A zinc pot roller shaft sleeve with low thermal expansion coefficient, high wear resistance and corrosion resistance and a manufacturing process thereof

Abstract

The application discloses a zinc pot roller shaft sleeve with low thermal expansion coefficient, high wear resistance and corrosion resistance, which comprises a shaft sleeve base body and a hardening layer, and the chemical components and mass percentage of the shaft sleeve base body are as follows: C: <=0.05, Mn: <=1.00, Si: <=1.00, Cr: 16.00-18.00, Ni: 4.0-6.0, Cu: 2.0-2.5, Ti: 0.3-0.45, and the balance is Fe; and the thermal expansion coefficient is 11.3*10 ‑6 / ℃. Meanwhile, the hardening layer is divided into at least three layers, and the material and thickness of each layer are as follows: the first layer is 10% WC / TiC+Ni-based alloy, 1mm; the second layer is 30% WC / TiC+Ni-based alloy, 1mm; and the third layer is 60% WC / TiC+Ni-based alloy, 1.5mm. The zinc pot roller shaft sleeve reduces assembly difficulty, guarantees the surface quality of the strip steel, prolongs the service life, and improves the production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the structure of zinc pot roller shaft sleeve and its manufacturing process. BACKGROUND

[0002] The zinc pot roller shaft sleeve is an important consumable part in the production of continuous hot galvanizing of strip steel. Its working conditions are harsh: firstly, it works in a molten liquid metal with strong corrosive property, and the working temperature is generally high, i.e. 460-700℃; secondly, it is subjected to complex compound wear, including corrosion and wear of molten zinc and aluminum liquid, sliding wear between the contact surface of the sleeve and the liner, abrasive wear and fatigue wear, etc. The surface quality of the worn shaft sleeve is decreased, which leads to the decrease of the surface quality of the produced strip steel, and even causes shutdown and replacement in serious cases. In addition, the zinc pot roller shaft sleeve is installed on the submerged roller shaft head (the material of the submerged roller shaft head is 316L), and the sleeve and the shaft head must be in interference fit without relative sliding during use. Therefore, the zinc pot roller shaft sleeve needs to have the properties of low thermal expansion coefficient, high wear resistance and corrosion resistance.

[0003] At present, the zinc pot roller shaft sleeve mainly has the following two materials: firstly, the cast cobalt-based alloy sleeve, which has the advantages of high hardness, low thermal expansion coefficient and easy installation; however, the sleeve has too much brittleness, and is prone to cracking at high temperature, and the cobalt-based alloy is greatly softened at above 600℃, resulting in the decrease of wear resistance; secondly, the composite sleeve of "316L stainless steel sleeve + hardening layer", which solves the problems of brittleness of the cast cobalt-based alloy sleeve and the decrease of wear resistance at high temperature; however, since the sleeve and the submerged roller shaft head are both made of 316L stainless steel, and the 316L stainless steel has a large thermal expansion coefficient, the sleeve and the shaft head must be in interference fit when they are assembled offline, so that the sleeve and the shaft head can be in interference fit without relative sliding when they are used in the zinc pot at about 500℃, which increases the difficulty of on-site assembly of the sleeve and the shaft head, and there is a large thermal expansion gradient between the base material with a large thermal expansion coefficient and the hardening layer with a small thermal expansion coefficient, which causes the difference in thermal expansion between the two and results in large internal stress due to the difference in cooling shrinkage, so the hardening layer is prone to cracking and peeling. In addition, the hardening layer is prone to cracking due to its poor plasticity and toughness caused by the existence of a large amount of hard phases. SUMMARY

[0004] The present application solves the problem of providing a zinc pot roller shaft sleeve with low thermal expansion coefficient, high wear resistance and corrosion resistance, which reduces the assembly difficulty, ensures the surface quality of the strip steel, prolongs the service life and improves the production efficiency.

[0005] The application discloses a zinc pot roller shaft sleeve with low thermal expansion coefficient, high wear resistance and corrosion resistance, which comprises a shaft sleeve base body and a hardening layer. -6 / ℃.

[0006] Preferably, the chemical composition of the shaft sleeve base body comprises the following components in percentage by mass: C: 0.04, Mn: 0.09, Si: 0.09, Cr: 16.00, Ni: 5.8, Cu: 2.1, Ti: 0.3, and the balance of Fe.

