JPS5823539A - Mold for continuous casting of iron or steel - Google Patents

Abstract

PURPOSE:To reduce the friction between molten metal and an ingot by forming the 1st covering layer consisting of >=1 kind of Ni and Co on the inside surface of a mold made of Cu or a Cu alloy having rough surfaces, and forming the 2nd covering layer consisting of specific contents of >=1 kind of P, B and >=1 kind of Ni, Co. CONSTITUTION:A rough surface of about 20-200 S (in accordance with JIS B 0601), more preferably about 50-150 S is formed on the inside surface of a mold made of Cu or a Cu alloy. A plating layer consisting of >=1 kind of Ni and Co is formed on the inside surface of the mold, and further, an alloy plating layer consisting, by weight %, of >=1 kind of 3-20 P, and 2-15 B and the balance >=1 kind of Ni and Co is formed thereon. The effect is higher if the 3rd coating layer is formed thereon by carrying out Cr plating or forming an oxidized film by oxidizing said alloy plating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a mold for continuous casting of steel, such as low, medium, and high carbon steel, stainless steel, and special steel. The base is made of steel or copper alloy, which has good thermal conductivity, and a protective coating such as a metal layer is provided on the inner surface. In order to reduce the friction between the steel slab and the inner surface of the mold, a lubricating material such as glass powder is interposed between the molten steel and the inner surface of the mold, and is melted by the heat of the molten steel. The inventors of the present invention have discovered that problems often occur in known continuous casting ingots, such as reduced mold life due to damage to the molten steel pouring surface, and so-called breakage caused by molten copper adhesion during the early stages of pouring. It is necessary to eliminate or reduce the difficult problems such as the occurrence of out-of-control problems. Various researches have already been carried out, and many remarkable results have already been achieved (Special Publication No. 6F 40733, 111H-6073).
No. 4, No. 84-375111, No. 1 $1-40341
Reference number M). Starting from the results of the inventor Hiroko,
As a result of repeated experiments and research in order to further improve the performance of continuous casting molds, we decided to roughen the inner surface of the mold and form a specific plating layer on the surface in good condition, completely contrary to the conventional wisdom of those skilled in the art. We have discovered that this object can be achieved when the invention is carried out, and have finally completed the present invention.

The inner surface of a known continuous casting mold should be finished as smoothly as economically possible in order to reduce the friction between the molten metal and the slab and to make the surface condition of the slab as smooth as possible. has been done. In other words, the inner surface of the mold has good smoothness.
It is thought that the life of the mold will be longer and the surface condition of the slab will be better, so there are even large bowl-shaped molds that are finished to a mirror or near-mirror surface and have rounded inner surfaces.

However, according to the research conducted by the present inventor, it has been found that molds with such extremely smooth inner surfaces may have the following problems.

(1) When the inner surface of the mold is highly smooth, the lubricating material also tends to move due to contact with the moving slab, resulting in uneven distribution. In extreme cases, there may be a significant lack of lubricant material between the molten steel and the inner surface of the mold, or there may be a portion where it is virtually absent. In such a case, the inner surface of the mold corresponding to the part in question is worn away by the slab, causing large friction, and as a result, the resistance to pulling out the slab increases, causing the thin solidified film on the slab to break. , a so-called restrictive breakout may even occur.

(-) On the other hand, in areas where there is an excess of lubricant material that inevitably occurs due to the non-uniform distribution of the lubricant material, poor cooling of the molten metal and the slab occurs due to the low thermal conductivity of the material. If the coagulated film is extremely thin, the inside will be the cause of p ε6 out. This phenomenon often occurs when a large amount of lubricant material is used to ensure that the lubricant material is present on the entire inner surface of the continuous casting mold. l) A large amount of lubricating material tends to be unevenly distributed, and this can be the cause of breakouts from some corners and corner cracks due to delayed growth of the assimilated film at some corners of the slab.

Since the lubricating material is easily discharged with the slab drawing @Pc, it is necessary to supply it frequently. Therefore, not only is the operation complicated, but also a large amount of lubricating material is wasted, which is economically disadvantageous.

M If two or more types of metal coatings are provided as protective coatings on the inner surface of the continuous casting mold, each! Due to the difference in the elongation rate of the cast iron, a large stress strain occurs in the outermost layer, and the occurrence of cracks in this layer inevitably shortens the life of the mold and causes the slab to deteriorate. It also impairs the quality of the product.

