IMPROVEMENT OF STRUCTURE OF TITANIUM MATERIAL AND TITANIUM ALLOY MATERIAL

摘要

PURPOSE:To make the structure of a Ti-base metallic material fine and equiaxial by allowing a Ti-base metallic material to occlude specific amounts of hydrogen and subjecting this material to ageing treatment in a specific temp. region and then to annealing in vacuum. CONSTITUTION:A Ti material, an alpha Ti alloy material, and an alpha plus beta Ti alloy material are allowed to occlude 0.02-2wt.% hydrogen, and these materials are subjected to ageing treatment at 20-530 deg.C and then to annealing in vacuum, by which recrystallization is performed and also hydrogen is removed. When the amount of hydrogen occluded is less than 0.02%, the amount of hydride is small though hydride is precipitated at the time of ageing treatment, and as a result, a fine and equiaxial structure cannot be obtained by means of annealing. Further, when the amount of hydrogen occluded exceeds 2%, a large amount of hydride is precipitated at the time of ageing treatment, but the material becomes brittle in this stage and problems in the handling of the material, such as infeasibility of working, e.g. annealing, are brought about. Moreover, hydride is finely precipitated but the precipitation of hydride requires a very long time when ageing treatment temp. is below 10 deg.C, and, when it exceeds 530 deg.C, hydride is precipitated by large amounts but it is coarsened and reenters into solid solution, and as a result, the fine and equiaxial structure cannot be obtained by means of annealing.