Member for apparatus to be used in bath

Abstract

To provide a member for an apparatus to be used in a bath, the member being excellent in terms of sliding wear resistance and cracking resistance.SOLUTION: A member for an apparatus to be used in a bath, which receives sliding wear caused by a rotating operation in a molten metal plating bath, wherein a build-up layer is formed on the surface of the member. The build-up layer comprises a matrix part containing at least Cr and C, with the balance being Fe and unavoidable impurities, and hard particles dispersed within the matrix part. The component composition of the matrix part contains 3.0 mass% to 15.0 mass% inclusive of Cr, and 0.5 mass% to 5.0 mass% inclusive of C. The hard particles contain at least one substance selected from the group consisting of tungsten carbide, chromium carbide, titanium carbide, niobium carbide, and vanadium carbide. When the build-up layer is taken as 100 mass%, the content of the hard particles is 1 mass% to 50 mass% inclusive.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a member for a bath-immersed equipment that is subjected to sliding wear due to rotational movement in a molten metal plating bath. [Background technology]

[0002] Hot-dip metal coated steel sheets are produced by a process in which a steel strip passes through a snout, enters a molten metal bath contained in a pot, has its passing direction changed upward by a sink roll, is guided by support rolls, and is carried out of the molten metal bath, where the coating thickness is adjusted by a gas wiping nozzle, and is then cooled. Hereinafter, rolls such as sink rolls and support rolls that are used by being immersed in a metal bath are also referred to as bath rolls.

[0003] The shaft member of the bath roll (hereinafter also referred to as the roll shaft member) is rotatably supported by a bearing in the metal bath. The roll shaft member rotates while immersed in the metal bath and in contact with the bearing, and therefore receives sliding resistance from the bearing. Therefore, in order to use the bath roll for a long period of time, excellent sliding wear resistance and crack resistance are required.

[0004] Patent Document 1 discloses a roll shaft member for use in a hot-dip metal coating bath, which includes a metal base, a first weld buildup layer made of a cobalt-based alloy formed on the metal base, and a second weld buildup layer made of a cobalt-based alloy formed on the first weld buildup layer, wherein the second weld buildup layer has a higher hardness than the first weld buildup layer, the second weld buildup layer contains a plurality of tungsten carbide particles, and at least some of the tungsten carbide particles contained in the second weld buildup layer are at least a portion of at least some of the tungsten carbide particles added to a welding material forming the second weld buildup layer that have once dissolved in the cobalt-based alloy and then precipitated.

[0005] Patent Document 2 discloses a bath-immersed equipment component used in a molten metal bath in a continuous hot-dip metal plated material manufacturing apparatus, the bath-immersed equipment component having a coating layer provided on at least a portion of the surface of the bath-immersed equipment component, the coating layer comprising hard particles and a matrix that holds the hard particles, the matrix being a cobalt-based alloy containing Co as a main component, the hard particles being at least one element selected from the group consisting of tungsten carbide, ditungsten carbide, chromium carbide, titanium carbide, and niobium carbide, or granules obtained by granulating the element using a binder, and the hard particles having an average shape factor of 1.55 or less, the shape factor being expressed as the area of the smallest circle that encompasses the projected shape of the hard particles divided by the area corresponding to the projected shape of the hard particles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-101273 [Patent Document 2] Japanese Patent Application Publication No. 2018-40022 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a member for bath equipment that is excellent in sliding wear resistance and crack resistance. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a bath-immersed equipment component (1) that is subject to sliding wear due to rotational movement in a molten metal plating bath, characterized in that a buildup layer is formed on the surface of the bath-immersed equipment component, the buildup layer comprising a matrix portion containing at least Cr and C with the remainder being Fe and unavoidable impurities, and hard particles dispersed within the matrix portion, the matrix portion having a component composition of Cr: 3.0% by mass to 15.0% by mass, and C: 0.5% by mass to 5.0% by mass, the hard particles containing at least one selected from the group consisting of tungsten carbide, chromium carbide, titanium carbide, niobium carbide, and vanadium carbide, and the content of the hard particles is 1% by mass to 50% by mass when the buildup layer is taken as 100% by mass.

[0009] (2) The component for bathing equipment described in (1) above, characterized in that the component composition of the matrix portion further contains at least one selected from the group consisting of Mo: 0.5 mass% or more and 10.0 mass% or less, Co: 0.5 mass% or more and 10.0 mass% or less, and V: 0.5 mass% or more and 10.0 mass% or less.

