracking (SCC) of iron and nickel base alloys in aqueous solutions at 289 C (552 F) has been studied using a straining electrode apparatus. Cracking susceptibility decreas...
TL;DR: In this article, a new criterion has been developed for predicting failure of materials by environment-induced cracking by the use of fracture mechanics concepts and assumes that the relationship between crack growth rate and stress intensity can be described by three separable regions of behavior as first suggested by Wiederhorn.
Abstract: A new criterion has been developed for predicting failure of materials by environment-induced cracking. The criterion has been developed by the use of fracture mechanics concepts and assumes that the relationship between crack-growth rate and stress intensity can be described by three separable regions of behavior as first suggested by Wiederhorn. The analytical form of the criterion relates failure time to the initial crack length and the critical crack length or alternatively, to the initial stress intensity and the fracture toughness for various conditions of stress and the environmental variables. The analytical expression is examined by the use of some experimental data on the hydrogen-induced cracking of Ti-5Al-2.5 Sn, and it is demonstrated that the expression predicts the general expected form of the relationship between the normalized stress intensity parameter and the failure time.
TL;DR: In this paper, the authors investigated the stress corrosion cracking (SCC) characteristics of ASTM A517 Grade F steel in liquid ammonia environments and demonstrated the acceleration of the cracking process.
Abstract: The stress corrosion cracking (SCC) characteristics of ASTM A517 Grade F steel in liquid ammonia environments have been investigated. Acceleration of the cracking process was accomplished ...
TL;DR: In this paper, a structural metal is tested in hydrogen gas and its mixture with SO2, CS2, CO2, N2 and Ar are tested and the toxicity of CO2 is moderate.
TL;DR: In this article, it was shown that stress corrosion cracking of unnotched Zircaloy-2 specimens can be obtained in neutral aqueous chloride solutions provided the specimen is polarized anodicall...
Abstract: Studies have shown that stress corrosion cracking (SCC) of unnotched Zircaloy-2 specimens can be obtained in neutral aqueous chloride solutions provided the specimen is polarized anodicall...
TL;DR: In this article, the stress corrosion resistance of 90/10 cupro-nickel in a moist NH 3 atmosphere has been considerably improved by the addition of Fe, and the results for solutionized alloys are discussed in light of current theories.
TL;DR: Although mild steels will not fail by stress corrosion cracking (SCC) in a boiling MgCl2 solution, the addition of only 1% Ni to such steels would promote a susceptibility that becomes more susceptible as discussed by the authors.
Abstract: Although mild steels will not fail by stress corrosion cracking (SCC) in a boiling MgCl2 solution, the addition of only 1% Ni to such steels will promote a susceptibility that becomes more...
TL;DR: In this paper, the authors investigated the stress corrosion cracking of mild steel in a phosphate environment at both room temperature and 100°c and found that at 100°C, the strength of stress corrosion was related to the type of phosphate film formed at the metal surface.
Abstract: Stress corrosion cracking of mild steel in a phosphate environment has been investigated at both room temperature. and 100°c: Prediction of this solution as a cracking medium was made on the basis of results obtamed from high and low sweep rate potentiodynamic polarisation curves.X-ray analysis indicates that at 100°c the stress corrosion behaviour may be related to the type of phosphate film formed at the metal surface.
TL;DR: A variety of experimental test procedures are being used to determine the susceptibility of high strength materials to stress corrosion cracking (SCC) as discussed by the authors, and much controversy exists over the int...
Abstract: A variety of experimental test procedures are being used to determine the susceptibility of high strength materials to stress corrosion cracking (SCC). Much controversy exists over the int...
TL;DR: In this paper, it was shown that early slow growth of stress corrosion cracks in Ti-Al alloys in methanol-HCl solutions occurs by slip-induced grain boundary splitting.
Abstract: Initiation and early slow growth of stress corrosion cracks in Ti-Al alloys in methanol-HCl solutions occurs by slip-induced grain boundary splitting. Later crack propagation occurs by cle...
