JP2571639Y2 - Skid button for heating furnace - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a skid button which is a member for supporting a steel material to be heated in a heating furnace.

[0002]

2. Description of the Related Art A skid beam, which is a means for transferring a steel material to be heated in a heating furnace, has a structure in which a skid button is attached to a top of a peripheral surface of a skid pipe (carbon steel pipe or the like) at a predetermined interval in a pipe axis direction. I have. In FIG. 3, P is a skid pipe, and 10 is a skid button attached to the pipe P by welding W1. The skid button 10 is made of nickel-chromium alloy steel (SCH 12, SCH 2
2), and is a block having a columnar / frustum shape or a prism / pyramidal shape made of a heat-resistant alloy steel typified by (2), on which a steel material S to be heated is placed in contact. Cooling water is fed into the skid pipe P, and the cooling action of the skid pipe P alleviates the thermal effect of the high-temperature oxidizing atmosphere in the furnace on the skid button 10 and maintains the strength to withstand the load of the steel material to be heated, and the oxidation damage of the surface Try to prevent. Further, on the side peripheral surface of the skid button 10, an irregular refractory layer R for cutting off contact with a high-temperature oxidizing atmosphere in the furnace is provided.
Is usually applied.

[0003]

In recent years, high-temperature operation at 1300 ° C. or higher has become popular for the purpose of improving the operation efficiency of a heating furnace. Along with this, the skid button accelerates the compression deformation due to the load of the steel material to be heated and the oxidative damage of the surface, and the service life is shortened and the maintenance burden is remarkably increased. This reduction in the strength of the skid button and oxidative damage during high-temperature operation can be mitigated to a certain extent by strengthening the forced cooling effect of the cooling water in the skid pipe. The loss of heat in the furnace taken out of the furnace by the cooling water is inevitably increased, and uneven heating of the steel to be heated (so-called skid mark, which is a local low-temperature portion generated on the contact surface with the skid button) is caused. It is inevitable that the quality of the rolling of the steel material deteriorates afterwards.

As a countermeasure, an attempt has been made to use a sintered block of ceramic as a skid button. However, since ceramic is a brittle material, cracks and breakage due to repeated impacts during the operation of transporting the steel to be heated are liable to occur, and there is no practical application yet. The present invention provides an improved skid button for solving the above problems.

[0005]

According to the present invention, there is provided a skid button which is mounted on a skid pipe with a top face as a supporting surface of a steel material to be heated, and an upper block on a top face side, and a lower block which carries this and is fixed to the skid pipe. And the upper block is 70-95 % Cr by weight%.
%, N 0.5-1.5%, with the balance being substantially Fe and a Cr-N-Fe alloy which is an impurity, and the lower block is a block made of a heat-resistant alloy, and the lower block is composed of an upper block. It is characterized in that it is detachably connected to the lower block by screw fitting or the like.

Hereinafter, the present invention will be described in detail. What
In addition, all component contents of the alloy are% by weight. The skid button of the present invention has a laminated structure of an upper block made of a Cr-N-Fe alloy and a lower block made of a heat-resistant alloy. In FIG. 1, reference numeral 20 denotes an upper block;
Is the lower block. The top surface of the upper block 20 is a loading surface on which a steel material to be heated is placed in contact, and the lower block 3
Numeral 0 is applied to the skid pipe P and is fixed by welding W.

[0007] Cr-NF constituting the upper block 20
e alloy is Cr: 70-95%, N: 0.1-1.5
%, The balance is Fe and impurities. The upper block is a block of a cast body obtained by injecting a molten Cr-N-Fe alloy of a predetermined composition by high frequency melting or the like into a mold and solidifying it, or a Cr-N-Fe alloy powder of a predetermined composition as a sintering raw material. And a block of a sintered body manufactured by a hot isostatic pressing sintering method or the like.