[0010] (3) The component for bath equipment according to (2) above, characterized in that the content of Mo in the matrix portion is greater than the content of Co and V.

[0011] (4) A member for bath equipment according to any one of (1) to (3) above, characterized in that the hard particles have an average particle size of 5 μm or more and 200 μm or less.

[0012] (5) The bath equipment member according to any one of (1) to (3) above, characterized in that the hard particles are two types of particles: tungsten carbide and titanium carbide.

[0013] (6) The component for bath equipment according to (4) above, characterized in that the hard particles are two types of particles: tungsten carbide and titanium carbide.

[0014] (7) A component for bath equipment described in any one of (1) to (3) above, characterized in that the buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, the shaft sleeve attached to the roll shaft portion of the sink roll, the shaft sleeve attached to the roll shaft portion of the support roll, the bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and the bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll.

[0015] (8) The buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, the shaft sleeve attached to the roll shaft portion of the sink roll, the shaft sleeve attached to the roll shaft portion of the support roll, the bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and the bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll, as described in (4) above.

[0016] (9) The buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, the shaft sleeve attached to the roll shaft portion of the sink roll, the shaft sleeve attached to the roll shaft portion of the support roll, the bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and the bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll, as described in (5) above.

[0017] (10) The component for bath equipment described in (6) above, characterized in that the buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, the shaft sleeve attached to the roll shaft portion of the sink roll, the shaft sleeve attached to the roll shaft portion of the support roll, the bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and the bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a member for bath equipment that is excellent in sliding wear resistance and crack resistance. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of a molten metal plating facility. [Figure 2] FIG. 2 is a schematic cross-sectional view of a sink roll. [Figure 3] FIG. 2 is a schematic cross-sectional view of a shaft sleeve and a buildup layer. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1 shows a schematic configuration of a molten metal plating facility, which includes a pot 11, a sink roll 13 (corresponding to a bath roll), and a support roll 14 (corresponding to a bath roll). The pot 11 stores molten metal M. The molten metal M may be, for example, molten zinc, molten aluminum, molten Zn—Al, molten Al—Si, or the like. The sink rolls 13 are disposed in the molten metal M and change the conveying direction of the steel sheet A. The support rolls 14 are provided at positions that sandwich the steel sheet A, stabilizing the passing position of the steel sheet A and leveling the thickness of the coating.

[0021] After immersion in the molten metal M, the steel sheet A is turned by a sink roll 13, and after the coating thickness is leveled by a support roll 14, it is carried out to the outside of the pot 11.

[0022] Fig. 2 is a schematic cross-sectional view of a sink roll, and Fig. 3 is a schematic cross-sectional view of a shaft sleeve and a cladding layer.

[0023] The sink roll 13 includes a roll body 131, roll shafts 132 formed on both ends of the roll body 131, and shaft sleeves 133. The support roll 14 has the same configuration as the sink roll 13 in that it includes a roll body, a roll shaft, and a shaft sleeve. In the following description, the sink roll 13 may be read as the support roll 14.

[0024] The base material of the roll body 131 and the roll shaft 132 is not particularly limited and can be appropriately selected from known steel materials depending on the strength and other characteristics required of the sink roll 13. For example, the sink roll 13 can be made of stainless steel such as SUS316L.

[0025] The shaft sleeve 133 is formed in a cylindrical shape and disposed in a position covering the outer peripheral surface of the roll shaft portion 132. The roll shaft portion 132 is rotatably supported by a bearing portion (not shown) via the shaft sleeve 133. The sink roll 13 is rotated in the direction of the arrow (see FIG. 1) around the roll shaft portion 132 as a rotation axis, whereby the steel sheet A can be transported in and out of the molten metal M.

[0026] The buildup layer 133a can be formed on bath-immersed equipment components that are subject to sliding wear due to rotational movement in the molten metal plating bath. Specifically, the buildup layer 133a can be formed on the shaft sleeve 133 of the sink roll 13 and the bearing portion that supports the shaft sleeve 133. When the roll shaft portion 132 of the sink roll 13 is directly supported by the bearing portion, the buildup layer 133a may be formed on the roll shaft portion 132. Moreover, a buildup layer may be formed on the shaft sleeve of the support roll 14 and on the bearing portion that supports this shaft sleeve. When the roll shaft portion of the support roll 14 is directly supported by the bearing portion, a buildup layer may be formed on the roll shaft portion.

