An alloy material for laser cladding layer of roll with wear resistance and thermal fatigue resistance

Abstract

The present invention provides an alloy material for a laser cladding layer of a roll with wear resistance and thermal fatigue resistance. It is a mixed powder, and is characterized in that: by mass percentage, it includes: 67.76 - 91.562% of 2Cr13 powder; 4.418 - 16.16% of nickel-coated graphite powder; 1.947 - 7.787% of pure titanium powder; 2.073 - 8.293% of pure vanadium powder. By using the alloy material of the present invention to process the roll, by controlling the alloy component formula of the material and optimizing the process of the cladding process, the high-temperature wear resistance and thermal fatigue resistance of the roll surface are effectively improved, and the service life of the roll is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and particularly relates to an alloy material for a laser cladding layer of a roll with wear resistance and thermal fatigue resistance. Background Art

[0002] Rolls are essential parts for a rolling mill to produce sheets. Generally, a paired or grouped roll mode is adopted, and the extrusion force generated during rolling is used to roll or roll steel. Therefore, during the working process, it mainly bears the influence of temperature changes, static and dynamic loads, and wear during rolling.

[0003] Traditional roll materials, such as gray cast iron and chilled cast iron, can no longer meet the performance requirements of current rolled steel sheets. Currently, the main roll materials are forged steel, usually high-hardness stainless steel, alloy semi-steel, high-speed steel, high-manganese steel, etc. However, during the continuous casting and rolling process, such forged steel rolls will still fail due to extreme environmental conditions. The general failure forms are fracture, roll surface spalling, wear, etc. Any form of failure will shorten the service life of the roll and reduce the quality of the rolled sheets. Therefore, in order to meet the increasing production demands of the manufacturing industry, a roll material is needed whose service performance, including hardness, strength, wear resistance, high-temperature resistance, thermal fatigue resistance, etc., has been significantly improved. Summary of the Invention

[0004] In view of the above-mentioned background art, the purpose of the present invention is to provide a new alloy material, which can overcome the defects of easy wear, poor thermal fatigue resistance, and easy high-temperature oxidation of the laser cladding layer on the surface of the roll in the prior art, thereby extending the service time of the roll and improving production efficiency.

[0005] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0006] An alloy material for a laser cladding layer of a roll with wear resistance and thermal fatigue resistance, which is a mixed powder. By mass percentage, it includes: 67.76 - 91.562% of 2Cr13 powder; 4.418 - 16.16% of nickel-coated graphite powder; 1.947 - 7.787% of pure titanium powder; 2.073 - 8.293 of pure vanadium powder.

[0007] In the above formula, 2Cr13 is martensitic stainless steel, which contains Cr: 8.85 - 12.88%; Si: ≤0.92; Mn: ≤0.92; C: 1.118 - 4%; P: <0.041; S: <0.027; the balance is Fe.

[0008] Specifically, the mixed powder is mixed by mechanical grinding at room temperature.

[0009] In the alloy material, the mass percentage of nickel in the nickel-coated graphite powder is 3.3 - 12.16%, and the mass percentage of graphite is 1.118 - 4%.

[0010] Preferably, for the laser cladding layer alloy material for wear-resistant and heat-fatigue-resistant rolls, by mass percentage, it includes: nickel in nickel-coated graphite powder: 3.49%, graphite: 1.173%; pure titanium powder 1.947%; pure vanadium powder 2.073%, and the balance is 2Cr13 powder. In this formula, the specific components are: Cr: 11.97%; Ni: 3.49%; Si: ≤0.92%; Mn: ≤0.92%; C: 1.173%; Ti: 1.947%; V: 2.073%; P: <0.041%; S: <0.027; the balance is Fe.

