JPH08143881A - Lubricant composition for hot rolling of steel material - Google Patents

Abstract

PURPOSE: To obtain a lubricant composition for hot rolling of steel material, capable of producing and keeping stable black film (oxidized film) onto the surface of a hot rolling roll by adding a prescribed amount of highly basic calcium phenate to a base oil. CONSTITUTION: This lubricant composition for hot rolling of steel is obtained by adding (B) 30-90wt.% of highly basic calcium phenate having >=100mgKOH base value to (A) a base oil which is a mixture of one or two more kinds of oils among a mineral oil such as spindle oil, a synthetic oil such as silicone oil, oil and fat such as tallow and a synthetic ester. Dynamic viscosity of the lubricant composition is preferably <=1000mm<2> /s at 40 deg.C.

Description

Detailed Description of the Invention

[0001]

The present invention relates to hot rolling of steel,
The present invention relates to a lubricant composition for hot rolling developed for the purpose of stably forming an oxide film (black scale) on the surface of a hot rolling roll.

2. Description of the Related Art Conventionally, the rolls used in the hot rolling process of steel products include high chromium cast iron, adamite cast iron,
Rolls made of nickel grain cast iron have been mainly used. In recent years, these rolls are being replaced by high carbon high alloy cast iron rolls (Japanese Patent Laid-Open No. 58-87249) which have further improved wear resistance and surface roughening resistance.

When these rolls are used in a hot rolling process, a film called iron oxide mainly composed of iron oxide is formed on the surface of the rolls. It is said that this black skin is composed of a film in which the rolling roll itself is oxidized and a film in which the surface scale (oxide film) of the rolled material is transferred. In particular, the scale transfer from the surface of the rolled material has a great influence on the growth of black skin (increase in film thickness). The black skin significantly improves the wear resistance of the roll, acts as an insulating material, moderates the temperature rise of the rolling roll, prevents seizure due to welding between the rolling roll and the rolling material, and reduces the quality of the rolling material. It has the property of preventing. As a method for forming and maintaining an oxide film including the black skin, one of the compounds such as alkali metal and alkaline earth metal disclosed in JP-A-53-100130 is used.
A method of supplying more than one kind to a steel plate surface in a state of being suspended in rolling lubricating oil, and JP-A-5-306397 and JP-A-6-
A method of incorporating a highly basic calcium sulfonate disclosed in No. 200282 into a rolling lubricant is known.

However, while the black skin formed on the surface of the roll has the above-mentioned effect, a part of the black skin peels off during rolling, resulting in a step between the black skin remaining portion and the black skin peeling portion, which results in rolling. There is a problem that the surface quality of the product is remarkably deteriorated by being transferred to the material, and the rolled material is seized at the peeled place, so that not only the surface quality of the product is deteriorated but also the roll life is shortened. In particular, for high carbon high alloy cast iron rolls that have been applied in recent years, the wear resistance of the roll material is very high, and it is possible to obtain wear resistance higher than that of conventional rolls without relying on black skin, Peeling of the skin hinders the extension of life. Generally, it is said that the peeling of the black skin is more likely to occur as the film thickness becomes thicker, and in order to prevent the peeling of the black skin, the film thickness of the black skin must be made thin to some extent.
On the other hand, if the black skin formation is suppressed too much, the roll material is exposed and becomes a starting point of image sticking, and it is desirable that the black skin of the roll is stably formed and maintained while maintaining a certain film thickness. From this point of view, looking at the conventional technology, Japanese Patent Laid-Open No.
The techniques disclosed in JP-A-306397 and JP-A-6-200282 aim to suppress the formation of black skin, and it is difficult to form and maintain a stable black skin having sufficient seizure resistance. .

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to stably produce an extremely thin black skin on the roll surface in order to prevent the black skin from peeling and effectively prevent the occurrence of image sticking. A hot rolling lubricant is provided.

