JPH0243316A - Skid button for walking beam type heating furnace and production thereof - Google Patents

Abstract

PURPOSE:To provide the skid button having high strength and high toughness at a low production cost by constituting the base part of the button of a heat resistant alloy block having an upward projection and forming a top surface part of a pressurized and sintered body composed of ceramics and a heat resistant alloy to clad the upward projection. CONSTITUTION:A skid pipe is provided in a heating furnace. The base part 11 of the button is fixed by welding to the surface of the skid pipe 1. The top surface part 13 of the button to carry steel products to be heated is mounted to the upper part thereof. The base part 11 is constituted of the heat resistant alloy block and is provided with the upward projection 12. The top surface part 13 is formed to clad the projection 12 and is constituted of the hot hydrostatically pressurized and sintered body of the uniform mixture composed of the ceramics and the heat resistant alloy. The skid button having the high strength and high toughness is produced at the low production cost in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a skid button that is attached to a skid pipe for forming a fixed beam and a moving beam of a walking beam for conveying heated steel materials in a heating furnace, and its manufacture. Regarding the method.

[Conventional technology]

Steel material to be heated in the steel heating furnace (tlii 1 piece, slab, etc.)
The fixed beam and moving beam that make up the walking beam conveyor for conveying the materials from the inlet side to the outlet side of the furnace are made of heat-resistant alloy steel skid pipes (as shown in Fig. 5).
1) and skid buttons (10) fixed at regular intervals on the top surface thereof. The pipe (1) and the button (10) have the cooling effect of the cooling water flowing through the pipe (1) and the atmosphere inside the furnace due to the monolithic refractory layer (2) coated on the outer circumferential surface of the pipe (1). It is protected from the high temperature atmosphere (approximately 1200 to 1350°C) inside the furnace by the insulation and insulation effect.

Since the skid button (10) has a steel frame on which the heated steel material is supported on its top surface, it needs to have high-temperature strength and toughness that can withstand the high load and mechanical shock of the heated steel material. Insulation properties that prevent reaction at the contact surface with the steel material, so-called buildup, and prevent skid marks (localized low temperature areas caused by heat being taken away from the steel material through the contact surface with the skid button) on the steel material. etc. are required.

Recently, attempts have been made to use ceramic as the skin topotan instead of the conventional heat-resistant copper alloy. Specifically, there are two methods: using a ceramic sintered block in a predetermined shape as a skid button, and using a mixture of ceramic powder and heat-resistant alloy powder as a build-up material, and using plasma powder welding etc. to attach a skid button to the skid pipe surface. Methods of overlaying buttons have been proposed.

[Problem to be solved by the invention]

When using a block of ceramic sintered body as a skid button, unlike the conventional skid button made of heat-resistant alloy steel, it cannot be attached to a skind pipe by welding. ) and
There is no choice but to put this over the skid button (10) and weld the metal fitting (3) to the skind pipe (1). However, since the thermal expansion coefficients of ceramic and metal are significantly different, the thermal expansion and contraction of the skid button (ceramic) due to temperature changes during use in the furnace is restricted by the presser metal fitting (3), resulting in cracking and chipping. There is a problem in that it is easy to occur. It is extremely difficult to fix the ceramic skid button with a presser metal fitting so that it does not wobble and is not restricted by thermal expansion and contraction.

In addition, the ceramic skid button is manufactured one by one through compaction of raw ceramic powder and sintering treatment, so the manufacturing efficiency is extremely low. Moreover, attaching each of them to the skid pipe with strict dimensional accuracy using the holding metal fittings as described above requires extremely troublesome and inefficient work.

On the other hand, the method of forming a skid button on the skinned pipe surface using a mixture of ceramic powder and heat-resistant alloy powder as overlay material does not have the problems with installation as in the case of using the ceramic sintered block described above, but on the other hand, ,
Due to the construction shape, thermal management that takes into account the occurrence of thermal stress due to localized heat input is important, and there is a drawback that production efficiency is low.

The present invention has been made to solve the above-mentioned problems regarding skid buttons.

[Means and effects for solving the problems] The skid button of the present invention consists of a button base that is fixed to the surface of a skind pipe by welding, and a button top surface that supports the heated steel material on the upper part of each button base, The button base is a heat-resistant alloy block having upward protrusions, and the button top is formed by hot isostatic pressing of a homogeneous mixture of ceramic and heat-resistant alloy, which is formed by encompassing the upward protrusions of the button base. It is characterized by being a pressed sintered body.

The skid button of the present invention will be described with reference to drawings showing embodiments. In FIG. 1, (11) is a button base, and (13) is a button top surface formed on the top thereof. The button base (11) has an upward projection (12) on its upper surface.
), and the bottom part is a block of heat-resistant alloy with an arcuate surface that roughly matches the circumferential surface of the skid pipe, and the button top part (13) has an upward protrusion (
12) is a composite sintered body made of ceramic and a heat-resistant alloy formed by hot isostatic pressing sintering. The shape and size of the skid button (10), which consists of the button base (11) and the button top (13), are not particularly different from conventional ones, nor do they need to be different.