[0011] As a preference, the particle size of the mixed powder of the alloy material is 50 - 150 μm. Among them, the particle size of the 2Cr13 powder and the nickel-coated graphite powder as the main powder is 50 - 150 μm, and the particle size of the pure titanium powder and the pure vanadium powder is about 50 μm.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] In the present invention, by introducing elements such as Ti and V into the stainless steel iron-based alloy powder, a molten pool is generated under the input of high energy density during laser cladding. In the molten pool, TiC, VC, and TiVC formed by Ti, V elements and C 2 Due to having a lower formation energy, fine strengthening phases are preferentially formed in-situ and are dispersedly distributed in the cladding layer matrix. The remaining elements form a bonding phase alloy matrix. These strengthening phases have a non-coherent relationship with the matrix lath martensite, but because they are synthesized in-situ in the matrix, they have good metallurgical bonding with the matrix, are not easily detached during the wear process, and play a strengthening effect. The alloy powder itself is a stainless steel antioxidant and corrosion-resistant material, and has better oxidation resistance than the matrix at high temperatures. It should be noted that carbon is not directly added, but carbon elements are added in the form of nickel-coated graphite because adding carbon elements in the form of graphite and other carbon elements will cause excessive burning loss and poor forming quality of the cladding layer.

[0014] Preheating the substrate before cladding can effectively prevent the generation of cold cracks after cladding and inhibit shrinkage cracks, making the bonding between the cladding layer and the matrix good. During the cladding process, by directly blowing high-purity argon gas, the oxidation reaction during the process can be effectively prevented, making the surface of the cladding layer flat and without voids, and having a good morphology.

[0015] In summary, when using the alloy material of the present invention to process rolls, by controlling the alloy composition formula of the material and optimizing the process of the cladding process, the high-temperature wear resistance and heat fatigue resistance of the roll surface are effectively improved, and the service life of the roll is increased.

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0017] Figure 1 It is a macroscopic morphology diagram of the cladding layer: (a)-(d) are respectively the macroscopic morphology diagrams of the cladding layers of the products in Examples 1-4, and (e) is the macroscopic morphology diagram of the cladding layer of the comparative example;

[0018] Figure 2 It is a scanning electron microscope tissue diagram of the cladding layer: (a)-(d) are respectively the scanning diagrams of the products in Examples 1-4, and (e) is the scanning diagram of the comparative example.

[0019] Figure 3 It is a backscattered scanning electron microscope diagram of the ceramic phase of the cladding layer: (a)-(d) are respectively the scanning diagrams of the products in Examples 1-4, and (e) is the scanning diagram of the comparative example. Specific Embodiments

[0020] Example 1

[0021] For the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy of this example, the mass percentages of its various elements are shown in Table 1 below:

[0022]

[0023]

[0024] In the above table, Cr, Si, Mn, P, S, Fe, and some Ni elements and some C elements are all components of martensitic stainless steel 2Cr13. Among them, the C element is dissolved in the α-Fe in the Fe element. The remaining Ni element and C element exist in the form of nickel-coated graphite powder.

[0025] The specific steps for cladding the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example on the surface of the substrate are as follows:

[0026] 1. Powder treatment: The alloy powder is uniformly mixed in a planetary ball mill for 4 h, and then dried in a vacuum drying oven at 100 °C for 2 h to remove moisture for later use;

[0027] 2. Substrate preheating treatment: Grind it flat with 400, 800, and 1200-mesh sandpapers respectively; clean the oil stains with acetone, and then clean it with alcohol to make the surface to be clad clean; preheat the substrate to 200 °C with a preheating copper plate before cladding;

[0028] 3. Laser cladding: The spot diameter is 3 mm, the laser power is 2000, the scanning rate is 250 mm / min, the overlapping rate is 50%, the protective gas is high-purity argon at 40 L / min, the powder feeding disk rotation speed is 1 r / min, and the powder-carrying gas is also high-purity argon at 7 L / min;

[0029] 4. Cooling: Slow cooling in air.

[0030] Example 2

[0031] For the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example, the mass percentages of its various elements are shown in Table 2 below:

[0032]

[0033] The specific steps for cladding the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example on the substrate surface are as follows:

[0034] 1. Powder treatment: The alloy powder is evenly mixed in a planetary ball mill for 4 h, and then dried in a vacuum drying oven at 100 °C for 2 h to remove moisture for use.

