Nodular cast iron surface laser repairing method

Abstract

The invention relates to the technical field of laser repairing, in particular to a nodular cast iron surface laser repairing method which comprises the following steps: S1, pretreating to obtain a nodular cast iron workpiece, and derusting and cleaning nodular cast iron to obtain pretreated nodular cast iron; and S2, coating treatment is conducted, specifically, the pretreated nodular cast iron surface is coated with a coating material, the coating position is the defect position of the nodular cast iron, and coating treatment of the nodular cast iron is completed. In the surface laser repairing treatment process of the nodular cast iron, the graphite powder can be used for additional carbon source supplementation, formation and uniform distribution of graphite nodules are guaranteed, metallurgical bonding of a cladding layer and a base body is better, the bonding strength is improved, and meanwhile the good heat conductivity of the graphite powder is utilized; the temperature distribution of the nodular cast iron in the laser cladding process can be improved, so that a cladding repair layer is uniformly combined and generated, and the repair effect on the nodular cast iron is improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser repair, in particular to a method for laser repairing the surface of ductile iron. Background Art

[0002] Ductile iron is a high-strength cast iron material whose comprehensive properties are close to those of steel. Based on its excellent properties, it has been successfully used to cast some parts with complex stresses and high requirements for strength, toughness and wear resistance.

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

[0004] The purpose of the present invention is to provide a method for laser repairing the surface of ductile iron. The ductile iron laser repaired surface treated by the method for laser repairing the surface of ductile iron not only has good wear resistance, but also has excellent hardness, thereby effectively improving the performance of the ductile iron.

[0005] To achieve the above object, the present invention provides the following technical solutions: A laser repair method for the surface of ductile iron comprises the following steps: 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; 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, the defective position of the ductile iron is repaired, and the cladding treatment of the ductile iron is completed; S5: Finishing treatment to complete the laser repair of the ductile iron surface.

[0006] Furthermore, the pretreatment method of the ductile iron is: using an electric grinding wheel to remove rust on the surface of the ductile iron, then immersing the ductile iron in acetone and letting it stand for 10 to 20 minutes. After the immersion is completed, the surface of the ductile iron is rinsed with deionized water, and after rinsing, it is sent to an oven, and the oven is set at 70 to 80° C. for drying for 2 to 4 hours to complete the pretreatment of the ductile iron.

[0007] Furthermore, the raw materials of the coating material are 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 meshes.

[0008] Furthermore, the coating material is prepared by the following method: paraffin is added into a reactor, the temperature of the reactor is set at 40-50°C, after the heating is completed, toluene is added, the temperature is set at 70-80°C, the rotation speed is 120-160r / min, the heat preservation and stirring are carried out for 8-12 minutes, and then graphite powder is added, and the above heat preservation and stirring conditions are continued for 16-20 minutes to obtain the coating material.

[0009] Furthermore, the coating treatment method is: brushing the coating material on the defective position of the ductile iron surface, after the brushing is completed, 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.

[0010] Furthermore, the treatment liquid is silicone oil.

[0011] Furthermore, the hot dip treatment method is: immersing the ductile iron in silicone oil, the silicone oil is kept at 42-46° C. during immersion, and the immersion time is 12-16 minutes to complete the hot dip treatment of the ductile iron.

[0012] Furthermore, 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 800-900 W, the feed rate to 16-18 g / min, the travel rate to 4-6 mm / s, the nozzle spacing to 4-6 cm, the protective gas to argon, the gas flow rate to 8-12 L / min, and the powder carrier gas to nitrogen, the gas flow rate to 6-10 L / min.

[0013] Furthermore, 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.

[0014] Furthermore, 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, and the oven is set to 160-180°C for insulation for 40-50 minutes. After the insulation is completed, the ductile iron is taken out, and the repair position on the surface of the ductile iron is polished to remove excess repair surface, thereby completing the laser repair of the ductile iron surface.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, during the surface laser repair process of ductile iron, the ductile iron is pre-coated so that the graphite powder is evenly attached to the position to be repaired on the surface of the ductile iron. When the ductile iron is clad, the paraffin wax used as a binder will be gasified, and the graphite powder can be supplemented with an additional carbon source to ensure the formation and uniform distribution of graphite balls, so that the metallurgical bonding between the cladding layer and the substrate is better and the bonding strength is improved. At the same time, the good thermal conductivity of the graphite powder can be used to improve the temperature distribution of the ductile iron during the laser cladding process, so that the cladding repair layer is evenly combined and generated, thereby improving the repair effect of the ductile iron.