[0007] Preferably, the chemical composition of the shaft sleeve base body comprises the following components in percentage by mass: C: 0.04, Mn: 0.09, Si: 0.09, Cr: 16.00, Ni: 5.8, Cu: 2.1, Ti: 0.3, and the balance of Fe.

[0008] Preferably, the chemical composition of the shaft sleeve base body comprises the following components in percentage by mass: C: 0.04, Mn: 0.09, Si: 0.09, Cr: 16.00, Ni: 5.8, Cu: 2.1, Ti: 0.3, and the balance of Fe.

[0009] Preferably, the hardening layer is divided into at least three layers.

[0010] Preferably, the material and thickness of each layer are as follows: the first layer is 10% WC / TiC+Ni-based alloy, 1mm; the second layer is 30% WC / TiC+Ni-based alloy, 1mm; and the third layer is 60% WC / TiC+Ni-based alloy, 1.5mm.

[0011] The manufacturing process of the zinc pot roller shaft sleeve is as follows:

[0012] ①Manufacturing the shaft sleeve base material: the shaft sleeve base material is manufactured by using a casting process and is processed to a required size;

[0013] ②Manufacturing the hardening layer: the shaft sleeve base material is preheated to 200 DEG C, and a hardening layer is manufactured according to design requirements by using a laser cladding or plasma cladding method;

[0014] ③Heat treatment: after the cladding is completed, 600 DEG annealing treatment is carried out;

[0015] ④Machining: after the shaft sleeve is processed into a finished product according to the drawing, the finished product is inspected; the hardness and PT flaw detection of the finished product are detected.

[0016] The zinc pot roller shaft sleeve has the following advantages: 1. The shaft sleeve base material has a low thermal expansion coefficient by adjusting the content ratio of Cr, Ni and Cu elements, which is lower than the thermal expansion coefficient of the submerged roller shaft head. Therefore, when the shaft sleeve and the submerged roller shaft head are installed offline, they can be gap fitted. When entering the 500℃ zinc pot, the shaft head expands greatly and the shaft sleeve expands slightly, so that the interference fit is formed between them, thereby reducing the difficulty of on-site assembly of the shaft sleeve and the submerged roller shaft head, and the shaft sleeve is easy to install; 2. The low thermal expansion coefficient of the base material and the low thermal expansion coefficient of the hardening layer make the thermal expansion gradient between the base material and the hardening layer small, thereby avoiding the generation of a large internal stress. Therefore, the hardening layer and the shaft sleeve are combined well even in a high-temperature use state, and the phenomenon of cracking and peeling basically does not occur during use; 3. The hardening layer adopts a gradient coating design. With the base body from the inner layer to the outer layer, the content of the hard alloy forms a gradient rise, thereby enhancing the toughness and preventing the hardening layer from cracking; 4. The hardening layer has high wear resistance and corrosion resistance due to the good corrosion resistance of the nickel-based alloy and the high wear resistance of the tungsten carbide (titanium carbide) hard alloy, thereby ensuring the surface quality of the strip steel. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below.

[0018] Example 1

[0019] The present application relates to a zinc pot roller shaft sleeve with low thermal expansion coefficient, high wear resistance and corrosion resistance, which comprises a shaft sleeve base body and a hardening layer. The chemical composition and mass percentage of the shaft sleeve base body are as follows: C: ≤0.05, Mn: ≤1.00, Si: ≤1.00, Cr: 16.00-18.00, Ni: 4.0-6.0, Cu: 2.0-2.5, Ti: 0.3-0.45, and the balance is Fe. The thermal expansion coefficient is 11.3*10 -6 / ℃.

[0020] Preferably, the mass percentage of the chemical composition of the shaft sleeve base body is shown in Table 1.

