| 摘要 |
PURPOSE:To efficiently obtain the member having high strength and high ductility with certainty by subjecting an alpha plus beta titanium alloy of specific composition to superplastic forming and then to cooling and age hardening treatment under respectively specified conditions. CONSTITUTION:An alpha plus beta titanium alloy, having a composition containing, by weight, 3.45-5.0% Al, 2.1-5.0% V, 0.85-2.85% Mo, 0.85-3.15% Fe, and 0.01-0.25% O, is subjected to superplastic forming, to cooling at (0.05-5) deg.C/sec cooling rate, and successively to age hardening treatment at 400-600 deg.C. By the above procedure, the occurrence of quenching strain after superplastic forming can be prevented and the necessity of new solution heat treatment can be obviated. Moreover, deterioration in material resulting from superplastic forming can be reduced by subjecting the alloy, after superplastic forming, to temp. rise up to a temp. higher than the forming temp. by >=5 deg.C and lower than the beta transformation point and then to heat treatment. Further, by performing diffusion joining after this temp. rise, joining strength and the strength of a formed body can be increased simultaneously. |
