Titanium alloy billet with superior defect detection capabilities in ultrasonic flaw detection test

摘要

PROBLEM TO BE SOLVED: To provide a titanium alloy billet having excellent flaw detectability in an ultrasonic test, which can undergo inspection of internal flaws by a generally used ultrasonic inspection method similarly to the case of the other metal products, even when the billet is made of titanium alloy prescribed in AMS 4981 being a material whose ultrasonic permeability is relatively inferior among titanium alloy and also is a large-sized billet with a diameter of ≥ϕ150 mm, and which can be mass-produced.;SOLUTION: The titanium alloy billet having excellent flaw detectability in an ultrasonic test is characterized in that in a region where the total area of the optional-cross section of the central part of a titanium alloy billet having a diameter of ≥ϕ150 mm and a columnar shape and prescribed by AMS 4981 is ≥400,000 μm², the cross section being parallel to the axial direction, the area ratio of the primary α phase occupied in the whole structure is ≥20%, and further, the area ratio of the primary α phase with an aspect ratio of ≤2.0 occupied in the whole structure is ≥12%.;COPYRIGHT: (C)2011,JPO&INPIT