JPH01255643A - Composite material for supporting member for material to be heated in heating furnace - Google Patents

Abstract

PURPOSE:To prevent the occurrence of high-temp. compressive deformation, skid marks, and wear by using ceramics in the form of powder or fiber of a specific grain size and also specifying the kind and content of the above ceramics in a composite material of sintered compact in which ceramics is dispersed in a heat-resisting alloy. CONSTITUTION:This composite material for supporting member is a composite material of sintered compact in which ceramics consisting of one or more kinds among AlN, TiN, Al2O3, and SiO2 and composed of powder or fiber of <=100mu grain size is uniformly dispersed in a Co- or Ni-base alloy or a ferrous heat- resisting alloy by 10-<50vol.%. In the above composite material, when ceramics content is >=50%, a striking energy-absorbing capacity is deteriorated and the segregation of ceramics grains is brought about, and, on the other hand, a compounding effect is insufficient when it is <10%. Further, when the size of the ceramics grains exceeds 100mu, sufficient high-temp. compressive strength cannot be produced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is suitable for use as a skid button, skid rider, or in-furnace roll that is a member to support a heated body in a heating furnace for hot rolling or steel heat treatment. , relates to a sintered composite material in which ceramics are dispersed in a heat-resistant alloy.

<Prior art> Generally, a heating furnace support member for holding a heated object such as a slab in a heating furnace is rotated at 900° to ensure stable operation of the furnace.
High-temperature compression resistance, oxidation resistance, high-temperature scale reactivity resistance, impact resistance, and abrasion resistance at temperatures exceeding C are required.

Conventionally, heat-resistant alloys have been mainly used for these heated object support members for heating furnaces. It had internal water cooling.

However, such cooling increases the energy loss of the heating furnace and further reduces the temperature of the contact surface between the heated object and the heating furnace support member, forming low-temperature spots called skid marks, which cause the heated material to deteriorate. This made uniform heating difficult.

In recent years, in order to solve this problem, attention has been focused on the heat resistance, heat insulation properties, etc. of ceramic materials, and it has been proposed to utilize them as a member to support a heated body in a heating furnace.

However, ceramics generally have poor mechanical or thermal shock properties and are easily broken, and ceramics such as SiC and Si3N, which have high strength at high temperatures, react with the scale of slabs at high temperatures and vitrify. This has the problem of cracking and wear and tear.

Therefore, in order to take advantage of the advantages of ceramics and heat-resistant alloys, research is being conducted on applying composite materials in which a large amount of ceramics (50 to 90% by volume) is uniformly dispersed in a heat-resistant alloy as a support member for heated objects in heating furnaces. (For example, see Japanese Patent Application Laid-Open No. 60-200948).

However, as is known from cemented carbide, cermet materials, etc., composite materials containing a large amount of ceramics have the problem of low toughness despite high hardness, and the heating furnace cannot be supported by the impact from the heated material. This may cause cracks in the component, peeling of the ceramic, etc., and damage to the surface of the heated material.

Therefore, it is of extremely important industrial significance to develop a material that satisfies the required characteristics of the heated object support member for a heating furnace described above.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems of the conventional heated object support members for heating furnaces, namely: (1) generation of high-temperature compression deformation and skid marks, which are disadvantages of heat-resistant alloy skin topotans, (2) Problems such as wear and tear of ceramics due to reactions with oxidized scales that occur in support members for heated objects in heating furnaces made of single ceramics or composite materials of heat-resistant alloys and ceramics, as well as cracking and damage caused by shock loads applied by heated materials. This is an attempt to resolve the issue.

Means for Solving the Problems> In order to solve the above-mentioned problems in a heated object support member for a heating furnace, the present invention incorporates jV N + T in a Co-based alloy, Ni-based alloy, or iron-based heat-resistant alloy. f N * /
V! 031 SiO The gist of this paper is a composite material for body support members.

In the case of the material of the present invention, the ceramic content in the sintered body has a significant effect on its properties. As the ceramic content increases, dislocation loops increase due to particle dispersion, and the strength increases, and the hardness of the sintered body also increases due to the hardness of the ceramic itself.

However, if the ceramic content exceeds 50% by volume, the amount of the soft heat-resistant alloy that forms the matrix decreases, reducing the impact energy absorption ability and making it difficult to fill enough heat-resistant alloy particles between the ceramic powder particles. , local segregation of ceramic particles occurs. This causes deterioration of fracture toughness and thermal shock properties. On the other hand, if the ceramic content is less than 10% by volume, the effect of containing the ceramic will not be sufficiently reflected in the properties of the sintered body. Therefore, in the case of the present invention material, the ceramic content is 10
- Less than 50% by volume.

