71 Thermohydrogen Treatment of Highly Beta-Stabilized Titanium Alloy Ti 38-644 (Beta-C™)

Increasing demands for better performance of structures necessitate innovative thermomechanical treatments of materials. Thermohydrogen Treatment (THT) is postulated to be an auspicious approach in order to modify microstructures of titanium alloys. The present study introduces THT of highly β-stabilized titanium alloy Ti 38-644. Hydrogenating the β phase resulted in early hydride formation leading to a strong local matrix deformation and accumulation of dislocations. The high lattice distortion remains when hydrides were dissolved by vacuum annealing, promoting a homogeneous formation of α nuclei indirectly via hydride precursors. Consequently, THT provides a convenient way to obtain homogeneously distributed fine α precipitates. Strength properties are shown to improve as compared to an optimized and time-consuming duplex aging treatment serving as a reference microstructure.