# US 12,000,021 B2 · α+β type titanium alloy wire and manufacturing method of α+β type titanium alloy wire

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- Number: US 12,000,021 B2
- Document ID: US12000021B2
- Status: Granted
- Kind: B2
- Application number: 17/281,029
- Filed: 2019-10-07
- Published: 2021-11-11
- Granted: 2024-06-04
- Earliest claimed: 2018-10-09
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Ryotaro Miyoshi; Tomonori Kunieda; Kazuhiro Takahashi; Tatsuo Yamazaki; Akira Kawakami
- Web page: https://patentgrep.com/patent/US12000021B2

## CPC

- C22C 14/00: Alloys based on titanium
- C22F 1/183: {of titanium or alloys based thereon}
- C21D 8/06: during manufacturing of rods or wires
- C21D 9/525: {for wire, for rods (C21D9/54 takes precedence)}
- C22F 1/18: High-melting or refractory metals or alloys based thereon
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)

## Abstract

An α+β type titanium alloy wire contains, in mass %, Al: 4.50 to 6.75%, Si: 0 to 0.50%, C: 0.080% or less, N: 0.050% or less, H: 0.016% or less, O: 0.25% or less, Mo: 0 to 5.5%, V: 0 to 4.50%, Nb: 0 to 3.0%, Fe: 0 to 2.10%, Cr: 0 to less than 0.25%, Ni: 0 to less than 0.15%, Mn: 0 to less than 0.25%, and the balance being Ti and impurities, the contents of Al, Mo, V, Nb, Fe, Cr, Ni, and Mn satisfying an equation, in which an average aspect ratio of an α crystal grain is 1.0 to 3.0, a maximum crystal grain diameter of the α crystal grain is 30.0 μm or less, an average crystal grain diameter of the α crystal grain is 1.0 to 15.0 μm.

## Claims

### Claim 1

An α+β type titanium alloy wire, containing: in mass %,
Al: 4.50 to 6.75%;
Si: 0 to 0.50%;
C: 0.080% or less;
N: 0.050% or less;
H: 0.016% or less;
O: 0.25% or less;
Mo: 0 to 5.5%;
V: 0 to 4.50%;
Nb: 0 to 3.0%;
Fe: 0 to 2.10%;
Cr: 0 to less than 0.25%;
Ni: 0 to less than 0.15%;
Mn: 0 to less than 0.25%; and
the balance being Ti and impurities,
the contents of Al, Mo, V, Nb, Fe, Cr, Ni, and Mn satisfying the following equation (1), wherein:
a diameter of the wire of 15 mm or less:
an average aspect ratio of an α crystal grain is 1.0 to 3.0;
a maximum crystal grain diameter of the α crystal grain is 30.0 μm or less;
an average crystal grain diameter of the α crystal grain is 1.0 μm to 15.0 μm; and
an area ratio of the α crystal grain, out of the α crystal grains in a cross section orthogonal to a long axis direction of the wire, regarding which an inclination angle in a c-axis direction of a hexagonal close packing crystal that forms the α crystal grain relative to the long axis direction is within a range of 15° to 40°, is 5.0% or less,
−4.0≤[Mo]+0.67 [V]+0.28 [Nb]+2.9 [Fe]+1.6 [Cr]+1.1 [Ni]+1.6 [Mn]−[Al]≤2.0 (1)
in the above equation (1), notation of [symbol of element] represents a content (mass %) of a corresponding symbol of element, and a symbol of element which is not contained, is substituted by 0.

### Claim 2 (depends on 1)

The α-β type titanium alloy wire according to claim 1 containing: in mass %,
Al: 5.50 to 6.75%;
V: 3.50 to 4.50%; and
Fe: 0.10 to 0.40%.

### Claim 3 (depends on 1)

The α-β type titanium alloy wire according to claim 1 containing: in mass %,
Al: 4.50 to 6.40%; and
Fe: 0.50 to 2.10%.

### Claim 4 (depends on 1)

The α+β type titanium alloy wire according to claim 1, wherein
the number of internal defects per unit area is 0 pieces/mm2 to 13 pieces/mm2.

### Claim 5

A manufacturing method of an α+β type titanium alloy wire being a method of manufacturing a α+β type titanium alloy wire, containing: in mass %,
Al: 4.50 to 6.75%;
Si: 0 to 0.50%;
C: 0.080% or less;
N: 0.050% or less;
H: 0.016% or less;
O: 0.25% or less;
Mo: 0 to 5.5%;
V: 0 to 4.50%;
Nb: 0 to 3.0%;
Fe: 0 to 2.10%;
Cr: 0 to less than 0.25%;
Ni: 0 to less than 0.15%;
Mn: 0 to less than 0.25%; and
the balance being Ti and impurities,
the contents of Al, Mo, V, Nb, Fe, Cr, Ni, and Mn satisfying the following equation (1), wherein:
a diameter of the wire is 15 mm ore less:
an average aspect ratio of an α crystal grain is 1.0 to 3.0;
a maximum crystal grain diameter of the α crystal grain is 30.0 μm or less;
an average crystal grain diameter of the α crystal grain is 1.0 μm to 15.0 μm; and
an area ratio of the α crystal gram, out of the α crystal grains in a cross section orthogonal to a long axis direction of the wire, regarding which an inclination angle in a c-axis direction of a hexagonal close packing crystal that forms the α crystal grain relative to the long axis direction is within a range of 15° to 40°, is 5% or less,
−4.0≤[Mo]0.67 [V]+0.28 [Nb]+2.9 [Fe]+1.6 [Cr]+1.1 [Ni]+1.6 [Mn]−[Al]≤2.0 (1)
in the above equation (1), notation of [symbol of element] represents a content (mass %) of a corresponding symbol of element, and a symbol of element which is not contained, is substituted by 0,
the method comprising:
first performing working of one time or two times or more on a titanium alloy material comprising the chemical components in the α+β type titanium alloy wire at a working temperature in a range of 0° C. to 500° C., in which a reduction of area per one time of working is set to 10 to 50%, and a total reduction of area is set to 50% or more; and
second performing, with respect to the titanium alloy material after being subjected to the first performing, final heat treatment in which a heat treatment temperature T is set to fall within a range of 700° C. to 950° C., and a heat treatment time t is set to a heat treatment time satisfying the following equation (2),
21000<(T+273.15)×(log10(t)+20)<24000 (2)
Here, in the above equation (2), T indicates the heat treatment temperature (° C.) in the second performing, and t indicates the heat treatment time (hr) in the second performing.

### Claim 6 (depends on 5)

The manufacturing method of the α+β type titanium alloy wire according to claim 5, wherein
when the working is performed a plurality of times in the first performing, intermediate annealing is performed between the working and the working.