[0021] Table 1

[0022] C Mn Si Cr Ni Cu Ti Fe Matrix 1 0.04 0.09 0.09 16 5.8 2.1 0.3 Balance Matrix 2 0.04 0.09 0.09 16.5 5.5 2.3 0.42 Balance Matrix 3 0.04 0.08 0.09 17.4 4.4 2.4 0.4 Balance

[0023] As can be seen from the above, the shaft sleeve base material of the present application has a low thermal expansion coefficient by increasing Cu and Ti and adjusting the content ratio of Cr, Ni and Cu elements, so that the thermal expansion coefficient at 500℃ is 11.3*10 -6C: 0.030-0.040, Si: 0.30-0.50, Mn: 0.50-1.00, Cr: 16.00-18.00, Ni: 10.00-14.00, Mo: 2.00-3.00, and the thermal expansion coefficient thereof is 18.0 x 10-6 / ℃ at 500℃. -6 / ℃.

[0024] Since the thermal expansion coefficient of the shaft sleeve substrate of the zinc pot roller shaft sleeve of the present application is less than that of the submerged roller shaft head, the shaft sleeve and the submerged roller shaft head can be in clearance fit when they are installed offline, so that when entering the 500℃ zinc pot, the shaft head expands greatly and the shaft sleeve expands less, so that an interference fit is formed between them and they do not slide relative to each other, thus reducing the difficulty of on-site assembly of the shaft sleeve and the submerged roller shaft head; at the same time, since the thermal expansion coefficient of the substrate is low and the thermal expansion coefficient of the hardening layer is low, the thermal expansion gradient between the substrate and the hardening layer is small, thus avoiding the generation of a large internal stress, so that the hardening layer and the shaft sleeve are combined well even in a high-temperature use state, and cracking and peeling basically do not occur.

[0025] Example 2

[0026] The zinc pot roller shaft sleeve of the present application: the hardening layer is divided into three layers, and the materials and thicknesses of each layer are shown in Table 2:

[0027] Table 2

[0028] Number of layers Hardened layer material Thickness First layer 10% WC / TiC + Ni-based alloy 1 mm Second layer 30% WC / TiC + Ni-based alloy 1 mm Third layer 60% WC / TiC + Ni-based alloy 1.5 mm

[0029] As can be seen from the above, the hardening layer of the zinc pot roller shaft sleeve of the present application adopts a gradient coating design, i.e. the content of the hard alloy in the coating is gradiently increased from the inside of the substrate to the outside: the first layer is directly coated on the substrate, the content of WC or TiC in the coating is 10%, and the rest is Ni; the second layer is coated on the first layer, the content of WC or TiC in the coating is 30%, and the rest is Ni; the third layer is coated on the second layer, the content of WC or TiC in the coating is 60%, and the rest is Ni.

[0030] Since the content of the hard alloy in the coating of the hardening layer of the zinc pot roller shaft sleeve of the present application is gradiently increased, the toughness thereof is enhanced and cracking of the hardening layer is prevented; at the same time, since the thermal expansion coefficient of the substrate is low and the thermal expansion coefficient of the hardening layer is low, the thermal expansion gradient between the substrate and the hardening layer is small, thus avoiding the generation of a large internal stress, so that the hardening layer and the shaft sleeve are combined well even in a high-temperature use state, and cracking and peeling basically do not occur. In addition, since the nickel-based alloy has good corrosion resistance and the hard alloy such as tungsten carbide (titanium carbide) has high wear resistance, the hardening layer has high wear resistance and corrosion resistance.

[0031] Example 3

[0032] The manufacturing process of the zinc pot roller shaft sleeve is as follows:

[0033] ①Manufacture the shaft sleeve base material: adopt casting process to manufacture the shaft sleeve base material, and process to the required size;

[0034] ②Manufacture the hardening layer: preheat the shaft sleeve base material to 200 DEG C, and adopt laser cladding or plasma cladding method to manufacture the hardening layer according to the design requirements;

[0035] ③Heat treatment: after cladding, carry out 600 DEG annealing treatment;

[0036] ④Machining: after processing into finished products according to the drawings, carry out inspection; carry out hardness and PT flaw detection on the finished products.

