JPH07118687A - Lubricant for high-temperature processing for stainless steel or alloy steel - Google Patents

Abstract

PURPOSE:To obtain the lubricant capable of reducing a coefficient of friction between a mandrel bar and a material to be rolled, preventing occurrence of a flaw, by comprising graphite, a water dispersion type or water-soluble polymer compound and iron oxide as essential components, adding glass-based powder to these components, and dispersing the mixture into water. CONSTITUTION:20-80wt.% of scaly natural graphite ground into 10.0mum average particle diameter, 2-40wt.% of a water dispersion type or water-soluble polymer compound such as vinyl acetate polymer and 1-20wt.% of one or more iron oxides which are ferrous oxide or triiron tetroxide and have <=10mum particle diameters are mixed as essential components, blended with 1-20wt.% of glass- based powder which has <=1,00 deg.C temperature to make 1,000P of viscosity and <=30mum particle diameters. 5-80wt.% of the blend is dispersed into water to give the lubricant for high-temperature processing for stainless steel or alloy steel reducing a coefficient of friction between a mandrel bar and a material to be rolled and preventing occurrence of a flaw caused by fusing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant for high-temperature processing of stainless steel or alloy steel, and in particular to a stainless steel or alloy steel capable of reducing the coefficient of friction between a tool and a raw material when manufacturing a seamless steel pipe by a mandrel mill. The present invention relates to a lubricant composition for high temperature processing.

[0002]

2. Description of the Related Art In the manufacture of seamless steel pipes by the Mannesmann mandrel mill method, a round steel piece heated in a rotary hearth type heating furnace is pierced by a piercing machine to form a hollow shell, and the shell is lubricated on the surface. The mandrel bar coated with the agent is inserted into a skewer, and the mandrel bar including 7 to 9 stands is rolled to a predetermined size in one pass. After rolling, the pipe with the mandrel bar pulled out is cut with a hot saw at the portion with poor pipe end shape, and the pipe reheated in the reheating furnace undergoes descaling by high-pressure water, and the outside diameter is reduced by the stretch reducer. And the product dimensions are subject to a slight reduction in wall thickness. Then, the pipe is cooled in a cooling bed, cut into a required length by a cold saw, and sent to a rectification line.

The lubricant used in the production of the seamless steel pipe by the mandrel mill system is 1100 to 1000 for the mandrel bar.
Since it is inserted into the shell at 1200 ° C., it is put in a state where it is easily seized, and thus acts as a protective film. The shape and thickness of the shell are affected by the friction between the mandrel bar and the material, as well as the number of roll rotations and the roll hole shape. When a lubricant having a small friction coefficient is used, uniform deformation is made in the circumferential and longitudinal directions, and a stable shell shape and wall thickness distribution are obtained. Furthermore, after rolling, the mandrel bar is pulled out from the shell by a burst slipper after rolling, but if the lubricity is poor, the material and the mandrel bar will be seized and the bar will not pull out, impairing workability.

In particular, the production of seamless steel pipe by the mandrel mill method of stainless steel or alloy steel has a higher rolling load and friction coefficient than the production of ordinary carbon steel seamless steel pipe, and sometimes a rolled material and a mandrel bar. Surface defects may occur due to the seizure of. When such surface defects occur, even if they are mild, stainless steel and alloy steel require a beautiful surface, which makes them unsuitable for some applications, and post-treatment such as polishing and reworking is not suitable. Will be needed. Further, if the surface flaw is deep, it becomes a defective product and is scraped, resulting in a large economic loss.

Generally, in hot working, the presence of iron oxides present on the tool surface and the material surface, in particular FeO and Fe ₃ O ₄ which are dense and have a relatively small hardness, does not have a favorable effect on the lubricity. Well known. It is difficult to manufacture a seamless steel pipe made of stainless steel or alloy steel unlike carbon steel because the material of the mandrel bar used at the time of pipe production is generally a Co-Mo system such as SKD-61 or a Cr-Mo system.
Since a -V heat-resistant low alloy is used, the iron oxide production rate is low, and the stainless steel and alloy steels used as the processing materials also have extremely low iron oxide production rates or almost none. Therefore, hot working of stainless steel and alloy steel is
It is more harsh than carbon steel.