Considering the improved wettability with ceramics due to Ni, heat resistance, and oxidation resistance of the heat-resistant alloy used in the present invention,
Co-based alloys, Ni-based alloys, iron-based heat-resistant alloys, etc. are preferred,
The powder particle size is desirably 200 or less in order to enable uniform mixing of ceramics and improve mechanical properties.

Further, as a result of various studies, it has been found that nitride ceramics such as Aj N and T t N and oxide ceramics such as Aj t Os are effective as the ceramics used. The ceramic particle size is preferably 100 μm or less. It is known that if the particle size exceeds 100 μm, sufficient high-temperature compressive strength cannot be obtained.

The lower limit of the ceramic particle size is not limited in any way,
In order to improve strength and toughness, it is desirable to reduce the particle size as much as possible. However, if the particle size is less than 0.5 μm, it becomes necessary to take measures to prevent secondary powder agglomeration and oxidation, which makes handling of the powder complicated. Therefore, considering economic efficiency, the lower limit is 0.5 μm. It is desirable to do so.

The composite material for supporting members to be heated in a heating furnace of the present invention is manufactured by kneading and adjusting the raw material powders of heat-resistant alloy and ceramics, granulating them to an appropriate particle size as necessary, and then performing a sintering process. As for the sintering process, there is no problem in using the conventional method of pressure forming and sintering, but it is preferable to use the hot isostatic pressure sintering method (hereinafter referred to as HIP sintering method), which is a hot pressure sintering method. ) and r.

This is done by extrusion or pultrusion sintering. H
In the case of IP sintering method, the temperature is 1150°C or higher and the pressure is 80°C.
Good results can be obtained by processing under conditions of MPa or more and retention time of 1 hour or more.

The sintered composite material thus obtained exhibits excellent compressive strength, scale reactivity resistance, and low thermal conductivity at high temperatures, and is suitable as a composite material for a member to support a heated body in a heating furnace.

<Example> The production and high-temperature characteristics of the sintered composite material for a member to be heated according to the present invention will be explained with reference to an example.

■ Manufacture of sintered composite materials The heat-resistant alloy serving as the matrix has the composition shown in Table 1, and C.

-Ni -Cr-Fe system, Fe-Cr-Ni system and Ni
-Cr-based heat-resistant alloy was used. The powder particle size used was one having an average particle size of 63 μm or less. A7 to these heat-resistant alloys
One or both of N, TiN, and M2O3 were added at various volume mixing ratios.

Table 2 shows the composition of the composite material.

After thoroughly mixing the above powder, it was fired by HIP sintering method. The HIP sintering method is shown in FIG.

First, (a) the mixed powder 3 is filled into a mild steel or stainless steel capsule 1 (container), (b) it is degassed and evacuated through the deaeration hole 2 attached to the capsule, and (c) the deaeration hole 2 is Seal by pressure welding, welding, etc. Then HI the capsule
A sintered body was obtained by charging the product into a P apparatus and subjecting it to HIP treatment under conditions of 1150°C or higher and 1500 atm.

Samples Nα (1) to (8) in Table 2 are the composite sintered bodies, samples Nα (9) and 00) are comparative materials made using the sintering method, and sample Nα (10 is made by the casting method). It is a conventional material.

A high temperature compression test, a scale reactivity evaluation test, and a workability evaluation test were conducted on these 11 types of test materials.

Furthermore, the thermal conductivity of some of the test materials was measured.

■ High temperature compression test A 12φ x 21L (nu++) test piece was heated to 1300°C5.
Uniaxial pressure was applied at a crosshead speed of 0.5 mm/min in an air atmosphere. The 0.2% yield strength obtained at this time was defined as the compressive yield strength (kgf/■shi). As shown in Table 2, the compressive yield strength of the material of the present invention at 1300°C increased from 1.9 times to more than 6.3 times compared to the conventional material. Therefore,
By applying the present invention material to skid buttons, for example, it is possible to prevent the reduction in height due to deformation of skid buttons during use, which occurs with conventional materials, and it is also possible to supply skid buttons with a higher height than conventional materials. Become. on the other hand,
Despite being the same composite sintered material, comparative material sample N
As shown in o and Q■, when the ceramic grain size was large, the high temperature compression yield strength was lower than that of the conventional material.