[0037] The zinc pot roller shaft sleeve has the following advantages: 1. The shaft sleeve base material obtains a low thermal expansion coefficient by adjusting the component proportion of Cr, Ni and Cu elements, so that the thermal expansion coefficient is smaller than that of the submerged roller shaft head, thus the shaft sleeve and the submerged roller shaft head can be gap fitted when being installed offline, so that when entering the 500 DEG C zinc pot, the shaft head expands greatly and the shaft sleeve expands slightly, so that an interference fit is formed between them, thereby reducing the on-site assembly difficulty of the shaft sleeve and the submerged roller shaft head, and the shaft sleeve is easy to install; 2. The thermal expansion coefficient of the base material and the thermal expansion coefficient of the hardening layer are low, so that the thermal expansion gradient between the base material and the hardening layer is small, thereby avoiding the generation of a large internal stress, so that the combination of the hardening layer and the shaft sleeve is good even in a high-temperature use state, and the phenomenon of cracking and peeling basically does not occur in the use process; 3. The hardening layer adopts a gradient coating design, and the content of hard alloy increases gradually from the inner layer to the outer layer of the base body, thereby enhancing the toughness and preventing the hardening layer from cracking; 4. The nickel-based alloy has good corrosion resistance, and the tungsten carbide (titanium carbide) hard alloy has high wear resistance, so that the hardening layer has high wear resistance and corrosion resistance, thereby ensuring the surface quality of the strip steel.

[0038] The assembly difficulty, use cycle and use performance of the zinc pot roller shaft sleeve and the two kinds of shaft sleeves of the background art, i.e. the cast cobalt-based alloy shaft sleeve and the 316L stainless steel + hardening layer shaft sleeve, are compared as shown in Table 3:

[0039] Table 3

[0040]

[0041] In summary, the zinc pot roller shaft sleeve has the advantages of low thermal expansion coefficient, hardening layer not easy to crack, high wear resistance and corrosion resistance, thereby reducing the assembly difficulty, ensuring the surface quality of the strip steel, prolonging the service life and improving the production efficiency.

Claims

1. A low thermal expansion coefficient, high wear resistance, corrosion resistance of zinc pot roller shaft sleeve, characterized by: It includes shaft sleeve base body and hardening layer, the chemical composition and mass percentage of the shaft sleeve base body are as follows: C: ≤0.05, Mn: ≤1.00, Si: ≤1.00, Cr: 16.00-18.00, Ni: 4.0-6.0, Cu: 2.0-2.5, Ti: 0.3-0.45, and the balance is Fe; the thermal expansion coefficient is 11.3*10 -6 / ℃; the hardening layer is three layers: the first layer is directly coated on the base body, the thickness is 1mm, the content of WC or TiC in the coating is 10%, and the balance is Ni-based alloy; the second layer is coated on the first layer, the thickness is 1mm, the content of WC or TiC in the coating is 30%, and the balance is Ni-based alloy; the third layer is coated on the second layer, the thickness is 1.5mm, the content of WC or TiC in the coating is 60%, and the balance is Ni-based alloy.

2. The zinc pot roller shaft sleeve of claim 1, wherein: The mass percentage of the chemical composition of the bush base body is: C: 0.04, Mn: 0.09, Si: 0.09, Cr: 16.00, Ni: 5.8, Cu: 2.1, Ti: 0.3, and the balance is Fe.

3. The zinc pot roller shaft sleeve of claim 1, wherein: The mass percentage of the chemical composition of the bush base body is: C: 0.04, Mn: 0.09, Si: 0.09, Cr: 16.50, Ni: 5.5, Cu: 2.3, Ti: 0.42, and the balance is Fe.

4. The zinc pot roller shaft sleeve of claim 1, wherein: The mass percentage of the chemical composition of the bush base body is: C: 0.04, Mn: 0.08, Si: 0.09, Cr: 17.40, Ni: 4.4, Cu: 2.4, Ti: 0.4, and the balance is Fe.

5. The manufacturing process of the zinc pot roller bushing according to any one of claims 1-4, comprising the following steps: ①Manufacturing the bush base material: using casting process to manufacture the bush base material and processing to the required size; ②Manufacturing the hardening layer: preheating the bush base material to 200℃ and manufacturing the hardening layer according to the design requirements; ③Heat treatment: performing 600℃ annealing treatment after the cladding is completed; ④Machining: performing inspection after processing into the finished product according to the drawing; and performing hardness and PT flaw detection on the finished product.

6. The manufacturing process of claim 5, characterized by: In step ②, the hardening layer is manufactured by laser cladding or plasma cladding method.

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