JPS6217118A - Skid button - Google Patents

Abstract

PURPOSE:To provide superior heat insulating properties, superior compressive creep strength at high temp. and superior shock resistance to a skid button, to enable the welding of the button to a skid pipe and to facilitate attachment by entirely coating the outside of the support base of the button made of ceramics with a metal to the required thickness. CONSTITUTION:The outside of ceramics 1 forming the support base of a skid button is entirely coated with a metal 2 to 0.5-2cm thickness. A Co alloy or a heat resistant alloy such as HS21, UMCo5, or S816 is used as the metal 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a skid button that is provided on the upper surface of an in-furnace skid in a steel heating furnace and directly supports the steel material.

(Prior Art) Skid buttons used in heating furnaces must support the weight of the steel material to be heated in a high-temperature atmosphere, and therefore require high compressive creep strength at high temperatures.

Therefore, conventionally the material was 00MCo50, r-
rs-21,5816,5CI (13 etc. or C
Skid buttons using O-based or Ni-Cr-based heat-resistant alloys, and (2) single ceramics or composites of solid ceramics and metals have been used.

(Problems to be Solved by the Invention) However, in the former skid button using heat-resistant steel, creep deformation occurs on the top surface when used for a long time in a high-temperature atmosphere, no matter how heat-resistant the steel is. ■Therefore, their lifespan is short and they need to be replaced every six months. ■In order to reduce the high-temperature compression creep deformation described in ■ above, cooling water is flowed into the skid pipe for water cooling, but as a result, the temperature of the part of the skid button that comes into contact with the steel material decreases, causing skid marks on the steel material. There are disadvantages such as causing

The latter type of skid button was proposed in order to eliminate the drawbacks of the former method, that is, to increase the compressive creep strength at high temperatures without generating skid marks. The composite skid button has a structure in which the ceramic is exposed on the surface in contact with the heated steel material (Japanese Patent Publication No. 60-9566, Utility Model Publication No. 58-356).
(No. 40, Utility Model Application No. 59-449), (1) Ceramics react with oxide scale and the atmosphere in the furnace and are worn out. ■If there is a height difference in the height of the skid button due to wear and tear from use, or if the steel material is warped, an impact load will be applied to the skid button when the steel material is transferred, which will cause the ceramics to break and scatter. There are drawbacks such as.

By the way, according to the inventor's actual in-furnace tests conducted over a period of six months, ceramics (S i 3N4. S i C) alone or ceramics (S i zNa, S i
In the conventional composite skid button with C) exposed, no ceramic remained on the skid pipe at the end of the test due to damage due to breakage or reaction.

Furthermore, since it is not possible to use welding as a means of fixing a skid button made of ceramic alone on a skid pipe, a special structure for fixing is required, resulting in high costs.

In addition to the above-mentioned skid button, there is also a so-called hot type, which has a cylindrical body filled with heat insulating material and a lid attached to the upper opening. There are drawbacks to mention.

In other words, in this skid button, the cylinder and the lid are not integrated, so the cylinder is pushed outward by the heat in the furnace and the weight of the steel material, flattening the skid button and causing skid marks. It gets bigger.

The present invention solves the above-mentioned conventional drawbacks, namely: (1) prevents the occurrence of skid marks and high-temperature compression creep deformation, especially the wear of the upper surface of the skid button, which are the drawbacks of skid buttons made of heat-resistant alloy; The disadvantages of single ceramics or conventional composite skid buttons with exposed ceramics are the wear and tear of the ceramics due to reactions with oxide scale and the furnace atmosphere, as well as the wear and tear of the ceramics that occurs due to the shock load that is applied during the transfer of steel materials. This was done to prevent breakage and scattering of the broken ceramics, and also to prevent (1) the expansion of skid marks due to flattening, which is a drawback of hot-type skid buttons.

(Means for Solving the Problems) The present invention provides a skid button in which the entire outer periphery of a ceramic support aggregate is coated with a metal of a required thickness.

That is, the skid button of the present invention having the above-mentioned configuration can fully satisfy the various requirements that a skid button must have for the reasons explained below.

■Insulation As explained earlier, the quality of insulation has a large effect on the occurrence of skid marks on steel materials.

Therefore, the skid button of the present invention can obtain good heat insulation properties by using ceramics as the supporting aggregate, which has better heat insulation properties than metals, that is, has low thermal conductivity and excellent high-temperature compression resistance. It is preferable that the thermal conductivity of the ceramic used be as low as possible, but according to experiments conducted by the present inventors, a high effect in reducing skid marks was achieved when at least a metal with a thermal conductivity of 2 or less was used.