[0035] 2. Substrate preheating treatment: Grind it flat with 400, 800, and 1200-mesh sandpapers respectively; clean the oil stains with acetone, and then clean it with alcohol to make the surface to be clad clean; use a preheating copper plate to preheat the substrate to 200 °C before cladding.

[0036] 3. Laser cladding: The spot diameter is 3 mm, the laser power is 2500, the scanning rate is 250 mm / min, the overlapping rate is 50%, the shielding gas is high-purity argon at 40 L / min, the powder feeding disk rotation speed is 1 r / min, and the powder-carrying gas is also high-purity argon at 7 L / min.

[0037] 4. Cooling: Slow cooling in air.

[0038] Example 3

[0039] For the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example, the mass percentages of its various elements are shown in Table 3 below:

[0040]

[0041] The specific steps for cladding the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example on the substrate surface are as follows:

[0042] 1. Powder treatment: The alloy powder is evenly mixed in a planetary ball mill for 4 h, and then dried in a vacuum drying oven at 100 °C for 2 h to remove moisture for use.

[0043] 2. Substrate preheating treatment: Grind it flat with 400, 800, and 1200-mesh sandpapers respectively; clean the oil stains with acetone, and then clean it with alcohol to make the surface to be clad clean; use a preheating copper plate to preheat the substrate to 200 °C before cladding.

[0044] 3. Laser cladding: The spot diameter is 3 mm, the laser power is 2500, the scanning speed is 200 mm / min, the overlapping rate is 50%, the shielding gas is high-purity argon at 40 L / min, the powder feeding disk rotates at 1 r / min, and the powder-carrying gas is also high-purity argon at 7 L / min;

[0045] 4. Cooling: Slow cooling and air cooling.

[0046] Example 4

[0047] For the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example, the mass percentages of its various elements are shown in Table 4 below:

[0048]

[0049] The specific steps for cladding the high-temperature wear-resistant and thermal fatigue-resistant laser cladding alloy material of this example on the substrate surface are as follows:

[0050] 1. Powder treatment: The alloy powder is evenly mixed in a planetary ball mill for 4 h, and then dried in a vacuum drying oven at 100 °C for 2 h to remove moisture for use;

[0051] 2. Substrate pre-treatment: Grind and level with 400, 800, and 1200-mesh sandpapers respectively; clean the oil stains with acetone, etc., and then clean with alcohol to make the surface to be clad clean; pre-heat the substrate to 200 °C with a pre-heating copper plate before cladding;

[0052] 3. Laser cladding: The spot diameter is 3 mm, the laser power is 2000, the scanning speed is 250 mm / min, the overlapping rate is 50%, the shielding gas is high-purity argon at 28 L / min, the powder feeding disk rotates at 1 r / min, and the powder-carrying gas is also high-purity argon at 4.9 L / min;

[0053] 4. Cooling: Slow cooling and air cooling.

[0054] Comparative Example 1

[0055] The name of the cladding alloy material without adding strengthening elements is 420, the powder particle size is 50 - 150 μm, provided by Chengdu Ketailong Alloy Co., Ltd., and the mass percentages of its various elements are shown in Table 5 below:

[0056]

[0057] In Table 5, Cr, Si, Ni, C, Mn, P, S, and Fe are all components of martensitic stainless steel 2Cr13. Among them, the C element is dissolved in the α-Fe in the Fe element.

[0058] The specific steps are as follows:

[0059] 1. Powder treatment: The alloy powder is dried in a vacuum drying oven at 100 °C for 2 h to remove moisture for use;

[0060] 2. Substrate preheating treatment: Grind it flat with 400, 800, and 1200 - mesh sandpapers respectively; clean the oil stains etc. with acetone, and then clean it with alcohol to make the surface to be clad clean; preheat the substrate to 200 °C with a preheating copper plate before cladding;

[0061] 3. Laser cladding: The spot diameter is 3 mm, the laser power is 2000, the scanning speed is 250 mm / min, the overlapping rate is 50%, the shielding gas is high - purity argon at 40 L / min, the rotating speed of the powder - feeding disk is 1 r / min, and the powder - carrying gas is also high - purity argon at 7 L / min;

[0062] 4. Cooling: Slowly cool in air.

