HOT ROLLED STRIP, HOT ROLLED PLATE OR HOT ROLLED BAR OF TI-FE-O-N TITANIUM ALLOY AND THESE PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide the hot rolled strip, the hot rolled plate and the hot rolled bar with practicality having high ductility in the plate width direction and these production method. ;SOLUTION: The hot rolled strip, the hot rolled plate and the hot rolled bar, which contain, by weight, 0.8-2.3 % Fe, ≤0.05% N and the balance essentially Ti, which have an oxygen equivalent value Q=(O)+2.7(N)+0.1(Fe) in range of 0.35-1.00, an equiaxial α phase of 5-30% in volume and the balance of a mixing structure of a fine needle shaped α phase/β phase, and which have tensile strength of ≥700 MPa in the longitudinal direction and tensile elongation of ≥10% in the plate width direction, are obtained. These products are produced by which a titanium alloy slab of the above composition is heated to a temp. region of the β transformation point or lower, hot rolled, coiled to a coil, subjected to a first heat treatment consisting of heating/holding to and at a temp. or higher at which a volume ratio of α phase/β phase of the alloy becomes 3:7 at an equilibrim state and cooling at a cooling rate of air cooling or slower, next a second heat treatment at ≥500°C to a temp. or lower at which a volume ratio of α phase/β phase of the alloy becomes 7:3 at an equilibrium state.;COPYRIGHT: (C)1998,JPO