A laser repair method for the surface of ductile iron

Abstract

The present invention relates to the technical field of laser repair, and specifically provides a method for laser repair of the surface of ductile iron, which includes the following steps: S1: Pretreatment. Obtain a ductile iron workpiece, remove rust and clean the ductile iron to obtain pretreated ductile iron; S2: Coating treatment. Use a coating material to coat the surface of the pretreated ductile iron, and the coating position is the defective position of the ductile iron to complete the coating treatment of the ductile iron. In the present invention, during the laser repair treatment of the surface of ductile iron, graphite powder can provide additional carbon source supplementation, ensure the formation and uniform distribution of graphite nodules, make the metallurgical bonding between the cladding layer and the substrate better, improve the bonding strength. At the same time, by utilizing the good thermal conductivity of graphite powder, the temperature distribution of ductile iron during the laser cladding process can be improved, enabling the cladding repair layer to be uniformly combined and generated, and enhancing the repair effect on ductile iron.

Description

Technical Field

[0001] The present invention relates to the technical field of laser repair, and particularly to a method for laser repair of the surface of ductile iron castings. Background Art

[0002] Ductile iron castings are high-strength cast iron materials, and their comprehensive properties are close to those of steel. Due to their excellent properties, they have been successfully used in casting some parts with complex stress, high requirements for strength, toughness, and wear resistance.

[0003] In the prior art, laser cladding treatment for surface defects of ductile iron castings is a common surface repair method. However, there are strength defects at the bonding surface between the cladding layer and the ductile iron casting, which affects the repair effect of the ductile iron casting. Based on this, the present invention provides a method for laser repair of the surface of ductile iron castings. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for laser repair of the surface of ductile iron castings. The laser repair surface of the ductile iron casting processed by the method for laser repair of the surface of ductile iron castings of the present invention not only has good wear resistance but also has excellent hardness performance, effectively improving the service performance of the ductile iron casting.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A method for laser repair of the surface of ductile iron castings, comprising the following steps:

[0007] S1: Pretreatment to obtain a ductile iron casting workpiece, removing rust and cleaning the ductile iron casting to obtain the pretreated ductile iron casting;

[0008] S2: Coating treatment, coating the surface of the pretreated ductile iron casting with a coating material, and the coating position is the defective position of the ductile iron casting to complete the coating treatment of the ductile iron casting;

[0009] S3: Hot dipping treatment, immersing the ductile iron casting after the coating treatment in a treatment liquid to complete the hot dipping treatment of the ductile iron casting;

[0010] S4: Cladding treatment, performing laser cladding on the surface of the ductile iron casting after the hot dipping treatment to repair the defective position of the ductile iron casting and complete the cladding treatment of the ductile iron casting;

[0011] S5: Trimming treatment to complete the laser repair of the surface of the ductile iron casting.

[0012] Further, the pretreatment method of the ductile iron is as follows: Use an electric grinding wheel to remove rust from the surface of the ductile iron, then immerse the ductile iron in acetone and let it stand for 10 - 20 min. After the immersion is completed, rinse the surface of the ductile iron with deionized water. After the rinsing is completed, send it into an oven, and set the oven temperature at 70 - 80 °C for drying treatment for 2 - 4 h to complete the pretreatment of the ductile iron.

[0013] Further, the raw materials of the coating material are paraffin, graphite powder and toluene. The mass ratio of paraffin, graphite powder and toluene is 1:(2.2 - 2.6):(0.2 - 0.4), and the graphite powder selected has a particle size of 200 mesh.

[0014] Further, the coating material is prepared by the following method: Add paraffin into a reaction kettle, set the temperature of the reaction kettle at 40 - 50 °C. After the temperature rise is completed, add toluene, set the temperature at 70 - 80 °C, the rotation speed at 120 - 160 r / min, carry out heat preservation and stirring treatment for 8 - 12 min, then add graphite powder, and continue the above heat preservation and stirring conditions for treatment for 16 - 20 min to obtain the coating material.

[0015] Further, the coating treatment method is as follows: Brush the coating material on the defective position on the surface of the ductile iron. After the brushing is completed, send it into an oven, and set the oven temperature at 120 - 160 °C for drying treatment for 10 - 20 min to complete the coating treatment of the ductile iron.

[0016] Further, the treatment liquid selected is silicone oil.

