Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Kouji Yamane

Kazuhiro Shimoda

Tomio Yamakawa

Yuji Inoue

Yuji Arai

Yasuyoshi Hidaka

Shusuke Shimooka

Koichi Kuroda

Akihiro Sakamoto

Hiroki Kamitani

Atsushi Soma

Yasuto Higashida

Kazuyuki Murakami

Kouji Muramatsu

Yasuhiko Daimon

Haruka Obe

Yosuke Tatebayashi

Takenori Kuramoto

Yuichi Yamanari

Syusuke Shimooka

Kota Shindo

Keisuke Furo

A method disclosed herewith is a method for producing a first seamless metal tube with a first wall thickness and a second seamless metal tube with a second wall thickness by using a three-roll-type inclined rolling mill, and the method includes a first inclination rolling step (#5), a setting changing step (#10), and a second inclination rolling step (#15). At the first inclination rolling step, a first workpiece is rolled by the inclined rolling mill. At the setting changing step, a setup condition of the inclined rolling mill is changed in a manner (a) or (b) as described below. At the second inclined rolling step, a second workpiece is rolled by the inclined rolling mill under the changed condition. (a) When the second wall thickness is smaller than the first wall thickness, the cross angle of each of the inclined rolls is made greater than the cross angle set for the first inclination rolling step. (b) When the second wall thickness is larger than the first wall thickness, the cross angle of each of the inclined rolls is made smaller than the cross angle set for the first inclination rolling step.

Method for producing seamless metal tube

The production method of a seamless steel pipe includes a heating step of heating an Nb-containing steel material to 800 to 1030&#xb0; C., a pipe-making step of producing a hollow shell by performing piercing-rolling or elongation-rolling on the Nb-containing steel material, by using a piercing mill including a plurality of skewed rolls, a plug disposed between the plurality of skewed rolls, and a mandrel bar, and a cooling step immediately after rolling, of carrying out cooling using a cooling liquid on a hollow shell portion that passes between rear ends of the plurality of skewed rolls, in the hollow shell, so as to reduce an outer surface temperature of the hollow shell portion to 700 to 1000&#xb0; C. within 15.0 seconds after the hollow shell portion passes between the rear ends of the plurality of skewed rolls.

Production method of seamless steel pipe

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 method for producing a seamless metal pipe includes the steps of: preparing a billet having a diameter (B); heating the billet; forming, in a center part of a rear end of the heated billet, a hole including four grooves extending in an axial direction of the billet, the grooves each having a groove width (D) satisfying Formula (1), a groove height (H) satisfying Formula (2), and a groove depth (L) satisfying Formula (3); and subjecting the billet provided with the hole to piercing-rolling from a front end thereof by means of a piercing machine. By this means, the generation of burrs and internal defects at the rear end of a hollow shell after piercing-rolling can be suppressed.0.12&#x2264;&#x2264;0.25&#x2003;&#x2003;(1)0.10&#x2264;&#x2264;0.20&#x2003;&#x2003;(2)0.05&#x2264;1/&#x2264;0.10&#x2003;&#x2003;(3)

Method for producing seamless metal pipe

There is provided a piercing apparatus in which the occurrence of an inner surface flaw in a hollow shell is suppressed. A piercing apparatus () according to an embodiment of the present invention is the piercing apparatus () which pierces a billet (). The piercing apparatus () has a plug (). The plug () has a through hole (). The through hole () extends along the central axis, and allows the central portion of the billet () being pierced to pass therethrough.

Piercing apparatus, plug used for piercing apparatus, and method for producing seamless steel pipe

An inner surface regulation tool includes a mandrel, a plug which is detachably connected to the mandrel, and a connection member which connects the plug and the mandrel by a magnetic force. One of the plug and the mandrel includes a column-shaped portion which extends in an axial direction of the one, and the other of the plug and the mandrel includes a joining hole which extends in an axial direction of the other and into which the column-shaped portion is inserted. In addition, the connection member is a permanent magnet which is attached to at least one of the column-shaped portion and the joining hole.

Inner surface regulation tool, plug, mandrel, hot rolling mill, press piercing machine, and drawing machine

A method of producing a seamless metal pipe, which can suppress the occurrence of lamination defects, is provided. A method of producing a seamless metal pipe according to an embodiment of the present invention includes the steps of: heating a high alloy containing, by mass %, Cr: 20 to 30% and Ni: more than 22% and not more than 60% in a first heating furnace (S2); piercing-rolling the high alloy heated in the first heating furnace with a first piercing machine to produce a hollow shell (S3); heating the hollow shell in a second heating furnace (S4); and elongation-rolling the hollow shell heated in the second heating furnace with the first piercing machine or a second piercing machine which is different from the first piercing machine (S5).

Method of producing seamless metal pipe

A plug for hot pipe making includes a plurality of plug pieces which is attachable to and detachable from one another, and a connection member which connects the plug pieces by a magnetic force. One of the plug pieces connected to each other includes a column-shaped portion which extends in an axis direction of the plug for hot pipe making, and the other includes a joining hole which extends in the axis direction of the plug for hot pipe making and into which the column-shaped portion is inserted. The connection member is a permanent magnet which is attached to at least one of the column-shaped portion and the joining hole.

Plug for hot pipe making

A method of producing a seamless metal pipe, which can suppress the occurrence of inner surface flaws, is provided. A method of producing a seamless metal pipe according to an embodiment of the present invention includes the steps of: heating a high alloy billet BL containing, by mass %, Cr: 20 to 30% and Ni: more than 22% and not more than 60% in a heating furnace F(S); piercing-rolling the high alloy billet BL heated in the heating furnace Fwith a piercing machine Pto produce a hollow shell (S); cooling the hollow shell and then reheating the hollow shell in the heating furnace F(S); and elongation-rolling the heated hollow shell with the piercing machine P(S).

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Tokyo, Japan

Kouji Yamane