JPH03232922A - Scale modifier easy of peeling for ferrous slab - Google Patents

Abstract

PURPOSE:To improve the peeling characteristic of scale occurring at the time of heating in the hot and warm workings of a steel plate by incorporating the powder of specific metals, such as zinc, iron, and Al, easily forming iron oxide and multiple oxide in an oxidation stage or the powder of alloys thereof. CONSTITUTION:This modifier contains the powder of metals easily forming iron oxide and multiple oxide in an oxidation stage or the powder of alloys thereof and a powder mixture, and further, the above powdered metals are selected from zinc, iron, Al, lead, tin, Sb, Zr, Si, Bi, Sr, and Mn. This modifier is a coating agent which contains the above powdered metals and also contains a resin easily formed into a film with superior adhesive strength at the time of coating at ordinary temp. and easy of complete combustion at 120-500 deg.C. By using this modifier, at the same time as the steel plate is drawn out from a heating furnace and its temp. begins to fall, the scale is immediately peeled off from the whole surface or the greater part of the surface owing to the difference in shrinkage between iron and the scale part, and further, even if residual scale parts exist, they can be easily and completely peeled off by a slight impact.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a treatment agent for modifying scale generated during heating during thermal processing of a steel plate.

(Prior Art) Usually, when the thickness of a steel plate to be processed exceeds 3 mm, a hot (including warm) processing method is used. That is, hot working is mainly a continuous process such as rolling a steel ingot into a steel plate, and warm working is - heating a quantitatively cut or sheared steel plate piece at a temperature of 1000°C or less. It is used to produce special processing such as mirror plates.

During heat treatment in both hot and warm working processes, oxygen in the air reacts with the surface of the steel ingot or the steel plate piece, and oxide scale is generated, although there are differences in degree between the two.

If this scale is not removed as much as possible during the next hot-warm processing step, the remaining scale will cause processing flaws on the product surface, reducing yield. Furthermore, the composition and amount of the generated scale differs depending on the heat treatment conditions, but the removal conditions are not constant, and in some cases, the peeling operation may take a long time, making the operation extremely complicated.

In other words, the scale part that is difficult to peel off becomes the rule for peeling work.

For example, in the processing of mirror plates, the normal method is 900
It took about 2 hours or more, including shot blasting, to peel off the scale that had formed after heating to around 10°C.

In addition, pickling and blasting are typical methods for removing scale, but these methods are difficult to implement from the perspective of pollution control, such as problems with subsequent waste liquid treatment and dust and noise control caused by blasting. There was a condition.

Therefore, conventional countermeasures for reducing yield and descaling have been taken: firstly, by blocking oxygen in the air during heating to prevent the formation of scales, and secondly, conversely, the countermeasures are to prevent scale from peeling off at all. A method of actively generating scale was investigated.

[Problem to be solved] However, the former method includes heating in an inert atmosphere such as nitrogen or argon, or applying an antioxidant to block oxygen, but these methods are more cost-effective than iron scale. Not only is it difficult to completely eliminate scale generation using this coating method, but if the scale generation is small in quantity, removability will be affected due to the complicated scale composition. It tended to get worse.

As mentioned above, even if the scale exhibits good releasability over most of the area, if there are some areas where the releasability is poor, that part becomes the rule. That is, when using a coating agent, it is quite difficult to generate and control a uniform scale composition over the entire surface.

Furthermore, at present, no success story has yet been found in the latter case of generating a strong scale that does not peel off.

To explain the background of the present invention, the inventors
The main focus is not on preventing oxide scale or generating scale that does not peel off, but rather on reducing the scale treatment work before the next processing process, from the perspective that the loss due to iron scale is not significant in terms of cost. The idea was to prevent the occurrence of defects.

[Means for Solving the Problems] To explain the present invention, the characteristics that the scale modifier should have are as follows: 1. Forms a composite iron oxide that is easy to peel off, 2. Forms a film with good adhesion at room temperature. 3. It has a film-forming function with good adhesion when heated (up to 900°C). 4. It has a composition that peels off immediately when it is cooled (left to cool).

By the way, the first feature of the easily peelable scale modifier for iron slabs of the present invention is that it contains metal powders or alloy powders and mixed powders thereof that easily form iron oxides and composite oxides in the oxidation process. Features.

In this way, it is very effective to apply a metal powder that is as difficult to form an alloy with iron as possible, or that does not form an alloy, in order to produce a composite iron oxide that has good peelability when heated.

As the equivalent of this metal, Z n + Fe+
Pb, Sn, Sb, AI, Zr, Nb, Bi.

One or a mixture of two or more of Mn, Sr, and Ba metal powders or alloy powders thereof were effective.

Note that metals that form alloys with iron, such as Ni and Co, do not cause any interference up to an amount equivalent to 30% of the added metal or alloy powder, and even if alkali metal oxides are shared in a part of the composite oxide. No problem.

The second feature of the present invention is that the scale modifier has good adhesion when applying the above-mentioned metal powder-containing coating agent at room temperature, is easy to form a film, and can be easily formed in the range of 120°C to 500°C. It contains resin that burns completely.

At this time, the combustibility is good, i.e. 120°C to
In the range of 0° C., it is preferable that the material gradually and easily decomposes into water and carbon dioxide without undergoing a carbonization process.