The material of the upper block 20 is Cr-N-
The Fe alloy is used because it has a high compressive deformation strength that hardly deforms even under the repetitive action of a high load of a steel material to be heated in a high temperature oxidizing atmosphere exceeding 1300 ° C. This is because they have oxidation resistance that is hardly damaged by oxidation. With regard to the chemical composition, the reason why the Cr content is set to 70% or more is that a high melting point of about 1600 ° C. or more is obtained and the conventional heat-resistant alloy is greatly increased when used in a high-temperature oxidizing atmosphere furnace exceeding 1300 ° C. This is because superior high-temperature strength and outstanding oxidation resistance are secured. The higher the Cr content, the higher the above-mentioned material properties are, but on the other hand, in order to avoid deterioration in castability, sinterability, etc., and to make it difficult to ensure the alloy quality of the block as a cast or sintered body, The upper limit is 95%. The N content of 0.1% or more is because the alloy block has higher compressive deformation resistance and higher rupture strength in a high temperature range, and the upper limit of the content is set to 1%. The reason for setting the content to 5% is to prevent the disadvantage that the melting point of the alloy is lowered due to the excessive addition of N, and the resistance to compression deformation and the strength of the rupture are rather lowered. The impurity (typically, C, Si, etc.) derived from the raw material of the Cr—N—Fe alloy has a high melting point (about 160 ° C.).
0 ° C or more) may be mixed within the range where
For example, the purpose of the present invention is not impaired by the mixture of 0.8% or less of C or 1% or less of Si.

The upper block 20 preferably has a coarse crystal structure (average crystal grain size of about 50 μm or more). This is because the coarser the structure, the higher the high-temperature compressive strength and rupture strength. There is no difficulty in having the upper block 20 have a coarse-grained structure, and in the block of the casting, a sand mold is used for the casting, and relatively slow cooling and solidification is performed. 5-20H at 1300-1600 ° C
r holding) to obtain a coarse-grained structure. In the case of a block of a sintered body, coarse powder (average particle size of about 200 μm or more) is used as an alloy powder,
Alternatively, a coarse-grained structure can be obtained by performing the same heat treatment as described above after sintering.

The high-temperature characteristics of the Cr-N-Fe alloy block 20 are determined by using a high-Co Cr-Ni alloy steel (40Co-27Cr-17N) which is a conventional typical skid button material.
Compared with i-Fe), for example, a high temperature compression test (temperature:
1350 ° C, vertical load: 0.5 kgf / mm ² , time:
50%) Deformation speed D% / Hr [deformation amount D% =
(L ₀ −L) / L ₀ × 100 (%), L ₀ : height of the specimen before the test, L: height of the specimen after the test] is about 0.5 to About 0.04 to 0.6% / Hr
0.06% / Hr and extremely high compression deformation resistance,
In addition, high temperature oxidation test (temperature: 1350 ° C, time: 100H
r, atmosphere: air), oxidation loss (g / m ² hr)
Is about 3 g / m ² compared to about 70 g / m ² hr of the conventional material.
hr and outstanding oxidation resistance.

The material of the lower block 30 supporting the upper block 20 is not special, but is a heat-resistant alloy conventionally used as a skid button material, for example, SCH.
12 (0.2 to 0.4C-8 to 12Ni-18 to 23C
r-Fe), SCH22 (0.35-0.45C-19)
~ 22Ni-23 ~ 27Cr-Fe) or 0.0
7-0.15C-15-19Ni-25-29Cr-3
It is sufficient to use a cast block made of 8-42Co-Fe alloy steel or the like.

The upper block 20 and the lower block 30 are connected by a detachable connection method such as screw fitting. In the example shown in FIG. 1, the upper block 20 has a male screw 21 projecting downward at the center of the lower surface thereof, and a female screw 31 is formed in the lower block 30 in correspondence with the male screw 21. Stably connected and fixed. The male screw and the female screw formed on the upper block 20 and the lower block 30 may be turned upside down.

