JPS6233714A - Skid button - Google Patents

Abstract

PURPOSE:To provide a skid button having an excellent heat insulation characteristic and high-temp. compressive creep strength by forming the outside periphery in the corner part at the bottom end of a heat resistant alloy over the entire surface thereof and forming the remaining part of a heat resistant alloy into which ceramic grains are dispersed and incorporated. CONSTITUTION:The skid button 1 is attached by welding to a pedestal 3 welded atop a skid pipe 2. The bottom end of the skid button 1 is formed of the heat resistant alloy 4 to permit welding and the remaining part is formed of the heat resistant alloy 5 into which the ceramic grains are dispersed and incorporated. The ceramic grains having about 1-5mmphi grain size are used and the content thereof is preferably about 50-80% ratio by volume. The skid button 1 which has the excellent impact resistance and is free from the ceramic wear by reaction is thus 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 rope material to be heated in a high-temperature atmosphere, and therefore require high compressive creep strength at high temperatures.

Therefore, in the past, the materials used were ■UMCo50, MS
-21,5CH13 etc., or CO 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 Skirad 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. ■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 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 caused by breakage and reactions. Ta.

Furthermore, since it is not possible to use welding as a means for fixing a skid button made of ceramic alone onto a skid vibe, 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; This occurs due to the wear and tear of the ceramic due to the reaction with oxidized scale and the atmosphere in the furnace, which is a drawback of single Ceraminx or conventional composite skid buttons with exposed ceramic, and due to the shock load that is applied when the steel material is transferred. This was done to prevent the destruction of ceramics, the scattering of the broken ceramics, etc., and also to prevent 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 that at least the entire outer periphery of the lower end corner portion is made of a heat-resistant alloy, and the remaining part is made of a heat-resistant alloy containing ceramic grains or ceramic rods dispersed therein or a heat-resistant alloy-impregnated ceramic. The gist is the skid button.

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 have better heat insulation properties than metals, that is, have 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 ceramics were used that were at least A or lower than metals.

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, the compressive strength of ceramics is very high, while that of heat insulating materials is small.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. They were smaller and had shorter lifespans.

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 described above.

■ Impact resistance and prevention of wear and tear of ceramics due to reactions As explained above, ceramics have good effects on heat insulation and high-temperature compression creep strength, but as mentioned earlier, this ceramic has It has disadvantages such as being weak against force, 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, at least the entire outer periphery of the lower end corner portion is made of a heat-resistant alloy, and the remaining part is made of a heat-resistant alloy containing dispersed ceramic grains or ceramic rods or a heat-resistant alloy-impregnated ceramic.

Here, the heat-resistant alloy containing dispersed ceramic grains is one in which ceramic grains with a grain size of φ1 to 51 cm are contained inside the heat-resistant alloy, and the content of ceramic grains is 50 to 80% by volume. degree is desirable. The reason why the volume ratio is preferably within this range is that if it is less than 50%, the compression resistance will deteriorate, and if it exceeds 80%, the impact resistance will decrease.

In addition, heat-resistant alloys containing ceramic rods dispersedly include, for example, high-strength dense alloys with a diameter of 51 m or more.
A 10-day-old ceramic rod is placed vertically inside a heat-resistant alloy, and the area ratio of the ceramic rod 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 rod is to receive the 1 ton load, a minimum diameter of 5 tsuru is required, and the maximum diameter Considering impact damage, the limit is about 10 cranes. In addition, the reason why it is preferable that the area ratio is within the range is as follows.
In order to disperse the impact force as much as possible and suppress damage caused by impact, a minimum area ratio of 25% is required, and the maximum is 7%.
The reason why it is set at 5% is that a certain amount of heat-resistant alloy layer is required between the ceramic rods in order to increase the heat insulation effect and to sufficiently restrain the ceramic rods by the impact-resistant material on the outer periphery.

Furthermore, heat-resistant alloy-impregnated ceramics have a three-dimensional skeleton structure and have continuous ventilation holes, for example, a porosity of 60 to 60.
It has a structure in which the ventilation holes of the ceramic foam, which is 80% porous ceramic, are impregnated with a heat-resistant alloy by casting, that is, it has a composite structure of ceramics and metal, and therefore, it can withstand high temperatures compared to heat-resistant alloys, etc. It has good compressive creep strength, and the wear and tear of the ceramic due to oxidation scale and reaction with the furnace atmosphere is significantly reduced compared to the case of ceramic alone.

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. The reason why this porosity is preferable is the same as the reason for the volume ratio of the heat-resistant alloy containing dispersed ceramic grains.

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 size is crane or higher.

(Function) In the skid button according to the present invention, at least the entire outer circumference of the lower end corner is made of a heat-resistant alloy, and the remaining part is made of a heat-resistant alloy containing dispersed ceramic grains or ceramic rods or a heat-resistant alloy-impregnated ceramic. It has excellent heat insulation properties, high-temperature compression creep strength, and impact resistance, and also has no ceramic wear due to reaction.
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.