There are three types of lubricants that reduce the friction coefficient between the mandrel bar and the material: oil-based, water-soluble and solid lubricants. Generally, a water-dispersed lubricant containing graphite and a resin as main components. Is used. Although these lubricants are sufficiently satisfactory for carbon steel pipes, they have problems for stainless steel and alloy steel pipes, and cannot prevent defects due to seizure between the mandrel bar and the material. Sometimes the pipe itself stops due to seizure.

As a lubricant for hot rolling of stainless steel,
A lubricant containing 5 to 50% by weight of iron oxide powder based on the weight of the composition, or a lubricant containing 5 to 50% by weight of iron oxide powder and 5 to 20% by weight of a polymer compound based on the weight of the composition ( JP-A-63-254195), a lubricant in which graphite powder is dispersed in a viscous aqueous solution in an amount of 1 to 30% by weight (JP-A-1-167396), and the like are proposed.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The lubricant disclosed in Japanese Patent No. 4195 is iron oxide powder 5 to 50.
% Or iron oxide powder 5 to 50% by weight and polymer compound 5 to 20% by weight added to mineral oil, which is suitable for rolling stainless steel sheet, but made by stainless steel mandrel mill method. It cannot be applied as is to tubes. Further, the lubricant disclosed in Japanese Patent Application Laid-Open No. 1-167396 is a water-dispersed lubricant containing graphite and a resin as main components, and there is a problem in producing stainless steel or alloy steel. It is not possible to prevent defects due to seizure with the material.

It is an object of the present invention to reduce the friction coefficient between a mandrel bar and a material to be rolled in a pipe manufacturing of a stainless steel or an alloy steel by a mandrel mill system and prevent the occurrence of inner surface flaws due to fusion. It is to provide a lubricant for high temperature processing of steel.

[0010]

In order to achieve the above object, the inventors of the present invention have made a lubricant in which a material to be rolled and a mandrel bar have the same insufficient lubricity in a pipe made by a mandrel mill system of stainless steel or alloy steel. The study was conducted by focusing on the fact that carbon steel does not pose a problem even if used. As a result, iron oxide, which is easily generated in hot working of carbon steel, is difficult to generate in stainless steel and alloy steel. It has been clarified that the lack of lubricity between the material to be rolled and the mandrel bar in the hot working of stainless steel or alloy steel can be eliminated by adding the system powder, and the present invention has been reached.

That is, according to the present invention, 20 to 80% by weight of graphite, 2 to 40% by weight of a water-dispersible or water-soluble polymer compound and 1 to 20% by weight of iron oxide are essential components, and 1% of glass-based powder is added thereto. It is a lubricant for high temperature processing of stainless steel or alloy steel which is mixed in an amount of -20% by weight and dispersed in water in an amount of 5-80% by weight.

Further, as the iron oxide in the present invention,
Ferrous oxide or triiron tetroxide having a particle size of 10 μm or less is preferably used as a mixture of one or two kinds.
Furthermore, it is preferable that the glass-based powder has a viscosity of 1000 P and a temperature of 1000 ° C. or less and a particle diameter of 30 μm or less.

[0013]

In the present invention, 20 to 80% by weight of graphite,
Water-dispersible or water-soluble polymer compound 2 to 40% by weight and iron oxide 1 to 20% by weight as essential components, and 1 to 20% by weight of glass-based powder mixed therein to 5 to 80% by weight in water.
By dispersing, it is possible to solve the lack of lubricity between the material to be rolled and the mandrel bar in the hot working of stainless steel or alloy steel.

The graphite used in the present invention is a main constituent of lubrication in hot working and may be any of natural graphite, quiche graphite, artificial graphite and the like. From the viewpoint of lubricity, natural graphite and quiche are used. Scaled graphite belonging to graphite is preferred. The purity of graphite is preferably at least 80% or more, and the average particle size is preferably 100 μm or less. If the purity of graphite is less than 80%, the lubricity is impeded by impurities present as impurities, and if the average particle size exceeds 100 μm, the dispersibility deteriorates and the supply to the lubrication surface is poor. It causes difficulty in storage and stability.

The water-dispersible or water-soluble polymer compound used in the present invention brings about dispersion stability when graphite and other solid components are mixed with water, and at the same time, provides a lubricant as a pipe during supply. It also provides uniform spreadability on the high temperature mandrel bar and plays an auxiliary role of lubricity during lubrication. Examples of the polymer compound include polymers and copolymers of vinyl esters such as vinyl acetate and ethylene vinyl acetate, polymers and copolymers of acrylic acid or its esters, and polymers of olefins such as ethylene and butadiene. And copolymers, polymers and copolymers of unsaturated dicarboxylic acid esters, methylcellulose and carboxymethylcellulose, and polysaccharides such as polysaccharides and alginates.

