FORGED TITANIUM ALLOY MATERIAL AND METHOD FOR PRODUCING SAME, AND ULTRASONIC TESTING METHOD

摘要

A forged titanium alloy material having a duplex grain structure composed of flat grains and non-flat grains, wherein the flat grains are crystal grains of prior-² grains each having an aspect ratio of more than 3 and the non-flat grains are crystal grains of prior-² grains each having an aspect ratio of 1 to 3 inclusive. The forged titanium alloy material is characterized in that the average equivalent circle diameter of the non-flat grains is 100 µm or less, flat grains each having a thicknesswise diameter of 20 to 500 µm are contained in an amount of 40 to 98%, non-flat grains each having a thicknesswise diameter of 10 to 150 µm are contained in an amount of 2 to 50 %, and the flat grains each having the above-mentioned thicknesswise diameter and the non-flat grains each having the above-mentioned thicknesswise diameter are contained in the total amount of 90% or more.