[0016] 2. In the present invention, by hot-dip treatment of the ductile iron after coating treatment, when the ductile iron is immersed in silicone oil, the silicone oil can fill the tiny pores and defects in the wax layer, so that the graphite powder is more closely combined with the surface of the ductile iron, avoiding the graphite powder from falling off during the treatment process, thereby enhancing the adhesion stability of the graphite powder on the surface of the ductile iron, reducing the loss of graphite powder during cladding treatment, improving the use effect of the pre-coating of the graphite powder, and further improving the repair effect of the ductile iron. DETAILED DESCRIPTION

[0017] The following will be combined with the experiments of the present invention to clearly and completely describe the technical solutions in the experiments of the present invention. Obviously, the experiments described are only part of the experiments of the present invention, not all of the experiments. Based on the experiments in the present invention, all other experiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] This embodiment provides a method for laser repairing the surface of ductile iron, comprising the following steps: 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; 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.

[0019] In some embodiments, the pretreatment method of ductile iron is: use an electric grinding wheel to remove rust on the surface of the ductile iron, then immerse the ductile iron in acetone and let it stand for 10 to 20 minutes. After the immersion is completed, use deionized water to rinse the surface of the ductile iron, and after rinsing, send it into an oven, set the oven to 70 to 80° C. for drying for 2 to 4 hours to complete the pretreatment of the ductile iron.

[0020] In some embodiments, the raw materials of the coating material are paraffin wax, graphite powder and toluene, the mass ratio of 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.

[0021] In some embodiments, the coating material is prepared by the following method: paraffin is added into a reactor, the temperature of the reactor is set to 40-50°C, after the heating is completed, toluene is added, the temperature is set to 70-80°C, the rotation speed is 120-160r / min, and the heat preservation and stirring are carried out for 8-12 minutes, then graphite powder is added, and the above heat preservation and stirring conditions are continued for 16-20 minutes to obtain the coating material.

[0022] In some embodiments, 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.

[0023] In some embodiments, the treatment liquid is silicone oil.

[0024] In some embodiments, the method of hot dip treatment is: immersing the ductile iron in silicone oil, the silicone oil is kept at 42-46° C. during immersion, and the immersion time is 12-16 minutes, thereby completing the hot dip treatment of the ductile iron.

[0025] In some embodiments, 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.

[0026] In some embodiments, 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.

[0027] In some embodiments, 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, and the oven is set to 160-180°C for insulation for 40-50 minutes. After the insulation 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, thereby completing the laser repair of the ductile iron surface.

[0028] In this embodiment, during the surface laser repair process of ductile iron, the ductile iron is pre-coated so that the graphite powder is evenly attached to the position to be repaired on the surface of the ductile iron. When the ductile iron is clad, the paraffin wax as a binder will be gasified, and the graphite powder can be supplemented with an additional carbon source to ensure the formation and uniform distribution of graphite balls, so that the metallurgical bonding between the cladding layer and the substrate is better and the bonding strength is improved. At the same time, the good thermal conductivity of the graphite powder can be used to improve the temperature distribution of the ductile iron during the laser cladding process, so that the cladding repair layer is evenly combined and generated, thereby improving the repair effect of the ductile iron. Through the hot dip treatment of ductile iron after coating treatment, when the ductile iron is immersed in silicone oil, the silicone oil can fill the tiny pores and defects in the wax layer, so that the graphite powder is more closely combined with the surface of the ductile iron, avoiding the falling of graphite powder during the treatment process, thereby enhancing the adhesion stability of graphite powder on the surface of ductile iron, reducing the loss of graphite powder during cladding treatment, improving the use effect of graphite powder pre-coating, and thus improving the repair effect of ductile iron.