[0005]

The present invention provides a base oil comprising 30
A 90% by weight, preferably 40-80% by weight, of a highly basic calcium phenate is a lubricant composition for hot rolling of steel products. In order to solve the above problems, the present inventors supply oxygen to the roll surface to generate an extremely thin black skin, while suppressing the transfer of scale from a rolled material that greatly affects the increase in the film thickness of the black skin. I thought the means was desirable. That is, the highly basic calcium phenate is added to the surface of the roll used for hot rolling in an amount of 30 to 90.
By supplying the lubricant containing the weight%, the surface scale of the rolled material is modified in the roll bite to suppress the transfer to the roll,
In addition, by supplying oxygen to the roll surface to slightly accelerate the oxidation of the roll, a thin and stable black scale is produced and maintained.

Base oils usable in the present invention include medium and heavy mineral oils such as spindle oil, machine oil, dynamo oil, motor oil, cylinder oil and bright stock; beef tallow, lard, whale oil, palm oil, palm. Oils, rapeseed oil, rice bran oil, soybean oil and other animal and vegetable oils and fats; esters of fatty acids having 8 to 22 carbon atoms and monohydric and polyhydric alcohols,
Examples include synthetic oils such as α-olefins, polybutene, silicone oils and fluorine oils; and mixed oils thereof. In the overbased calcium phenate of the present invention, CaCO ₃
Is at least 100 mgKOH / g, preferably 150 mgKOH / g or more in terms of base number. Base number of highly basic calcium phenate is 1
When it is less than 00 mgKOH / g, the solid solution formation with FeO becomes insufficient, which is not preferable.

The lubricant of the present invention has an intrinsic kinematic viscosity of 40 ° C.
Is preferably 1000 mm ² / s or less, more preferably 5
It is not more than 00 mm ² / s. The reason for this is that the pump that is generally used for supplying lubricant is a gear system or a plunger system, and if the viscosity of the lubricant is too high, lubrication becomes impossible due to poor suction or increased pressure loss. This is because the lubricant cannot be stably supplied to the roll. The present invention utilizes a highly basic calcium phenate unlike JP-A-53-100130 in that it suppresses the phase transition of the scale to prevent the growth of black skin and that the obtained lubricant is a homogeneous system. In this respect, JP-A-5-3
The technology is completely different from 06397 and Japanese Patent Laid-Open No. 6-200282. The lubricant of the present invention includes extreme pressure agents such as sulfur compounds, phosphorus compounds, chlorine compounds and organometallic compounds; alcohols such as lauryl alcohol, stearyl alcohol and oleyl alcohol; polyisobutylene and acrylic acid copolymers. It is also possible to improve the lubricity and adhesiveness by adding such polymers.

[0008]

The structure and operation of the present invention will be described. The lubricant of the present invention is obtained by adding a highly basic calcium phenate to a base oil. The overbased calcium phenate used in the present invention is a known substance, for example, Adibi
ADX400 etc. of s company can be applied. Overbased calcium phenate is an alkylphenol, sulfur, base,
It is synthesized by the reaction of ethylene glycol (or other alcohol) and stabilization treatment with carbon dioxide. The details of the mechanism of action of the overbased calcium phenate are unknown, but the present inventors consider the following two actions.

The first effect is the production of black skin by phenate. That is, when supplying the overbased calcium phenate to roll, to decompose a portion of the calcium phenate phenates (R-O ^-; R is alkyl phenol) adsorbed next to the roll surface, further alkylphenol (R
-) Is desorbed and only oxygen remains on the roll surface. This remaining oxygen has the effect of increasing the production of iron oxide,
As a result, a thin black skin is formed on the roll surface. The second effect is a scale modifying effect on the surface of the rolled material by CaCO ₃ in the overbased calcium phenate. That is, Ca
CO ₃ comes into contact with the hot rolled material in the roll bite and CaO
And decomposes into CO ₂ . CO ₂ diffuses into the atmosphere, but Ca
O reacts with the scale (wustite (FeO) is the main component) on the surface of the rolled material and changes the surface scale to wustite in which CaO is solid-dissolved. This modified wustite has a eutectoid transformation region (300 to 570 ° C) as compared with ordinary wustite.
The change to magnetite (Fe ₃ O ₄ ) is small. Since this modified wustite does not easily transfer to the roll surface, the black skin is maintained in a thin state.