In the drawings, reference numeral 1 indicates a skid button according to the present invention, and the skid button 1 has a lower end formed of a heat-resistant alloy 4 so that it can be attached by welding to a base 3 welded to the upper surface of a skid pipe 2, for example. However, the remaining portion is made of, for example, a heat-resistant alloy 5 containing ceramic grains dispersed therein. For example, in FIG. 1, the heat-resistant alloy 4 is disposed at the center and lower end portions below the approximately central position in the height direction, respectively.
It has improved impact resistance even at the expense of some degree of heat insulation. Further, in FIG. 2, a heat-resistant alloy 4 is provided only at the lower end, and this is simply to improve weldability. The embodiments shown in FIGS. 1 and 2 are as follows:
In either case, the heat-resistant alloy 4 and the heat-resistant alloy 5 containing ceramic particles dispersed therein can be manufactured by integral casting, so there is no decrease in strength at the boundary between the two heat-resistant alloys 4 and 5. Furthermore, the third
In the figure, the boundary between the two heat-resistant alloys 4.5 is formed into a shape that allows dovetail fitting, and the heat-resistant alloy 5 has ceramic grains cast in a predetermined shape dispersed therein. The purpose is to prevent the heat-resistant alloy 5 containing the ceramic grains dispersed therein from being removed and to improve the weldability of the skid button 1.

FIG. 4 shows a structure in which the outer peripheral side surface of a heat-resistant alloy 7 containing ceramic rods 6 dispersed therein is coated with the heat-resistant alloy 4. As shown in FIG.

In the case of this embodiment, the ceramic grains or ceramic rod 6 exposed on the top surface are thought to pose a problem in terms of impact resistance and prevention of wear and tear of the ceramic due to reaction. If the upper end of 6 is damaged or worn out,
By using the skid button, the heat-resistant alloy surrounding the ceramic grains or ceramic rod 6 will cover the upper end of the ceramic grain or ceramic rod 6, so that damage to the ceramics due to impact or wear due to reactions can be prevented from then on. , there is no problem.

The skid button according to the embodiment shown in FIG. 4 is manufactured as follows.

First, ceramic rods are distributed at required intervals in a mold, and then placed in an electric furnace that can be preheated to, for example, 1,300°C or higher to maintain a heating rate (200° C.) that does not cause thermal shock damage to the ceramic rods. ℃/hr or less).

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, and the upper and lower surfaces of the skid button are slightly machined to produce the skid button shown in FIG. 4.

(Experimental Results) Various types of skid buttons according to the present invention were manufactured with different composition structures and components constituting the skid button 1 of the present invention, and tests were conducted in a heating furnace of an actual furnace. The results are shown in Table 1. For comparison, a skid button made of heat-resistant alloy,
Table 1 also shows the results when using a single ceramic skid button or the like.

The operating conditions for this experiment were 200T Noh crab.

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 A-% 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, it was confirmed that the life of the skid button of the present invention was three times longer than that of the conventional skid button.

(2) Since the skid button of the present invention is mainly composed of a heat-resistant alloy in which ceramic grains or rods are dispersed, or a heat-resistant alloy-impregnated ceramic, the impact resistance, which is a disadvantage of ceramics, is greatly improved. what if,
Even if the ceramic is broken, it will not be scattered to the outside due to the heat-resistant alloy, so the performance against load will 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, there is no need for 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.

■Since the skid button of the present invention has at least the entire outer periphery of the lower end corner portion made of a heat-resistant alloy, it can be easily fixed to the skid pipe by welding.

(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.

Although this experiment was conducted only with alumina-based ceramics, other ceramics such as silicon nitride, zirconia, and silicon carbide ceramics, and alumina-based high-strength bricks were also used. Good too.

In addition, although this experiment was conducted using heat-resistant alloy-impregnated ceramics in which an alumina-based ceramic foam was impregnated with a Co% heat-resistant alloy, countermeasures such as using a zirconia-based ceramic foam to lower the thermal conductivity were used. The heat-resistant alloy may also be coated with Co-based H3
21, UMCO50, 5816, etc., other Co-based, Fe-based, Ni-based heat-resistant alloys may be used.

[Brief explanation of drawings]

1 to 4(a) are front views and central vertical sectional views showing embodiments of the skid button of the present invention, and FIG. 4(b) is a plan view of FIG. 4(a). 1 is a skid button, 4 is a heat-resistant alloy, 5 is a heat-resistant alloy in which ceramic grains are dispersed, 6 is a ceramic rod, and 7 is a heat-resistant alloy in which 6 is dispersed. Patent applicant: Sumitomo Metal Industries, Ltd. Figure 1: Figure 2

Claims (1)

[Claims] (1) A skid button characterized in that at least the entire outer periphery of the lower end corner portion is made of a heat-resistant alloy, and the remainder is made of a heat-resistant alloy containing ceramic grains or ceramic rods dispersed therein or a heat-resistant alloy-impregnated ceramic.