Hydrogen embrittlement of metals

Brittle fracture mechanisms of the type first proposed by Griffiths [122] are based on the concept of cpmpetition between a decrease of 

Orowan [123] proposed a modification in which a plastic deformation energy, P, replaces the surface tension, S. This arose because X-ray back reflection showed a thin layer of plastic deformation at brittle fractures. Orowan s condition is 

The relationship of brittle fracture to plastic deformation has, of course, been elaborated in various ways with the aid of dislocation theory, e.g. nucleation of microcracks has been discussed in terms of piling-up of dislocations [124]. Davies [145] has shown that embrittlement requires the presence of islands of martensite (about 1 pm in size) and has suggested that cracks are initiated in the martensite or at the martensite-ferrite interface. 

This phenomenon therefore appears to involve most of the concepts of interest to the kineticist of gas—solid reactions, 

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B.A. Kolachev, Hydrogen Embrittlement of Metals, Metallurgia, Moscow, (1985). 

Kolachev, B.A. (1999) Hydrogen embrittlement of metals (in Russian), Moscow, Metallurgy ... 

Pure Natural gas (methane) has little odor so trace quantities of sulfur such compounds, as ethyl mercaptain, are added. These compounds have a powerful odor and serve to warn of a gas leak. They also tend to reduce hydrogen embrittlement of metals. They have been suggested as a solution to the embrittlement problem. Addition of these materials has the shortcoming that these compounds are toxic and can bum to produce toxic combustion products. Unfortunately, the toxicity and polluting combustion products negate the main purpose for the adoption of hydrogen. The use of chemical inhibitors to provide pipeline safety can be avoided by development of other methods. 

MR Louthan, GR Caskey, JA Donovan, and DE Rawl, Hydrogen embrittlement of metals . Materials Science and Engineering, vol. 10, 1972, pp. 357-68. 

Microorganisms may act as a source of hydrogen and/or produce hydrogen sulphide (sulphate-reducing prokaryotes) and, thus, influence the hydrogen embrittlement of metals. 

Gaseous hydrogen embrittlement of metals in energy technologies Volume 1 The problem, its characterisation and effects on particular alloy classes (ISBN 978-1-84569-677-1)... 

Cotterill, P., 1961, The hydrogen embrittlement of metals, Prog. Mater. Sci. 9, 205. 

S tandard Methods of Test for Hydrogen Embrittlement of Copper, ASTM B 577, American Society for Testing and Materials, Philadelphia, Pa., 1992. Welding Braying and Soldering Vol. 6, Metals Handbook, 9th ed., ASM International, Materials Park, Ohio, 1983. 

For many years hydrogen was considered as a deleterious impurity which deteriorates mechanical properties of materials. This is clearly illustrated by hydrogen embrittlement of ferrous metals and alloys. The main effort of the research was aimed therefore at the study of hydrogen embrittlement and at the ways to avoid it. ... 

The content of this chapter is closely related to permeation, which is the transport of a solute across a layer of solvent (or membrane) under the action of a difference in activity. For example, the permeation of hydrogen through a metal foil has been studied, particularly for palladium [F.A. Lewis (1967)] and iron [J. P. Hirth (1980) H. H. Johnson (1988)]. One reason for studying the permeation of hydrogen through iron is to understand the hydrogen embrittlement of steel. 

If local stresses exceed the forces of cohesion between atoms or lattice molecules, the crystal cracks. Micro- and macrocracks have a pronounced influence on the course of chemical reactions. We mention three different examples of technical importance for illustration. 1) The spallation of metal oxide layers during the high temperature corrosion of metals, 2) hydrogen embrittlement of steel, and 3) transformation hardening of ceramic materials based on energy consuming phase transformations in the dilated zone of an advancing crack tip. 

Glass that has been under stress for a period of time may fracture suddenly. Such delayed fracture is not common in metals (except in cases of hydrogen embrittlement of steels) but sometimes does occur in polymers. It is often called static fatigue. The phenomenon is sensitive to temperature and prior abrasion of the surface. Most important, it is very sensitive to environment. Cracking is much more rapid with exposure to water than if the glass is kept dry (Figure 15.11) because water breaks the Si-O-Si bonds by the reaction — Si-O-Si—H H2O -> Si-OH + HO-Si. 

M.S. Daw, M.I. Baskes Semiempirical, quantum mechanical calculation of hydrogen embrittlement in metals. Physl. Rev. Lett. 50, 1285-1288 (1983)... 

M. S. Daw and I. Baskes, Semiempirical, Quantum Mechanical Calculation of Hydrogen Embrittlement in Metals, Phys. Rev. Lett. 50 (1983) 1285. 

RP Jewitt, RJ Walter, WT Chandler, and RP Erohmberg, Hydrogen Environment Embrittlement of Metals, NASA CR-2163, Rocketdyne for the National Aeronautics and Space Administration, Canoga Park, CA, March 1973. 

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