[0029] Based on the above embodiments, the following experiments were performed: It should be noted that the raw materials used in the following experiments are all commercially available raw materials.

[0030] Experiment 1: 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; 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.

[0031] The pretreatment method of ductile iron is: use an electric grinding wheel to remove rust on the surface of the ductile iron, then immerse the ductile iron in acetone and let it stand for 10 minutes. After the immersion is completed, use deionized water to rinse the surface of the ductile iron, and then send it to an oven after rinsing. Set the oven to 70°C for drying for 2 hours to complete the pretreatment of the ductile iron.

[0032] The raw materials of the coating material are paraffin wax, graphite powder and toluene, the mass ratio of paraffin wax, graphite powder and toluene is 1:2.2:0.2, and the particle size of the graphite powder is 200 meshes.

[0033] The coating material is prepared by the following method: paraffin is added into the reactor, the temperature of the reactor is set to 40°C, after the heating is completed, toluene is added, the temperature is set to 70°C, the speed is 120r / min, and the heat preservation and stirring are carried out for 8 minutes, then graphite powder is added, and the above heat preservation and stirring conditions are continued for 16 minutes to obtain the coating material.

[0034] The coating treatment method is: brushing the coating material on the defective position of the ductile iron surface, after the coating is completed, sending it into an oven, setting the oven at 120°C for drying for 10 minutes, and completing the coating treatment of the ductile iron.

[0035] Silicone oil is used as the treatment fluid.

[0036] The method of hot dip treatment is: ductile iron is immersed in silicone oil, the silicone oil is kept at 42°C during immersion, the immersion time is 12 minutes, and the hot dip treatment of ductile iron is completed.

[0037] The cladding treatment method is: use cladding powder in conjunction 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. The laser cladding machine sets the laser power to 800W, the feed rate to 16g / min, the travel rate to 4mm / s, the nozzle spacing to 4cm, the protective gas to argon, the gas flow rate to 8L / min, and the powder carrier gas to nitrogen, the gas flow rate to 6L / min.

[0038] The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum. The weight percentage of each raw material is: 3% carbon, 2% silicon, 0.6% manganese, 0.03% magnesium, 0.03% lanthanum, and the balance is iron. All raw materials are powdered, and the powder particle size is 300 mesh.

[0039] 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, and the oven is set at 160°C for 40 minutes. After the insulation is completed, the ductile iron is taken out, and the repair position on the surface of the ductile iron is polished to remove the excess repair surface, thereby completing the laser repair of the ductile iron surface.

[0040] Experiment 2: 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; 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.

[0041] The pretreatment method of ductile iron is: use an electric grinding wheel to remove rust on the surface of the ductile iron, then immerse the ductile iron in acetone and let it stand for 15 minutes. After the immersion is completed, use deionized water to rinse the surface of the ductile iron, and then send it to an oven. Set the oven to 75°C for drying for 3 hours to complete the pretreatment of the ductile iron.

[0042] The raw materials of the coating material are paraffin wax, graphite powder and toluene, the mass ratio of paraffin wax, graphite powder and toluene is 1:2.4:0.3, and the particle size of the graphite powder is 200 meshes.

[0043] The coating material is prepared by the following method: paraffin is added into the reactor, the temperature of the reactor is set to 45°C, after the heating is completed, toluene is added, the temperature is set to 75°C, the speed is 140r / min, and the heat preservation and stirring are carried out for 10 minutes, then graphite powder is added, and the above heat preservation and stirring conditions are continued for 18 minutes to obtain the coating material.

[0044] The coating treatment method is: brushing the coating material on the defective position of the ductile iron surface, after the coating is completed, sending it into an oven, setting the oven at 140°C for drying for 15 minutes, and completing the coating treatment of the ductile iron.

[0045] Silicone oil is used as the treatment fluid.

[0046] The method of hot dip treatment is: ductile iron is immersed in silicone oil, the silicone oil is kept at 44°C during immersion, the immersion time is 14 minutes, and the hot dip treatment of ductile iron is completed.

[0047] The cladding treatment method is: use cladding powder in conjunction 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. The laser cladding machine sets the laser power to 850W, the feed rate to 17g / min, the travel rate to 5mm / s, the nozzle spacing to 5cm, the protective gas to argon, the gas flow rate to 10L / min, and the powder carrier gas to nitrogen, the gas flow rate to 8L / min.

