Problem Of Stress Corrosion Cracking Research Articles

A Proposed General Solution for Li Dendrite Penetration into Solid Electrolytes

We propose a general solution to the problem of Li dendrite penetration through solid electrolytes such as LLZO. The solution is based on an analogy of Li dendrite penetration to stress corrosion cracking, a process in which a very soft material--water--penetrates through a very hard material--steel--generally at grain boundaries. The problem of stress corrosion cracking was solved many years ago by putting the surface into a state of residual compressive stress. A variety of materials have been strengthened this way, including metals, glasses (e.g., Gorilla glass), and ceramics. However, for this approach to be useful, it is critical, at a minimum, that the presence of a significant residual compressive stress not block ion transport. In this work, we used DFT to show that isotropic compressive residual stresses as high as -10 GPa—the maximum observed in strengthened ceramics—have only a minimal impact on the diffusion rate of Li+ ions through a near-surface region of LLZO. Figure 1

A New General Paradigm for Understanding and Preventing Li Metal Penetration through Solid Electrolytes

Summary The use of lithium (Li) or sodium (Na) metal anodes together with highly ion-conductive solid electrolytes (SEs) could provide batteries with a step improvement in volumetric and gravimetric energy densities. Unfortunately, these SEs face significant technical challenges, in large part because Li and Na dendrites can penetrate through SEs, leading to short circuits. The ability of such a soft material (Li or Na metal) to penetrate through ceramic is surprising from the point of view of models widely used in the Li-battery field. We introduce a concept, new to the battery field, for preventing penetration of lithium dendrites through SEs by putting the SE surfaces into a state of residual compressive stress. For a sufficiently high compressive stress, cracks have difficulty forming, and cracks that do form are forced to close, inhibiting dendrite penetration. This approach is widely used to solve commercially important stress corrosion cracking problems in metals and static fatigue problems in ceramics and glasses (e.g., Gorilla Glass). However, the technique will not be useful for SEs if the Li-ion transport rate through a SE is substantially reduced when the SE is under compression. Our molecular dynamics calculations for Li-ion transport through a common SE demonstrate that the introduction of even very high residual compressive stresses (∼10 GPa) has only a modest effect on Li-ion transport kinetics, suggesting that this approach is viable and capable of providing a new paradigm for developing high-performance and mechanically stable SEs.

GS0114-346 超音波振動を利用した溶接残留応力の低滅 : SUS304薄板溶接に対する加速度振幅の影響

In welding, material is heating locally. Therefore, it generates tensile residual stress in the heat affected zone and changes the quality of material. Those will be causes problem of stress corrosion cracking in SUS304. One of the conventional prevention is to use material that hardly occur heat sensitization, but stress corrosion cracking is observed in that material. Therefore, it is desired to reduce or remove the tensile residual stress generated by welding. Accordingly, we have been proposed a method that adds ultrasonic vibration during welding. The method can reduce the tensile residual stress easily in a shorter time than conventional methods. Experimentally, it has ever been shown that this method can reduce the tensile residual stress on heated zone for thin plate of SUS304. In this study, it is examined that acceleration amplitude influences to reduction of the tensile residual stress for welding of thin plate of SUS304.

1999 W.R. Whitney Award Lecture:Past, Present, and Future of Stress Corrosion Cracking

Abstract The systematic study of the problem of stress corrosion cracking of metals started in the middle of the 19th century. At the end of the 20th century, there is still no general agreement about the mechanisms involved in the process. In the present review, an analysis was made of the difficulties found in the study of this problem, the achievements in the field, and what should be expected for future decades.

Stress corrosion cracking and component failure: Causes and prevention

The century-old problem of stress corrosion cracking (SCC) in metals and alloys has been reviewed highlighting the metallurgical factors like grain boundary precipitation and grain boundary segregation contributing to the process, the electrochemical aspects of the phenomenon and the current knowledge of the mechanisms which can be broadly classified as dissolution-based and cleavage-based models. The introduction covers some field examples of SCC. SCC test methods and preventive measures for SCC have also been discussed.

VALINOX VLX 439L

Abstract VALINOX VLX 439L is a ferritic stainless steel with 18% chromium, low carbon, and titanium stabilization to present an entirely ferritic structure; resistance to corrosion in fresh water, boiler water, and cooling waters; and an almost freedom from stress-corrosion cracking problems due to chlorinated water. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and heat treating. Filing Code: SS-531. Producer or source: Vallourec Inc..

