| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing aβ-type titanium alloy superior in tensile strength, ductility and fatigue strength. SOLUTION: This manufacturing method comprises previously making aβ-type titanium alloy having an average grain size of anα-phase controlled to 0.1 to 10μm and an average grain size of aβ-phase controlled to 0.1 to 10μm, and heat-treating it in a range of "βtransformation temperature minus 450°C" or higher but lower than "βtransformation temperature minus 100°C" for 15 minutes to 100 hours. Before the above heat treatment, theβ-type titanium alloy may be heat-treated in the range of "βtransformation temperature minus 100°C" or higher but lower than theβtransformation temperature for 1 minute to 2 hours. Theβ-type titanium alloy having the above particle diameters is obtained through processing it in the temperature range of "βtransformation temperature minus 100°C" or higher but lower than theβtransformation temperature so as to make a value (A) expressed in the following expression (1) to be 0.5 or higher: A=ä(ε<SB>1</SB><SP>2</SP>+ε<SB>2</SB><SP>2</SP>+ε<SB>3</SB><SP>2</SP>)×2/3}<SP>0.5</SP>(1), wherein (A) in the expression (1) is an equivalent strain; andε<SB>1</SB>,ε<SB>2</SB>andε<SB>3</SB>are logarithmic strains in principal directions. COPYRIGHT: (C)2004,JPO
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