In carbon steel, iron oxide already formed on the surface of the material exhibits a subtle lubricating effect and facilitates pipe manufacturing, but in stainless steel and alloy steel, the generation of iron oxide from the material itself is expected. Can not. The iron oxide used in the present invention plays an auxiliary role of lubricity at the time of lubrication at around 1000 ° C. The average particle size of the iron oxide used in the present invention is 10 μm or less, preferably 5 μm or less, most preferably 1 μm or less, and the finer the better.
As the type of iron oxide, ferrous oxide (FeO) and triiron tetraoxide (Fe ₃ O ₄ ) are preferable in terms of hardness, but it is not necessary to be one type, and a mixture of these may be used. There is no problem even if diiron trioxide (Fe ₂ O ₃ ) is mixed, but the mixed amount is preferably 30% or less, and as a result, ferrous oxide, triiron tetroxide alone or in a mixture. Therefore, if impurities other than ferrous oxide or triiron tetroxide exceed 30%, lubricity deteriorates. Therefore, it is necessary to suppress impurities other than ferrous oxide or triiron tetroxide to 30% or less. Is.

The glass-based powder used in the present invention, together with graphite and iron oxide, plays an auxiliary role of lubricity at around 1000 ° C., and the effect is that graphite and iron oxide control solid lubrication. On the other hand, the glass itself enhances the effect of fluid lubrication while melting and holding the graphite and iron oxide appropriately. Therefore, the glass-based powder has a viscosity of 1
The temperature of 000P is 1000 ° C. or lower, preferably 800 to
A material having a viscosity of 1000 P and a temperature of 1000 ° C. or higher at 400 ° C. is not preferable because it exhibits an abrasion effect rather than a lubricating effect.
The particle size of the glass-based powder is preferably 30 μm or less, preferably 10 μm or less, because it dissolves faster under appropriate temperature conditions and for dispersion stability. As the type, oxide glass is preferable from the viewpoint of solubility. .

In the composition ratio of each component of the lubricant of the present invention, graphite is 20 to 80% by weight, more preferably 30 to 60% by weight. If the graphite in the lubricant is less than 20% by weight, the lubricating effect will be reduced, and if it exceeds 80% by weight, the mixing ratio of other additives will be small and the lubricating effect will be reduced. The composition ratio of the water-dispersible or water-soluble polymer compound is 2 to 40% by weight, and more preferably 10 to
It is 30% by weight. If the polymer compound in the lubricant is less than 2% by weight, the stability of graphite and other solid lubricants during storage,
There is a problem in the feedability to the lubrication surface and the uniform adherence to the mandrel bar, and when it exceeds 40% by weight, the mixing ratio of other components becomes small, which causes a problem in lubricity. The composition ratio of iron oxide is 1 to 20% by weight, and more preferably 3
10 to 10% by weight. If the iron oxide content in the lubricant is less than 1% by weight, the lubricating effect cannot be expected, and if it exceeds 20% by weight, the friction coefficient becomes high, which is not preferable. The composition ratio of the glass-based powder is 1 to 20% by weight, and more preferably 3 to
It is 10% by weight. If the amount of the glass-based powder in the lubricant is less than 1% by weight, the lubricating effect cannot be expected, and if it exceeds 20% by weight, the fluidity becomes too high and the lubricity becomes a problem. The composition ratio of the lubricant having the above composition with water is 5 to 80.
%, More preferably 10 to 50% by weight. If the dispersion ratio of the lubricant is less than 5% by weight, a proper lubricating film cannot be formed on the mandrel bar, and 80% by weight
When it exceeds, the viscosity becomes too high, which causes a problem in supplyability to the lubrication surface.

The dispersion of the composition of the present invention in water is carried out by a conventional dispersant for maintaining storage stability, for example, various surface active agents such as sulfonate, carboxylate, sorbitan alkylate, polyoxyalkylene alkylphenol ether and the like. A dispersing agent or a defoaming agent, such as dimethylphenol silicon, may be added as necessary to improve the dispersion effect.

