Plug for rolling of seamless steel pipe, method for manufacturing the same and method for manufacturing seamless steel pipe using the same
First Claim
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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 with pure cobalt comprising 99 mass % or more of cobalt and a balance being inevitable impurities or a cobalt-nickel alloy, the cobalt-nickel alloy containing 0.3 mass % or more and 30 mass % or less of Ni; and
an oxide layer including a cobalt-base oxide formed on a surface of the coating layer,wherein an average thickness of the oxide layer is in the range of 10 μ
m to 40 μ
m.
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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.
6 Citations
14 Claims
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1. A plug for rolling of a seamless steel pipe, the plug comprising:
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a base metal; a coating layer formed on the base metal by coating a surface of the base metal with pure cobalt comprising 99 mass % or more of cobalt and a balance being inevitable impurities or a cobalt-nickel alloy, the cobalt-nickel alloy containing 0.3 mass % or more and 30 mass % or less of Ni; and an oxide layer including a cobalt-base oxide formed on a surface of the coating layer, wherein an average thickness of the oxide layer is in the range of 10 μ
m to 40 μ
m. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for manufacturing a plug for rolling of a seamless steel pipe, the method comprising:
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coating a surface of a metallic plug with a film including pure cobalt comprising 99 mass % or more of cobalt and a balance being inevitable impurities or a cobalt-nickel alloy having a thickness in the range of 0.1 mm to 2 mm, the cobalt-nickel alloy containing 0.3 mass % or more and 30 mass % or less of Ni; and after the coating step, performing a 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. - View Dependent Claims (10, 11, 12)
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13. A plug for rolling of a seamless steel pipe, the plug comprising:
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a base metal; a coating layer formed on the base metal by coating a surface of the base metal with pure cobalt comprising 99 mass % or more of cobalt and a balance being inevitable impurities; and an oxide layer including a cobalt-base oxide formed on a surface of the coating layer, wherein an average thickness of the oxide layer is in the range of 10 μ
m to 40 μ
m. - View Dependent Claims (14)
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Specification