Microstructure Optimization by Hydrogen Treatment of β-Titanium Alloys
Using hydrogen as a temporary alloying element is a promising approach in order to enhance mechanical properties by means of microstructure modification. Utilizing the β-stabilizing effect of hydrogen enables to retain fine β-grains during the solution heat treatment and to establish an auspicious precipitation condition of the hardening α-phase during aging. This extrinsic: hydrogen effect is considered to be beneficial to mechanical properties with respect to applications of β-titanium alloys in high-strength and fatigue-critical components. The present study introduces various Thermo-Hydrogen-Processing (THP)-routes for β-titanium alloys differing considerably in βstability. In case of highly β-stabilized Ti 38-644, which is usually solution-annealed in the single-phase β-regime, two different hydrogen treatments were devised. The microstructure modifications associated with the 1st THP-route feature a (TixZry)hydride phase. The 2nd concept utilizes lower hydrogen concentrations in a fully re-crystallized β-microstructure. The nearβ-titanium alloy Ti 10-2-3 is usually solution-annealed below the βtransition temperature. By means of temporary alloying with hydrogen .close attention can be paid in order to retain a small volume fraction of primary α-phase to avoid β-grain coarsening. Alternatively,solution annealing can be performed in the singlephase β-regime provided that hydrogenation has significantly reduced the β-transition temperature, thereby keeping β-grain growth moderate and facilitating a maximum volume fraction of the strengthening α-phase during subsequent aging. The microstructure response upon THP was evaluated and consequences for monotonic and cyclic strength (fatigue limit) were determined. The results clearly show that each particular THP-step has to be adapted carefully with respect to the resulting microstructural modifications which strongly affect the mechanical properties of the respective p-titanium alloy.
Thermohydrogen Processing Ti 38-644 (Betar-CTM) Ti 10-2-3 microstructure refinement transition temperature
Peter Schmidt Hans-Jürgen Christ
Institut für Werkstof ftechnik,Universit(a)t Siegen,57068 Siegen,Germany
国际会议
The 12th World Conference Titanium(第十二届世界钛会 Ti-2011)
北京
英文
502-507
2011-06-19（万方平台首次上网日期，不代表论文的发表时间）