An ultra-high-hard-phase wear-resistant coating and a preparation method and application thereof

Abstract

The application provides an ultra-high-hard-phase wear-resistant coating and a preparation method and application thereof, and comprises a medium-carbon forged steel base and a coating cladded on the medium-carbon forged steel base. The ultra-high-hard-phase wear-resistant coating is obtained by cladding a metal-based powder on the medium-carbon forged steel base by using a plasma surfacing process. The ultra-high-hard-phase wear-resistant coating is applied to a descaling roller. The ultra-high-hard-phase wear-resistant coating on the descaling roller has a hardness of HV600, no cracks in WC phases and metal phases, and excellent bonding performance between key phases in the obtained ultra-high-hard-phase wear-resistant coating.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of descaling roll coating, and particularly relates to an ultra-high-hard-phase wear-resistant coating and a preparation method and application thereof. BACKGROUND

[0002] In the prior art, document CN110093580A discloses a metallurgical roll surface composite wear-resistant alloy coating, which comprises a metallurgical roll base body, and an inner coating and an outer coating are sequentially arranged on the surface of the metallurgical roll base body from inside to outside. The inner coating raw material is a mixture of NiCrAl alloy powder and SiBCrFe alloy powder, and the outer coating raw material is a mixture of CrN powder, Cr3C2 powder, WC-Co-Cr type powder and BNi powder, the mass percentage of each element is Cr 5-7%, Si 4-6%, Fe 1.5-3.5%, B 2.95-3.75%, P 0.34-0.87%, C 1.5-2.4%, and the balance is Ni. However, as mentioned above, the Ni-based WC coating is prone to cracking during plasma surfacing, especially the WC is prone to cracking, and the crack is prone to gradually expanding to the surfacing surface.

[0003] For example, Ni45 (the mass percentage of WC% is 45%) will appear typical cracks on the WC phase obtained under the same plasma surfacing process parameters as in Example 1, as shown in FIG. 1. Figure 1

[0004] In order to solve the problems such as cracks and holes in the cladding layer, Anhui University of Technology has developed a Co-based alloy powder and WC ceramic powder synergistic strengthening composite coating (CN116334619A), which uses Co, Cr, W, B, C and Fe element powder as raw material, and a plurality of hard eutectic carbide reinforcing phases are distributed in the coating. The mass percentage of ceramic powder in the composite powder is more than 60%, and the balance is Co-based metal alloy powder. Although this scheme can achieve good metallurgical bonding, the forming quality and surface continuity of the coating are relatively good. However, it needs to use a large amount of Mo element, and needs to cooperate with elements such as B to achieve strengthening.

[0005] More importantly, for the existing ultra-high-hard-phase WC wear-resistant coating applied to the roll, the current technical route basically focuses on the bonding performance of the coating and the substrate, and the bonding performance between the phases in the coating has not been deeply studied. SUMMARY

[0006] The application aims to provide an ultra-high-hard-phase wear-resistant coating and a preparation method and application thereof, which, based on solving the problems of easy cracking and chunk falling of the existing ultra-high-hard-phase WC wear-resistant coating, further optimizes the bonding performance between the key phases in the coating by using a specific formula and preparation process. ​

[0007] The application adopts the technical scheme as follows.

[0008] An ultra-high-hard-phase wear-resistant coating, comprising a medium-carbon forged steel base and a coating cladded on the medium-carbon forged steel base, wherein the coating is obtained by cladding a metal-based powder on the medium-carbon forged steel base by using a plasma surfacing process.

[0009] As a preferred scheme, the metal-based powder comprises Fe powder and / or Co powder and / or Cr powder and / or Ni powder, and WC powder.

[0010] As a preferred scheme, the particle size of the metal-based powder is not greater than 300 mesh.

[0011] As a preferred scheme, in the metal-based powder, the alloy powder composed of Fe powder, Co powder, Cr powder and Ni powder accounts for 20 parts, and the WC powder accounts for 15-81 parts; in the alloy powder, the volume ratio of Fe powder:Co powder:Cr powder:Ni powder is 23-26%:23-26%:23-26%:23-26%.

[0012] As a preferred scheme, the thickness of the coating is 1-10 mm.

[0013] As a preferred scheme, the WC powder is a spherical carbide prepared by using a vacuum gas atomization process, and the particle size is not greater than 300 mesh.

[0014] The preparation process of the aforementioned ultra-high-hard-phase wear-resistant coating comprises the following steps.

[0015] Step 1: removing defects such as pits and pores on the surface of the base material;

[0016] Step 2: cleaning the surface of the base material;

[0017] Step 3: sending the cleaned base material into a heating furnace, and preheating at a temperature of 300-350°C for 3-4 hours;

[0018] Step 4: after the furnace is started, the prepared metal-based powder is cladded and surfacing on the surface of the base material by using a plasma surfacing process to form a coating.