As an invention similar to the present invention, Japanese Patent Laid-Open No. 6-
No. 200282 discloses a technique of using CaCO ₃ in highly basic calcium sulfonate to prevent roughening of a high carbon high alloy cast iron roll. However, this object could not be achieved with highly basic calcium sulfonate. The present inventors consider the reason for this as follows. That is, the overbased calcium sulfonate and calcium is supplied to a roll sulfonium partially decomposed organic sulfonic acid sulfonate (R-SO ₃ ^-; R is as alkylbenzenes or alkylnaphthalenes) adsorbed next to the roll surface, further Alkylbenzene or alkylnaphthalene (R-) is eliminated and sulfonic acid (H-SO
₃ ^-) forming an inorganic film on the next roll surface. This film inhibits the supply of oxygen to the roll surface and thus prevents the roll itself from being oxidized and suppresses the formation of black skin.

In the present invention, the amount of the highly basic calcium phenate added is defined to be 30 to 90% by weight. The amount of less than 30% by weight is sufficient to oxidize the surface of the roll. This is because not enough CaCO ₃ is supplied to form a solid solution, and if the addition amount is 90% by weight or more, the respective effects are saturated. The method for producing the lubricant of the present invention may be a general method, and as an example, in a stainless steel heating / mixing pot having a stirrer,
It can be produced by adding the base oil and the highly basic calcium phenate in a predetermined weight ratio and stirring the mixture at 50 to 80 ° C. until uniform.

EFFECTS OF THE INVENTION By utilizing the lubricant composition of the present invention, a stable black scale can be generated and maintained on the surface of the hot rolling roll.

[0012]

【Example】

Examples 1 to 12 and Comparative Examples 1 to 4 Base oil and highly basic calcium phenate were blended in the weight ratios shown in Table 1, and uniformly in a stainless steel heating / mixing pot having a stirrer at 60 ° C. for 1 hour. Stir until
Lubricant compositions of Examples 1 to 12 and Comparative Examples 1 to 4 were prepared. The performances of these compositions were evaluated by the following test methods, and the obtained results are also shown in Table 1.

(Performance Test Method) Black Skin Formation Test Using a hot rolling wear tester (FIG. 1), the film thickness of the black skin formed on the surface of the test piece corresponding to the roll material was measured after the test. Was measured by slicing and observing the cross section. Table 1 shows the lubricant used in the black skin production test and the film thickness of the produced black skin. The test conditions are as follows. (Test conditions) Test piece: High carbon high alloy cast iron roll Counterpart piece: S45C Pressing load: 50 kgf Rotation speed: 500 rpm Slip rate: 5% Test piece surface temperature: 650 ° C Counterpart surface temperature: 900 ° C Rolling number: 2000 times Lubricant supply amount: 200 ml / min The lubricant was supplied by a water injection type supply device, and the mixing ratio of the lubricant and water was 99: water to 1: 1. 20 minutes per minute of mixed liquid of the lubricant and water
A 0 ml test piece was supplied.

E-12 Type Hot Lubricity Test The principle of the E-12 type hot lubricity tester is that the both ends are fixed, then induction heated test pieces are lubricated, and are sandwiched by rolls, slip lubricated, and various lubricants are used. The seizure resistance is evaluated to evaluate the lubricity. (a) Model: Two-stage sliding lubrication tester (b) Roll size: Diameter 124 mm x Length 80 mm (c) Roll material: High carbon high alloy cast iron roll (d) Roll speed: 100 rpm (e) Specimen material SS400 (length 20 mm x width 20 mm x length 580 mm) (f) Specimen temperature; 1000 ° C (g) Applied load; 500 to 4000 kgf (increase the load in units of 500 kgf) (h) Lubricant supply method; Air atomization (5 ml / min)

[0015]