01 Jan 1973
TL;DR: In this article, the role of localized electrochemical reactions in the wear of sliding surfaces is discussed and several processes leading to erosive wear are discussed, including fretting corrosion, stress corrosion cracking, corrosion fatigue, and erosion corrosion.
Abstract: The various forms of corrosion are discussed and the role of localized electrochemical reactions in the wear of sliding surfaces are considered. It is stated that there is evidence that fretting corrosion, stress corrosion cracking, corrosion fatigue, and erosion corrosion have as a common basis the localized electrochemical reactions caused by a combination of the induced homogeneity of the surfaces and the corrosive environment. Several processes leading to erosive wear are discussed.
TL;DR: In this article, Annealed Zircaloy-2 cracks intergranularly when uniaxially stressed in boiling methanol-iodine solutions containing 0.002 to 20.0 g I21.
Patent•
16 Feb 1973TL;DR: In this article, a steel blade for an axial-flow turbo-machine is disclosed which has a hardened leading edge portion, which is imparted with a permanent compressive prestress in the direction of the longitudinal axis of the blade.
Abstract: A steel blade for an axial-flow turbo-machine is disclosed which has a hardened leading edge portion. In accordance with the invention, the hardened edge portion is imparted with a permanent compressive prestress in the direction of the longitudinal axis of the blade. This protects the blade against stress corrosion cracking.
TL;DR: In this paper, it was shown that the apparent disagreements in the literature between the results of various workers who have studied the effects of quenching and tempering treatments upon the stress corrosion of C steels in a nitrate environment is due to their use of steels of different C contents.
Abstract: It is shown that the apparent disagreements in the literature between the results of various workers who have studied the effects of quenching and tempering treatments upon the stress corrosion of C steels in a nitrate environment is due to their use of steels of different C contents. Very low C steels are made more resistant to cracking by quenching, whilst in higher C steels (> 0·1%) the opposite effect is observed as compared with the cracking responses in the annealed states. Subsequent tempering at sufficiently high temperatures increases the resistance of higher C steels but decreases the resistance of very low C materials. Whilst these effects of the C content and structure may be partly due to their effects upon mechanical and macroscopic electrochemical properties, the various trends are most readily rationalised in relation to the effects upon the nature and distribution of sites for localised corrosion.
01 Apr 1973
TL;DR: In this article, the subcritical crack velocity was measured as a function of applied stress-intensity and showed that the minimum applied stress intensity which produces subcritical cracking varies inversely with the average chloride-ion concentration of the environment, but does not vary significantly with temperature.
Abstract: Precracked specimens of Ti-8Al-lMo-lV were tested in salt-water, and the subcritical crack velocity was measured as a function of applied stress-intensity. The minimum applied stress intensity which produces subcritical cracking,K
Iscc, varies inversely with the average chloride-ion concentration of the environment, butK
Iscc does not vary significantly with temperature. Plots of subcritical crack velocity,a, against applied stress intensity,K
I, reveal two types of cracking behavior. At low stress intensitiesa is approximately proportional toK
I (Stage I crack propagation). At high stress intensities,a is approximately constant, independent ofK
I (Stage II crack propagation). The apparent activation energy for subcritical crack propagation is 5600 cal-(g-mole)-1, anda ∞ [Cl-]1/6. It is suggested that the instantaneous subcritical crack velocity is limited by the rate of production or by the diffusion of some embrittling species.
TL;DR: In this article, the authors investigated the correlation between the direct crack-velocity measurements and the emission count rate at all stress intensities and showed that, as the cracking velocity increases, the counts per unit area of new crack surface increase.
Abstract: Stress-corrosion crack propagation in U-4 1/2 wt%Nb has been monitored with crack-opening displacement and acoustic-emission techniques. Excellent correlation was obtained between the direct crack-velocity measurements and the emission count rate at all stress intensities. The data also show that, as the cracking velocity increases, the counts per unit area of new crack surface increase. The results of the investigation show the feasibility of acousticemission detection techniques as a useful stress-corrosion testing tool.