Further, as for the composite ratio of the ceramics as the supporting aggregate, it is desirable that the area occupation ratio of the ceramics in the cross section of the skid button is 50% or more on average in the height direction.

This value of 50% is a value obtained based on the strength and heat insulation properties of the skid button, and if it is less than 50%, the required strength and heat insulation properties cannot be obtained and there is little effect on reducing skid marks.

Next, we will explain the differences between ceramics and heat insulating materials, which are generally said to be the same.

Although there is no difference between the two in terms of materials, (1) the pores generated inside are significantly different; in terms of porosity, ceramics has a porosity of 0.1% or less, whereas heat insulating materials have a porosity of about 10%. This is because the particles of the raw materials are different. Therefore, (1) the compressive strength of ceramics is very high, whereas that of heat insulating materials is low. Therefore, conventional products in which a heat insulating material is interposed within a heat-resistant alloy material have good heat insulating properties, but have low compressive strength and a short lifespan.

On the other hand, the ceramics used in the skid button of the present invention are made of the same material as the heat insulating material, so they have excellent heat insulating properties, and have high compressive strength, so they can be used as supporting aggregates.

■About high-temperature compression creep strength High-temperature compression creep strength affects the service life as explained in the section (2) above regarding insulation properties.

However, in the skid button of the present invention, there is no problem because ceramics having high high-temperature compression creep strength is used as the supporting aggregate as described above.

■Impact resistance strength and prevention of wear and tear of ceramics due to reactionsAs explained above, ceramics have good effects on heat insulation and high temperature compression creep strength, but as mentioned earlier, this ceramic has ■impact resistance. It has drawbacks such as being weak and being damaged by reacting with the oxidized scale of the heated material and the atmosphere in the furnace.

Therefore, in the skid button of the present invention, the entire outer periphery of the ceramic supporting aggregate is coated with metal.

Here, the type of metal covering the skid button is not limited in any way, but in consideration of the heat resistance of the upper surface of the skid button, a heat-resistant alloy is preferable. The thickness of the metal layer on the top surface of the skid button is 0.5 to 2.
It is desirable that the distance be within the range of 0 cm. This is 2.0
This is because if it exceeds 0.0, the metal layer on the top surface of the skid button will undergo high-temperature compression creep deformation, resulting in the same drawbacks as conventional skid buttons made of heat-resistant alloy.
This is because if the thickness is less than 5 cm, the effect of covering the ceramic with the metal layer will not be exhibited.

In addition, considering the coverage of the metal layer, it is desirable that the corners of the ceramic supporting aggregate be chamfered.

In addition, in order to enable the skid button of the present invention to be welded to the skid pipe, the lower part of the skid button has the same shape as the conventional skid button made of heat-resistant alloy, and the distance between the welding part and the built-in ceramic is 15 mm at the shortest position. It is desirable that it is longer than the fin.

(Function) The skid button according to the present invention uses ceramic as the supporting aggregate and has a structure in which the entire outer periphery of the ceramic is coated with metal, so it has excellent heat insulation properties, high temperature compression creep strength, and It has impact resistance, does not cause ceramic wear due to reactions, and can be welded to skid pipes for easy installation.

(Example) The present invention will be described below based on an example shown in the accompanying drawings.

FIG. 1 is a front view and central vertical sectional view showing one embodiment of the skid button according to the present invention, and numeral 1 in the figure indicates ceramics forming the supporting aggregate of the skid button according to the present invention. and,
The entire outer periphery of this ceramic 1 is coated with a metal 2 of a required thickness.

By the way, the shape of the ceramic 1 is not limited in any way, and the cross section may be as shown in FIG. 2 (
Any shape such as a solid circle as shown in (a), a hollow circle as shown in (b), a polygon as shown in (c) and (b), an ellipse as shown in (e), etc. Also, the vertical cross-sectional view may be uniform in the height direction as shown in Figure 3 (A), or the lower part required for weldability can be shaped like an inverted truncated cone as shown in Figure 3 (B). It can be of any shape, such as a barrel-shaped one as shown in (c), a trapezoidal one as shown in (b), or one with a partially hollow bottom as shown in (e). .

In addition, what is shown in FIG. 3 (e) is intended to compensate for the decrease in strength against horizontal force due to the enlargement of the occupied area of the ceramic 1 by the metal 2 existing in the lower hollow part 3. , and may be used in combination with Figures 3 (a) to 3).

That is, according to the inventor's experiments and analysis, the thermal conductivity of the ceramic 1 is A or less than that of metal, and the area occupation rate of the ceramic 1 in the cross section of the skid button is 50% or more on average in the height direction. It has become clear that it is highly effective in reducing skid marks in some cases, and the shape is not limited in any way as long as it satisfies this.

