Sumitomo Metal Industries, Inc.

Nippon Steel Sumitomo Metal Corporation

Sumio Iida

Yasuyoshi Hidaka

Shizuo Mori

Kenichi Sasaki

Kouji Nakaike

Masami Imamura

Satoshi Matsumoto

Kazuhiro Shimoda

Kazuo Tanaka

Toshihide Ono

Hirofumi Hori

Kenichi Saito

Tetsuya Nakanishi

Kenji Takeuchi

Yuuji Tanaka

Tomio Yamakawa

Hiroshi Nogami

Hirokazu Okada

Kazutaka Asabe

Yasuto Higashida

Toshiro Anraku

Takayuki Fukushima

Naoya Hirase

Mitsuru Yoshizawa

Shuichi Akiyama

Atsushi Ito

Yosuke Tatebayashi

Akira Motoki

Koji Nakaike

Hiroki Kusuda

Masami Sakiyama

A powder lubricant composition according to the present invention includes 65 parts by mass to 95 parts by mass of sodium borate, and 5 parts by mass to 35 parts by mass of cryolite. A method for manufacturing a seamless steel pipe according to the present invention includes adhering the above-described powder lubricant composition to a pipe inner surface of a work piece which is piercing rolled to have a tubular shape, and elongation rolling on the work piece after the adhering of the powder lubricant composition.

Powder lubricant composition and method for manufacturing seamless steel pipe

The present invention provide a two-component anti-seizure agent for hot metal working process comprising the first aqueous solution and the second aqueous solution, wherein the first aqueous solution contains 10&#x2dc;30 mass % of sodium silicate equivalent to anhydride to 100 mass % of total mass of the first aqueous solution, and the second aqueous solution contains at least one kind selected from a group consisting of: an organic acid and water-soluble amine salts thereof, an inorganic acid and water-soluble amine salts thereof, a water-soluble amine, a water-soluble alcohol, and a water-soluble metal chloride. When the two-component anti-seizure agent is applied onto disk-roll type guide shoes, it can be provided and maintained on the circumferential surface of the disk-roll type guide shoes without washed away by rolls' cooling water. Thereby, the anti-seizure agent does not adhere to rolls and the rolls and a pipe material do not cause slippage each other. Thus, it is capable to carry out piercing-rolling of the pipe material.

Two-component anti-seizure agent for hot metal working process, and method of manufacturing seamless pipe using thereof

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

A process for producing seamless pipes which comprises conducting a piercing rolling step, a elongating rolling step using a mandrel bar, and a sizing rolling step and subsequently conducting a product heat treatment. In the process, when the carbon-equivalent weight, namely the sum of the weight of graphite in the lubricant and the carbon content in the organic binder, per unit area of the lubricant adhering to the mandrel bar surface in the above-mentioned step of elongating rolling is expressed by C (g/m) or the maximum extent of carburization in the inner surface of the pipe to be heat-treated but prior to the heat treatment is expressed by &#x394;C (% by mass), the heating temperature for the pipe to be heat-treated is expressed by T (&#xb0; C.), and the time during which a decarburizing gas is blown into the inside of the pipe to be heat-treated is expressed by tor t(seconds), and further, the blowing time calculated taking into account the wall thickness reduction in the step of cold working is expressed by tor t(seconds), a predetermined relation is satisfied and the actual decarburizing gas blowing time in the heat treatment is longer than the time t, t, tor t(seconds), whereby seamless stainless steel pipes reduced in carburized layer formation can be produced even when the carbon adhesion to the pipe inner surface is caused in, for example, mandrel mill rolling.

Process for producing seamless stainless steel pipe

The present invention provides a lubricant composition for hot forming which makes it possible to provide lubricity at 80&#xb0; C. or more without being peeled or washed by the roll cooling water, and which is easily washed under 40&#xb0; C. without having water resistance. The lubricant composition for hot forming of the present invention comprises: a solid lubricant from 10 to 40% by mass; water-dispersible synthetic resin from 5 to 20% by mass; inorganic acid amine salt from 0.5 to 5% by mass; and water from 45 to 80% by mass.

Lubricant composition for hot forming

The present invention provides a lubricant for hot metal working which is capable of inhibiting generation of white scale, attributed to the lubricant, on the surface of a workpiece material and is capable of improving lubricity to obtain favorable appearance of the finished product. The lubricant for hot metal working comprises a silicate compound used for adding to a lubricant composition mainly containing sodium borate.

Lubricant for hot metal working and powder lubricant composition for hot metal working

A method for surface treating a mandrel bar used for hot rolling of high-alloy seamless steel pipe is provided. The method includes heat treating the mandrel bar to develop a scale, and after heat treatment, rolling ordinary steel comprising 8% or less of chromium for at least 50 passes. This achieves a mandrel bar for rolling high-alloy steel possessing both durability and superior resistance to seizure.

