JPS6233715A - Skid button - Google Patents

Abstract

PURPOSE:To provide a skid button having excellent heat resistance and high- temp. compressive creep strength by coating the entire surface on the outside periphery in the bottom end corner part of supporting skeleton consisting of a heat resistant alloy and ceramics with the heat resistant alloy and the entire periphery in the remaining part of the outside periphery with an impact resistant material, respectively. CONSTITUTION:High strength and dense Al2O3 rods each having about 5-10mm diameter are bundled and are subjected to insert casting by the heat resistant alloy to form the supporting aggregate 1 having about 25-75% area rate of the Al2O3 rods. The entire surface on the outside periphery in the bottom end corner part of such aggregate 1 is coated with the heat resistant alloy 3 and the entire surface in the remaining part on the outside periphery is coated with the impact resistant material 4. The thickness of the impact resistant material 4 is made about 0.5-2.0cm and the coating is preferably applied on the top surface as well. The skid button which has the excellent impact resistance strength and prevents the wear of the ceramics in this obtd.

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, the conventional materials were 00MCO50, H3
-21,5CH13 etc., or C0 group or Ni-
Skid buttons made of Cr-based heat-resistant alloys, single ceramics, or composites of solid ceramics and metal were 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. cause it to happen. There are drawbacks such as.

The latter skid button was proposed in order to eliminate this former drawback, that is, to increase compressive creep strength at high temperatures without producing skid marks, but conventional ceramics alone or composites of ceramics and metal were proposed. The type of skid button has a structure in which the ceramic is exposed on the surface in contact with the steel material to be heated (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. ■There may be a height difference in the skid button height due to the T scallop due to use,
Furthermore, if the steel material is warped, an impact load will be applied to the skid button during transfer of the steel material, which will cause the ceramics to break and scatter. There are drawbacks such as.

By the way, according to the inventor's half-year in-furnace tests, with conventional skid buttons made of ceramic alone or with exposed ceramics, no ceramic remained on the skid pipe at the end of the test due to wear and tear due to breakage and reactions. There wasn't.

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 for the purpose of preventing breakage, scattering of the broken ceramics, etc., and further preventing (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 support aggregate made of a composition of ceramics and a heat-resistant alloy. This is a skid button that basically consists of:

Here, the composition of ceramics and heat-resistant alloy refers to a composition in which ceramic grains are dispersed in a heat-resistant alloy, a ceramic rod assembly cast in a heat-resistant alloy, or a ceramic impregnated with a heat-resistant alloy.

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 steel skid marks. Therefore, the skid button of the present invention has good heat insulation properties by using ceramics as the main component, which has better heat insulation properties than metals, that is, has low thermal conductivity and excellent high temperature compression resistance. You get it. 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 ceramics as the main component of the support aggregate, it is desirable that the area occupation ratio of 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 less than 0.1%, while heat insulating materials have a porosity of more than 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 main component of 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 lower end corner of the ceramic, which is the main component of the supporting aggregate, is made of a heat-resistant alloy.
In addition, the entire remaining outer periphery is coated with an impact-resistant material.

Here, the type of impact-resistant material covering the skid button is not limited in any way, but may include a heat-resistant alloy, a heat-resistant alloy containing dispersed ceramic grains, or
Ceramics impregnated with heat-resistant alloys are preferred. Further, the impact-resistant material may be made of the same material for the entire covering portion, or may be made of a different material for part of the covering portion. For example, the upper part of the skid button is particularly marked by high-temperature compression creep deformation, or
The upper and lower parts are coated with heat-resistant alloy-impregnated ceramics,
Others are coated with a heat-resistant alloy.

That is, the heat-resistant alloy-impregnated ceramic is a porous ceramic having a three-dimensional skeleton structure and continuous vent holes, for example, with a porosity of 60 to 80%. Because it is an impregnated structure, that is, a composite structure of ceramics and metal, it has better high-temperature compression creep strength than heat-resistant alloys, etc., and is also more resistant to oxidation scale and reaction with the furnace atmosphere than ceramics alone. This is because the wear and tear on the ceramics caused by this process is significantly reduced.