[0027] The buildup layer 133a will be described in detail below. In this embodiment, it is assumed that the buildup layer 133a is formed on the shaft sleeve 133 of the sink roll 13. The buildup layer 133a is made up of a matrix portion and hard particles contained in the matrix portion.

[0028] The matrix portion is made of an alloy (hereinafter also referred to as a predetermined alloy) containing at least Cr and C, with the remainder being Fe and unavoidable impurities. The matrix portion is an alloy that functions as a matrix that holds hard particles. The hard particles are dispersed within the matrix portion. By forming the matrix portion from a predetermined alloy, the sliding wear resistance and crack resistance of the matrix portion are improved. The predetermined alloy will be described in detail. In the following description, % means mass % unless otherwise specified.

[0029] (basic ingredients) The matrix portion of the present invention contains 3.0% to 15.0% of Cr, 0.5% to 5.0% of C, and the balance being Fe and unavoidable impurities.

[0030] Cr:3.0% or more and 15.0% or less Cr combines with C to form chromium-containing carbides, improving sliding wear resistance. If the Cr content is less than 3.0%, this effect cannot be fully achieved. On the other hand, if the Cr content exceeds 15.0%, the amount of coarse Cr carbides increases, which reduces toughness and may lead to cracking, which is undesirable. The Cr content is preferably 6.0% or more and 10.0% or less.

[0031] C: 0.5% or more and 5.0% or less C combines with Cr and optional elements (Mo, V) described below to form carbides, improving sliding wear resistance. If C is less than 0.5%, the formation of carbides effective for improving sliding wear resistance is low. On the other hand, if C exceeds 5.0%, excessive carbide formation occurs, which may reduce toughness and cause cracking, which is undesirable. The C content is preferably 1.0% or more and 3.5% or less.

[0032] The basic components have been described above, but the preferred component composition of the matrix portion can contain the following elements as needed.

[0033] (optional ingredient) A preferred component composition of the matrix portion further contains at least one selected from the group consisting of Mo: 0.5% to 10.0%, Co: 0.5% to 10.0%, and V: 0.5% to 10.0%. All of these are optional components, and the scope of the present invention also includes a matrix portion containing at least one selected from the group consisting of Mo: 0.0% to less than 0.5%, Co: 0.0% to less than 0.5%, and V: 0.0% to less than 0.5%.

[0034] Mo: preferably 0.5% or more and 10.0% or less Like Cr, Mo bonds with C to form hard carbides containing molybdenum, further improving sliding wear resistance. If Mo is less than 0.5%, this effect cannot be fully exerted. On the other hand, if Mo exceeds 10.0%, the amount of carbides becomes excessive, which reduces toughness and may cause cracking, which is undesirable. The Mo content is more preferably 2.0% or more and 5.0% or less.

[0035] Co: preferably 0.5% or more and 10.0% or less Co has the effect of further improving high-temperature hardness and sliding wear resistance. If the Co content is less than 0.5%, this effect cannot be fully exerted. On the other hand, if the Co content exceeds 10.0%, the toughness decreases and cracking may occur, which is not preferable. The Co content is more preferably 1.0% or more and 3.0% or less.

[0036] V: preferably 0.5% or more and 10.0% or less V combines with C to form hard vanadium-containing carbides, further improving sliding wear resistance. If V is less than 0.5%, this effect cannot be fully exerted. On the other hand, if V exceeds 10.0%, toughness decreases and cracking may occur, which is undesirable. The V content is more preferably 1.0% or more and 3.5% or less.

[0037] Here, the content of Mo is preferably greater than the content of Co and greater than the content of V. This makes it possible to more effectively improve the sliding wear resistance. In this case, the content of Mo is preferably 3.5% or more.

[0038] Components other than those mentioned above are Fe(Bal) and unavoidable impurities.

[0039] The Vickers hardness of the matrix portion is preferably 500 HV or more, more preferably 600 HV or more. If it is less than 500 HV, the wear resistance of the matrix portion is low, and localized wear may occur. There is no particular upper limit, but if the hardness is equal to or higher than that of the hard particles, the toughness is low and cracking is expected. In this way, by increasing the sliding wear resistance and hardness of the matrix portion, it is possible to suppress localized wear caused by the low sliding wear resistance of the matrix portion.

