Wide and thick plate rolling mill high-toughness stainless steel lining plate manufactured through laser cladding and preparation method of wide and thick plate rolling mill high-toughness stainless steel lining plate

Abstract

The invention belongs to the technical field of surface treatment, and particularly relates to a wide and thick plate rolling mill high-toughness stainless steel lining plate manufactured through laser cladding and a preparation method of the wide and thick plate rolling mill high-toughness stainless steel lining plate. The functional layer alloy powder of the lining plate comprises the following components in percentage by mass: 10%-15% of (Ti, W) C composite powder and the balance of iron-based alloy powder, wherein the iron-based alloy powder comprises the following components in percentage by mass: 0.1%-0.2% of C, 11%-13% of Cr, 0.2%-0.4% of Si, 0.2%-0.4% of Mn, 8%-10% of Ni, 1.0%-1.3% of Mo, 1.0%-1.5% of Al, 0.3%-0.5% of Nb, 0.3%-0.5% of Zr and the balance of iron. After a special coating material is adopted for cladding the plate surface, the impact resistance, the oxidation skin pricking resistance and the oxidation skin abrasive wear resistance of the plate surface under large rolling force can be improved, and the service life of the lining plate is prolonged; and a laser composite manufacturing method is adopted, so that the production cost of an enterprise can be reduced while the service life is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface treatment, and particularly relates to a high-strength and tough stainless steel liner for a wide and heavy plate rolling mill manufactured by laser cladding and a preparation method thereof. Background Art

[0002] The wide and heavy plate rolling mill is a key equipment for wide and heavy plate production, and its operating state directly affects the quality of the wide and heavy plate finished products. Wide and heavy plates mainly refer to plates with a width greater than 2m and a thickness of 5 - 100mm, and the common plate width specifications are 2.8m, 3.5m, 4.3m, 5m, 5.5m, etc. The liner of the rolling mill is located on the side of the rolling mill frame, the working plate, and the bearing box side of the support plate, and mainly plays a role in protecting the rolling mill frame, the working plate, and the bearing box of the support plate. During the wide and heavy plate rolling process, the working condition environment of the rolling mill is very harsh. Especially when biting and discharging steel, the rolling mill bears a large impact force, which is prone to local overload and causes cracking of the liner. At the same time, due to the continuous generation of scale, it is easy to have scale penetration at the interface, forming local pits and causing fitting clearances; meanwhile, it brings a certain degree of abrasive wear; in addition, the liner under the rolling line works in an environment with water circulation. If there is a fitting clearance between the liner and the frame, the water vapor corrosion and the intrusion of scale will exacerbate the wear and corrosion of the housing.

[0003] Currently, the imported Koses liner, which is relatively good for use in wide and heavy plate rolling mills, is not only expensive but also has a long supply cycle. It is very difficult to solve problems that occur during use. In China, explosive composite bimetallic liners are used, and the use effect is unstable, which completely depends on the stability of the explosive composite process. The first-generation laser cladding composite liner has a high hardness and low toughness, and cracks appear after one month of use under such a large rolling force, and its service life is extremely short, unable to meet the use requirements.

[0004] Currently, based on the working condition requirements of wide and heavy plates and combined with failure analysis and evaluation, the rolling mill liner needs to have a certain toughness, good wear resistance, and certain anti-corrosion performance. How to find a balance between "wear resistance" and "toughness", two contradictory aspects, and give full play to their respective properties is the key point and core point of the research and development of the wide and heavy plate liner in this patent. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a high-strength and tough stainless steel liner for a wide and heavy plate rolling mill manufactured by laser cladding and a preparation method thereof. After the surface of the plate is clad with a special coating material, the impact resistance of the plate under a large rolling force, the resistance to scale penetration, and the resistance to abrasive wear of scale can be improved, and the service life of the liner can be extended; by using the laser composite manufacturing method, while ensuring the service life, the production cost of the enterprise can be reduced.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions.

[0007] A functional layer alloy powder for a high-strength and high-toughness stainless steel lining plate of a wide and heavy plate rolling mill manufactured by laser cladding, comprising the following components in mass percentage: 10%-15% of (Ti, W)C composite powder, and the balance is iron-based alloy powder.