The ceramic foam of the heat-resistant alloy-impregnated ceramic used in the skid button of the present invention has a porosity of 6.
0 to 80% is desirable. That is, if it is less than 60%, the impact resistance decreases, and if it exceeds 80%, the compression resistance deteriorates.

The heat-resistant alloy containing dispersed ceramic grains is:
For example, ceramic grains having a grain size of φ1 to φ51u are contained inside a heat-resistant alloy, and the content of the ceramic grains is preferably about 50 to 80% by volume. The reason why the volume ratio is preferably within this range is that if it is less than 50%, the compression resistance
This is because the heat insulation properties deteriorate, and if it exceeds 80%, the impact resistance decreases.

In addition, the above-mentioned assembly of ceramic rods cast in a heat-resistant alloy is, for example, a high-strength dense A1t03
It is made by bundling rods with a diameter of 5 fl to 10 mm and casting them in a heat-resistant alloy, and the area ratio of the ceramic rods in this case is preferably about 25 to 75%. In other words, assuming that the load that each skid button receives is approximately 1 ton, and considering the worst case scenario, if one ceramic bar is to receive the load of 1 ton, a minimum diameter of 5 mm is required, and a maximum diameter The limit is about 10m if impact damage is taken into account. In addition, the reason why it is preferable to keep the area ratio within the above range is that a minimum area ratio of 25% is required in order to disperse the impact force as much as possible and suppress damage caused by impact, and the reason why the maximum area ratio is 75% is because the insulation This is because a certain amount of heat-resistant alloy layer is required in order to increase the effectiveness and to sufficiently restrain the bundled ceramic rods by the impact-resistant material on the outer periphery.

The thickness of the impact-resistant material layer on the top surface of the skid button is 0.5~
It is desirable that it be within the range of 2.Q cm.

This is 2. If Qcm is exceeded, the impact-resistant material 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 impact-resistant material layer will not be exhibited.

Note that, in consideration of the covering properties of the impact-resistant material layer, it is desirable that the corners of the 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 the person is at least 30 years old.

(Function) The skid button according to the present invention uses ceramics as the main component of the supporting aggregate, and the entire outer periphery of the lower end corner of the supporting aggregate is made of a heat-resistant alloy, and the entire remaining outer periphery is made of an impact-resistant material. Since it adopts a covered structure, it has excellent heat insulation, high temperature compression creep strength, and impact resistance, and there is no wear and tear on the ceramics due to reaction, and it can be welded to skid pipes, making installation easy. .

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

FIGS. 1 and 2 are front views and central vertical cross-sectional views showing one embodiment of the skid button according to the present invention, and numeral 1 in the figures is the supporting aggregate of the skid button of the present invention.

The supporting aggregate 1 is made of a composition of ceramics and a heat-resistant alloy, and in this embodiment, a large number of ceramic rods 2 are bundled and cast in a heat-resistant alloy. The entire outer periphery of the lower end corner portion of the support aggregate 1 is made of heat-resistant alloy 3, and
The entirety of the remaining outer periphery is coated with an impact-resistant material 4, respectively.

In the case of this example, the impact-resistant material 4 is coated only on the side surface of the outer peripheral part, and the upper surface is not coated, but it is of course better to coat the upper surface with the impact-resistant material 4 as well. It is.

In the case of this example, the ceramic rod 2 exposed on the top surface is considered to have problems in terms of impact resistance and prevention of wear and tear of the ceramic due to reaction, but if the upper end of the ceramic rod 2 were to be damaged or If the ceramic rods 2 are worn out, the heat-resistant alloy that is cast around the ceramic rods 2 will cover the upper ends of the ceramic rods 2 by using a skid button, so that damage to the ceramic rods due to impact or wear due to reactions cannot be prevented from then on. , there is no problem. In addition, in the figure, 5 is a pedestal, and 6 is a heat insulating material.

The skid button according to this embodiment is manufactured as follows.

First, a large number of ceramic rods are bundled and set in a mold, and this is placed in an electric furnace that can be preheated to, for example, 1,300°C or higher, so that the ceramic rods are subjected to thermal shock...at a heating rate that does not cause damage (200°C/hr (below).

After holding the temperature at 1300° C. for 2 hours in this manner, for example, a CO-based heat-resistant alloy melted in a separate furnace is cast from the upper part of the electric furnace at a temperature of 1500° C.