[0017] Further, the hot dipping treatment method is as follows: Immerse the ductile iron in silicone oil. When immersing, keep the silicone oil at a temperature of 42 - 46 °C, and the immersion time is 12 - 16 min to complete the hot dipping treatment of the ductile iron.

[0018] Further, the cladding treatment method is as follows: Use a cladding powder in combination with a laser cladding machine to output the cladding powder to form a cladding layer at the defective position on the surface of the ductile iron. Set the laser power of the laser cladding machine at 800 - 900 W, the feeding rate at 16 - 18 g / min, the traveling rate at 4 - 6 mm / s, the nozzle spacing at 4 - 6 cm, the shielding gas as argon, the gas flow rate at 8 - 12 L / min, and the powder-carrying gas as nitrogen, the gas flow rate at 6 - 10 L / min.

[0019] Further, the raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum. The weight percentages of each raw material are: 3 - 5% carbon, 2 - 4% silicon, 0.6 - 0.8% manganese, 0.03 - 0.05% magnesium, 0.03 - 0.05% lanthanum, and the balance is iron. Each raw material is selected as a powder, and the particle size of the powder is 300 mesh.

[0020] Further, the method of the trimming process is as follows: After the nodular cast iron is subjected to cladding treatment on the surface to form a cladding layer, the nodular cast iron is sent into an oven. The oven is set to be kept at 160-180°C for 40-50 minutes. After the heat preservation is completed, the nodular cast iron is taken out, and the repaired position on the surface of the nodular cast iron is polished to remove the redundant repair surface, thus completing the laser repair of the surface of the nodular cast iron.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. In the present invention, during the laser repair treatment on the surface of nodular cast iron, through the pre-coating treatment of nodular cast iron, the graphite powder is evenly attached to the position to be repaired on the surface of nodular cast iron. When the nodular cast iron is subjected to cladding treatment, the paraffin wax serving as an adhesive will be gasified, and the graphite powder can provide additional carbon source supplementation, ensuring the formation and uniform distribution of graphite balls, making the metallurgical bonding between the cladding layer and the matrix better, improving the bonding strength. At the same time, by utilizing the good thermal conductivity of the graphite powder, the temperature distribution of the nodular cast iron during the laser cladding process can be improved, enabling the cladding repair layer to be uniformly combined and generated, and enhancing the repair effect on the nodular cast iron.

[0023] 2. In the present invention, through the hot dipping treatment of nodular cast iron after the coating treatment, when the nodular cast iron is immersed in silicone oil, the silicone oil can fill the tiny pores and defects in the wax layer, making the graphite powder combine more tightly with the surface of the nodular cast iron, preventing the graphite powder from falling off during the treatment process, thereby enhancing the attachment stability of the graphite powder on the surface of the nodular cast iron, reducing the loss of graphite powder during the cladding treatment, improving the use effect of the pre-coating of the graphite powder, and further enhancing the repair effect on the nodular cast iron. Specific Embodiments

[0024] Next, the technical solutions in the experiments of the present invention will be clearly and completely described in combination with the experiments of the present invention. Obviously, the described experiments are only a part of the experiments of the present invention, rather than all the experiments. Based on the experiments of the present invention, all other experiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0025] This embodiment provides a method for laser repairing the surface of nodular cast iron, including the following steps:

[0026] S1: Pretreatment, obtaining a nodular cast iron workpiece, removing rust and cleaning the nodular cast iron to obtain the pretreated nodular cast iron;

[0027] S2: Coating treatment, using a coating material to coat the surface of the nodular cast iron that has completed the pretreatment, and the coating position is the defective position of the nodular cast iron, thus completing the coating treatment of the nodular cast iron;

[0028] S3: Hot dipping treatment. The nodular cast iron after the coating treatment is immersed in the treatment liquid to complete the hot dipping treatment of the nodular cast iron;

[0029] S4: Cladding treatment. Laser cladding is performed on the surface of the nodular cast iron after the hot dipping treatment to repair the defective positions of the nodular cast iron and complete the cladding treatment of the nodular cast iron;

[0030] S5: Trimming treatment. Laser repair of the surface of the nodular cast iron is completed.

[0031] In some embodiments, the pretreatment method of nodular cast iron is as follows: Use an electric grinding wheel to remove rust from the surface of the nodular cast iron, then immerse the nodular cast iron in acetone, let it stand for 10 - 20 min. After the immersion is completed, rinse the surface of the nodular cast iron with deionized water. After the rinsing is completed, send it into an oven, and the oven is set at 70 - 80 °C for drying treatment for 2 - 4 h to complete the pretreatment of the nodular cast iron.