According to the common knowledge of those skilled in the art, the continuous casting mold of the present invention, which has a roughened inner surface, may deteriorate the surface condition of the slab! Although it costs 9 and 100 yen per serving, Liaoji is completely unexpectedly able to produce slabs of excellent quality that are equal to or better than Kame's conventional products.

In other words, the lubricant material is uniformly held over the entire surface of the mold inner surface by the minute recesses in the rough surface of the mold inner surface, so that the breakout due to insufficient or excessive presence of the lubricant material is prevented. , no corner cracks occur. In addition, the lubricating material is held in the recesses of the rough surface, making it more effective! Since it remains in the tank, the number of times of feeding and the total amount of feeding can be significantly reduced. Since cracks hardly occur even in the alloy plating layer, which is the outermost layer of the plurality of metal plating layers provided in the mold, its oxide film layer, or the four-metal plating layer, the life of the mold is extended and the cracks of the slab are prevented. It improves quality. More specifically, the difference in thermal stress strain rate between the mold base and each plated layer is absorbed and relaxed by the nine enlarged surface layer formed by the rough surface, thereby preventing cracks in the plated layer.

The basic constituent ore of the mold of the present invention is i made of known copper or prepared alloy.
The structure is similar to that of the continuous casting mold □. In the casting IEI of the present invention, the mold inner surface Kgo-goos (JIS B
At 0601! degree), preferably 50 to 1508
If the surface roughness, which forms a certain degree of roughness, is less than Gos, the effect of improving lubricity and preventing the outermost plating layer from sticking will not be sufficiently achieved. The morphology of the zero-rough surface, which is undesirable because it makes the surface rough, may be one in which minute irregularities are regularly distributed macroscopically and structurally, or microscopically irregular but macroscopically irregular. As a 0-wave rough surface, it may be distributed almost uniformly, or it may be a so-called wavy surface in which concave portions and convex portions are continuous in parallel in the same direction.
Although the direction in which the concave portions and convex portions are continuous is not limited to that of Samurai, it is preferable that the direction is the same as the flow of molten steel. Methods for forming the rough surface include shot blasting, forming fine partial masking parts on the inner surface of the mold and selectively etching the non-masked parts, machining with a shaver, etc., and small protrusions or fine waves. Any method may be used, such as an indentation method in which a roll having a pattern is rolled onto the inner surface of the mold. Furthermore, in the case of new steel or copper alloy molds, the first layer plating or the tm and ! layers can be applied directly without surface roughening. The surface roughening may be performed after spring plating and after death. Next, a predetermined plating layer is formed in a mold with a rough surface according to the 1iKf method.

In the invention as set forth in claim 1 of the present patent application (hereinafter referred to as the first invention of the present application), first, a first covering layer consisting of a plating layer of nickel and/or cobalt is formed on the inner surface of the mold. The plating layer is.

The inner surface of the mold, which has a rough surface, is treated using a conventional method.

Easily formed by conventional electroplating methods. Then,
Gino 3~ on the first coating layer! O weight - and/or boron 1
Form a second coating layer of an alloy plating layer containing ~16 kg by weight and am consisting of nickel and/or cobalt. If the content of phosphorus and boron in the alloy plating layer is less than the above-mentioned amount, the heat resistance and hardness will tend to decrease), while if it exceeds the above-mentioned amount, it will be economically disadvantageous. The alloy plating layer can be formed by electroplating, but in general, the precipitated crystals are dense, and even if they fall on a flat or curved mold surface, they will be assembled and have a large angle. Also inside the cylindrical mold*, l! It is more advantageous to use the electroless plating method because it is easy to form a plating layer of uniform thickness even in a cylindrical cast iron.◇The first coating layer and the second coating layer. The thickness of the molten steel varies depending on the molten metal temperature R% sl * mold size, etc.), but it is
Covering layer go-tsoop Otori, second covering layer! O~10oμ
It is best to have a total thickness of about 40 to 1000 μm.

