PLUG FOR ROLLING OF SEAMLESS STEEL PIPE, METHOD FOR MANUFACTURING THE SAME AND METHOD FOR MANUFACTURING SEAMLESS STEEL PIPE USING THE SAME

• US 20150217349A1
• Filed: 09/09/2013
• Published: 08/06/2015
• Est. Priority Date: 09/11/2012
• Status: Active Grant

• Current Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Original Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Inventors: Iguchi, Takaaki, Katsumura, Tatsuro, Kimura, Hideto
• Granted Patent: US 10,441,982 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B21B 19/04 Rolling basic material of solid, i.e. non-hollow, structure; Piercing , e.g. rotary piercing mills
• CPC Class Codes: B21B 25/00 Mandrels for metal tube rolling mills, e.g. mandrels of the types used in the methods covered by group B21B17/00; Accessories or auxiliary means therefor ; Construction of, or alloys for, mandrels or plugs
• CPC Class Codes: B21B 28/00 Maintaining rolls or rolling equipment in effective condition lubricating, cooling or heating rolls while in use B21B27/06
• CPC Class Codes: C23C 8/02 Pretreatment of the material to be coated C23C8/04 takes precedence
• CPC Class Codes: C23C 8/12 using elemental oxygen or ozone
• CPC Class Codes: C25D 5/50 by heat-treatment
• CPC Class Codes: C25D 7/00 Electroplating characterised by the article coated

Abstract

A plug for rolling of a seamless steel pipe, the plug having an oxide layer composed of a cobalt-base oxide on a surface of a coating layer formed by coating a surface of a base metal with cobalt or a cobalt-base alloy, a method for manufacturing the plug and a method for manufacturing a seamless steel pipe using the plug.

Claims

1. A plug for rolling of a seamless steel pipe, the plug comprising:

a base metal;

a coating layer formed on the base metal by coating a surface of the base metal cobalt or a cobalt-base alloy; and

an oxide layer including a cobalt-base oxide formed on a surface of the coating layer.

2. The plug for rolling of a seamless steel pipe according to claim 1, wherein the cobalt-base alloy contains 30 mass % or less of nickel.

3. The plug for rolling of a seamless steel pipe according to claim 1, wherein the oxide layer is formed by performing a heat treatment by holding at a high temperature.

4. The plug for rolling of a seamless steel pipe according to claim 3, wherein the oxide layer is also formed using heat applied when rolling of a seamless steel pipe is performed.

5. The plug for rolling of a seamless steel pipe according to claim 1, wherein the oxide layer is formed using heat applied when rolling of a seamless steel pipe is performed.

6. The plug for rolling of a seamless steel pipe according to claim 1, wherein an average thickness of the oxide layer is in the range of 10 μ

m to 40 μ

m.

7. The plug for rolling of a seamless steel pipe according to claim 1, wherein the base metal includes a ferrous material.

8. A method for manufacturing a seamless steel pipe, the method comprising using the plug for rolling of a seamless steel pipe according to claim 1.

9. A method for manufacturing a plug for rolling of a seamless steel pipe, the method comprising:

coating a surface of a metallic plug with a film including cobalt or a cobalt-base alloy having a thickness in the range of 0.1 mm to 2 mm; and

after the coating step, performing heat treatment in atmospheric air at a temperature of 300°

C. to 1000°

C. in order to form an oxide layer including a cobalt-base oxide, the oxide layer having an average thickness in the range of 10 μ

m to 40 μ

m.

10. The method for manufacturing a plug according to claim 9, wherein the heat treatment is a heat treatment by holding at a high temperature.

11. The method for manufacturing a plug according to claim 9, wherein the heat treatment is performed using heat applied when rolling of a seamless steel pipe is performed.