[0032] In some embodiments, the raw materials of the coating material are paraffin, graphite powder, and toluene. The mass ratio of paraffin, graphite powder, and toluene is 1:(2.2 - 2.6):(0.2 - 0.4), and the graphite powder is selected with a particle size of 200 mesh.

[0033] In some embodiments, the coating material is prepared by the following method: Add paraffin into a reaction kettle, set the temperature of the reaction kettle at 40 - 50 °C. After the temperature rise is completed, add toluene, set the temperature at 70 - 80 °C, the rotation speed at 120 - 160 r / min, carry out heat preservation and stirring treatment for 8 - 12 min, then add graphite powder, and continue the above heat preservation and stirring conditions for treatment for 16 - 20 min to obtain the coating material.

[0034] In some embodiments, the coating treatment method is as follows: Brush the coating material on the defective positions on the surface of the nodular cast iron. After the brushing is completed, send it into an oven, and the oven is set at 120 - 160 °C for drying treatment for 10 - 20 min to complete the coating treatment of the nodular cast iron.

[0035] In some embodiments, the treatment liquid is selected as silicone oil.

[0036] In some embodiments, the hot dipping treatment method is as follows: Immerse the nodular cast iron in silicone oil. When soaking, the silicone oil is kept at 42 - 46 °C, and the soaking time is 12 - 16 min to complete the hot dipping treatment of the nodular cast iron.

[0037] In some embodiments, the method of cladding treatment is as follows: Using cladding powder in combination with a laser cladding machine, the cladding powder is output to form a cladding layer at the defect position on the surface of ductile iron. The laser cladding machine is set with a laser power of 800 - 900 W, a feeding rate of 16 - 18 g / min, a traveling rate of 4 - 6 mm / s, a nozzle spacing of 4 - 6 cm, a protective gas of argon with a gas flow rate of 8 - 12 L / min, a powder-carrying gas of nitrogen with a gas flow rate of 6 - 10 L / min.

[0038] In some embodiments, the raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium, and lanthanum. The weight percentages of each raw material are as follows: 3 - 5% carbon, 2 - 4% silicon, 0.6 - 0.8% manganese, 0.03 - 0.05% magnesium, 0.03 - 0.05% lanthanum, and the balance is iron. Each raw material is selected as a powder, and the powder particle size is 300 mesh.

[0039] In some embodiments, the method of finishing treatment is as follows: After the ductile iron forms a cladding layer on the surface after cladding treatment, the ductile iron is sent into an oven. The oven is set to keep warm at 160 - 180 °C for 40 - 50 min. After the heat preservation ends, the ductile iron is taken out, and the repaired position on the surface of the ductile iron is polished to remove the excess repair surface, thus completing the laser repair of the surface of the ductile iron.

[0040] In this embodiment, during the laser repair treatment on the surface of ductile iron, through the pre-coating treatment of the ductile iron, the graphite powder is evenly attached to the position to be repaired on the surface of the ductile iron. When the ductile iron is subjected to cladding treatment, the paraffin wax used as an adhesive will vaporize, and the graphite powder can provide additional carbon source supplementation to ensure the formation and uniform distribution of graphite balls, making the metallurgical bonding between the cladding layer and the substrate better, improving the bonding strength. At the same time, using the good thermal conductivity of the graphite powder can improve the temperature distribution of the ductile iron during the laser cladding process, enabling the cladding repair layer to be evenly combined and generated, thus enhancing the repair effect on the ductile iron;

[0041] Through the hot dipping treatment of the ductile iron after coating treatment, when the ductile iron is immersed in silicone oil, the silicone oil can fill the micro-pores and defects in the wax layer, making the graphite powder bind more tightly to the surface of the ductile iron, preventing the graphite powder from falling off during the treatment process, thereby enhancing the attachment stability of the graphite powder on the surface of the ductile iron, reducing the loss of graphite powder during the cladding treatment, improving the use effect of the pre-coating of the graphite powder, and further enhancing the repair effect on the ductile iron.

[0042] Based on the foregoing embodiments, the following multiple groups of experiments were carried out:

[0043] It should be noted that the raw materials used in the following experiments are all commercially available raw materials.

[0044] Experiment 1:

[0045] S1: Pretreatment to obtain a ductile iron workpiece. Rust removal and cleaning are performed on the ductile iron to obtain pretreated ductile iron.