[0008] Further, the iron-based alloy powder comprises the following components in mass percentage: 0.1%-0.2% C, 11%-13% Cr, 0.2%-0.4% Si, 0.2%-0.4% Mn, 8%-10% Ni, 1.0-1.3% Mo, 1.0-1.5% Al, 0.3%-0.5% Nb, 0.3%-0.5% Zr, and the balance is iron.

[0009] Further, the (Ti, W)C composite powder has a particle size of -500 to +1000 mesh and a purity of over 99%.

[0010] Further, the iron-based alloy powder has a particle size of -125 to +300 mesh.

[0011] A preparation method for a high-strength and high-toughness stainless steel lining plate of a wide and heavy plate rolling mill manufactured by laser cladding, comprising the following steps: Step 1: Perform quenching and tempering heat treatment on the substrate blank plate 2Cr13 to obtain a quenched and tempered substrate; Step 2: Process the quenched and tempered substrate to a predetermined size to meet the requirements before cladding; Step 3: Mix the above functional layer alloy powders, and perform double-sided laser cladding on the surface of the substrate with the uniformly mixed powders to obtain a substrate after cladding; Step 4: Perform surface flaw detection on the substrate after cladding, and then perform heat treatment. The heat treatment process is 510°C, holding for 2 hours, and the cooling method is air cooling, and the hardness can reach 57±1 HRC; Step 5: Perform grinding to the required size to obtain a high-strength and high-toughness stainless steel lining plate of a wide and heavy plate rolling mill manufactured by laser cladding.

[0012] Further, in Step 1, the quenched and tempered hardness of the quenched and tempered substrate is 35-38 HRC, and the tensile strength is ≥680 Mpa.

[0013] Further, in Step 3, the laser cladding process parameters are: preheating temperature is 100°C - 150°C, powder feeding rate is 15 g / min - 25 g / min, laser power is 3 kw - 4 kw, spot diameter is 4.0 mm, scanning speed is 600 mm / min - 800 mm / min, step is 1.7 mm, overlap rate is 40 - 60%, and single-layer cladding thickness is 1.0 mm - 1.3 mm.

[0014] Furthermore, in step 3, an atmosphere protection cover with local atmosphere protection is adopted during the cladding process to ensure the stable progress of the cladding process. As measured by an oxygen analyzer, it reaches 50 ppm, ensuring the purity of the structure.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0016] (1) In the cladding material of the wide and thick plate rolling mill liner for laser cladding provided by the present invention, (Ti, W)C composite powder with a preferably selected particle size range is added. The density of this substance is 9.46 g / cm 3 , the density of TiC is 4.93 g / cm 3 , and the density of WC is 15.63 g / cm 3 . Adding them alone will cause particle aggregation and sinking due to the large density difference, and serious cracks will appear macroscopically. The (Ti, W)C composite powder has a density similar to that of the iron-based matrix and is more likely to be evenly distributed in the matrix. Its size is about 1 - 3 μm, and the nature of dissolution and precipitation presents an irregular spherical shape, which can well serve as wear-resistant support and has good wettability with the iron-based matrix. The strength and toughness of the matrix and the good wear-resistant support of the wear-resistant particles work together; at the same time, the (Ti, W)C composite powder can promote the formation of more nuclei during crystallization, and the grain size is finer, so it has good fatigue performance, such as Figure 1 、 Figure 2 .

[0017] (2) In the present invention, C is controlled at 0.1 - 0.2%, which mainly plays a role in solid solution strengthening. By reasonably controlling the carbon content, lath martensite is formed. This is mainly because carbon causes lattice distortion in the matrix, hindering the movement of dislocations and strengthening the matrix. However, due to its self-tempering, the lattice tetragonality is small, the non-uniformity of the high-density dislocation network generates a large number of low-density regions, providing conditions for the movement of dislocations. Therefore, the formed martensite is lath-shaped and has good toughness.