The superposed surface of the upper block 20 and the lower block 30 carrying the upper block 20 may be a horizontal plane, but as shown in the figure, is a substantially mortar-shaped slope that descends from the peripheral edge toward the center. This increases the stability of the seating posture of the upper block 20 with respect to the lower block 30, and is effective in preventing horizontal displacement of the upper block 20 and damage of the connecting portion when a horizontal load is applied to the upper block 20. is there. The same applies to a substantially umbrella-shaped slope that is inclined downward from the center toward the peripheral edge, in the opposite direction to the illustrated one.

The skid button of the present invention may optionally include an upper block 20 and a lower block 30 as shown in FIG.
A heat-insulating material layer 40 for suppressing heat transfer between the blocks is interposed on the superposed surface of the above. The heat insulating material layer 40 can be formed of, for example, a ceramic fiber felt, an asbestos felt, or the like, and its layer thickness may be about 2 to 5 mm.

The height of the skid button of the present invention, which comprises an upper block 20 and a lower block 30 and in which a heat insulating material layer 40 is interposed between the overlapping surfaces thereof, if desired, is approximately 100 to 100, similar to the conventional skid button. It may be 200 mm. The thickness ratio of the upper block 20 to the lower block 30 in the height direction may be about 3: 7 to 7: 3.

The skid button of the present invention has, for example, the same external appearance as a conventional cylinder or truncated cone, or a prism or truncated pyramid, except for having the above-mentioned laminated structure. The mode in which the irregular-shaped refractory layer 50 is applied to the side peripheral surface while being fixed to P is not different from the conventional one.

[0017]

The skid button of the present invention has a top surface of Cr.
-N-Fe alloy block 20, so that
Even in a high-temperature oxidizing atmosphere exceeding 300 ° C., there is no need to apply strong forced cooling to the top surface as in the past, and if the operating temperature is about 1350 ° C., the forced cooling to the top surface is omitted. I can do it. The lower block 30 has a forced cooling action from the skid pipe,
Since it is protected from the high-temperature oxidizing atmosphere in the furnace by the amorphous refractory layer 50, the upper block 20 is stably supported even with a block made of a conventional heat-resistant alloy. A heat insulating material layer 40 is provided at the interface between the upper block 20 and the lower block 30.
The upper block 20 can be easily maintained at a high temperature while sufficient forced cooling is applied to the lower block 30. Further, since the upper block 20 and the lower block 30 have a laminated structure, when replacing the skid button, only the upper block 20 needs to be replaced.

[0018]

[Effect of the Invention] The skid button of the present invention can be used more stably than a conventional skid button in a high-temperature oxidizing atmosphere furnace, and can suppress and alleviate the forced cooling on the top side of the button. Can be reduced, more uniform heating can be achieved, and the quality of the steel material to be heated can be improved. Further, as a forced cooling moderating effect, the amount of heat loss brought out of the furnace by the cooling water is reduced, and effects such as improvement in thermal economy are obtained. Furthermore, since the skid button of the present invention has a detachable laminated structure of the upper block and the lower block, the replacement of the skid button can be performed by replacing only the upper block.
It is economical with less waste of material, and replacement work is easy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a conventional skid button.

[Explanation of symbols]

20: upper block, 21: male screw, 30: lower block, 31: female screw, 40: heat insulating material layer, 50: amorphous refractory layer, P: skid pipe.

Claims (2)

(57) [Scope of request for utility model registration] 1. A skid button mounted on a skid pipe having a top face as a supporting surface of a steel material to be heated, comprising: an upper block on a top face side; and a lower block supporting the same and fixed to the skid pipe, wherein the upper block has a weight. %, Cr 70-95%, N
0.5-1.5%, balance Fe and impurity Cr-
A heating furnace comprising: a block made of an N-Fe alloy; a lower block made of a heat-resistant alloy; and an upper block and a lower block detachably connected by screw fitting or the like. For skid button. 2. The skid button for a heating furnace according to claim 1, wherein a heat insulating material layer is interposed between the superposed surfaces of the upper block and the lower block.