[0046] S2: Coating treatment. The surface of the pretreated ductile iron is coated with a coating material. The coating position is the defective position of the ductile iron, and the coating treatment of the ductile iron is completed.

[0047] S3: Hot dipping treatment. The ductile iron after coating treatment is immersed in a treatment liquid to complete the hot dipping treatment of the ductile iron.

[0048] S4: Cladding treatment. Laser cladding is performed on the surface of the ductile iron after hot dipping treatment to repair the defective position of the ductile iron and complete the cladding treatment of the ductile iron.

[0049] S5: Trimming treatment. Laser repair of the surface of the ductile iron is completed.

[0050] The pretreatment method of ductile iron is as follows: Use an electric grinding wheel to remove rust from the surface of the ductile iron. Then immerse the ductile iron in acetone and let it stand for 10 minutes. After soaking, rinse the surface of the ductile iron with deionized water. After rinsing, send it into an oven, and the oven is set at 70 °C for drying treatment for 2 hours to complete the pretreatment of the ductile iron.

[0051] The raw materials of the coating material are paraffin, graphite powder, and toluene. The mass ratio of paraffin, graphite powder, and toluene is 1:2.2:0.2, and the graphite powder has a particle size of 200 mesh.

[0052] The coating material is prepared by the following method: Add paraffin into a reaction kettle, set the temperature of the reaction kettle at 40 °C. After the temperature rise is completed, add toluene, set the temperature at 70 °C, and the rotation speed at 120 r / min. Keep warm and stir for 8 minutes, then add graphite powder and continue the above-mentioned warm-keeping and stirring conditions for 16 minutes to obtain the coating material.

[0053] The coating treatment method is as follows: Brush the coating material on the defective position of the surface of the ductile iron. After brushing, send it into an oven, and the oven is set at 120 °C for drying treatment for 10 minutes to complete the coating treatment of the ductile iron.

[0054] The treatment liquid is selected as silicone oil.

[0055] The hot dipping treatment method is as follows: Immerse the ductile iron in silicone oil. When soaking, keep the silicone oil at 42 °C, and the soaking time is 12 minutes to complete the hot dipping treatment of the ductile iron.

[0056] The method of cladding treatment is as follows: Using cladding powder in combination with a laser cladding machine, the cladding powder is output to form a cladding layer at the defect position on the surface of ductile iron. The laser cladding machine is set with a laser power of 800 W, a feeding rate of 16 g / min, a traveling rate of 4 mm / s, a nozzle spacing of 4 cm, a protective gas of argon with a gas flow rate of 8 L / min, a powder-carrying gas of nitrogen with a gas flow rate of 6 L / min.

[0057] The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum. The weight percentages of each raw material are: 3% carbon, 2% silicon, 0.6% manganese, 0.03% magnesium, 0.03% lanthanum, and the balance is iron. Each raw material is selected as a powder, and the powder particle size is 300 mesh.

[0058] The method of finishing treatment is as follows: After the ductile iron forms a cladding layer on the surface after cladding treatment, the ductile iron is sent into an oven, and the oven is set to keep warm at 160 °C for 40 min. After the heat preservation is completed, the ductile iron is taken out, and the repaired position on the surface of the ductile iron is polished to remove the excess repair surface, and the laser repair of the surface of the ductile iron is completed.

[0059] Experiment Two:

[0060] S1: Pretreatment to obtain a ductile iron workpiece. Rust removal and cleaning treatments are carried out on the ductile iron to obtain pretreated ductile iron.

[0061] S2: Coating treatment. Use a coating material to coat the surface of the pretreated ductile iron. The coating position is the defect position of the ductile iron, and the coating treatment of the ductile iron is completed.

[0062] S3: Hot dipping treatment. The ductile iron after coating treatment is immersed in a treatment liquid to complete the hot dipping treatment of the ductile iron.

[0063] S4: Cladding treatment. Laser cladding is carried out on the surface of the ductile iron after hot dipping treatment to repair the defect position of the ductile iron, and the cladding treatment of the ductile iron is completed.

[0064] S5: Finishing treatment to complete the laser repair of the surface of the ductile iron.

[0065] The pretreatment method of ductile iron is as follows: Use an electric grinding wheel to carry out rust removal treatment on the surface of the ductile iron, and then immerse the ductile iron in acetone and let it stand for 15 min. After the immersion is completed, use deionized water to rinse the surface of the ductile iron. After the rinsing is completed, send it into an oven, and the oven is set to dry at 75 °C for 3 h to complete the pretreatment of the ductile iron.