The upward protrusion (
12) is the button base (11) and the button top part (13)
In addition to stabilizing and strengthening the bonding relationship with the top of the button (
13) It has the effect of increasing the high temperature compressive strength.

The material of the button base is CO-based alloy steel (for example, UMCo), which is similar to that of conventional heat-resistant alloy steel skid buttons.
-50 equivalent) or Co-Ni alloy steel (e.g. 2
7Cr-17Ni-40Co alloy), etc.

The composite sintered body that is the button top portion (13) has a composite structure in which ceramic particles are uniformly mixed as a dispersed phase in a heat-resistant alloy matrix. Since the composite sintered body is a hot isostatic pressed sintered body, unlike a button which is formed as a weld build-up layer, restrictions on the amount of ceramic compounded are loose, and the composite structure is rich in ceramic particles. The combined effects include high-temperature strength that can withstand high loads on the heated steel, build-up resistance with little reactivity with the heated steel, and good properties to prevent skin marks on the heated steel. It provides excellent insulation properties, etc. A preferable example of the heat-resistant alloy that is a component of the composite sintered body is C.
o-based alloy, especially Cr: 25-30%, Ni: 15-1
9%, Fe: 16% or less, C: 0.2% or less, Si: 2
% or less, the remainder being substantially C.

Examples of ceramics that are dispersed phase particles include chromium carbide (Cr3C2), zirconia (ZrOz), alumina (A l 203), titania (T i O□), silicon carbide (S iC ) etc. Among the above ceramics, especially Cr, C2ZrO
7, At203 is a suitable dispersed phase particle having excellent high temperature stability, dispersion strengthening effect, etc. When using Cr5Cz as the ceramic particles, it is preferable that the proportion included in the composite structure be 50% by weight or more in order to obtain a sufficient dispersion effect. The dispersion effect will be enhanced as the proportion increases, but if it exceeds 90% by weight, the toughness of the sintered body will become poor and the high temperature compressive strength will tend to decrease, so 90% by weight is the upper limit. It is better. A1□03 and Z
When rO2 is used, its proportion in the composite structure to ensure the dispersion effect is preferably 5% by weight or more, but even if it exceeds about 50% by weight, the effect will not increase much.
Furthermore, the upper limit should be 50% by weight, since cracks and chips are likely to occur due to a decrease in the toughness of the composite sintered body.

The method for manufacturing the skid button of the present invention includes forming a set of a plurality of button bases (11) each having a predetermined shape made of a heat-resistant alloy and having an upward protrusion formed on the upper surface, and dividing the button bases (11) between adjacent side surfaces of the button bases (11). loading the ceramic sheet (20) into the capsule (30) as a button base assembly;
The upper space in the capsule (30) loaded with the button base assembly is divided into spaces for each button base using a ceramic sheet, and a button top surface is formed in each divided space. A mixed powder (P) of ceramic and heat-resistant alloy is filled as a sintering material, degassed and sealed, and then subjected to hot isostatic pressure sintering. After sintering is completed, the capsule material is removed and the button is sealed. It is characterized by being divided into a plurality of skin button buttons (10) consisting of a base portion (11) and a button top portion (13) formed as a composite sintered body above the base portion (11).

To explain the above manufacturing method with reference to the drawings, the second
The figure shows a set of button bases (11) made of a heat-resistant alloy that have been pre-processed into a predetermined shape, and the button bases are stacked together with dividing ceramic sheets (20) interposed between their adjacent sides. An example of an aggregation is shown. FIG. 3 shows the capsule (30) loaded with a set of button bases (11) as an assembly (lla) as described above. The capsule (30) is made of a metal material (such as heat-resistant steel) that will not crack or break during hot isostatic pressing and sintering, and the button base (11, 11, . . .
The upper space (the sintering raw material filling space for forming the button top part) of the assembly (11a) of the buttons is divided into spaces for each button base using dividing ceramic sheets (20°20,...). A mixture (P) of ceramic and heat-resistant alloy, which is a sintering raw material powder, is filled into each divided space. In the figure, the upper part of the ceramic sheet (20, 20, . . . ) interposed between the adjacent side surfaces of the button base (ILIL...) is extended vertically to form each button base (11, . . . ).
The sintering material powder is divided into spaces for each IL...) and filled with sintering raw material powder. Ceramic Sea) (20) is the fusion between the adjacent side surfaces of each button base (11) in the hot isostatic pressing sintering process, and the fusion between the adjacent side surfaces of the button top surface (13) formed as a sintered body. It forms a release layer to prevent the side surfaces from sticking to each other and to facilitate the division of each skin to potion after sintering. Examples of the material include vapor, felt, etc. made of ceramic mainly composed of zirconia. Blankets etc. are used. Note that if a ceramic sheet lining (20) is provided on the inner surface of the capsule (30) and its lid (31) as shown in the figure, the capsule material (30) after the hot isostatic pressure sintering treatment is ) (31)
can be easily removed.