Resins that fall under this category include natural polymer carrageenan,
Gelatin, semi-synthetic polymer hydroxyethyl cellulose,
Ethyl hydroxyethyl cellulose, sodium carboxymethyl cellulose, methyl hydroxypropyl cellulose, carboxy methyl starch synthetic polymer polyvinyl alcohol.

Polyvinylpyronthone, carboxyvinyl polymer polyvinyl methyl ether, sodium polyacrylate, water-soluble resin of water-soluble acrylic polymer, acrylic ester copolymer resin, styrene-acrylic ester copolymer resin, ethylene-vinyl acetate-acrylic acid Vinyl acetate type, typified by ester copolymer resin, ethylene-vinyl acetate-vinyl versatate copolymer resin, and styrene type.

There are aqueous emulsions (however, anionic type) of acrylic type 9 synthetic rubber type and their copolymer type.

Also, amide type waxes, ester type waxes, and solvent type polymers may require a little heating when used.
If the conditions at 0°C to 500°C are met, it can be used even if it is not the best.

Furthermore, the third feature of the present invention is that if the film is damaged, cracked, or partially peeled off for some reason during heating after application of the liquid agent, that part will come into direct contact with oxygen in the air and normally Iron scale occurs even partially, and the peelability of the scale becomes a rule in this part, making the peeling work complicated.

The third feature was developed for this purpose, and it is added to prevent cracking and deterioration of the film at high temperatures of 700°C to 1000°C. is valid.

Mixtures are also natural. Namely lithium metasilicate, sodium metasilicate, potassium metasilicate.

Magnesium silicate or mixtures thereof.

Furthermore, it is necessary to prevent these metal powders or alloy powders from being easily oxidized after being inserted into the heating furnace. For this reason, Sio2. AN203+
ZnO, Fe203+F e304 , SnO2 and mixtures thereof may be added. This is the fourth aspect of the present invention.
It is a characteristic of

Additionally, general paint additives such as cellosolve, preservatives, antifoaming agents, and antifreeze agents are required for coating properties.

From the above, the basic formulation as a scale modifier (however, the mixture is 100 nt%) is as follows.

0 Basic composition % Water-soluble (solvent-based) polymer 0.2-1.0 Ceramic powder 4-25 Alkaline silicate (water glass) 10-85 Extender pigment
0~20 Cellosolve 1~10 Preservative 0~0.1 Antifoaming agent
0.1-2.0 antifreeze
0.1~2.0 metal (including alloy) powder
5 to 25 The antioxidant ability of this formulation is a scale generation rate of 30 to 40% compared to normal scale generation.

[Effects] According to the present invention, scale is generated, but as soon as the temperature begins to drop after being taken out of the heating furnace after heat treatment, the entire surface or most of the scale is immediately peeled off by utilizing the shrinkage difference between the iron and the scale part. However, even if there is any remaining scale, it can be modified into a scale that can be completely and easily peeled off with a slight impact.

[Examples] Examples 1 to 2o are shown in Attached Table 1, and Comparative Examples 1 to 5 are shown in Attached Table 2 to clarify the peeling effect of this example.

that's all

Claims (4)

[Claims] (1) Contains metal powders that easily produce iron oxides and composite oxides in the oxidation process, or alloy powders and mixed powders thereof, and the metal powders include zinc, iron, aluminum, lead, tin, antimony, An easily removable scale modifier for iron-based slabs, characterized in that it is selected from zirconium, silicon, bis-asu, strontium, and manganese. (2) A coating agent comprising the metal powder according to claim 1,
Good adhesion and easy film formation when applied at room temperature and 120℃
Contains resins that are easily completely combusted in the range of ~500°C, and the above resins include natural polymer carrageenan, gelatin, semi-synthetic polymer hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, sodium carboxymethyl cellulose, methyl hydroxypropyl cellulose, and synthesized carboxy methyl starch. polymer polyvinylallol,
Polyvinylpyrrolidone, carboxyvinyl polymer, polyvinyl methyl ether, sodium polyacrylate,
Water-soluble resin of water-soluble acrylic polymer, acrylic ester copolymer resin, styrene-acrylic ester copolymer resin, ethylene-vinyl acetate-acrylic ester copolymer resin, ethylene-vinyl acetate-vinyl versatate copolymer resin. Typical examples are vinyl acetate, styrene,
Easily peelable iron-based slab characterized by being made of one or more of aqueous emulsions of acrylic, synthetic rubber, and copolymers thereof, and solvent-based waxes such as amide and ester waxes. Scale modifier. (3) The easily peelable scale modifier according to claim 1 has a composition of 70%
Easily peelable scale modification for iron-based slabs characterized by having lithium metasilicate, sodium metasilicate, potassium metasilicate, or a mixture thereof added to prevent cracking deterioration of the film at high temperatures of 0°C to 1000°C. Pawn agent. (4) The easily peelable scale modifier for iron-based slabs according to claim 1 is an additive for slowing oxidation during heating of metal powder or alloy powder, such as SiO_2, Al_2O
_3, ZnO, Fe_3O_4, Fe_3O_4, Sn
O_2 or their composite oxide nSiO_2・Al_
2O_3, or mixture thereof SiO_2+Al_2
An easily peelable scale modifier for iron-based slabs, characterized by containing at least one of O_3.