[0066] The raw materials of the coating material are composed of paraffin, graphite powder and toluene. The mass ratio of paraffin, graphite powder and toluene is 1:2.4:0.3, and the graphite powder is selected with a particle size of 200 mesh.

[0067] The coating material is prepared by the following method: Paraffin is added into the reaction kettle, and the set temperature of the reaction kettle is 45°C. After the temperature rise is completed, toluene is added, the temperature is set at 75°C, the rotation speed is 140 r / min, and it is kept warm and stirred for 10 min. Then, graphite powder is added, and the above-mentioned conditions of heat preservation and stirring are continued for 18 min to obtain the coating material.

[0068] The method of coating treatment is as follows: The coating material is brushed on the defective position on the surface of the ductile iron. After the brushing is completed, it is sent into the oven, and the oven is set at 140°C for drying treatment for 15 min to complete the coating treatment of the ductile iron.

[0069] The treatment liquid selected is silicone oil.

[0070] The method of hot dipping treatment is as follows: The ductile iron is immersed in silicone oil. When immersed, the silicone oil is kept at 44°C, and the immersion time is 14 min to complete the hot dipping treatment of the ductile iron.

[0071] The method of cladding treatment is as follows: Using the cladding powder and a laser cladding machine, the cladding powder is output to form a cladding layer at the defective position on the surface of the ductile iron. The laser power of the laser cladding machine is set at 850 W, the feeding rate is 17 g / min, the traveling rate is 5 mm / s, the nozzle spacing is 5 cm, the shielding gas is argon, the gas flow rate is 10 L / min, the powder-carrying gas is nitrogen, and the gas flow rate is 8 L / min.

[0072] The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium, and lanthanum. The weight percentages of each raw material are: 4% carbon, 3% silicon, 0.7% manganese, 0.04% magnesium, 0.04% lanthanum, and the balance is iron. Each raw material is selected as a powder, and the particle size of the powder is 300 mesh.

[0073] The method of finishing treatment is as follows: After the ductile iron forms a cladding layer on the surface after the cladding treatment, the ductile iron is sent into the oven, and the oven is set at 170°C for heat preservation for 45 min. After the heat preservation is completed, the ductile iron is taken out, and the repaired position on the surface of the ductile iron is polished to remove the excess repaired surface, thus completing the laser repair of the surface of the ductile iron.

[0074] Experiment Three:

[0075] S1: Pretreatment. Obtain a ductile iron workpiece, remove rust and clean the ductile iron to obtain the pretreated ductile iron.

[0076] S2: Coating treatment. Use the coating material to coat the surface of the pretreated ductile iron, and the coating position is the defective position of the ductile iron to complete the coating treatment of the ductile iron.

[0077] S3: Hot dipping treatment. Immerse the ductile iron after the coating treatment into the treatment liquid to complete the hot dipping treatment of the ductile iron.

[0078] S4: Cladding treatment. Laser cladding is carried out on the surface of the ductile iron that has completed the hot dipping treatment to repair the defective positions of the ductile iron, and the cladding treatment of the ductile iron is completed.

[0079] S5: Trimming treatment. Laser repair of the surface of the ductile iron is completed.

[0080] The pretreatment method of ductile iron is as follows: Use an electric grinding wheel to remove rust from the surface of the ductile iron, then immerse the ductile iron in acetone and let it stand for 20 minutes. After the immersion is completed, rinse the surface of the ductile iron with deionized water. After the rinsing is completed, send it into an oven, and the oven is set at 80°C for drying treatment for 4 hours to complete the pretreatment of the ductile iron.

[0081] The raw materials of the coating material are paraffin, graphite powder and toluene. The mass ratio of paraffin, graphite powder and toluene is 1:2.6:0.4, and the graphite powder is selected with a particle size of 200 mesh.

[0082] The coating material is prepared by the following method: Add paraffin into the reaction kettle, set the temperature of the reaction kettle at 50°C. After the temperature rise is completed, add toluene, set the temperature at 80°C, and the rotation speed at 160 r / min. Carry out heat preservation and stirring treatment for 12 minutes, then add graphite powder and continue the above heat preservation and stirring conditions for 20 minutes to obtain the coating material.

