Patent ID: 6979375

Claim:
A titanium alloy member comprising 40% by weight or more of titanium (Ti), a IVa group element other than titanium as a first substitutional element, a Va group element as a second substitutional element, and 0.25 to 2.0% by weight of one or more interstitial elements selected from the group consisting of oxygen (O), nitrogen (N) and carbon (C), wherein the titanium alloy member contains a summed amount of the Va group element, the IVa group element other than titanium, and the titanium of 90% by weight or more; the titanium alloy member has a composition in which a compositional mean value of the substitutional elements is 2.43<Md<2.49 with regard to the energy level “Md” of the d-electron orbit and a compositional mean value of the substitutional elements is 2.86<Bo<2.90 with regard to the bond order “Bo”, where the “Md” and the “Bo” are each a parameter obtained by the “DV-Xα” cluster method; the titanium alloy member is in a cold-worked condition; the titanium alloy member comprises grains having a body-centered tetragonal or a body-centered cubic crystal structure, in which a ratio (c/a) of a distance between atoms on the c-axis with respect to a distance between atoms on the a-axis falls in a range of from 0.9 to 1.1; the titanium alloy member has a texture such that, when a polar figure of the (110) or (101) crystal plane of the grains is measured parallel to a working direction, in ranges of 20°<α′<90° and 0°<β<360° by the Schulz reflection method, (ν 2 /Xm 2 ) is 0.3 or more, and (ν 3 /Xm 3 ) is 0.3 or more, where ν 2 ={Σ( X−Xm ) 2 }/N, ν 3 ={Σ( X−Xm ) 3 }/N,and Xm is the mean value of N measurement values X; and the titanium alloy member has a tensile deformation property such that a gradient of the tangential line in a stress-strain diagram obtained by a tensile test within an elastic deformation range, in which the stress ranges from 0 to the tensile elastic limit strength, decreases continuously with increase in stress.