[0040] The hard particles contain at least one selected from the group consisting of tungsten carbide, chromium carbide, titanium carbide, niobium carbide, and vanadium carbide. Tungsten carbide, titanium carbide (TiC), and vanadium carbide (VC) are hard particles that improve the sliding wear resistance of the buildup layer 133a. Tungsten carbide includes WC and W2C. Chromium carbide is a hard particle that relieves the internal stress of the buildup layer 133a. 23 Includes C6, Cr7C3, and Cr3C2. Niobium carbide (NbC) is a hard particle that improves the lubricity of the buildup layer 133a.

[0041] The hard particles are preferably made of two types of materials, tungsten carbide and titanium carbide. By using two types of hard particles, tungsten carbide and titanium carbide, the sliding wear resistance can be further improved.

[0042] The average particle size of the hard particles is preferably 5 μm or more and 200 μm or less, and more preferably 30 μm or more and 180 μm or less. If the average particle size of the hard particles is 5 μm or less, the hard particles will not disperse well and may not mix with the alloy in the matrix, reducing the effectiveness of improving sliding wear resistance. If the average particle size is 200 μm or more, the distance between the hard particles in the matrix increases, reducing the effectiveness of improving sliding wear resistance. In other words, even if the hard particle content is the same, if the average particle size of the hard particles exceeds 200 μm, the distance between the hard particles increases, causing the matrix to wear, reducing the effectiveness of improving sliding wear resistance.

[0043] The thickness of the buildup layer 133a is preferably 0.1 mm or more and 5 mm or less. When the buildup layer 133a is taken as 100%, the content of hard particles is preferably 1% or more and 50% or less, and more preferably 5% or more and 30% or less.

[0044] The average particle size of the hard particles can be determined by the following method. For hard particles with an average particle size of 45 μm or more, the average particle size is calculated by sieving. Sieving is performed using a sieve specified in JIS Z 8801, and the mass of the hard particles remaining on each sieve is measured, after which a cumulative distribution graph is created. From this graph, the particle size at 50% of the cumulative value is read and this can be used as the "average particle size." For hard particles with an average particle size of less than 45 μm, the average particle size is calculated using the air permeability method. When air is passed through a packed bed of hard particles (powder), the finer the hard particles, the more difficult it is for the air to flow through. The specific surface area of a powder can be calculated using the correlation between the particle size of the hard particles and their fluid permeability. Because the average area and particle size are functions of pressure, the average particle size of hard particles can be determined by passing air through a powder bed consisting of hard particles packed into a sample tube and measuring the pressure drop and flow rate. For example, the average particle size can be determined using a fully automatic dry particle size measuring device (Subsieve Auto Sizer).

[0045] The buildup layer 133a can be formed by powder plasma welding or laser welding.

[0046] (Example) The present invention will be specifically described with reference to examples. Welding materials consisting of the chemical compositions of samples 1 to 37 in Table 1 were welded onto the outer periphery of a test specimen substrate simulating a shaft sleeve made of SUS316L stainless steel. Using the PTA (powder plasma welding) method, circumferential buildup welding was performed, forming a buildup layer approximately 3 mm thick on the substrate surface. The plasma arc current was 150 to 180 A, the plasma arc voltage was 22 to 26 V, the feed rate was 9 to 13 cpm, and the interpass temperature was 150 to 200°C. The buildup welding (circumferential direction) was performed by gradually shifting the roll axially so that the entire surface was covered. The hard particle content was approximately 25%. The Vickers hardness of the matrix was 500 HV or higher in all samples, lower than that of the hard particles. For hard particles with an average particle size of 45 μm or larger, the average particle size was calculated using the sieving method described above. For hard particles with an average particle size of more than 45 μm, the average particle size was calculated using a fully automatic dry particle size measuring device (Subsieve Auto Sizer) manufactured by Shimadzu Science East Japan Co., Ltd.

[0047] (Method for evaluating the life of roll shaft components) Test pieces simulating the shaft sleeve material were placed in test equipment simulating a hot-dip galvanizing line and used for the specified periods of time. The specified periods were 10, 20, 30, and 40 days. After the specified periods had elapsed, the test pieces simulating the shaft sleeve material were visually inspected for wear and cracks.