[0083] The coating treatment method is: Brush the coating material on the defective positions on the surface of the ductile iron. After the brushing is completed, send it into an oven, and the oven is set at 160°C for drying treatment for 20 minutes to complete the coating treatment of the ductile iron.

[0084] The treatment liquid is selected as silicone oil.

[0085] The hot dipping treatment method is: Immerse the ductile iron in silicone oil. When immersing, the silicone oil is kept at 46°C, and the immersion time is 16 minutes to complete the hot dipping treatment of the ductile iron.

[0086] The cladding treatment method is: Use cladding powder in combination with a laser cladding machine to output the cladding powder to form a cladding layer at the defective positions on the surface of the ductile iron. The laser cladding machine is set with a laser power of 900 W, a feeding rate of 18 g / min, a traveling rate of 6 mm / s, a nozzle spacing of 6 cm, a shielding gas of argon, a gas flow rate of 12 L / min, a powder-carrying gas of nitrogen, and a gas flow rate of 10 L / min.

[0087] The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum. The weight percentages of each raw material are: 5% carbon, 4% silicon, 0.8% manganese, 0.05% magnesium, 0.05% lanthanum, and the balance is iron. Each raw material is selected as powder, and the powder particle size is 300 mesh.

[0088] The method of finishing treatment is as follows: After the nodular cast iron is subjected to cladding treatment on the surface to form a cladding layer, the nodular cast iron is sent into an oven, and the oven is set to keep warm at 180°C for 50 minutes. After the heat preservation is completed, the nodular cast iron is taken out, and the repaired position on the surface of the nodular cast iron is polished to remove the excess repaired surface, thus completing the laser repair of the surface of the nodular cast iron.

[0089] Comparative Example 1. The difference between this comparative example and Experimental Example 1 is that: in this comparative example, the nodular cast iron is not pretreated.

[0090] Comparative Example 2. The difference between this comparative example and Experimental Example 1 is that: in this comparative example, the nodular cast iron is not subjected to hot dipping treatment.

[0091] Comparative Example 3. The difference between this comparative example and Experimental Example 1 is that: in this comparative example, graphite powder is not added in the preparation of the coating material.

[0092] Comparative Example 4. The difference between this comparative example and Experimental Example 1 is that: in this comparative example, an equal amount of iron powder is selected to replace the cladding powder.

[0093] Performance test: The nodular cast iron treated in Experimental Example 1, Experimental Example 2, Experimental Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 is subjected to performance testing.

[0094] The obtained test data are recorded in the following table:

[0095]

[0096] In the performance test, the nodular cast iron treated in Experimental Example 1, Experimental Example 2, Experimental Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 is obtained, and the wear amount (wear resistance) and hardness of the laser repair position on the surface of each nodular cast iron are tested. Among them, the test method for the wear amount is: Use a wear testing machine to conduct wear tests on the laser repair surface of the nodular cast iron treated in Experimental Example 1, Experimental Example 2, Experimental Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. The hardness of the abrasive is 260 HBS, the rotation speed is 400 r / min, the contact load is 6 kg, and the total wear test time is 25 minutes. The weights of the nodular cast iron are recorded respectively before and after the wear test, and the wear amount data of the nodular cast iron treated in Experimental Example 1, Experimental Example 2, Experimental Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 are obtained.

[0097] It can be seen that the wear resistance and hardness data of the laser repaired surface of ductile iron after the treatments of Comparative Examples 1, 2, 3, and 4 are all lower than those of Experiments 1, 2, and 3. This shows that: during the laser repair treatment on the surface of ductile iron, through the pre - coating treatment of ductile iron, graphite powder is evenly attached to the position to be repaired on the surface of ductile iron. When the ductile iron is subjected to cladding treatment, the paraffin wax acting as an adhesive will vaporize, and the graphite powder can provide additional carbon source supplementation, ensuring the formation and uniform distribution of graphite balls, making the metallurgical bonding between the cladding layer and the substrate better, improving the bonding strength. At the same time, using the good thermal conductivity of graphite powder can improve the temperature distribution of ductile iron during the laser cladding process, enabling the cladding repair layer to be evenly combined and generated, and enhancing the repair effect on ductile iron.

[0098] By comparing and analyzing the relevant data in the table, it can be known that the laser repaired surface of ductile iron processed by the laser repair method for the surface of ductile iron in the present invention not only has good wear resistance but also excellent hardness performance. This indicates that the laser repair method for the surface of ductile iron provided by the present invention has a broader market prospect and is more suitable for popularization.

