The effect of stress on hydride precipitation

Flanagan, Ted B.; Mason, N.B.; Birnbaum, H.K.

doi:10.1016/0036-9748(81)90148-4

Cited by 79 publications

(28 citation statements)

References 11 publications

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“…Hydride formation and cleavage fracture occur in systems where hydrides are stable or can be stabilised by application of stress. Microscopical observations and thermodynamic analysis confirm this process [55,191]. The FCC hydride phase, called c Hydride , is formed through phase separation in the matrix enriched with hydrogen.…”

Section: Hydrogen-induced Phase Transformationmentioning

confidence: 64%

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

et al. 2018

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Hydrogen embrittlement is a complex phenomenon, involving several lengthand timescales, that affects a large class of metals. It can significantly reduce the ductility and load-bearing capacity and cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Despite a large research effort in attempting to understand the mechanisms of failure and in developing potential mitigating solutions, hydrogen embrittlement mechanisms are still not completely understood. There are controversial opinions in the literature regarding the underlying mechanisms and related experimental evidence supporting each of these theories. The aim of this paper is to provide a detailed review up to the current state of the art on the effect of hydrogen on the degradation of metals, with a particular focus on steels. Here, we describe the effect of hydrogen in steels from the atomistic to the continuum scale by reporting theoretical evidence supported by quantum calculation and modern experimental characterisation methods, macroscopic effects that influence the mechanical properties of steels and established damaging mechanisms for the embrittlement of steels. Furthermore, we give an insight into current approaches and new mitigation strategies used to design new steels resistant to hydrogen embrittlement.

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Section: Hydrogen-induced Phase Transformationmentioning

confidence: 64%

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

et al. 2018

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“…the energy DE(x) must be determined fully self-consistently. In the presence of a loaded crack, a major component of the energy is the elastic interaction energy p(x)DV [40,49] where p(x) = P 3 i¼1 r ii ðxÞ=3 is the crack-induced pressure field at position x and DV is Table 1 Properties of the Ni-H system as the potential cut-off distance r cut for Ni varies: cohesive energy E coh ; lattice constant a 0 ; elastic constants C 11 , C 12 and …”

Section: Hydride Formation Around the Crack Tipmentioning

confidence: 99%

“…However, the actual process of embrittlement at the crack tip is difficult to determine, while increases in flow stress in the presence of H are also observed in various materials [33][34][35][36][37][38]. Finally, hydride formation and cleavage is a viable embrittlement mechanism when brittle hydride precipitates form [39][40][41][42], but is only expected in "hydride-forming" systems such as V and Nb, although limited hydride formation can be observed in other materials (e.g. Ni) [7,33] undergoing hydrogen embrittlement.…”

Section: Introductionmentioning

confidence: 99%

A nanoscale mechanism of hydrogen embrittlement in metals

2011

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“…hydrides, martensitic phases 14-17, etc. The basic requirements are that these phases be stabilipd by the presence of hydrogen and the crack tip stress field 10,16, 18 and that the phase which forms be brittle 19,20. The typical system which exhibits failure by this mechanism forms stable hydrides in the absence of stress and these hydrides, by virtue of their large AVformation, are thermodynamically more stable under the stress and hydride fugacity conditions at the crack tip 18.…”

Section: Hydrogen Related Phase Change Mechanismsmentioning

confidence: 99%

Mechanisms of Hydrogen Related Fracture of Metals

Birnbaum¹

1989

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INTRODUCTIONThe number of studies of hydrogen related fracture in recent years is quite impressive both in the variety of systems studied and in the amount of materials characterization which has been obtained 1-3. Despite this effort there is still incomplete understanding of the mechanisms by which the hydrogen related failures occur and hence each material becomes a new and novel problem. The advantage of obtaining an adequate understanding of the failure mechanisms is that general rules of behavior can then guide the selection and application of new materials in aggressive environments.In focussing on the understanding of the basic mechanisms of environmental!y related fracture it is important to distinguish between those experiments and effects which are dependent on the kinetics of fracture and those which are mechanistically related. Kinetic studies can be applied to develop an understanding of the factors which determine the failure rates but should not be used to classify materials with respect to the mechanisms of failure. Thus materials which had been classified as insensitive to hydrogen effects , e.g. Al 4, stainless steels 5,6, etc. have recently been shown to be highly susceptible to "hydrogen embrittlement" when exposed to a sufficiently high fugacity of hydrogen or tested at sufficiently low strain rates and the proper temperature range.There has been no shortage of suggested mechanisms 1,2,7; but few have stood the test of critical examination; particularly as new experimental and theoretical methods become available. At the present time several viable mechanisms remain, each of which can be supported by some experimental and theoretical evidence. The preponderance of evidence is that there are several hydrogen related failure mechanisms rather than a single dominant mechanism and that even within one material system several of these may be operative. In cases where this is true, the particular mechanism which leads to failure is controlled by kinetics. An example of this will be discussed subsequently. In the present paper three mechanisms will be discussed; embrittlement due to hydrogen related phase changes, hydrogen enhanced plasticity related fracture and the decohesion mechanisms. HYDROGEN RELATED PHASE CHANGE MECHANISMSA number of metallic systems have demonstrated hydrogen embrittlement due to stress induced formation of hydrides or other relatively brittle phases and the subsequent brittle fracture of these phases 8- 13 Several types of phases may take part in this failure mechanism; e.g. hydrides, martensitic phases 14-17, etc. The basic requirements are that these phases be stabilipd by the presence of hydrogen and the crack tip stress field 10,16,18 and that the phase which forms be brittle 19,20. The 2 typical system which exhibits failure by this mechanism forms stable hydrides in the absence of stress and these hydrides, by virtue of their large AVformation, are thermodynamically more stable under the stress and hydride fugacity conditions at the crack tip 18. In some cases hydr...

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The effect of stress on hydride precipitation

Cited by 79 publications

References 11 publications

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

A nanoscale mechanism of hydrogen embrittlement in metals

Mechanisms of Hydrogen Related Fracture of Metals

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