The invention as assigned in Clause 2 of the IIN patent claim (hereinafter referred to as the second invention) is that a coating layer and a second coating layer are provided on the inner surface of the mold according to the ninth invention. In addition, a chrome plating layer is formed as a three-layer coating to extend the # type life.
r? The formation of the layer, which has been successfully achieved and achieved by the conventional electroplating method, is a remarkable achievement.
The peelable layer has the effect of preventing the adhesion of molten steel sgrashes at the initial stage of pouring, and therefore prevents the adhesion of the molten steel. In general, a coating of about 6 to 60 μm is sufficient.Furthermore, the invention set forth in claim 3 of the present application (hereinafter referred to as the third invention of the present application) provides a second coating of the mold of the first invention of the present application. By oxidizing the surface of the layer, the oxide film layer becomes IR-
Ii, thus casting Il as in the case of the second invention of the present application.
#I To form a 0 oxide film layer, which has a remarkable effect on preventing adhesion of molten steel during the initial stage, an aqueous solution of an alkaline substance such as caustic soda is used to form an alloy layer, which is the second coating layer, as an anode. Known methods of oxidizing brass, such as a method of electrolytic anodization in the atmosphere or a flame oxidation method of heating the surface of the alloy layer with a gas burner in the atmosphere, are employed. The thickness of the oxide film layer is
, O.1 μm or more is required, and it is preferable to set the upper limit to %O, Spml thickness.

The mold of the present invention has the above-described A4I! I1
The present invention will be described in more detail with reference to Examples below.

Example 1 (1) Formation of rough surface: Copper continuous casting casting tunnel (short side medium 30
A molten steel injection surface with a diameter of 0 mm, a long side width of 1300 m, and a height of 80 G-) is roughened to a predetermined surface roughness using a shaver so that the turning portion and the convex portion are continuous in the flow direction of the molten steel.

(11) Pretreatment M: Masking the parts of the above mold other than the melt casting surface with vinyl chloride resin paint, and applying 9 bales of caustic soda 51r/j, *acid powder 261/1, and ionic surfactant 69 The sample is immersed in an aqueous solution containing /l for 40 minutes at 60°C to degrease it. After washing with water, caustic soda 3011/1. The mold was immersed in an aqueous solution containing sodium orthosilicate 11OJI/j and anionic surfactant 1011/I, and the mold was immersed in an aqueous solution containing sodium orthosilicate 11OJI/j and an anionic surfactant 1011/I under the conditions of a cathode radio wave density of 10 m/dm" and 60°C.
Perform electrolytic desorption for 1 minute. After washing the mold with water, it is activated by immersing it in an aqueous hexasulfuric acid solution at room temperature for 10 minutes.

(To) Formation of nickel plating layer: Wash the activated mold with water and apply nickel sulfamate j%'50011/
1. *Nikke/'3011/l, boric acid 10971
and sodium naphthalene trisulfonate 311/l, and the bath was continuously filtered, bath temperature 46 ° C, I)
li4.8. 10 under the condition of cathode current dF*lm/dba
Perform time electrolytic plating to form a 120 μm nickel plating layer◇・.

・ψ Formation of alloy plating layer Two nickel plating layers form s0
1//1. Sodium hypophosphite 18ON/J and sodium hypophosphite 1811/I are immersed in a bath containing phosphorous acid Y-DA 18ON/J and sodium hypophosphite 1811/I, and the bath temperature is SO℃, P
H11! Electroless plating was carried out for 8 hours under the conditions of % nickel &! 88 weight vomit and 9 n 1! A nickel-phosphorous alloy plating layer of 23 μm thick was formed. After washing the mold with water, dry it and remove the masked eyelid material.

Table #11 shows the influence of the surface roughness of the inner surface of the mold on the cracking and peeling of the alloy plating layer, the life of the mold, and the surface condition of the slab when the mold of the present invention was used for continuous casting of medium carbon sea bream. Shown below.

Notes to Table 1 (1) Molten steel of 1 charge is gas@).

(2) 0-・Good, Δ-Normal (minor cracks on the meniscus part), ×... wear on the convex ridges) O (-〇-* good, 0-... good, Δ・・・Universal 111
1 table b@b kanyo (, this 1191#■ has excellent durability and improves the quality of slabs.In addition, the basic unit of glassy powder is 0.45~O1s#/1ll steel compared to conventional steel. By applying rough surface processing and using the mold of the present invention, the amount used was reduced by an average of ~30% to 90. Example 2 (1) Formation of a rough surface Made of prepared alloy containing 11! of nichrome Continuous casting casting 1ft (short side width! 00m, long side width 1s
...■, height TOO■) is roughened in the same manner as in Example IK.

(it) Pre-am: Performed in the same manner as in Example 1.