[0018] (3) It is found that after adding Zr element to the cladding material, the Zr element reacts with the residual oxygen in the molten pool to form ZrO2, forming nano-scale nucleation particles with dispersed distribution, promoting crystallization, refining grains, and further improving the toughness and impact resistance of the coating; at the same time, it consumes the residual oxygen, converts the harmful phase into a beneficial phase, and improves the overall performance. It is found that after adding Te element to the cladding material, it can control the dissolution and precipitation size and morphology of the (Ti, W)C composite powder during the cladding process. Under the appropriate addition amount, the particles precipitated from the (Ti, W)C composite powder are granular and evenly distributed, ensuring wear resistance without sacrificing its toughness. Under the inappropriate addition amount, the particle size of the (Ti, W)C composite powder precipitated is large, and the morphology presents a sharp angle shape, damaging the toughness and impact resistance of the coating, such as Figure 3 .

[0019] (4)The present invention adds 1.0% - 1.5% Al. The main purpose is to form fine and dispersed intermetallic compound Ni3Al during aging heat treatment. This microstructure with micro-nano structure can achieve ultra-high strength level while ensuring toughness, and it is an ultra-high strength material with integrated strength, hardness and toughness.

[0020] (5)The corrosion resistance of the coating material of the present invention can reach level 9 - 10 in neutral salt spray test for 96 hours. Description of the Drawings

[0021] Figure 1 Metallographic diagram of (Ti, W)C200× formed by adding Zr in Example 1.

[0022] Figure 2 Metallographic diagram of (Ti, W)C 500× formed by adding Zr in Example 2.

[0023] Figure 3 Metallographic diagram of (Ti, W)C 200× formed without adding Zr.

[0024] Figure 4 Specimen for salt spray corrosion test of the coating. Detailed Description of the Invention

[0025] The technical solutions and drawings in the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] A functional layer alloy powder for a high-strength and tough stainless steel lining plate of a wide and thick plate rolling mill manufactured by laser cladding, comprising the following components by mass percentage: 10% - 15% of (Ti, W)C composite powder, and the balance is iron-based alloy powder.

[0027] Further, the iron-based alloy powder comprises the following components by mass percentage: 0.1% - 0.2% C, 11% - 13% Cr, 0.2% - 0.4% Si, 0.2% - 0.4% Mn, 8% - 10% Ni, 1.0 - 1.3% Mo, 1.0 - 1.5% Al, 0.3% - 0.5% Nb, 0.3% - 0.5% Zr, and the balance is iron.

[0028] Further, the particle size of the (Ti, W)C composite powder is -500~+1000 mesh, and the purity is above 99%; the particle size of the iron-based alloy powder is -125~+300 mesh.

[0029] A preparation method for a high-strength and tough stainless steel lining plate of a wide and thick plate rolling mill manufactured by laser cladding, comprising the following steps: Step 1: Perform quenching and tempering heat treatment on the base material blank plate of 2Cr13. The tempering hardness of the tempered base material is 35 - 38HRC, and the tensile strength is ≥680Mpa to obtain the tempered base material. Step 2: Process the tempered base material to the specified dimensions to meet the requirements before cladding. Step 3: Mix the above functional layer alloy powders, and perform double-sided laser cladding on the surface of the base material with the evenly mixed powders; a gas protection cover with local gas protection is used during the cladding process to ensure the stable progress of the cladding process. After being measured by an oxygen analyzer, it reaches 50ppm to ensure the purity of the structure; the laser cladding process parameters are: the preheating temperature is 100℃ - 150℃, the powder feeding rate is 15g / min - 25g / min, the laser power is 3kw - 4kw, the spot diameter is 4.0mm, the scanning speed is 600mm / min - 800mm / min, the step is 1.7mm, the overlapping rate is 40 - 60%, and the single-layer cladding thickness is 1.0mm - 1.3mm; the clad base material is obtained. Step 4: After the surface flaw detection of the clad base material is qualified, perform heat treatment. The heat treatment process is 510℃, hold for 2 hours, and the cooling method is air cooling, and the hardness can reach 57 ± 1HRC. Step 5: Perform grinding to the dimensional requirements to obtain the high-strength and tough stainless steel liner for the wide and thick plate rolling mill manufactured by laser cladding.

