Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Yosuke Tatebayashi

Yasuyoshi Hidaka

Yasuto Higashida

Yuji Arai

Kazuhiro Shimoda

Hiroki Kamitani

Sumio Iida

Atsushi Soma

Kouji Yamane

Kouji Nakaike

Takenori Kuramoto

Takateru Inage

Keisuke Furo

The seamless steel pipe of the present embodiment consists of in mass %, C: 0.21 to 0.35%, Si: 0.10 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.010% or less, Al: 0.005 to 0.100%, N: 0.010% or less, Cr: 0.05 to 1.50%, Mo: 0.10 to 1.50%, Nb: 0.010 to 0.050%, B: 0.0003 to 0.0050%, and Ti: 0.002 to 0.050%, the balance being Fe and impurities. In a main body region of the seamless steel pipe, a grain size number of prior-austenite grain conforming to ASTM E112 is 7.0 or more, a difference between a maximum value and a minimum value of the grain size number is 1.0 or less, yield strength is 655 to less than 862 MPa, and a difference between a maximum value and a minimum value of tensile strength is 27.6 MPa or less.

Seamless steel pipe and method for producing the seamless steel pipe

A piercing plug includes a plug main body, and a sprayed coating which is formed on a surface of the plug main body and includes iron and iron oxide. A chemical composition of the sprayed coating includes, in addition to the iron and the iron oxide, by mass %, C: 0.015% to 0.6%, Si: 0.05% to 0.5%, Mn: 0.1% to 1.0%, and Cu: 0 to 0.3%.

Piercing plug and manufacturing method of piercing plug

It is an objective to provide a plug capable of enhancing a usage count of the plug, which is for use in a piercing machine for piercing-rolling a billet, and a regenerating method of the plug. The plug () is for use in a piercing machine () for piercing-rolling a billet (). The plug () includes a body (), a columnar portion (), and a sprayed film (). The body () has a maximum diameter at its rear end. The columnar portion () has the same diameter as the diameter of the rear end of the body (), and extends from the rear end of the body (). The sprayed film () is formed on a surface of the body () and on a surface of the columnar portion ().

Method for regenerating a plug for use in a piercing machine

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Tokyo, Japan

Yosuke Tatebayashi