| 摘要 |
PURPOSE: To produce a Ti alloy hot forged member having high strength and high rigidity by specifying the composition and structure of a Ti alloy containing Al, Mo, Zr, and Si. CONSTITUTION: This Ti alloy hot forged member has a composition consisting of, by weight, 7.5-11% Al, 0.5-3% Mo, 0.5-2% Zr, 0.01-0.5% Si, and the balance Ti and also has a structure in which equiaxialα-phases are distributed by 70-90area% in a matrix ofβ-phase. When Al content is below the lower limit, the proportion of the equiaxialα-phases to be formed becomes less than 70area% and the desired strength and rigidity cannot be secured and, on the other hand, the proportion of the equiaxialα-phases exceeds 90area% and toughness is deteriorated when it is above the upper limit. As to Mo content, when it is below the lower limit, hot forgeability cannot be secured, and rigidity is deteriorated when it exceeds the upper limit. When Zr content is below the lower limit, a rigidity-improving effect cannot be obtained, and, when it exceeds the upper limit, strength is deteriorated. Further, when Si content is below the lower limit, a strength-improving effect cannot be obtained, and, on the other hand, hot forging crack is liable to occur when it exceeds the upper limit.
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