■ Scale reactivity evaluation test φ8×3L (n+m) on a 12φ×5L (body) test piece
5341M material was left still as a mating material and heated to 1300°C1.
It was left in an air atmosphere for 2 hours. In Table 2, when the mating material was peeled off by hand after cooling, it was marked as ○, and when it was peeled off using a tool, it was marked as △. It was found that the material of the present invention has scale reactivity resistance equal to or higher than that of the conventional material.

■ Thermal conductivity measurement table 2: Inventive material: Sample Nα (4) and conventional material: Sample No.
.

The thermal conductivity of (11) was measured by the laser flash method. As shown in the results in Figure 2, sample N, which is the material of the present invention,
α(4) has a thermal conductivity of approximately % at 1000°C compared to conventional materials. This means that by applying the material of the present invention to, for example, a skid button, it is possible to improve the heat insulation properties of the skid button and to suppress a decrease in the temperature of the heated object that comes into contact with the surface of the skid button.

■ Electric discharge machinability evaluation test Generally, ceramic-containing composite materials have a hard ceramic part and a soft metal or alloy part.
It is considered to be a difficult-to-process material, and electrical discharge machining is more desirable than cutting tool machining.

φ60X100L (Pink) test material 15 mm in the radial direction.

Electric discharge machining was performed under the condition of 50A. × if a crack of 0.5 mm or more depth occurs on the cut surface after electrical discharge machining; Δ if a conduction failure occurs; no crack occurs, or if it occurs, the depth is within 0.5 mm, and It was set as O when there was no conduction defect. In the case of the materials of the present invention, the electric discharge machinability was good in all cases, but deep cracks occurred in the comparative material Sample Nα (9), and poor conductivity occurred in the comparative materials Samples No. and Oω. did.

Generally for skid button material in heating furnace, 1
It is required that the surface pressure at 300°C is 0.1 to 0.2 kgf/- or more. Sample Nα of the present invention material (
In the case of 1) to (8), the high temperature compressive yield strength at 1300°C is 4.0 to 13.2 kgf/- or more, which satisfies the required high temperature compressive strength better than that of conventional products. The scale reaction resistance is also superior to conventional materials, making it extremely useful for use as a material for skid buttons. On the other hand, comparative material sample No. (9) has high high-temperature strength, but its toughness deteriorates due to the high ceramic content of 70% by volume, and even a slight thermal shock such as during electrical discharge machining causes large racks. Put it away. Also, the comparison material No.
Although Oω exhibits good scale reactivity resistance, it only exhibits a high-temperature compressive yield strength that is lower than that of conventional materials.Furthermore, it is dotted with large ceramic particles with an average grain size of 295 μm, which has inferior conductivity to metals or alloys, which induces conductivity failure. However, the electrical discharge machinability deteriorates. Therefore, it can be seen that these comparative materials are unsuitable as materials for skid buttons.

<Effects of the Invention> As described above, since the sintered composite material of the present invention has excellent high-temperature compressive strength, it is possible to hold a tall skid button in a heating furnace for a long period of time, which makes it possible to maintain a high skid button in a heating furnace. The service life can be made longer than conventional products. In addition, the radiant heat in the heating furnace can be evenly supplied to the heated object, and the excellent heat insulation properties can suppress the local temperature drop of the heated object due to cooling of the skid button, so that the heated object can be heated uniformly. It has become possible to reduce skid marks, which were a major problem with skid buttons using conventional materials, and the quality of the heated object has improved. Furthermore, the high heat insulation properties reduce heat loss within the furnace, resulting in significant energy savings.

[Brief explanation of the drawing]

Figures 1 (a) to (d) are schematic diagrams of the HIP sintering method for creating sintered composite materials, and Figure 2 shows the thermal conductivity of the inventive material and conventional material measured by the laser flash method. It is a figure showing a result. 1... Metal capsule, 2... Deaeration pipe, 3...
Metal-ceramic mixed powder. Figure 1 (a) (b) (c)
(d) 3-go" Crane, Serami, 7-gu Jinchiu Pass end 2nd figure profit degree ('C)

Claims (1)

[Claims] A in Co-based alloy, Ni-based alloy, or iron-based heat-resistant alloy.
One of lN, TiN, Al_2O_3, SiO_2
A composite material for a member to support a heated body in a heating furnace, characterized in that it is a sintered composite material in which 10 to less than 50% by volume of ceramics consisting of one or more kinds of powders or fibers of 100 μm or less are uniformly dispersed. .