[0099] In the description of this specification, the description referring to terms such as "one experiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with that experiment or example are included in at least one experiment or example of the present invention. In this specification, the schematic representations of the above - mentioned terms do not necessarily refer to the same experiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more experiments or examples.

[0100] The preferred experiments of the present invention disclosed above are only used to help explain the present invention. The preferred experiments do not elaborate on all the details, nor do they limit the invention to only the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. The present specification selects and specifically describes these experiments to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A laser repair method for ductile iron surface, characterized in that: The following steps are involved: S1: pretreatment to obtain a ductile iron workpiece, derusting and cleaning the ductile iron to obtain pretreated ductile iron; S2: coating treatment, using a coating material to coat the pre-treated ductile iron surface, the coating position is the defect position of the ductile iron, and the coating treatment of the ductile iron is completed; The raw materials of the coating material are composed of paraffin wax, graphite powder and toluene, the mass ratio of the paraffin wax, graphite powder and toluene is 1: (2.2-2.6): (0.2-0.4), and the graphite powder has a particle size of 200 mesh; The coating material is prepared by the following method: paraffin is added into a reaction kettle, the temperature of the reaction kettle is set at 40-50°C, toluene is added after the temperature is raised, the temperature is set at 70-80°C, the speed is 120-160r / min, the heat preservation and stirring are carried out for 8-12 minutes, then graphite powder is added, and the heat preservation and stirring conditions are continued for 16-20 minutes to prepare the coating material; S3: hot dip treatment, the ductile iron after the coating treatment is immersed in the treatment liquid to complete the hot dip treatment of the ductile iron; S4: Cladding treatment, laser cladding is performed on the surface of the ductile iron after hot dip treatment to repair the defective position of the ductile iron and complete the cladding treatment of the ductile iron; S5: Finishing treatment to complete the laser repair of the ductile iron surface.

2. The laser repair method for the surface of ductile iron according to claim 1, characterized in that: The ductile iron pretreatment method comprises: using an electric grinding wheel to remove rust from the surface of the ductile iron, then immersing the ductile iron in acetone, leaving it to stand for 10 to 20 minutes, rinsing the surface of the ductile iron with deionized water after immersion, and sending it into an oven after rinsing, setting the oven at 70 to 80° C. for drying for 2 to 4 hours to complete the pretreatment of the ductile iron.

3. The laser repair method for the surface of ductile iron according to claim 1, characterized in that: The coating treatment method is: brushing the coating material on the defective position of the ductile iron surface, after brushing, sending it into an oven, setting the oven at 120-160° C. for drying for 10-20 minutes, and completing the coating treatment of the ductile iron.

4. The laser repair method for the surface of ductile iron according to claim 1, characterized in that: The treatment liquid is silicone oil.

5. The laser repair method for the surface of ductile iron according to claim 1, characterized in that: The method of hot-dip treatment is as follows: the ductile iron is immersed in silicone oil, the silicone oil is kept at 42-46° C. during immersion, and the immersion time is 12-16 minutes, so as to complete the hot-dip treatment of the ductile iron.

6. The laser repair method for the surface of ductile iron according to claim 1, characterized in that: The cladding treatment method is: using cladding powder in conjunction with a laser cladding machine, outputting the cladding powder to form a cladding layer at the defective position on the surface of the ductile iron, the laser cladding machine sets the laser power to 800-900W, the feed rate to 16-18g / min, the travel rate to 4-6mm / s, the nozzle spacing to 4-6cm, the protective gas to argon, the gas flow rate to 8-12L / min, and the powder carrier gas to nitrogen, the gas flow rate to 6-10L / min.

7. The laser repair method for the surface of ductile iron according to claim 6, characterized in that: The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum, and the weight percentage of each raw material is: 3-5% carbon, 2-4% silicon, 0.6-0.8% manganese, 0.03-0.05% magnesium, 0.03-0.05% lanthanum, and the balance is iron. Each raw material is powdered, and the powder particle size is 300 mesh.

8. The laser repair method for the surface of ductile iron according to claim 1, characterized in that: The finishing method is as follows: after the ductile iron is clad on the surface to form a cladding layer, the ductile iron is sent into an oven, the oven is set at 160-180° C. for insulation for 40-50 minutes, after the insulation is completed, the ductile iron is taken out, the repaired position on the surface of the ductile iron is polished to remove the excess repair surface, and the laser repair of the ductile iron surface is completed.

Images