# US 6,719,856 B2 · Titaniums having excellent impact resistance and manufacturing methods

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- Number: US 6,719,856 B2
- Document ID: US6719856B2
- Status: Granted
- Kind: B2
- Application number: 09/919,392
- Filed: 2001-07-31
- Published: 2003-04-03
- Granted: 2004-04-13
- Earliest claimed: 2001-07-31
- Assignees: Nippon Steel Corporation; MIC Japan, Ltd.
- Inventors: Kazuhiro Takahashi; Motomi Masaki; Kazuyuki Miura; Tatsuo Ohya
- Web page: https://patentgrep.com/patent/US6719856B2

## CPC

- C22F 1/183: {of titanium or alloys based thereon}
- C22C 14/00: Alloys based on titanium
- B21B 3/00: Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences {; Rolling of aluminium, copper, zinc or other non-ferrous metals}(altering special metallurgical properties of alloys, other than structure consolidation or mechanical properties resulting therefrom C21D, C22F)
- B21B 2261/22: Hardness
- 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)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B21B: ROLLING OF METAL (auxiliary operations used in connection with metal-working operations covered in B21, see B21C; bending by rolling B21D; manufacture of particular objects, e.g. screws, wheels, rings, barrels, balls, by rolling B21H; pressure welding by means of a rolling mill B23K20/04)

## Abstract

Titaniums having excellent impact resistance are manufactured by methods that attain good cold workability by controlling the concentrations of oxygen, nitrogen, carbon and iron contained in ordinary pure titaniums in the desired range, applying combinations of preliminary working and annealing before or during the forming process, and controlling the Vickers hardness in the cross-sectional area to the desired range according to the concentrations, without adding aluminum, molybdenum, vanadium or other alloying elements.

## Claims

### Claim 1

Titanium having impact resistance consisting essentially of total concentration S of oxygen, nitrogen and carbon, [O], [N], and [C], between 0.04 and 0.27 mass percent, not more than 0.1 mass percent iron, substantially no copper, and the balance being titanium and unavoidable impurities, and having Vickers hardness Hv* controlled by work-hardening to the range satisfying one of the following equations (1), (2) and (3):
when 0.04≦S≦0.09 (mass percent)
150≦Hv*≦400×S+175 (1)
when 0.09≦S≦0.20 (mass percent)
510×S+104≦Hv*≦400×S+175 (2)
when 0.20≦S≦0.27 (mass percent)
510×S+104≦Hv*≦255 (3)
wherein S: [O]+[N]+[C] (mass percent)
Hv*: Vickers hardness in the cross-sectional area of the work-hardened product.

### Claim 2 (depends on 1)

A method for manufacturing the titanium with impact resistance according to claim 1 in which preliminary working is applied before forming so that Vickers hardness Hv* in the cross-sectional area of the formed product satisfies one of said equations (1), (2) and (3).

### Claim 3 (depends on 2)

A method for manufacturing the titanium with impact resistance according to claim 2 in which the preliminary working applied before forming so that Vickers hardness Hv* in the cross-sectional area of the formed product satisfies one of said equations (1), (2) and (3) comprises either or both of rolling with rolls applied in a direction perpendicular to the direction of hot- or cold-rolling applied prior to said preliminary working.

### Claim 4 (depends on 2)

A method for manufacturing the titanium with excellent impact resistance according to claim 2 in which annealing is applied before or during forming so that Vickers hardness Hv* in the cross-sectional area of the formed product satisfies one of said equations (1), (2) and (3).