JPH01258A - Conveyance roll for high temperature steel materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a roll disposed in a heat treatment furnace for annealing and conveying steel plates, which particularly has high-temperature wear resistance and build-up prevention effect. The present invention relates to a conveyor roll for high-temperature steel materials (hereinafter referred to as hearth roll) that has excellent adhesion to the hearth roll base, does not peel off, and has excellent high-temperature strength.

(Prior art) For example, a hearth roll disposed in a heat treatment furnace has a diameter of 600 mm.
The material to be heat treated is continuously annealed for a long time in an oxidizing or reducing atmosphere temperature of ~1300°C, and the surface is abraded due to conveyance, and the oxides and iron powder attached to the material to be heat treated may be deposited on the roll surface. It adheres and accumulates to form what is called a build-up.

When such unevenness due to wear and build-up occurs on the hearth roll, the steel plate, which is the material to be heat treated, is scratched while being transported, causing a decrease in quality. In order to prevent this kind of deterioration in the quality of steel sheets, after periodically suspending operations and cooling the inside of the heat treatment furnace, workers enter the furnace to perform grinding and maintenance on the surface of the hearth rolls, or to clean the rolls themselves. I am replacing the .

For this reason, heat-resistant alloys containing high chromium and high nickel have been improved for hearth roll materials, or
As described in Japanese Patent No. 7-29549, etc., the roll surface has been coated with ceramic such as zirconia or alumina by thermal spraying.

(Problem to be solved by the invention) However, even improvements in heat-resistant alloys are not effective in preventing build-up caused by cohesive accumulation of iron oxide powder, and the thermally sprayed coating layers of zirconia and alumina cannot be used in high-temperature environments. When used in the interior, the interparticle strength within the coating layer deteriorates and the coating itself peels off, which is why it is not fully satisfactory in preventing build amplifiers.

The inventors have discovered that ZrO□-Y! 0. System roll material and 1V
The zoi-Crt03 series roll material has excellent high-temperature strength and is effective in preventing build-up.
The present inventors took this idea a step further and applied it to a hearth roll used in an oxidizing or reducing atmosphere. As a result of research and examination of roll coating materials, we discovered a coating material that has a build-up prevention effect, excellent adhesion to the hearth roll base, does not peel off, and has excellent high-temperature strength, and completed the present invention. .

That is, when the present invention is used in an oxidizing or reducing atmosphere, it has excellent high-temperature abrasion resistance and build-up prevention effect, has excellent adhesion to the hearth roll base, and does not peel off. It is an object of the present invention to provide a hearth roll having a coating layer formed on the roll surface which also has excellent high-temperature strength.

(Means for solving the problems) The present invention provides ZrOg-Ajg (h-Cr2O3-YzO
The object of the present invention is to provide a conveyor roll for high-temperature steel materials in an annealing furnace that has a ceramic coating made of a :+-based solid solution material and has excellent high-temperature wear resistance and build-up prevention.

The present invention will be described in detail below.

The base of the hearth roll is made of heat-resistant cast steel.

Zr(h-Ajg(h-Crz(h-
It is formed using a Y2O3 solid solution raw material by thermal spraying.

In the present invention, ZrO□- to 1zOx-C is added to the coating raw material.
rz03-Y, 0. ZrO was used as the solid solution raw material.
This is because □ has excellent heat insulation properties and a high coefficient of thermal expansion among ceramics, and is advantageous for coating metal substrates. It is possible to change the crystal morphology of □ from monoclinic to tetragonal to alleviate temperature-induced deposition changes, and furthermore, M2O3 and CrzO.

This is because it forms a complete solid solution throughout the entire region, so it has excellent crystal stability at high temperatures.

The inventors have discovered that Zr0z4tOs and Altos-Cr2
10-4 obtained by electrically melting O3-based materials with various compositions
As a result of plasma spraying powder with a particle size of 0 μ- and investigating the morphology of the crystal structure of these quaternary systems,
It has been found that the crystal structure of the plasma sprayed coating is ZrO, a cubic single phase. That is, ZrO, is '1tOz
, l'Jzos and Cr,02 are completely stabilized as a solid solution, creating a new cubic Z
r0g, and as a result, it was thought that even higher heat resistance, high temperature strength, and build-up resistance could be expected.

The metal components of the bond coat layer and cermet layer of the thermally sprayed coating are made of heat-resistant alloys such as CoCrAjY and N1CrAjY, as well as Ni-Cr alloys, etc.
4. It is possible to improve releasability. Further, as for the construction method, in addition to the usual gas plasma method, water plasma method, and air plasma method, a reduced pressure plasma method and an explosive thermal spray method may be used.

Examples are given below, and ZrOg-Vz(h-Crz(h
The coating with -YzO+ type material will be explained in detail.

