| 摘要 |
Provided is a titanium-alloy forging material in which fatigue-strength characteristics are improved without worsening ultrasonic flaw detection. A ²-forged titanium-alloy forging material (1) is characterized in that the area ratio of non-flat grains, which are prior ²-grains (2) having an aspect ratio of 3 or less and a diameter in the forging direction of at least 20 µm, and an ±-phase ratio at the crystal grain boundary (3) of at least 80%, is less than 10%, and the area ratio of flat grains, which are prior ²-grains having an aspect ratio greater than 3 and a diameter in the forging direction of 20-700 µm, and an ±-phase ratio at the crystal grain boundary (3) of at least 80%, is 85% or greater, and the average orientation difference of the ±-phase crystal orientation deposited at the crystal grain boundary (3) of the flat grains is at least 6 °. |
