The effect of hydrogen on mechanical properties in Ti-10V-2Fe-3Al

Abstract

The effect of hydrogen on the mechanical properties of the metastable β alloy Ti-10V-2Fe-3Al was examined. The material was beta annealed and water quenched (B/WQ) to yield a nominally all-β microstructure, with a small volume fraction of athermal omega present. Tensile and notched bend bar tests were performed with differing levels of hydrogen concentration (~0 to >30 at. pct) obtained by Sieverts (gaseous) charging prior to beta annealing. The β phase was transformed to orthorhombic alpha double prime martensite (β") upon deformation. The volume fraction and morphology of the alpha double prime depended on the hydrogen concentration. The deformation-induced martensitic transformation changed from being stress-induced to being strain-induced with increased hydrogen concentration. High hydrogen concentrations also resulted in changes in fracture mode. At high hydrogen concentrations, where little or no martensite formed upon deformation, “intrinsic” (i.e., independent of microstructural modification) hydrogen effects were observed in the β phase. These intrinsic hydrogen effects, deleterious in nature, were taken to be evidence of hydrogen embrittlement in the body-centered cubic β phase.