[0048] (Sliding wear resistance) If wear was observed after 10 days, the sliding wear resistance was deemed to be extremely poor and rated D. If wear was observed after 20 days, the sliding wear resistance was deemed to be fairly good and rated C. If wear was observed after 30 days, the sliding wear resistance was deemed to be good and rated B. If no wear was observed after 40 days, the sliding wear resistance was deemed to be extremely good and rated A.

[0049] (About crack resistance) If cracking was observed after 10 days, the cracking resistance was deemed to be extremely low and was rated D. If cracks were observed after 20 days, the crack resistance was deemed to be fairly good and rated as C. If cracks were observed after 30 days, the crack resistance was deemed to be good and rated as B. If no cracks were observed after 40 days, the crack resistance was deemed to be extremely good and rated as A.

[0050] (Evaluation results) When there were no Ds in the evaluations of sliding wear resistance and cracking resistance, the sample was evaluated as passing (Examples). When there was even one D in the evaluations of sliding wear resistance and cracking resistance, the sample was evaluated as failing (Comparative Examples). [Table 1]

[0051] Even when the actual machine of the embodiment receives strong sliding resistance from the bearings during use, the occurrence of wear and cracking can be suppressed, thereby extending the life of the roll shaft members and enabling stable production of hot-dip metal-plated steel sheets. [Explanation of symbols]

[0052] 11 pot 13 Sync Roll 14 Support Roll 131 Roll body 132 Roll shaft 133 Shaft sleeve 133a Overlay layer M Molten metal

Claims

1. A bath equipment component that is subjected to sliding wear due to rotational movement in a molten metal plating bath, A build-up layer is formed on the surface of the submerged equipment component, The buildup layer includes a matrix portion containing at least Cr and C, with the balance being Fe and unavoidable impurities, and hard particles dispersed inside the matrix portion, The matrix portion has a component composition of Cr: 3.0 mass % or more and 15.0 mass % or less, and C: 0.5 mass % or more and 5.0 mass % or less, the hard particles contain at least one selected from the group consisting of tungsten carbide, chromium carbide, titanium carbide, niobium carbide, and vanadium carbide; When the buildup layer is 100% by mass, the content of the hard particles is 1% by mass or more and 50% by mass or less. A component for bath equipment characterized by:

2. the matrix portion further contains at least one selected from the group consisting of Mo: 0.5% by mass or more and 10.0% by mass or less, Co: 0.5% by mass or more and 10.0% by mass or less, and V: 0.5% by mass or more and 10.0% by mass or less; 2. The bath equipment member according to claim 1.

3. In the matrix portion, the content of Mo is higher than the content of Co and V.

3. The bath equipment member according to claim 2.

4. The hard particles have an average particle size of 5 μm or more and 200 μm or less.

4. A member for bath equipment according to claim 1, wherein the member is a member for bath equipment.

5. The hard particles are two types of particles: tungsten carbide and titanium carbide.

4. A member for bath equipment according to claim 1, wherein the member is a member for bath equipment.

6. The hard particles are two types of particles: tungsten carbide and titanium carbide.

5. The bathing equipment member according to claim 4.

7. The buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, a shaft sleeve attached to the roll shaft portion of the sink roll, a shaft sleeve attached to the roll shaft portion of the support roll, a bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and a bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll.

4. A member for bath equipment according to claim 1, wherein the member is a member for bath equipment.

8. The buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, a shaft sleeve attached to the roll shaft portion of the sink roll, a shaft sleeve attached to the roll shaft portion of the support roll, a bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and a bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll.

5. The bathing equipment member according to claim 4.

9. The buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, a shaft sleeve attached to the roll shaft portion of the sink roll, a shaft sleeve attached to the roll shaft portion of the support roll, a bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and a bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll.

6. A member for bathing equipment according to claim 5.

10. The buildup layer is formed on at least one of the roll shaft portion of the sink roll, the roll shaft portion of the support roll, a shaft sleeve attached to the roll shaft portion of the sink roll, a shaft sleeve attached to the roll shaft portion of the support roll, a bearing portion supporting the roll shaft portion or the shaft sleeve of the sink roll, and a bearing portion supporting the roll shaft portion or the shaft sleeve of the support roll.

7. A member for bath equipment according to claim 6.

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