| 摘要 |
A process for treating an alpha-beta titanium alloy to improve cryogenic notch tensile ratio comprises heating the alloy to near or above its beta transus temperature for a sufficient time to dissolve substantially all alpha grains and thus transform the alloy to the beta form, rapidly cooling the alloy from this temperature to induce a martensitic transformation and produce a fine platelet microstructure, isothermally forging the alloy about 50 to 80 percent at about 300° C. below the beta transus temperature to attain a fine equiaxed microstructure such that the largest microstructural unit is about 2-5 mum, and then aging the alloy at a temperature about 25° C. to 75° C. below the beta transus to grow the refined equiaxed microstructure such that the largest microstructural unit is about 5-10 mum. A titanium alpha-beta alloy having enhanced notch toughness comprises titanium, aluminum, and vanadium and is characterized by a microstructure having equiaxed alpha grains whose volume fraction is about 75 to 85 percent, a maximum grain size of the microstructure not exceeding about 10 mum, and with the volume fraction of primary alpha grains not exceeding about 2 percent.
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