[0030] Coating performance detection Perform 7-layer cladding in Step 3, with a total thickness of 7.5 - 8mm. After cladding, perform the heat treatment in Step 4. Respectively, make tensile standard parts and impact parts from the base material (1#) after 7-layer cladding and the base material (2#) after heat treatment after 7-layer cladding, and perform mechanical property tests. The results are shown in Table 1.

[0031] Table 1 Test results of the mechanical properties of the coating.

[0032] Perform 7-layer cladding on this coating, with a total thickness of 7.5 - 8mm. After cladding, perform aging heat treatment and prepare samples for salt spray corrosion, and evaluate them on a neutral salt spray test platform. The evaluation results can reach 9 - 10 levels in 96 hours, as Figure 4 .

[0033] It can be seen from the above performance tests that the method of first cladding and then heat treatment in the present invention has excellent mechanical properties and strong salt spray resistance (usually one-layer cladding in this field, but in the preliminary tests, multiple-layer cladding is required to prepare mechanical property evaluation samples to reach the state that meets the detection. Only after the detection is qualified can one-layer cladding be used to prepare qualified products).

[0034] Example 1.

[0035] A preparation method for a high-strength and tough stainless steel liner of a heavy and wide plate rolling mill manufactured by laser cladding, comprising the following steps: Step 1: Perform quenching and tempering heat treatment on the base material blank plate 2Cr13 to obtain a quenched and tempered base material, and the quenched and tempered hardness of the quenched and tempered base material is 35 - 38 HRC; Step 2: Process the quenched and tempered base material to the established dimensions to meet the requirements before cladding; Step 3: Mix the functional layer alloy powders: among them, the mass fraction of (Ti, W)C is: 10%; the chemical composition mass fraction of the iron-based alloy powder is: 0.2% C, 12% Cr, 0.35% Si, 0.4% Mn, 8.5% Ni, 1.1% Mo, 1.2% Al, 0.3% Nb, 0.35% Zr, and the rest is Fe; use a powder mixer to mix the powders, and the mixing time is not less than 2 h; Step 4: Preheat the liner of the heavy and wide plate rolling mill. After reaching the preheating temperature of 150 °C, carry out laser cladding manufacturing. Use a fiber laser, and the specific process parameters are as follows: powder feeding rate 18 g / min, laser power 3 kw, spot diameter 4.0 mm, scanning speed 600 mm / min, step 1.7 mm, overlapping rate 50%, single-layer cladding thickness 1.0 mm; Step 5: After passing the surface flaw detection after cladding, perform heat treatment. The heat treatment process is 510 °C and hold for 2 hours, The cooling method is air cooling; Step 6: Carry out grinding to the dimensional requirements. After hardness testing, it reaches 57 HRC to obtain a high-strength and tough stainless steel liner of a heavy and wide plate rolling mill manufactured by laser cladding.

[0036] The liner of a certain steel mill's heavy and wide plate rolling mill manufactured by this process is used online. The first-generation liner manufactured by laser composite manufacturing showed chipping and spalling after 1 month of use, while this coating material has been used for one year, and the service life has been greatly improved.

[0037] Example 2.

[0038] A preparation method for a high-strength and tough stainless steel liner of a heavy and wide plate rolling mill manufactured by laser cladding, comprising the following steps: Step 1: Perform quenching and tempering heat treatment on the base material blank plate 2Cr13 to obtain a quenched and tempered base material, and the quenched and tempered hardness of the quenched and tempered base material is 35 - 38 HRC; Step 2: Process the quenched and tempered base material to the established dimensions to meet the requirements before cladding; Step 3: Mix the functional layer alloy powders. The mass fraction of (Ti, W)C is 12%; the chemical composition mass fraction of the iron-based alloy powder is 0.15% C, 12.5% Cr, 0.35% Si, 0.4% Mn, 9.5% Ni, 1.3% Mo, 1.4% Al, 0.4% Nb, 0.4% Zr, and the rest is Fe. Use a powder mixer to mix the powders, and the mixing time is not less than 2 h. Step 4: Preheat the wide and heavy plate mill liner. After reaching the preheating temperature of 150 °C, carry out laser cladding manufacturing. Use a fiber laser. The specific process parameters are as follows: powder feeding rate 25 g / min, laser power 3.5 kw, spot diameter 4.0 mm, scanning speed 600 mm / min, step 1.7 mm, overlapping rate 50%, and single-layer cladding thickness 1.3 mm. Step 5: After passing the surface flaw detection after cladding, carry out heat treatment. The heat treatment process is 510 °C for 2 hours of heat preservation. The cooling method is air cooling. Step 6: Carry out grinding to the dimensional requirements. After hardness testing, it reaches 57.3 HRC, and a high-strength and tough stainless steel liner for the wide and heavy plate mill manufactured by laser cladding is obtained.