[Table 1] Table 1 Example 1 2 3 4 5 6 7 8 Lubricant composition Weight% Highly basic calcium phenate (base number 150) 50 ------ 90 Highly basic calcium phenate (base Valency 250) -50------ Highly basic calcium phenate (base number 400)--30 50 70 50 50 Refined mineral oil (ISO VG46) 50 50 70 50 30-30 10 Trimethylol propane trioleate-- --- 50 20- Lard sulfide --------Tricresyl phosphate-------- Oleyl alcohol-------- Polyisobutylene-------- Highly basic Calcium sulfonate (base number 400) --------Kinematic viscosity of lubricant (40 ℃, mm ² / s) 150 200 200 250 900 270 260 950 Black skin thickness (μm) ^{* 1} 3 3 3 2 2 2 2 2 Lubricity test (withstand load) (× 10 ³ (kgf)) 3.5 4.0 3.0 4.0 4.0 4.0 4.0 4.0 * 1; When the surface of the test material after the test was analyzed by XRD, the black skin component Is Fe ₂ O ₃ , Fe ₃ O ₄ , FeCr ₂ O ₄ was the main constituent, and this result was similar to the actual black skin analysis result. * 2: Commercial hot rolling oil * 3: Water only

[0016]

[Table 2] Table 1 (continued) Actual Examples Comparative Examples 9 10 11 12 1 2 3 ^{* 2} 4 ^{* 3} Lubricant composition Weight% Highly basic calcium phenate (base number 150) ------- - an overbased calcium phenate (base number 250) - - - - - - - - overbased calcium phenate (base number 400) 50 50 50 50 20 - - - refined mineral oil (ISO VG46) 47 47 47 49 80 70 Torimechirorufu ° Ropa down trioleate - - - - - - - - sulfide lard 3 - - - - - - - tricresyl phosphate - 3 - - - - - - oleyl alcohol - - 3 - - - - - polyisobutylene - - - 1 ----Highly basic calcium sulfonate (base number 400) ----- 30-- Kinematic viscosity of lubricant (40 ℃, mm ² / s) 260 240 235 280 170 250 80 1 Black skin thickness (Μm) ^{* 1} 2 2 2 2 5 0.8 8 10 < Lubricity test (load bearing) (× 10 ³ (kgf)) 4.0 4.0 4.0 4.0 2.5 4.0 2.5 0.5> * 1; was analyzed by XRD, mill scale components Fe ₂ O _3, F ₃ O _4, FeCr ₂ O ₄ is mainly the result was similar to the black scale analysis of actual. * 2: Commercial hot rolling oil * 3: Water only

[Brief description of drawings]

FIG. 1 is a schematic view of a hot rolling wear tester used for a black skin production test.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10M 105: 04 105: 28 105: 32) C10N 10:04 20:00 A 20:02 20:06 Z 40:24 Z (72) Inventor Fuyasu Yamamoto 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Go Inoue 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel (72) Inventor Masataka Shirata 1-4-1 Tsujido Shindai, Fujisawa-shi, Kanagawa Kyodo Yushi Co., Ltd. (72) Inventor Tsutomu Morini 1-4-1 Tsujido Shindai, Fujisawa, Kanagawa Kyodo Yushi Co., Ltd. In-house (72) Inventor Hiroshi Kamayapo 1-4-1 Tsujido Kandai, Fujisawa-shi, Kanagawa Kyodo Yushi Co., Ltd. In-house (72) Inventor Hajime Ihara 1-4-1 Tsujido Kandai, Kanagawa Kyodo Yushi Co., Ltd. In 會社

Claims (4)

[Claims] 1. A lubricant composition for hot rolling of steel material, wherein the base oil contains 30 to 90% by weight of a highly basic calcium phenate. 2. The lubricant composition for hot rolling of steel according to claim 1, wherein the base oil is one kind or a mixture of two or more kinds of mineral oil, synthetic oil, fat and oil and synthetic ester. 3. The lubricant composition for hot rolling of steel according to claim 1, wherein the base number of the highly basic calcium phenate is 100 mgKOH / g or more. 4. The lubricant composition for hot rolling of steel according to claim 1, wherein the lubricant composition has a kinematic viscosity of 1000 mm ² / s or less at 40 ° C.