(2) Formation of Koba N1 metal life layer: After completing the activation process and washing the mold with water, immerse it in a metal Φ bath containing chlorinated) Pat R@011/I and Pholic acid 801/I. The electrolysis process was carried out for 11 hours under the conditions of a bath temperature of 70℃, pHti, and a theoretical current density of 1 μm/d, to form a cobalt plating layer with a thickness of 1γO#. let

4V) 1 Formation of gold plating layer: Formation of cobalt plating layer After washing the above mold with water, immediately add sulfuric acid.
Sodium citrate A1401/1 was immersed in an electroless plating bath containing sodium hyposinite 1@I/l, and immersed for 10 hours at a bath temperature of 90°C and pH 10 to give nickel 93 weight φ. and thickness s consisting of phosphorus γ° weight
OSM nickel μm phosphorus gold plating layer is formed.

Formation of M alloy plating layer After forming the alloy plating layer and washing the mold with water, immediately add anhydrous chromium s**pii,
Immersed in a plating bath containing sulfuric acid O, 5pii and silicon + 7 potassium fluoride 69/I, the solution temperature is sO ℃, and the cathode current density gs
Electroplating was carried out for 60 minutes under the conditions of 1 to 1 to form a coating layer of 1 to 1. The large bowl mold obtained was washed with water, dried, the masking paint was removed, and then stainless steel 9 results used in continuous casting of steel
0 shown in the table (note Table 3), (1), (1) - Same as Table 1.

The mold of this example also has excellent durability and improves the quality of the shingle and slab. In addition, the basic unit of glassy powder was reduced by an average of 20 to 30% compared to conventional products. Roughen the surface using the same method.

(Pretreatment: Performed in the same manner as in Example 1. Formation of nickel layer: After rinsing the activated mold with water, chloride; Pal) 8001/1. jJ [chemical = Tsuke*4011/l and boric acid g.

11/l, and while continuously filtering the bath, the bath temperature was set to 0°C, PIi4. l! , cathode current density! Electrolytic plating was carried out for 10 hours under the condition of 0.5 mm/υ to form a plating layer with a thickness of 130#, nickel A/16 weight φ-cono (86 weight).

-Formation of alloy plating layer: 1 piece (nib part Φ layer)
The mold formed with nickel chloride I' was immediately washed with water, and nickel chloride I'
281/1. Immersed in a bath containing 3011/l of sodium citrate and 89/l of sodium borohydride, and the bath temperature was 86°C.
, pHs for 7 hours. Thus, nickel/l/97 heavy weight x8 heavy weight, thickness,
An alloy plating layer with a thickness of 31 μm is formed.

(■ Formation of a sticky layer: Formation of a 20 μm chrome plating layer using a method similar to Example 1) The mold of the present invention was formed by washing and drying the mold with water, and then removing the masking paint. The binding wire used for making low carbon steel from the obtained mold, as shown in Table 3) is 0. As is clear from the OSS table, the mold of this example also has excellent durability and improves the quality of the slab. Example 4 (1) Formation of rough surface: Copper continuous casting casting (m 40 m, long side 160, 0 (II) Pre-treatment: Performed in the same manner as in Example 1.

(I = Tsuke ~ Formation of plating layer: After completing the activation process and washing the mold with water, nickel 7-acenate 45011/I
and boric acid 'R@11/l, bath temperature 66°C, pH 8.1, cathode current density 8 μm/dIX.
Electrolytic plating was carried out for 26 hours under the conditions of 'As thickness 1f.
Form a nickel μ plating layer of i80e#.

Sauce ψ Formation of alloy plating layer Two nickel plating layers are formed, and the large shoes are washed with water, and nickel sulfate is applied! 201/I.

Chloride; PaA/) l 011/l, sodium citrate@@11/l and sodium hypophosphite 20971 were immediately immersed in a bath containing 20971 at bath temperature ss"c and pm under the conditions shown in Table 8. Electroless plating was carried out for an hour, and the part was 26 weight - phosphorus was 18 weight, and the thickness was 67.
A 4 m alloy plating layer is formed.

fJ) Formation of PU plating layer: Form a chromium plating layer of 2 and 1 in the same manner as in Example 1. Washing and drying the mold, and removing masking paint. is obtained.

The performance of each cast metal and the surface condition of the slab used in the casting of high carbon steel are shown in Table 4.

Table 4 [ Notes (1) 1 body), (3)...Same as Table 1.

This example mold 4g4 has excellent effects as shown in the table, and the amount of glass powder used is 3 to 3 times higher than that of conventional products.
FC decreased by a percentage.

