Hydrogen as a temporary alloying element in titanium alloys: thermohydrogen processing

Titanium alloys have been used extensively in industry fields including aviation, aerospace and automobile due to their excellent comprehensive properties. Research and development of advanced plastic forming technology are of great importance to manufacturing titanium products of high performance and lightweight with low cost and short cycle. This paper analyzes the development tendencies of titanium alloy forming technology. Recent achievements in precision forming, microstructure control and multi-scale simulation of titanium alloys are reviewed. The forming techniques of large-sale integral complex components are presented. titanium alloys, precision forming, microstructure control, multi-scale simulation, large-scale integral complex components Citation:Yang H, Fan X G, Sun Z C, et al. Recent developments in plastic forming technology of titanium alloys.

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“…[82,83]. It has attracted more interest due to the application of some new difficult-to-work titanium alloys and titanium matrix composites.…”

Section: Improvement Of Microstructure Mechanical Properties and Wormentioning

confidence: 99%

Recent developments in plastic forming technology of titanium alloys

Yang

Fan

Sun

et al. 2011

Sci. China Technol. Sci.

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“…It is also known that the hydrogen as a temporary alloying element [15,16] refines the microstructure of Ti alloys. Based on this, a process [17] has been developed to produce fully dense Ti6Al-4V alloy with refined microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effects of Powder Processing and Sintering on Tensile Ductility of Pm Ti‐6Al‐4V Alloy Made by Hydrogen Sintering of Titanium Hydride Powders

Kumar¹,

Chandran²,

Cao³

et al. 2016

Proceedings of the 13th World Conference on Titanium

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Powder metallurgical (PM) titanium alloys made by dehydrogenation of titanium hydride (TiH 2 ) have drawn attention due to the lower cost and excellent mechanical properties. In this work, tensile properties of Ti-6Al-4V alloy fabricated by the hydrogen sintering and phase transformation (HSPT) process were investigated. The effects of powder processing and sintering on the tensile properties of Ti-6Al-4V have been studied. It is found that the increase in TiH 2 powder milling time reduces the ductility due to increased oxygen levels. An increase in sintering time enhances the ductility of the material, due to a reduction in pore size, without significantly changing the yield strength and the ultimate tensile strength (UTS).

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Section: Comparative Analysis Of Aide and Help Hypothesesmentioning

confidence: 99%

“…This is why, in contrast to austenitic steels, even at rather high hydrogen contents, the brittleness in the titanium alloys occurs below ambient temperatures. Just for this reason, hydrogen is used as temporary alloying element for processing of titanium alloys [70,71].Therefore, the HELP hypothesis more adequately describes hydrogen embrittlement in comparison with the AIDE one. So far, a mechanism similar to HELP was not applied for interpretation of LME or, more generally, for surfactants effect on mechanical behavior of metals.…”

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confidence: 99%

On the Nature of Similarity in Embrittlement of Metals by Hydrogen and Surfactants

et al. 2017

MSEIJ

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A mechanism for a similar effect of hydrogen and surface-active elements, surfactants, on the structure and properties of metals is discussed based on studies of austenitic steels and using the ab initio calculations and experimental measurements of the electron structure, mechanical spectroscopy and tension tests. The similarity is originated from the local enhancement of the metallic character of interatomic bonds. The obtained results are interpreted within the frame of the electron approach to the hydrogen-enhanced localized plasticity phenomenon, HELP, in hydrogen embrittlement. The surfactants increase the density of electron states at the Fermi level and, correspondingly, the concentration of free electrons. As a response, a local decrease of the shear modulus resulted in the initiation of dislocation sources, decrease of the line tension of dislocations and distance between their assembles is expected, which facilitates the opening and propagation of cracks and mechanical degradation. The comparison with the adsorption-induced dislocation emission hypothesis, AIDE, for hydrogen and liquid metal embrittlements is carried out. Keywords: On the Nature of Similarity in Embrittlement of Metals by Hydrogen and Surfactants 2/10Copyright: ©2017 Gavriljuk et al.Important for clarification of the operative mechanism was the observation that, including LME, embrittlement by surfactants is accompanied by a local increase of plasticity [22][23][24]. In other words, the locally enhanced plastic deformation precedes the macrobrittle fracture. This unusual behavior was firstly interpreted as a local disintegration of solids resulted in colloidal disperse systems [4,5]. Later, such approach was supported by the ideas about liquid channels [14,15] and corresponding grain boundary phase transitions [25,26].However, such interpretation of preceded plastic deformation is seriously discredited by a remarkable similarity between LME and hydrogen embrittlement, HE, where local plastic flow always precedes the fracture. Systematic comparative studies of LME and HE were carried out by Lynch [27]. Based on these studies, he has proposed the adsorption-induced localized-slip process to be responsible for both the LME and HE phenomena [28] and, correspondingly, developed the hypothesis of adsorption-induced dislocation emission, AIDE [29]. Its main idea amounts to the adsorption of hydrogen and surfactant atoms at the internal crack tips, which facilitates the nucleation and emission of dislocations. Once nucleated, the dislocations can readily move away from the crack tip under applied stress.Along with AIDE hypothesis, hydrogen embrittlement of metals is described by hypotheses of hydrogen-enhanced decohesion, HEDE, hydrogen-enhanced localized plasticity, HELP, and hydrogen-enhanced strain-induced vacancies, HESIV. Their critical analysis is presented, e.g., in the review articles [29,30]. The AIDE and HELP hypotheses seem to be the most acceptable for application to the both HE and LME processes.Probably first time, the ...

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Hydrogen as a temporary alloying element in titanium alloys: thermohydrogen processing

Cited by 217 publications

References 73 publications

Recent developments in plastic forming technology of titanium alloys

Recent developments in plastic forming technology of titanium alloys

Effects of Powder Processing and Sintering on Tensile Ductility of Pm Ti‐6Al‐4V Alloy Made by Hydrogen Sintering of Titanium Hydride Powders

On the Nature of Similarity in Embrittlement of Metals by Hydrogen and Surfactants

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