[0063] Microstructure and property analysis:

[0064] For the clad layer prepared by laser cladding, wire - cut the metallographic samples, friction and wear samples, and thermal fatigue samples. After corroding with ferric chloride - hydrochloric acid etching solution, observe the microstructure of each area of the clad layer cross - section with an optical microscope (OM); use a ZEISS Gemini300 high - resolution scanning electron microscope and a backscattered scanning electron microscope to analyze the tissue elements of the clad layer; use a DHV - 1000ZTEST micro - Vickers hardness tester (136° regular square - pyramid diamond indenter, applying a pressure of 9.8 N, holding the pressure for 15 s) to test the hardness of the clad layer; use a micro - shear tester to conduct shear tests on the micro - area from the clad layer to the substrate; use an HT - 1000 type ball - disk friction and wear testing machine to conduct friction and wear experiments at room temperature and high temperature. The test force is 15 N, the wear time is 90 min, the spindle speed is 400 r / min, and the counter - grinding material is selected as U75V rolled rail material with a diameter of 6 mm and a surface roughness Ra of 0.25; use a self - built thermal fatigue tester to conduct anti - thermal fatigue experiments.

[0065] Table 6 Comparison of the properties of the example clad layer

[0066]

[0067]

[0068] Table 7 Detection results

[0069] Hardness High-temperature wear resistance Plasticity Thermal fatigue performance Example 1 Increase by 5.77% Increase by 2.56 times Increase by 46.4% Increase by 3.1 times Example 2 Increase by 25.41% Increase by 1.62 times Decrease by 29% Increase by 1.9 times Example 3 Increase by 10.14% Increase by 1.96 times Increase by 117.4% Decrease to 0.44 times Example 4 Increase by 6.64% Increase by 1.3 times Increase by 89.8% Decrease to 0.64 times

[0070] Compared with the prior art, the laser - clad alloy material of the present invention has higher hardness, better high - temperature wear resistance, and a lower thermal fatigue crack propagation rate. Example 1 has excellent comprehensive performance. As Figure 1 shown, Example 1 has better surface forming quality, and there are no defects such as inclusions and welding beads on the surface. As Figure 2The shown Example 1 has a finer structure compared with Comparative Example 1. The intragranular lath martensites are staggered, playing a strengthening role. Figure 3 The black precipitate phases therein are TiC, VC, and TiVC2 ceramic phases. The ceramic phases are uniformly distributed in the cladding layer of Example 1 and mainly precipitate at grain boundaries. Compared with Comparative Example 1, they have obvious solid solution strengthening and dispersion strengthening effects, and act as hard phases during the friction process to resist wear on the substrate.

[0071] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. An alloy material for a laser cladding layer of a wear-resistant and heat-fatigue-resistant rolling roll, which is a mixed powder, Characterized in that: By mass percentage, it includes: nickel in nickel-coated graphite powder: 3.49%, graphite: 1.173%; pure titanium powder 1.947%; pure vanadium powder 2.073%, and the balance is 2Cr13 powder; its specific components are: Cr: 11.97%; Ni: 3.49%; Si: ≤0.92%; Mn: ≤0.92%; C: 1.173%; Ti: 1.947%; V: 2.073%; P: <0.041%; S: <0.027; the balance is Fe.

2. The alloy material according to claim 1, Characterized in that, The particle size of the mixed powder of the alloy material is 50-150 μm.

3. The alloy material according to claim 2, Characterized in that, The particle size of the 2Cr13 powder as the main powder and the nickel-coated graphite powder is 50-150 μm, and the particle size of the pure titanium powder and the pure vanadium powder is 50 μm.

4. The alloy material according to claim 2, Characterized in that, The mixed powder is mixed by mechanical ball milling at room temperature.

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