After cooling, the mold is dismantled to obtain supporting aggregate.

Next, the supporting aggregate is set in the mold, and the heat-resistant alloy is cast in the same order as described above. After cooling, the mold is dismantled, and the top and bottom surfaces of the skid button are slightly machined. The skid button according to this example is manufactured by applying the following steps.

3 and 4 are front views and center vertical cross-sectional views showing other embodiments of the skid button according to the present invention. The remaining structure is the same as the embodiment shown in FIGS. 1 and 2 above. In addition,
In the embodiment shown in FIG. 4, the upper surface of the supporting aggregate 1 is coated with, for example, ceramics 7 impregnated with a heat-resistant alloy.

(Experimental Results) Various types of skid buttons according to the present invention were manufactured by varying the structures, components, etc. of the support aggregate 1, heat-resistant alloy 3, and impact-resistant material 4, and tests were conducted in an actual heating furnace. The results are shown in Table 1. For comparison, Table 1 also shows the results when heat-resistant alloy skid buttons, single ceramic skid buttons, etc. were used.

In addition, the operating conditions for this experiment were ■Nokani 200T [ Ta.

As is clear from Table 1, the superiority 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 following effects.

■The average thermal conductivity of the skid button of the present invention is -% of that of 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 No skid marks occur,
There is no need to reheat the material to be heated at the outlet of the heating furnace 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 about 2 or less compared to the conventional skid button. As a result, the life of the skid button of the present invention is more than three times that of the conventional skid button.
I was able to make an Lp.

(2) In the skid button of the present invention, the entire outer periphery of the support aggregate, which is mainly composed of ceramics, is coated with an impact-resistant material and a heat-resistant alloy, so the impact resistance, which is a disadvantage of ceramics, is greatly improved. Even if the ceramic were to break, it would not be scattered to the outside due to the coating layer, and therefore the performance under load would not change. In addition, almost no damage occurred in the actual furnace test.

■Since the skid button of the present invention has ceramics integrated with a heat-resistant alloy and impact-resistant material, it can be used as fired without requiring any processing required for joining ceramics, etc., resulting in cost reduction. The cost of the product of the present invention was reduced by about 5% compared to the conventional product.

(2) For the same reason as (2) above, the skid button of the present invention can prevent wear of 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 the skid vibe by welding for the same reason as (2) above.

(2) Also, due to the effect described in (2) above, the skid button of the present invention can be approximately 20% lighter than the conventional skid button using ceramics.

■Since the skid button of the present invention has ceramics completely isolated from the external atmosphere, it is possible to use ceramics with poor high-temperature oxidation resistance. In addition, the strength of the coating material can depend on ceramics as long as it has sufficient heat resistance, so it is possible to remove ceramics and coating materials in any combination depending on the purpose of use, eliminating restrictions in terms of materials. Become.

Although this experiment was conducted only with alumina ceramics as the main component of the support aggregate, other ceramics, such as silicon nitride, zirconia, and silicon carbide ceramics, as well as alumina with high strength Bricks etc. may also be used. In addition, in this experiment, as an impact resistant material,
We tested heat-resistant alloy-impregnated ceramics, which are alumina-based ceramic foam impregnated with a Co-based heat-resistant alloy, and ceramics that use a Co-based heat-resistant alloy. In addition, heat-resistant alloys are not limited to Co-based H321, UMC050, 5816, etc., but also other C-based alloys.
O-based, Fe-based, or Ni-based heat-resistant alloys may also be used.

[Brief explanation of the drawing]

FIG. 1 is a front view and central vertical sectional view showing one embodiment of the skid button of the present invention, FIG. 2 is a similar plan view, and FIGS. 3 and 4 are front views showing other embodiments of the skid button of the present invention. This is a longitudinal sectional view at the center of the figure. ■ is supporting aggregate, 2 is ceramic rod, 3 is heat-resistant alloy, and 4 is impact-resistant material. Patent applicant: Sumitomo Metal Industries, Ltd. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A skid button characterized in that the entire outer periphery of the lower end corner of a support aggregate made of a composition of ceramics and a heat-resistant alloy is coated with a heat-resistant alloy, and the entire remaining outer periphery is coated with an impact-resistant material. .