Environmental Effects on the Cracking of Engineering Materials

A material's susceptibility to cracking may be significantly affected by its chemical environment. Stress corrosion cracking (SCC), liquid metal embrittle-ment (LME), hydrogen embrittlement (HE), and corrosion fatigue are examples of environmental effects which cause ductility or endurance losses through environment-assisted cracking (EAC). Under certain conditions, virtually all commercially important materials are susceptible to one or more of the above embrittlement processes. Cracking may occur intergranularly, transgranularly, or in a mixed mode, depending on conditions. Much is known about the metallurgical and environmental conditions which promote environment-assisted cracking, and prudent control of these is often successful in mitigating or preventing cracking. However, in spite of our understanding of the factors controlling SCC, LME, and HE, the responsible mechanisms remain elusive.This article will (1) review some of the important variables affecting these phenomena, such as stress, stress intensity, material microstructure, strain rate, electrochemical potential and pH, and (2) attempt to relate phenomeno-logical characteristics of environment-induced embrittlement to several mechanisms proposed for environment-assisted cracking, as they are understood today.The problem of stress corrosion cracking is unquestionably the most costly of environmental cracking phenomena, with losses occurring in a wide variety of service environments. Liquid metal embrittlement is of concern in nuclear power and other industries. Hydrogen embrittlement, first recognized as an embrittler of iron in 1873, causes cracking problems in applications ranging from welding to oil drilling. In all, the list of situations in which environment-assisted cracking occurs is long and is likely to grow as materials are increasingly challenged by the severity of their service conditions.

BWR pipe crack and weld clad overlay studies

Several topics pertaining to the problem of stress corrosion cracking (SCC) of piping in boiling water reactors are addressed in this paper: (1) the effects of impurities, dissolved oxygen content, and strain rate on susceptibility of SCC of “Nuclear Grade” Type 316NG and sensitized Type 304 stainless steel, (2) finite-element analyses and experimental measurement of residual stresses in weldments with weld overlays, and (3) analysis of field components to assess effectiveness of in-service inspection techniques and the in-reactor performance of weld overlays. Several anion impurities including sulfates, chlorides, nitrates, borates, and carbonates were studied under both near neutral and slightly acidic conditions. At the low impurity concentrations expected in reactor coolant systems (<0.1 ppm), the sulfur species appear to be the most deleterious. They promote intergranular SCC in sensitized stainless steel and transgranular SCC in the low-carbon “Nuclear Grade” stainless steel. Correlations between experimental data and a phenomenological model that describes the effect of strain rate on SCC are presented. Measurements of the residual stresses produced by weld overlays confirm that the process is very effective in producing compressive stresses on the inner surface of the weldment. Examination of a weld overlay removed from service suggests that no additional throughwall crack growth had occurred after application of the overlay.

Rosenhain Centenary Conference - 2. Design implications for materials selection 2.7 The contributions of physical metallurgy and of fracture mechanics to containing the problem of stress-corrosion cracking

The features in the province of the physical metallurgist - grains, precipitate particles, inclusions and lattice imperfections - have sizes approximately in the range of 1 um -0.1 nm. The nature and properties of these microfeatures determine the engineering properties of alloys, including their resistance to stress-corrosion cracking. No basis has developed for confidence that knowledge of these microfeatures can be used to exclude the possibility of stress-corrosion cracking. Neither have we learned how to sum up the effects of these microfeatures to predict stress-corrosion cracking behaviour, nor is there any basis for predicting how soon we may be able to do this summing up analytically. In the meanwhile we need experimental means to do this summing up, and fracture mechanics appears to be an eminently suitable way to treat the stress factor. Other fundamentally different approaches may be found to be both valid and needed for special areas of the problem. Thus the role of fracture mechanics is to provide engineering data, and the role of physical metallurgy is to permit orderly alloy development through understanding of the data from fracture mechanics (and possibly other) tests. The two approaches are complementary, not competitive, and neither can fulfill the role of the other. . , Non-redundant load path designs may require specially competent attention to both stress-corrosion cracking and brittle fracture.

STRESS CORROSION CRACKING

SOLUTION of the problem of stress corrosion cracking has been claimed by Ampco Metal Inc., of Wisconsin, U.S.A., as a result of field testing of Ampco Grade 8 alloy. Differing only in one minor but vital respect from any other bronze, the alloy has been successfully patented in the U.S. and additional patents are pending in six foreign countries.