[0019] As a preferred scheme, in the plasma surfacing process, the plasma power is 25 KW, the lap joint amount is 3±0.5 mm, the plasma gas pressure is 0.25-0.4 Mpa, the powder feeding speed is 35-45 g / min, and the current is 145-155 A.

[0020] As a preferred scheme, the base material is a roller body, and the rotation speed of the roller in the plasma surfacing process is controlled to be 200-300 mm / min.

[0021] The aforementioned super-high-hard-phase wear-resistant coating is applied to the descaling roller.

[0022] Beneficial effects: The super-high-hard-phase wear-resistant coating on the descaling roller in the present application not only has a hardness of HV600, but also has no cracks in the WC phase and the metal phase; during the preparation process, the WC particles and the alloy powder are rapidly melted on the surface of the base material to form a common molten pool and solidify and crystallize, and through the melting of the plasma arc, the alloy powder is mutually soluble and recrystallized to form a new alloy material with new physical and chemical properties, generating a large amount of eutectic structure.

[0023] More importantly, the combination performance between the key phases in the obtained super-high-hard-phase wear-resistant coating is excellent, especially the strip / branch-shaped objects growing around the WC phase in the coating are embedded into the metal matrix to form a very stable structure that can adapt to thermal expansion and cold contraction, and has excellent wear resistance, vibration resistance and impact resistance, and can absorb and transfer energy during impact.

[0024] When the WC content is 80%, the network eutectic structure in the coating is clustered into blocks, and blocky, fishbone-shaped and dendritic carbide structures begin to appear, the undecomposed spherical WC particles are "embedded" into the alloy matrix, and dendritic structures are formed around the spherical WC particles, which are integrated with the WC particles, enhancing the combination of the WC hard phase and the alloy matrix, and eutectic structures appear between the dendrites, which are distributed in a network. Part of the WC is decomposed into W and C under the heating action of the plasma arc and enters the alloy matrix with the molten pool, and is dispersedly distributed, and strengthens the alloy matrix. Primary blocky carbides are generated on the surface of the WC particles, and fishbone-shaped and dendritic carbides (M6C phase) are generated in the multi-element alloy matrix away from the WC particles. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A typical crack morphology map appears on the WC phase in the coating (Ni45);

[0026] Figure 2 A coating morphology map in Example 1;

[0027] Figure 3 A coating morphology map in Example 2;

[0028] Figure 4 A hardness test result map of the coating with different contents. IMPLEMENTATION

[0029] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0030] An ultra-high hard phase wear-resistant coating comprises a medium-carbon forged steel substrate and a coating clad on the medium-carbon forged steel substrate. The coating is obtained by cladding a metal-based powder onto the medium-carbon forged steel substrate using a plasma surfacing process. The metal-based powder comprises 20 parts by weight of an alloy powder composed of Fe powder, Co powder, Cr powder, and Ni powder, and 80 parts by weight of WC powder. The alloy powder comprises a volume ratio of 25% Fe powder, 25% Co powder, 25% Cr powder, and 25% Ni powder. The WC powder is a spherical carbide produced using a vacuum gas atomization process and has a particle size no larger than 300 mesh.

[0031] The preparation process of the ultra-high hard phase wear-resistant coating used on the descaling roller in this example includes the following steps:

[0032] Step 1: Remove defects such as pits and pores on the surface of the parent material (roller body, material 20CrMo);

[0033] Step 2: Clean the surface of the base material;

[0034] Step 3: Place the cleaned base material into a heating furnace and preheat it at 320°C for 3.5 hours.

[0035] In step 4, after the furnace is opened, the prepared metal-based powder is welded onto the base material surface using a plasma cladding process to form a coating. During the plasma cladding process, the plasma power is 25 kW, the overlap is 3 mm, the plasma pressure is 0.3 MPa, the powder feed rate is 40 g / min, and the current is 150 A. The roller speed is controlled at 240 mm / min.

[0036] The ultra-high hard phase wear-resistant coating prepared in this embodiment was tested, and its hardness was HV600, and the microstructure morphology was shown in FIG. Figure 2 .

[0037] In this embodiment, the WC content is 80 parts, the network eutectic structure in the coating is clustered into blocks, and a large number of blocky, fishbone-shaped and dendritic carbide structures begin to appear. The undecomposed spherical WC particles are "embedded" into the alloy matrix, forming dendritic structures at the edge of the spherical WC particles, which are integrated with the WC particles, enhancing the binding of the WC hard phase and the alloy matrix. Eutectic structures appear between the dendrites, distributed in a network. Part of the WC decomposes into W and C under the heating action of the plasma arc and enters the alloy matrix from the molten pool, forming a dispersed distribution and strengthening the alloy matrix. Primary blocky carbides are generated on the surface of the WC particles. In the far-away multi-element alloy matrix, fishbone-shaped and dendritic carbides (M6C phase) are generated, and there are no cracks on the WC phase / particles. Figure 1 In this embodiment, the flocculation around the spherical WC particles exists independently, and only a small amount of flocculation adheres to the edge of the WC particles. Embodiment

[0038] An ultra-high-hard-phase wear-resistant coating, comprising a medium-carbon forged steel substrate and a coating fused on the medium-carbon forged steel substrate, wherein the coating is obtained by fusing a metal-based powder on the medium-carbon forged steel substrate using a plasma surfacing process. In the metal-based powder, alloy powder composed of Fe powder, Co powder, Cr powder and Ni powder accounts for 20 parts by mass, and WC powder accounts for 40 parts by mass; in the alloy powder, the Fe powder: Co powder: Cr powder: Ni powder = 25%: 25%: 25%: 25% by volume; the WC powder is spherical carbide prepared by a vacuum gas atomization process, and the particle size is not greater than 300 mesh.