Example 6 (-) Formation of rough surface: Steel pot mold containing 1 weight of silver. 0Oaae long side medium 1000
The inner surface of saX height 7@Osum) is converted to ff1- in the same manner as in Example 1. (1) Pretreatment: Same as in the actual example.
Formation of plating layer:/! After finishing the R sexing Asahi San and washing the Obachi with water, S/&/7 anoic acid ink Tsuke A'41! p[
1. Formation of a 200 μm nickel V metal layer tc by subjecting it to electrolytic plating for 11 hours under conditions of underground current rating of 2 μm/d− 0 − Formation of alloy plating layer 2 Wash the above IkIaiI with water,
Chloride (cobalt) 4G &/j, ethylene chloride (1sCO/)
a. Sodium taenate 1ull/4. Sodium hypophosphorus 1677/l and sodium borohydride 81/l
Immerse it in an electroless plating bath (PH1to)K'' and keep it at a bath temperature of 80℃ for 10 hours.
L capsule - phosphorus eIl amount Qi boron 6 weight ginseng, thickness 37μ
An alloy plating layer of m was formed, and an oxide film treatment was further applied.

Table 6 shows the performance of the bottle stand and the surface condition of the slab obtained by using the mold of the present invention obtained after washing with water, drying, and removal of the masking paint for continuous casting of medium carbon steel.

Table 6 18) Bottle note (1), 100 million) 1 unit) - Same as Table 1 The cast iron of this example also produced the excellent effects shown in Table 6. Example 6 (1) Formation of II surface: Copper sIIm casting cast W1
(Weir side width 310-.Long side width 1500m, 4th width 700m)
The inner surface of the sample was roughened in the same manner as in Example 1.

+1) Pretreatment: Performed in the same manner as in Example 1.

(To) Formation of nickel μ plating layer After finishing the activation and washing the large bowl with water, nickel sulfate ~ 81011/I.

Chloride JI-'l? #@011/1. Boric acid log/j1
Immerse it in a bath containing sodium naphthalene tris 81171 and adjust the bath temperature to 66℃ and pH while changing the bath temperature.
ts, hidden column electric book degree snow mu/di? 6 conditions KIO time electrolytic metal aFK (k), thickness t!・Formation of pHl nickel μ plating layer 0 4 ψ Formation of alloy plating layer: Wash the above # type with water, add nickel chloride #8011/l, sulfuric acid/4#) 1 chloride 1/1 sodium hypophosphite 1077/ Immediately immersed in a bath (PHIO) K' containing sodium borohydride 611/jl and sodium citrate 6611/I, bath temperature 72°C.
Electroless plating was performed for 9 hours. Hidden Nikke IV
84 weight weight 11 weight l-li/3 letters 1111G
An alloy plating layer of 211 pins thick consisting of - boron f weight - is formed on the mold surface Kjl. An oxide film layer is formed on the alloy plating layer.

When the uninvented mold obtained after water submersion 1 drying and removal of the masking paint is used for continuous casting of high carbon steel, the performance and surface condition of the slab are as shown in Table JlII.

Table 6 The present implementation of this alliance showed the excellent performance of Haruka>6 as shown in Table 6, and the amount of vitreous powder was also reduced by 80% on average compared to the conventional product.

(that's all) Continuation of page 1 ■Applicant: Satosen Co., Ltd. 3-7-27 Tsumori, Nishinari-ku, Osaka City

Claims (1)

[Claims] ■ #A on the inner surface of a steel or copper alloy mold with 11 sides! A plating layer consisting of at least one of copper and cobalt; A mold for casting S# iron and steel, characterized by sequentially forming an alloy plating layer consisting of at least one type of s weight and at least one type of nickel beta and cobalt. On the inner surface of the manufacturing mold, (4) a plating layer consisting of at least one of nickel and pult;
At least one of the following: 3-20 weight bags of water and 2-16 weight bags of boron, and IIIl! A mold for continuous casting of steel, characterized in that an alloy plating layer consisting of at least one of cobalt and cobalt, and an alloy plating layer are sequentially formed. ■ In a mold made of copper or copper alloy with a rough surface, a plating layer consisting of at least IM of nickel and cobalt, at least one of the following: 3-sO by weight and boron by 8-18% by weight, and the balance being nickel. A mold for continuous casting of steel, comprising: an alloy plating layer consisting of at least one of p and pult;