USING TEMPORARY HYDRIDE FORMATION IN METASTABLE BETA TITANIUM ALLOYS TO IMPROVE THE MICROSTRCTURE

摘要

Hydrogen can be used as a temporary alloying element during the heat treatment, often referred to as Thermohydrogen Treatment (THT), in order to improve the mechanical properties of titanium alloys by means of microstructure modification being unobtainable by conventional heat treatment. THT is based on the changes of the stability and transformation kinetics of phases as well as on the formation of hydrogen-induced phases. The volume effects associated with hydride formation lead to local matrix deformation accompanied by an increase in the dislocation density. It is shown in this contribution that hydride formation accompanied by a hydrogen-induced redistribution of alloying elements and subsequent complete hydride dissolution can be used to establish a fine microstructure via hydride-induced recrystallization (Ti 10-V-2Fe-3Al) and a homogeneous formation of alpha nuclei indirectly via hydride precursors (Ti 3Al-8V-6Cr-4Mo-4Zr).