As described above, the button base assembly (
11a) and the sintered raw material powder (P) for forming the top surface of the button are canned, covered with a lid material (31), the inside of the capsule is vacuum degassed and sealed, and then subjected to hot isostatic pressure sintering treatment. .

The sintering process is suitably achieved by holding at a temperature of about 1450 to 1600° C. and a pressure of about 300 to 600 kg/crM for an appropriate period of time (for example, about 1 to 5 Hr). By this hot isostatic pressure sintering process, a button top surface portion (13), which is a composite sintered body, is formed on the top surface of each button base portion (11, 11, . . . ) in the capsule. After the sintering process is completed, the capsule material is removed by machining and the ceramic sheet (20) is used as a dividing interface to separate the button base (11) and button top (13) as shown in FIG. A plurality of skin topotans (10) which are integrally joined products are obtained.

In the above explanation, it is assumed that a plurality of button bases (11) are accumulated and loaded into the capsule (30), but instead, as shown in FIG. A button base base material (l
lb) can also be used.

This is loaded into a capsule (30), and the upper space inside the capsule is divided into spaces for each planned button base using a ceramic sear (20), and sintered raw material powder (P) is prepared.
is filled and sintered to form a button top portion (13) which is a composite sintered body separated by ceramic sheets (20, 20, . . . ). After the sintering is completed, the capsule material is removed, the button base base material (llb) is cut along the planned cutting line (42), and the ceramic sheet (20) layer is separated between the adjacent button tops. By dividing into planes, a plurality of skid buttons (lO) can be obtained at the same time in the same way as above.

The manner in which the skid button of the present invention is attached to the skid pipe is the same as that of the conventional one, and is attached at regular intervals in the axial direction of the tube, and is made of an irregular shape such as castable for covering and protecting the pipe surface and the button base. A skid beam is completed by applying a refractory layer (2) as shown in FIG.

〔Effect of the invention〕

Since the base of the skin topotan of the present invention that comes into contact with the skid pipe is made of a metal material, it can be attached to the skid pipe by welding, and the installation using a presser metal fitting is cumbersome and difficult. There are no problems with cracking or chipping related to the use of the presser metal fittings. In addition, the top surface of the button on the side that the heated steel comes into contact with is a hot isostatically pressed sintered body that is highly dense and uniform and contains plenty of ceramic particles, so it can withstand high loads from the heated steel. It has high strength and toughness to withstand impact, as well as build-up resistance and good heat insulation properties necessary to prevent skid marks on heated steel materials. Further, according to the method of the present invention, a large number of skid buttons can be manufactured simultaneously through a cycle process consisting of loading button bases and sintering raw materials into capsules, followed by hot isostatic pressure sintering. The manufacturing efficiency is extremely high, and the manufacturing cost can be significantly reduced compared to manufacturing each item individually.

[Brief explanation of the drawing]

Fig. 1 (1) is a perspective view showing an example of the skin topotan of the present invention, [■] and [■] are respectively a sectional view in the tube diameter direction and a sectional view in the tube axis direction of Fig. 1 [I], and Fig. 2 3 is a perspective view showing a button base accumulation state in an example of the present invention, and FIGS. 3 and 4 are sectional views showing a canning state of the button base and sintering raw material into a capsule in the present invention, respectively,
Fig. 5 [I] is a cross-sectional view in the pipe diameter direction showing the conventional skid button and its attachment to the skind pipe;
) is a sectional view in the axial direction of the pipe, and FIG. 6 is a sectional view in the radial direction of the pipe showing another example of a conventional skid button and its attachment to the skid pipe. 10: Skinned Hotan, 11:
Button base, 13: Button top 20: Ceramic seam), 30: Capsule, 1 varnished pipe, 2: Monolithic refractory, 3: Holding metal fitting.

Claims (1)

[Scope of Claims] 1. Consisting of a button base fixed to the surface of the skid pipe by welding, and a button top portion on which the heated steel material is supported on the upper part of the button base, the button base has an upward protrusion. The button top portion is a hot isostatically pressed sintered body of a homogeneous mixture of ceramic and a heat-resistant alloy formed to encompass the upward protrusion of the button base. A skid button for walking beam heating furnaces. 2. A plurality of button bases of a predetermined shape made of heat-resistant alloy with upward protrusions formed on the upper surface are made into a set, and a dividing ceramic sheet is inserted between the adjacent sides of the button bases to form a capsule as a button base assembly. A button base base material, in which upward protrusions are formed at predetermined intervals on the top surface of a long block made of a heat-resistant alloy, is loaded into the capsule or cut and separated into a plurality of button bases. The upper space in the capsule loaded with the button base assembly or the button base base material is divided into spaces for each button base using a ceramic sheet, and a button top part is formed in each divided space. After filling the mixed powder of ceramic and heat-resistant alloy as sintering material, degassing and sealing, it is subjected to hot isostatic pressure sintering treatment. After sintering, the capsule material is removed and the button base and 2. The method of manufacturing a skid button according to claim 1, wherein the skid button is divided into a plurality of skid buttons each having a button top portion formed as a composite sintered body on the top thereof.