Sumitomo Metal Industries, Inc.

Nippon Steel Sumitomo Metal Corporation

Naoya Hirase

Kazuhiro Shimoda

Tomio Yamakawa

Yasuyoshi Hidaka

Hirokazu Okada

Tetsuya Nakanishi

Kenji Takeuchi

Yoshihiko Hayashi

Masanari Kimoto

Sumio Iida

Kazutaka Asabe

Yasuto Higashida

Kouji Nakaike

Shuichi Akiyama

Masaharu Nakamori

Takateru Inage

Jyun Nagakita

Fumihito Yoshikawa

Takayuki Aisaka

Yasuhiro Kouchi

Masaya Kimoto

Takanori Satou

A continuously cast slab with a rectangular cross section, and made of high alloy containing Cr of 20 to 30 mass %, Ni of 30 to 50 mass %, and at least one of Mo and W as Mo+0.5W of 1.5 mass % or more is subjected to blooming and billet-making to yield a round bar having a diameter of 150 to 400 mm as a starting material of the seamless tube. The blooming and billet-making process is performed under a condition satisfying a relation of 1.3&#x2266;H/D&#x2266;1.8 where a short side length of the cross section of the cast slab is defined as H (mm), and the diameter of the round bar is defined as D (mm). The round bar is pierced-rolled to make a hollow blank; the hollow blank tube is elongation-rolled, and then diameter-adjusting-rolled to make the seamless tube, thereby preventing end cracking during piercing-rolling, and increasing yield.

Production method of seamless tube using round bar made of high Cr-high Ni alloy

The present invention provides a lubricant composition for hot metal working which is capable of inhibiting generation of flaws on the surface of materials to be provided for hot metal working, and provides a method of hot metal working. The invention provides a lubricant composition for hot metal working comprising a plurality of glass frits respectively having different softening point from each other.

Lubricant composition for hot metal working and method of hot metal working using the same

The present invention is to provide a method for producing duplex stainless steel seamless pipe in which a duplex stainless steel billet can be inhibited from generating an oxide scale on the surface thereof during heating and the generation of outer surface flaw can also be prevented. The billet is heated in the a heating furnace for 1.5 hours or more and 4.0 hours or less at a heating temperature of 1250&#xb0; C. or more and 1320&#xb0; C. or less while regulating the average concentration of sulfur dioxide (SO) gas in the atmosphere within the furnace to 0.01 volume % or less.

Method for producing duplex stainless steel seamless pipe

A piercing mill includes a plurality of inclined rolls, a plug, a pusher, and an undriven guide roll. The pusher pushes a round billet from the rear end at least until the round billet advances for a prescribed distance after contacting the inclined rolls. The guide roll is between the inclined rolls and the pusher and includes a roll shaft and a roll surface, with the roll shaft arranged obliquely with respect to a pass line PL. The sectional shape of the roll surface is a concave arch shape. The round billet is rotated by the guide roll and the friction force generated when the round billet contacts the inclined rolls is reduced. Consequently, the wear of the inclined rolls can be restrained if the round billet is pierced and rolled while it is pushed in between the inclined rolls using the pusher.

Piercing mill

A piercing and rolling plug has a film composed of oxides such as FeOand FeO and Fe (metal) as being formed on the surface of the base metal by electric arc spraying using an iron wire whose main component is Fe and, owing to this film, a plug excellent in heat-shielding and seizure-preventing effects can be realized and the lifetime of the plug can be prolonged. Further, in regenerating this plug, a film can be re-formed via the steps of shot blasting of the as-used plug in piercing and rolling and electric arc spraying in that order; thus, it is possible to regenerate the plug at low cost and in a short period of time.

Piercing and rolling plug, method of regenerating such piercing and rolling plug, and equipment line for regenerating such piercing and rolling plug

A plug material having a prescribed shape is prepared, the prepared plug material is thermally treated in a heat treatment atmosphere that contains at least 1.0 vol. % oxygen at a heat treatment temperature of at least 950&#xb0; C. and less than 1050&#xb0; C. and thus a plug having an oxide scale layeron the surface is manufactured. According to the manufacturing method, pores PO that extend along the surface SF of the plug material are formed under outer scale layerin the oxide scale layer, which allows cracks to be more easily propagated in the outer scale layer. Therefore, the outer scale layeris more easily peeled off than the conventional one.

Method of manufacturing plug used to pierce and roll metal material, method of manufacturing metal pipe and plug used to pierce and roll metal material

a billet made of high Cr-high Ni alloy, which contains, by mass percent, 20 to 30% of Cr, 30 to 50% of Ni, and at least one element selected from Mo and W with a value 'Mo+0.5W' of 1.5% or more is heated under conditions satisfying the following formula (1), and then the billet is pierced and rolled using an inclined roll type piercing mill with a roll gouge circumferential speed of 2.28 m/sec or higher. This prevents melted rash on the inner surface and lengthens the plug life.&#x2266;1575&#x2212;4.45&#xd7;&#x2212;104.7&#xd7;{&#x2212;ln()}&#x2003;&#x2003;(1)

Method for manufacturing seamless steel pipe made of high Cr-high Ni alloy steel

By using a plating bath containing chromic acid: 100 to 250 g/L, sulfate radical: 3.0 to 5.5 g/L, and a catalyst: 100 to 200% (a weight ratio to the chromic acid content) for conducting electroplating, a Cr-plating film which has an increased film crack density is formed on the surface of a mandrel bar base metal, whereby peeling-off of the Cr-plating film can be suppressed in mandrel mill rolling for extending the service life of the mandrel bar.

Method for Cr-plating of mandrel bars, the mandrel bar, and process for producing seamless tubes using the method and the mandrel bar

Growing community of inventors

Osaka, Japan

Naoya Hirase