However, the thickness of the upper two metal layers in the skid button of the present invention is preferably in the range of 0.5 to 2.0 CII+ from the viewpoint of high temperature compression creep strength and impact strength.

The skid button of the present invention is manufactured in the following order.

(2) Support the ceramics in the mold using metal blocks. At this time, in order to prevent the ceramic from cracking due to thermal shock, the ceramic is preheated to 1300° C. or higher.

(2) Pour molten metal (heat-resistant alloy, 1500°C or higher) into the mold.

Note that the type of metal block used is the same as that of the cast metal, or one that has a higher melting point than the cast metal. Furthermore, a block made of the same metal as the cast metal is used for the top surface of the skid button.

(Experimental results) A solid circular cross section as shown in Figure 2 (A), and a central vertical cross section that is uniform in the height direction as shown in Figure 3 (A) (ml
), the lower part of Figure 3 (b) is shaped like an inverted truncated cone (N
a2), the seed type of figure 3 (c) (Arashi 3), figure 3 (
Four types of ceramics 1 (e) with a hollow part provided at the bottom (11h4) were preheated to 1300°C or higher, and a CO-based heat-resistant alloy with the ingredients shown in Table 1 below was cast.
A skid button of the present invention measuring m×1001 mm was manufactured.

Furthermore, the material of ceramics 1 is Table 1 Ingredient list (weight%) Al 103: 91% was used.

A mounting test was conducted for 6 months in a heating furnace using the four types of skid buttons of the present invention, magnetic 1 to IVh4. The results are shown in Table 2 below. For comparison,
Table 2 also shows the results when a heat-resistant alloy skid button (box 5) and a skid button with exposed ceramics (box 6) were used.

The operating conditions for this experiment were Φnōkani 200Ton/H.
r, Steel size: 4000fmx2000WwX32
0 tm, and the heating temperature was 1180°C.

((Bottom margin) As is clear from Table 2, the excellence of the skid button of the present invention was confirmed.

(Effects of the Invention) As explained above, the skid button of the present invention has the effects listed below.

■The average thermal conductivity of the skid button of the present invention is A-〃 compared to the conventional skid button made of heat-resistant alloy, so the temperature above the skid button can be maintained not much different from the atmosphere in the furnace, and therefore the material to be heated can be No skid marks occur,
There is no need to reheat the material to be heated at the outlet of the heating furnace in order to remove skid marks as in the conventional method.

■1200 for conventional heat-resistant alloy skid buttons
The high temperature compression creep deformation at temperatures above .degree. C. is particularly large in the upper part, but the skid button of the present invention has almost no high temperature compression creep deformation, which is less than about A of the conventional skid button. This confirms that the life of the skid button of the present invention can be significantly extended compared to the conventional skid button.

(2) In the skid button of the present invention, the entire outer periphery of the ceramic support aggregate is coated with metal to a required thickness, so the impact resistance, which is a drawback of ceramics, is significantly improved.

Even if the ceramic were to break, it would not be scattered to the outside due to the metal coating layer, so the performance under load would not change. In addition, almost no damage occurred in the actual furnace test.

(2) Furthermore, for the same reason as (2) above, the skid button of the present invention can prevent wear and tear on the ceramics due to oxidized scale on the surface of the heated material and reaction with the atmosphere in the furnace. In addition, in the actual furnace test, no wear and tear due to the reaction of the ceramics was observed.

(2) The skid button of the present invention can be easily fixed to a skid pipe by welding for the same reason as (2) above.

(2) Also, due to the effect explained in (2) above, the skid button of the present invention can be lighter in weight compared to the conventional skid button using ceramics.

Although this experiment was conducted only with Afz03:91% ceramics as the supporting aggregate, other ceramics such as silicon nitride, zirconia, and silicon carbide ceramics may also be used. Well, you may also use alumina award high strength brick. Furthermore, although CO-based metal was used as the coating metal in this experiment, H321,
A heat resistant alloy such as UMCo50.3816 may also be used.

[Brief explanation of the drawing]

Fig. 1 is a front view and center vertical sectional view showing one embodiment of the skid button of the present invention, Figs. 2 (A) to (E) and Figs. This is an illustrative drawing of the shape of ceramics, and FIGS.
3(e) is a cross-sectional view, and FIGS. 3(a) to 3(e) are longitudinal sectional views at the center of the front view. 1 is ceramic, 2 is metal. Patent applicant: Sumitomo Metal Industries, Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) A skid button characterized in that the entire outer periphery of a ceramic supporting aggregate is coated with metal of a required thickness.