[0039] In this example, the preparation process of the ultra-high-hard-phase wear-resistant coating applied to the descaling roller is as follows:

[0040] Step 1: Remove the defects such as pits and pores on the surface of the base material (roller body);

[0041] Step 2: Clean the surface of the base material;

[0042] Step 3: Put the cleaned base material into a heating furnace and preheat at a temperature of 320°C for 3.5 hours;

[0043] Step 4: After the furnace is started, the prepared metal-based powder is fused and surfacing on the surface of the base material using a plasma surfacing process to form a coating. In the plasma surfacing process, the plasma power is 25 KW, the overlap amount is 3 mm, the plasma gas pressure is 0.3 Mpa, the powder feeding speed is 40 g / min, and the current is 150 A; the roller rotation speed is controlled at 240 mm / min.

[0044] The ultra-high-hard-phase wear-resistant coating prepared in this embodiment is detected, and the hardness is HV510, and the microstructure morphology is shown in Figure 3In this embodiment, the WC content is 80 parts, and no blocky, fishbone-like and dendritic carbide structures appear in the coating. No dendritic structure is formed around the spherical WC particles, and no cracks are present on the WC phase / particles.

[0045] On the basis of Example 1, the proportion of WC powder is adjusted to 10 parts and 20 parts, and the hardness of the coating is measured to be HV231 and HV369, respectively, as shown in Table 1. Figure 4 ​

Claims

1. An ultra-high hardness phase wear resistant coating comprising a medium carbon forged steel substrate and a coating fused onto the medium carbon forged steel substrate, characterized in that: The coating is obtained by cladding metal-based powder on medium carbon forged steel substrate by plasma surfacing process; The metal-based powder is composed of 20 parts of alloy powder made of Fe powder, Co powder, Cr powder and Ni powder, and 80 parts of WC powder; in the alloy powder, the volume ratio of Fe powder, Co powder, Cr powder and Ni powder is 23-26%:23-26%:23-26%:23-26%; the coating has fishbone-shaped and dendritic carbide structure in the multi-element alloy matrix away from the WC particles, and the dendritic structure is formed on the edge of the WC particles and integrated with the WC particles; The preparation process of the coating comprises the following steps: Step 1: removing the pits and porosity defects on the surface of the base material; Step 2: cleaning the surface of the base material; Step 3: feeding the cleaned base material into a heating furnace and preheating at a temperature of 300-350℃ for 3-4 hours; Step 4: after the furnace is started, the prepared metal-based powder is cladded and surfacing on the surface of the base material by plasma surfacing process to form a coating; In the plasma surfacing process, the plasma power is 20-50kW, the overlapping amount is 3±0.5mm, the plasma gas pressure is 0.25-0.4MPa, the powder feeding speed is 35-45g / min, and the current is 145-155A.

2. The ultra-high hardness phase wear resistant coating of claim 1, wherein: The particle size of the metal-based powder is not greater than 300 mesh.

3. The ultra-high hardness phase wear resistant coating according to claim 1 or 2, characterized in that: The thickness of the coating is 1-10mm.

4. The ultra hard phase wear resistant coating according to claim 3, wherein: The WC powder is spherical carbide prepared by vacuum gas atomization process, and the particle size is not greater than 300 mesh.

5. The process for producing an ultra hard phase wear resistant coating according to any one of claims 1 to 4, wherein the step of Comprise: Step 1: removing the pits and porosity defects on the surface of the base material; Step 2: cleaning the surface of the base material; Step 3: feeding the cleaned base material into a heating furnace and preheating at a temperature of 300-350℃ for 3-4 hours; Step 4: after the furnace is started, the prepared metal-based powder is cladded and surfacing on the surface of the base material by plasma surfacing process to form a coating.

6. The manufacturing process of claim 5, wherein: In the plasma surfacing process, the plasma power is 20-50kW, the overlapping amount is 3±0.5mm, the plasma gas pressure is 0.25-0.4MPa, the powder feeding speed is 35-45g / min, and the current is 145-155A.

7. The manufacturing process of claim 6, wherein: The base material is a roller body, and the roller rotation speed in the plasma surfacing process is controlled at 200-300mm / min.

8. Use of an ultra hard phase wear resistant coating according to any one of claims 1 to 4, wherein: The ultra-high-hard-phase wear-resistant coating is applied to a descaling roller.

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