[0039] The liner of a wide and heavy plate mill of a certain steel plant manufactured by this process is used online. The first-generation liner manufactured by laser compounding showed chipping and spalling after 1 month of use, while this coating material has been used for one year, and the service life has been greatly improved.

Claims

1. A functional layer alloy powder for a high-strength and tough stainless steel lining plate of a wide and heavy plate rolling mill manufactured by laser cladding, characterized in that, It includes the following components by mass percentage: 10%-15% of (Ti, W)C composite powder, and the balance is iron-based alloy powder.

2. The functional layer alloy powder of the high-strength and tough stainless steel liner for a wide and heavy plate rolling mill manufactured by laser cladding according to claim 1, characterized in that, The iron-based alloy powder includes the following components by mass percentage: 0.1%-0.2% C, 11%-13% Cr, 0.2%-0.4% Si, 0.2%-0.4% Mn, 8%-10% Ni, 1.0-1.3% Mo, 1.0-1.5% Al, 0.3%-0.5% Nb, 0.3%-0.5% Zr, and the balance is iron.

3. The functional layer alloy powder of the high-strength and tough stainless steel lining plate for a wide and heavy plate rolling mill manufactured by laser cladding according to claim 1, wherein, The particle size of the (Ti, W)C composite powder is -500~+1000 mesh, and the purity is above 99%.

4. The functional layer alloy powder of the high-strength and tough stainless steel lining plate for a wide and heavy plate rolling mill manufactured by laser cladding according to claim 1, characterized in that, The particle size of the iron-based alloy powder is -125~+300 mesh.

5. A preparation method for a high-strength and tough stainless steel lining plate of a wide and thick plate rolling mill manufactured by laser cladding, characterized in that, It includes the following steps: Step 1: Perform quenching and tempering heat treatment on the substrate blank plate 2Cr13 to obtain a quenched and tempered substrate. Step 2: Process the quenched and tempered substrate to the specified size to meet the requirements before cladding. Step 3: Mix the above functional layer alloy powders, and perform double-sided laser cladding on the surface of the substrate with the evenly mixed powder to obtain the substrate after cladding. Step 4: After the surface flaw detection of the substrate after cladding is qualified, perform heat treatment. The heat treatment process is 510°C, hold for 2 hours, and the cooling method is air cooling. Step 5: Perform grinding to the dimensional requirements to obtain a high-strength and tough stainless steel lining plate for a wide and thick plate rolling mill manufactured by laser cladding.

6. The preparation method of the high-strength and tough stainless steel lining plate for a wide and heavy plate rolling mill manufactured by laser cladding according to claim 5, characterized in that, In the above Step 1, the quenched and tempered hardness of the quenched and tempered substrate is 35-38HRC, and the tensile strength is ≥680 Mpa.

7. The preparation method of the high-strength and tough stainless steel liner plate for a wide and heavy plate rolling mill manufactured by laser cladding according to claim 5, characterized in that, In the above Step 3, the laser cladding process parameters are: the preheating temperature is 100°C-150°C, the powder feeding rate is 15g / min-25g / min, the laser power is 3kw-4kw, the spot diameter is 4.0mm, the scanning speed is 600mm / min-800mm / min, the step is 1.7mm, the overlapping rate is 40~60%, and the single-layer cladding thickness is 1.0mm-1.3mm.

8. The preparation method of the high-strength and tough stainless steel lining plate for a wide and heavy plate rolling mill manufactured by laser cladding according to claim 5, characterized in that, In the above Step 3, a gas protection cover with local gas protection is used during the cladding process, and it reaches 50 ppm as measured by an oxygen analyzer.

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