Diffusion of hydrogen in titanium alloys due to composition, temperature, and stress gradients

Waisman, J. L.; Sines, George; Robinson, Lawrence Baylor

doi:10.1007/bf02649629

Cited by 88 publications

(33 citation statements)

References 3 publications

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“…The data for the two temperatures correlate on the basis of an activation energy of 38 kJ mol -~ . This value compares favourably with activation energies for diffusion of hydrogen in e and ~ titanium which are, respectively, 52 and 28 kJ tool 1 [5]. The correlation strongly supports the view that the movement of hydrogen atoms is closely associated with plastic flow in the alloy.…”

supporting

confidence: 76%

Dwell-sensitive fatigue in a near alpha-titanium alloy

Evans

1987

J Mater Sci Lett

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supporting

confidence: 76%

Dwell-sensitive fatigue in a near alpha-titanium alloy

Evans

1987

J Mater Sci Lett

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“…5. For the case of hydrogen migration, such equations had previously been used by Waisman et al [92] and Simpson and Ells [80] to explain the preferential formation and growth of hydrides at regions of elevated tensile stress. These flux equations can be formulated in terms of different thermodynamic variables, but when a tensile stress gradient is the source of hydride accumulation, it is most useful to formulate the driving force and boundary values in terms of chemical potential differences.…”

Section: Theory Of Dhc Growth Ratementioning

confidence: 98%

Delayed Hydride Cracking: Theory and Experiment

Püls¹

2012

The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components

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As noted in Chaps. 1 and 9, zirconium alloy components can fail by a time-dependent mechanism of cracking if hydrides can preferentially form and subsequently crack at locations of elevated tensile stress. This process of time-dependent hydride cracking, called delayed hydride cracking (DHC), is based on the mechanism of diffusion of hydrogen to a region of elevated tensile stress followed by nucleation, growth, and fracture of the hydrided region. By repeating these steps, a crack can propagate in a component at a rate that, above a threshold stress intensity factor, K IH ; is mainly dependent on temperature. In this chapter we present the status of the present state of understanding of DHC in zirconium alloys, emphasizing the connections between the models developed and the experimental data. The intent of this chapter is not to provide an exhaustive review of the literature but to focus on results that are deemed to have collectively advanced our understanding of this phenomenon. This chapter is divided into two main parts, the first part dealing with DHC propagation, the other with DHC initiation. Although it may appear backwards to start with DHC propagation rather than initiation, this approach is consistent with the historical development of the field and thus also helps somewhat in simplifying the exposition. Readers wishing to obtain a succinct recent overview of DHC and other aspects of the effects of hydrogen and hydrides on the integrity of zirconium alloys are referred to a recent review by Coleman [15]. In addition, an earlier review by Northwood and Kosasih [47] provides a comprehensive summary account of work published in this field up to the date of that publication.M. P. Puls, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components, Engineering Materials,

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“…Table I gives the standard enthalpy for the formation of the H 2 , O 2 , H 2 O, CO, and CO 2 substances, as a function of temperature. This table was built up from thermochemical data, i.e., solubility in liquid TA6V, [22,2] standard Gibbs energy of formation, [14,23] Sieverts law, and phase diagrams. [24] It can be used to evaluate the gas pressure when thermodynamic equilibrium is achieved between the gas and the surrounding melt.…”

Section: A Thermochemical Systems Involved In the Origin Of Poresmentioning

confidence: 99%

“…[35] A first attempt was made to estimate the characteristic times for the thermal diffusion and for the element diffusion. Considering the difference between the thermal diffusivity () around 7 и 10 Ϫ6 m 2 /s [35] and the atom diffusivity (D) of around 2 и 10 Ϫ7 m 2 /s, for the fastest element H in the solid state [36,22,2] and of less than 1 и 10 Ϫ11 m 2 /s for O in the liquid state, [37] it was decided that diffusion of elements would be ignored. Considering the lifetime of a bubble being about 0.1 seconds (diameter of the weld pool divided by the welding rate) in our EB welding process, the heat-affected zone around the bubble could be at the maximum of 0.8 mm (nearly half the weld-pool dimension).…”

Section: B Evolution Of Pores In the Weld Poolmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of the origin of porosity in electron-beam-welded TA6V plates

Gouret

Ollivier

Dour

et al. 2004

Metall Mater Trans A

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Experimental and theoretical analysis of the origin of porosity in electron-beam (EB) welding is detailed. The experiments are run with several surface treatments and reasonable welding parameters. The plate faces are characterized before welding with a number of methods, such as scanning electron microscope observation, X-ray photoemission spectroscopy (XPS) and, more significantly, secondary ion mass spectroscopy (SIMS) analysis, elastic-recoil detection analysis (ERDA) for hydrogen analysis, and surface roughness measurement. After welding, pores are sought with X-ray detection, phased-array ultrasonic (US) detection, and destructive control. An original comparison between ERDA and refined SIMS measurements allows a quantitative evaluation of surface pollution with hydrogen, oxygen, and carbon. The theoretical analysis is based on the literature concept that the cavities are nucleated from the adjacent plate faces in the solid state, just before melting. A less classical development is proposed in term of the evolution of bubbles in the weld pool. Once in the liquid, the cavities become bubbles. Their radius oscillates, according to Rayleigh-Plesset equations of bubbles, due to temperature and pressure driving forces. Solidification freezes them as they are, thus, forming pores. The extreme values of the oscillation give a good idea of the range of the size of pores in the weld joint, as the comparison between experiments and prediction states. A criterion of surface cleanliness is set, relating the surface pollution and the surface roughness. Above the criterion, the bubbles remain small during their oscillation. Below the criterion they tend to grow large. All the degraded-surface treatments are in dirty situation (large pores), and the reference surface treatment lies around the criterion for cleanliness.

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Diffusion of hydrogen in titanium alloys due to composition, temperature, and stress gradients

Cited by 88 publications

References 3 publications

Dwell-sensitive fatigue in a near alpha-titanium alloy

Dwell-sensitive fatigue in a near alpha-titanium alloy

Delayed Hydride Cracking: Theory and Experiment

Assessment of the origin of porosity in electron-beam-welded TA6V plates

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