Mandrel bar for high-alloy rolling, method for surface treating a mandrel bar, method for producing mandrel bar, and method for operating seamless pipe mill

A process for stainless-steel pipe production which comprises piercing rolling a raw material stainless steel containing, by mass, Cr: 10-30%, to give a hollow shell, elongating rolling the hollow shell using a mandrel bar, together with a graphite-free lubricant, to give a finishing rolling blank pipe and heating the blank pipe in a reheating furnace and subjecting the same to finishing rolling by sizing rolling to produce a hot-finished pipe, and then subjecting this pipe as a mother pipe to cold working to produce a stainless-steel pipe. In the reheating furnace, the finishing rolling blank pipe is heated to 1000&#xb0; C. or more and subjected to heating in which an oxidizing gas is blown into the pipe inside, whereby a stainless-steel pipe which is inhibited from forming a carburized layer in the pipe inner surface can be produced. When the finishing rolling by sizing rolling to give a cold working mother pipe is carried out by stretch reducer rolling at 860-1050&#xb0; C., an annealing heat treatment of the mother pipe for cold working can be omitted. Thus, a stainless-steel pipe having excellent surface quality can be efficiently produced.

Process for producing stainless steel pipe

There is provided a lubricant for hot plastic working, which contains 20 to 40 mass % of iron oxide and 10 to 30 mass % of sodium silicate, wherein impurities are 3 mass % or less, and the lubricant contains 40 to 60 mass % of water. By virtue of combined action of these components, the lubricant exhibits excellent lubricity and suppliability and does not adversely affect the corrosion resistance of product. The lubricant is suitably used for lubricating a guide shoe in piercing-rolling, for example, a high-Cr steel and achieves a great effect of preventing a seizure flaw from occurring on the outer surface of product by being applied directly to the outer surface of a workpiece just before piercing rolling, preferably, within one second before starting piercing rolling.

Lubricant for hot working and method for producing seamless steel pipe

With a powdered lubricant composition by the invention, in addition to the blending of one of anhydrous, pentahydrate or decahydrate salt in sodium borate and one of sodium or calcium salt of fat acid, mixing calcium or lithium carbonate as an auxiliary lubricant can prevent sodium borate (NaBO), solidified as amorphous after a tube-making process, from moisture absorbance, drying and crystallization to thereby suppress the formation of NaBO.5HO on inside surfaces of finished-product tubes, thus enabling to circumvent occurrence of the white scales. Concurrently, they provide good diffusivity toward the working surface of workpiece, thus enabling to prolong a life of the mandrel bar and to widely be adopted as the most suitable powdered lubricant for manufacturing seamless tubes by Mandrel Mill rolling.

Powdered lubricant composition for hot working and method for manufacturing seamless tubes

In applying a non-graphite-based lubricant composed of, by mass %, 10 to 70% of an oxide-based lamellar compound and 30 to 90% of boric acid onto a mandrel bar, the lubricant film thickness is set from a predetermined master curve for the lubricant film thickness corresponding to an amount of mica. This stably produces a seamless steel pipe of high quality, while preventing seizing marks and internal flaws.

Method for applying lubricant onto mandrel bar, method for controlling thickness of lubricant film on mandrel bar, and method for manufacturing seamless steel pipe

The present invention provides an application method of a Cr-plated mandrel bar repeatedly used in mandrel mill rolling by the Mannesmann tube making process. A regeneration treatment is performed to use the mandrel bar again as a tool of like size when an opening width H of a surface defect generated on the mandrel bar by its use in the mandrel mill rolling is not less than 1.5 mm and a depth of the surface defect is in the range of 0.3 mm to less than 2.0 mm. Alternatively, a downsizing treatment is performed to use the mandrel bar again as a tool of a smaller size when the depth of the surface defect generated on the mandrel bar by its use in the mandrel mill rolling is not less than 2.0 mm. The regeneration treatment or downsizing treatment is performed according to conditions or a configuration of the surface defect to achieve repeated application to the mandrel mill rolling, allowing life-extension of the mandrel bar and improvement of cost performance thereof.

Application method of Cr-plated mandrel bar for hot rolling

A seamless tube is manufactured while effectively suppressing the occurrence of carburization in the seamless tube without interfering with operations. A seamless tube is manufactured by a step of washing at least a portion of a conveyor installed in a conveying step of a mandrel bar B which is situated from a lubricant applying deviceto the entrance of a mandrel mill, a step of washing, on the upstream side of the lubricant applying device, a mandrel bar B which was used for elongation rolling, and a step of applying a non-graphite-based lubricant to the mandrel bar B with the lubricant applying device, wherein the conveyor and the mandrel bar B are each washed such that the amount of graphite C2 (g/m) adhering to the surface of the mandrel bar B before it is provided to elongation rolling and the amount of carbon C1 (g/m) contained in the organic binder of the applied lubricant satisfy Equation 1: 0.08&#xd7;C1+0.05&#xd7;C2&#x2266;3 and Equation 2: 3&#x2266;C1+C2&#x2266;50.

Manufacturing method and cleaning equipment for seamless tube

A process for producing a seamless steel pipe, in which the occurrence of inner surface flaws in the pipe can be reduced through the lowering of the friction coefficient during the elongation rolling by means of a mandrel mill is provided. The reduction of inner surface flaws is accomplished through the use of a lubricant composed mainly of either or both of graphite and mica coated to the surface of a mandrel bar, and another lubricant composed mainly of an alkali metal borate that is applied onto the inner surface of the hollow stock pipe. The temperature of the pipe prior to receiving the lubricant, during lubricant application, and prior to elongation rolling is controlled. The time between descaling or piercing and lubricant application and between lubricant application and elongation rolling is also controlled.

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Osaka, Japan

Sumio Iida