The test equipment used in the occlusion experiment is shown in Figures 1 and 2.5
A half-moon pressure roll 6 with a radius of 35 mm made of CH22 (25Cr-2ONi-0,4C) was manufactured, and it was rolled back and forth over each of the two thermally sprayed samples 4.4' that had been thermally sprayed as shown in Table 1. An evaluation device was used that could reproduce the occurrence of build-up by sliding. Two thermal spray samples 4.4' are 30 days x 50 songs x
5 Crane-sized SuS substrates 4 and 4' were sprayed on one side, and a build-up raw material 5 ( Fe3
0. Iron oxide powder such as

These devices are placed in a pot-type electric furnace 2, and N2
-4 at a constant temperature of 850°C in a reducing atmosphere of 5% lit.
The pressure roll 6 is reciprocated for a period of time to cause build-up to occur.

In the figure, 1 is an atmospheric gas introduction pipe, 7 is a pressurizing rod, 8 is a weighted material, 9 is a counterbalance, 10 is a seal plate,
11 is a speed reducer.

In the above reproduction test, as shown in FIG. The occurrence of F' amplifier was compared using the build-up resistance index as shown in Table 2, and the sum of the respective evaluation points.

In addition, the build-up resistance of the sprayed samples was evaluated based on the average value of Fe, which is a build-up source, and the 0.0 adhesion area ratio.

Table 2 Build-up resistance index The build-up resistance test results are shown in Table 3. The products of the present invention (■~@) shown in Table 1 also have a higher build-up resistance index than the comparative materials (Φ~■). It was found that the adhesion area ratio of Pe*Oa powder was also small, indicating excellent build-up resistance.

In addition, the products of the present invention include PJ, O, film (■), CrzO
It was also confirmed that the film did not peel off during the test unlike the x film (■) and had good spalling resistance. This is /V
2O3, CrJs+ Zr0z with Y2O2 as a solid solution
This is thought to be due to the fact that the cubic crystal system is resistant to volume changes such as thermal expansion and contraction and is stable.

On the other hand, by incorporating a large amount of AJz(h, crz(h) into solid solution, the reaction resistance to Fe-0wlde is extremely low (
, it was found that it was difficult to react with Fe-Oxide.

Note that CoCrVY type bond coat was used for all the thermal sprayed samples.

In order to investigate the high temperature wear resistance of the hearth roll material for continuous annealing furnaces, the following experiment was conducted. As shown in Figure 3 < 5u
A test roll 12 having a diameter of 120 fins and a body length of 100 cranes was prepared using s3ios as a material, and its surface was coated by thermal spraying with various materials shown in Table 4 to a thickness of 0.3 to 0.51 mm. This was heated to 850°C by the heating element 13 in an oxidizing atmosphere and a reducing atmosphere.
The high-temperature wear resistance was investigated by bringing the steel plate 14 into rotating contact with the steel plate 14 under its own weight at the end fulcrum I5.

The wear amount of each thermal spray roll was measured using a stylus roughness meter, and the results are shown in Table 5.

Comparative materials Zr (h (■), jV2O3 (■) and Z
rO, -3%'1tos (■), 50%AhOz-5
Compared to 0% Cr1es (■), the products of the present invention (■ to 0) have extremely excellent wear resistance.

This is due to the high hardness of kltos+ Cr2O2 and Zr0z
This is presumed to be due to the combination of high toughness of the system and the ability to overcome the brittleness of the ceramic coating microstructure.

The compositions of the Zr02-A/z03-Cr2O2-YzOt-based coating materials subjected to the build-up resistance test and the high-temperature abrasion resistance test are shown in Table 6 and in the ternary phase diagram of FIG. 4.

(Effects of the Invention) As shown in the examples above, the hearth roll of the present invention has excellent high-temperature abrasion resistance and build-up resistance, and has excellent adhesion to the hearth roll base, does not peel off, and has excellent high-temperature strength. It is also excellent and greatly contributes to extending the life of the roll.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of the build-up test evaluation apparatus and method, Figure 3 is an explanatory diagram showing the outline of the wear resistance evaluation test apparatus, and Figure 4 is the build-up resistance test in Example 2, Zr(h-/'Jz0) subjected to high-temperature wear resistance test
FIG. 3 is a ternary phase diagram showing the composition of a 3-CrzOi-YzCh-based coating material. 4.4'... Thermal spray sample, 5... Buildup raw material,
6... Pressure roll, 12... Thermal spray test roll, 1
4...Contact steel plate. Figure 1

Claims (1)

[Claims] ZrO_2-Al_2O_3-Cr_2O_3-Y_2
A conveyor roll for high-temperature steel materials in an annealing furnace that has a ceramic coating made of O_3 solid solution material and has excellent high-temperature wear resistance and build-up prevention.