Effect of hydrogen on mechanical properties of β -titanium alloys
Conflicting opinions exist in the literature on the manner in which hydrogen influences the mechanical properties ofβ-titanium alloys. This can be attributed to theβ-stabilizing effect of hydrogen in these materials leading to major changes in the microstructure as a result of hydrogen charging. The resulting (extrinsic) effect of hydrogen on the mechanical properties can possibly cover up the direct (intrinsic) influences.
On the basis of experimentally determined thermodynamic and kinetic data regarding the interaction of hydrogen withβ-titanium alloys, hydrogen concentrations of up to 8 at.% were established in three commercial alloys by means of hydrogen charging from the gas phase. In order to separate intrinsic and extrinsic effects the charging was carried out during one step of the two-step heat treatment typical of metastableβ-titanium alloys, while the other step was performed in vacuum.
The results on the single-phaseβ condition represent the intrinsic hydrogen effect. Monotonic and cyclic strength increase at the expense of ductility with increasing hydrogen concentration. The brittle to ductile transition temperature shifts to higher values and the fatigue crack propagation threshold value decreases. The microstructure of the metastable, usually two-phaseβ-titanium alloys is strongly affected by hydrogen, although the extent of this effect depends not only on the hydrogen concentration but also on the temperature of charging. This microstructural influence (extrinsic effect) changes the mechanical properties in the opposite direction as compared to the intrinsic hydrogen effect.
Keywordsβ-Titanium alloys hydrogen embrittlement hydrogen diffusion hydrogen solubility fatigue behaviour brittle to ductile transition
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- Alvarez A M 1999On the effect of hydrogen on the mechanical behavior of beta-C titanium in aged condition. Ph D thesis, University of Illinois at Urbana-Champaign, Urbana Champaign, ILGoogle Scholar
- Boyer R R 1993 Application of beta titanium alloys in airframes.Beta titanium alloys in the 90 ’s (eds) D Eylon, R R Boyer, D A Koss (Warrendale, PA: Miner. Met. Mater. Soc.) pp 335–346Google Scholar
- Broderick T F, Reshad J, Ward C H, Scheltens F J 1996 Solvus temperatures of various phases in alloy C.Titanium ’95: Science and technology (eds) P A Blenkinsop, W J Evans, H M Flower (London: Inst. Mater.) pp 2385–2392Google Scholar
- Costa J E, Banerjee D, Williams J C 1984 Hydrogen effect in β-titanium alloys.Beta titanium alloys in the 80’s (eds) R R Boyer, H W Rosenberg (Warrendale, PA: Metall. Soc.) pp 69–83Google Scholar
- Costa J E, Williams J C, Thompson A W 1987 The effect of hydrogen on mechanical properties in Ti-10V-2Fe-3Al.Metall. Trans. A18: 1421–1430Google Scholar
- Decker M 2002Kinetik und Thermodynamik der Wasserstoffaufnahme und -abgabe von Beta-Titanlegierungen. Doctorate thesis, University of Siegen, SiegenGoogle Scholar
- Decker M, Christ H-J 1998 Kinetik und Thermodynamik der Wasserstoffaufnahme und -abgabe in β-Titanlegierungen.Nichtmetalle in Metalle (ed.) D Hirschfeld (Clausthal-Zellerfeld: GDMB-Informationsgesellschaft) pp 79–88Google Scholar
- Hansen J O, Novotnak D, Welter M F, Wood J R 1996 Properties and processing of a high strength beta titanium alloy.Titanium ’95: Science and technology (eds) P A Blenkinsop, W J Evans, H M Flower (London: Inst. Mater.) pp 675–682Google Scholar
- Holman W R, Crawford R W, Paredes F 1965 Hydrogen diffusion in a beta-titanium alloy.Trans. AIME 233: 1836–1839Google Scholar
- Isaac G H, Hammond C 1984 Phase separation in deformed and aged Ti-10%V-2%Fe-3%Al.Titanium 84 — Science and technology (eds) G Lütjering, U Zwicker, W Bunk (Oberursel: Deutsche Gesellschaft für Metallkunde) pp 2479–2486Google Scholar
- Kuhlman G W 1993 Alcoa titanium alloy Ti-10V-2Fe-3Al forgings.Beta titanium alloys in the 90’s (eds) D Eylon, R R Boyer, D A Koss (Warrendale, PA: Miner. Met. Mater. Soc.) pp 485–511Google Scholar
- Lederich R J, Schwartz D S, Sastry S M L 1993 Effects of internal hydrogen on microstructure and mechanical properties of β-21S and Ti-15-3.Beta titanium alloys in the 90’s (eds) D Eylon, R R Boyer, D A Koss (Warrendale, PA: Miner. Met. Mater. Soc.) pp 69–83Google Scholar
- Peters M, Winkler P J 1992 Leichtmetalle in der Luft- und Raumfahrt.Metallurgica 46: 1226–1234Google Scholar
- Senemmar A 2002Einfluss von Wasserstoff auf die mechanischen Eigenschaften von Beta-Titanlegierungen. Doctorate thesis, University of Siegen, Siegen, GermanyGoogle Scholar
- Teter D 1996The effect of hydrogen on the deformation and fracture behavior of the metastable beta-titanium alloy Timetal 21S. Ph D thesis, University of Illinois at Urbana-Champaign, Urbana-Champaign, ILGoogle Scholar
- Terlinde G, Schwalbe K-H 1987 The role of α-phase in the fracture toughness and tensile fracture of an aged metastable β-Ti-alloy.Microstructure, fracture toughness and fatigue crack growth rate in titanium alloys (eds) A K Chakrabarti, J C Chesnutt (Warrendale, PA: Metall. Soc.) pp 97–109Google Scholar