[0020]

[Examples] Scaled natural graphite crushed to an average particle size of 10.0 μm, vinyl acetate polymer, and Fe having an average particle size of 1.0 μm
O, Fe ₃ O ₄ with an average particle size of 2.5 μm, average particle size of 21.0
μm glass powder A (SiO ₂ : 33%, B ₂ O ₃ : 37)
%, Al ₂ O ₃ : 2%, Na ₂ O: 16%, CaO: 7
%, MgO: 5%, viscosity 1000P, temperature 800
Glass powder B (Si) having an average particle size of 12.5 μm
O ₂ : 57%, B ₂ O ₃ : 19%, Na ₂ O: 22%, Ca
O: 1%, MgO: 1%, viscosity 1000P, temperature 9
50 ° C.), a dispersant was mixed in the composition ratio shown in Table 1, and each lubricant of Examples 1 to 6 dispersed in water, and an average particle size of 9.5 μm.
natural graphite pulverized to m, vinyl acetate polymer, Fe ₂ O _{3 having} an average particle diameter of 4.0 μm, glass powder C (SiO ₂ : 54%, B ₂ O ₃ : 8%) having an average particle diameter of 8.5 μm. , Al
₂ O ₃ : 14%, CaO: 21%, MgO: 2%, temperature of 1200P at a viscosity of 1000P) or average particle size 26.
3 μm glass powder D (SiO ₂ : 72%, Al ₂ O ₃ :
1%, Na ₂ O: 16%, CaO: 7%, MgO: 4
%, The viscosity is 1000 P, the temperature is 1200 ° C.), and the dispersant is mixed in the composition ratio shown in Table 2 and dispersed in water.
Each lubricant of No. 5 was applied to the surface of the mandrel bar having a predetermined size at room temperature using a brush, and dried at room temperature to obtain a film thickness of about 10
In the manufacturing process of the seamless steel pipe by the Mannesmann mandrel mill method using 2 mandrel bars of 0 μm each, stainless steel (SUS 304) was pierced and rolled, the outer diameter was 181.0 mm, the wall thickness was 16.0 mm, and the length was 16.0 mm. 700
A 0 mm 1100 ° C. blank tube was rolled to a diameter of 151.0 mm, a wall thickness of 5.0 mm and a length of 25300 mm by a mandrel mill consisting of 7 stands. Then, the friction coefficient of each lubricant during mandrel mill rolling and the presence or absence of flaws after rolling were visually evaluated. The results are shown in Table 3. The coefficient of friction is determined by the coefficient of friction = F / ΣPi by reading the ratio with the thrust force F acting on the mandrel bar in a steady state (Total load ΣPi) in which loads are applied to all stands during the mandrel mill rolling, and the coefficient of friction = F / ΣPi. It was In addition, the evaluation of the presence or absence of flaws is as follows: ⊚: No flaw was found, ○: Slight flaw was found, Δ:
Defects partially occurred, x: a large amount of defects occurred.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

As shown in Table 3, Examples 1 to 1 of the present invention
When a mandrel bar coated with the lubricant of 6 is used,
In all cases, there were no or only slight defects after the mandrel mill rolling, but when the mandrel bars coated with the lubricants of Comparative Examples 1 to 5 were used, all the defects after the mandrel mill rolling were observed. It occurred partially or in large amounts, and particularly when the mandrel bar coated with the lubricant of Comparative Example 4 was used, rolling was not possible.

[0025]

As described above, the lubricant of the present invention enables the production of seamless steel pipes from stainless steel and alloy steel by the mandrel mill method, which has been conventionally difficult, and requires new equipment. It has a great effect economically.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C10M 107: 26 125: 10 125: 28) C10N 30:06 30:08 40:20 (72) Invention Kazuo Tanaka 1-11-16 Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture Palace Chemical Co., Ltd.

Claims (3)

[Claims] 1. 20 to 80% by weight of graphite, 2 to 40% by weight of a water-dispersible or water-soluble polymer compound, and 1 to 1 of iron oxide.
20% by weight as an essential component, to which glass powder is added
A lubricant for high temperature processing of stainless steel or alloy steel, which is prepared by mixing 20% by weight and dispersing it in water by 5 to 80% by weight. 2. Lubrication for high temperature processing of stainless steel or alloy steel according to claim 1, wherein the iron oxide is ferrous oxide or triiron tetroxide, and one or two of those having a particle size of 10 μm or less are mixed. Agent. 3. The lubricant for high temperature processing of stainless steel or alloy steel according to claim 1, wherein the temperature at which the viscosity of the glass-based powder becomes 1000 P is 1000 ° C. or less, and the particle size is 30 μm or less.