[0048] The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum. The weight percentage of each raw material is: 4% carbon, 3% silicon, 0.7% manganese, 0.04% magnesium, 0.04% lanthanum, and the balance is iron. All raw materials are powdered, and the powder particle size is 300 mesh.

[0049] 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, and the oven is set to 170°C for 45 minutes. After the insulation is completed, the ductile iron is taken out, and the repair position on the surface of the ductile iron is polished to remove the excess repair surface, thereby completing the laser repair of the ductile iron surface.

[0050] Experiment 3: 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; 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, the defective position of the ductile iron is repaired, and the cladding treatment of the ductile iron is completed; S5: Finishing treatment to complete the laser repair of the ductile iron surface.

[0051] The pretreatment method of ductile iron is: use an electric grinding wheel to remove rust on 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, use deionized water to rinse the surface of the ductile iron, and then send it to an oven after rinsing. Set the oven to 80°C for drying for 4 hours to complete the pretreatment of the ductile iron.

[0052] The raw materials of the coating material are paraffin wax, graphite powder and toluene, the mass ratio of paraffin wax, graphite powder and toluene is 1:2.6:0.4, and the particle size of the graphite powder is 200 meshes.

[0053] The coating material is prepared by the following method: paraffin is added into a reactor, the temperature of the reactor is set to 50°C, after the heating is completed, toluene is added, the temperature is set to 80°C, the rotation speed is 160r / min, and the heat preservation and stirring are carried out for 12 minutes, then graphite powder is added, and the above heat preservation and stirring conditions are continued for 20 minutes to obtain the coating material.

[0054] The coating treatment method is: brushing the coating material on the defective position of the ductile iron surface, after the coating is completed, sending it into an oven, setting the oven at 160° C. for drying for 20 minutes, and completing the coating treatment of the ductile iron.

[0055] Silicone oil is used as the treatment fluid.

[0056] The method of hot dip treatment is: ductile iron is immersed in silicone oil, the silicone oil is kept at 46°C during immersion, the immersion time is 16 minutes, and the hot dip treatment of ductile iron is completed.

[0057] The cladding treatment method is: use cladding powder in conjunction 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. The laser cladding machine sets the laser power to 900W, the feed rate to 18g / min, the travel rate to 6mm / s, the nozzle spacing to 6cm, the protective gas to argon, the gas flow rate to 12L / min, and the powder carrier gas to nitrogen, the gas flow rate to 10L / min.

[0058] The raw materials of the cladding powder are composed of iron, carbon, silicon, manganese, magnesium and lanthanum. The weight percentage of each raw material is: 5% carbon, 4% silicon, 0.8% manganese, 0.05% magnesium, 0.05% lanthanum, and the balance is iron. All raw materials are powdered, and the powder particle size is 300 mesh.

[0059] 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, and the oven is set to 180°C for 50 minutes of insulation. After the insulation is completed, the ductile iron is taken out, and the repair position on the surface of the ductile iron is polished to remove the excess repair surface, thereby completing the laser repair of the ductile iron surface.

[0060] Comparative Example 1: The difference between this comparative example and Experiment 1 is that the ductile iron is not pretreated in this comparative example.

[0061] Comparative Example 2: The difference between this comparative example and Experiment 1 is that the ductile iron is not subjected to hot dip treatment in this comparative example.

[0062] Comparative Example 3: The difference between this comparative example and Experiment 1 is that no graphite powder is added in the preparation of the coating material in this comparative example.

[0063] Comparative Example 4: The difference between this comparative example and Experiment 1 is that in this comparative example, an equal amount of iron powder is used to replace the cladding powder.

[0064] Performance test: The performance test was carried out on the ductile iron treated in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4. The test data obtained are recorded in the following table:

[0065] In the performance test, ductile iron treated with Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 was obtained, and the wear amount (wear resistance) and hardness tests were performed on the laser repaired positions on the surfaces of each ductile iron. The wear amount test method is as follows: a wear tester is used to perform a wear test on the laser repaired surface of the ductile iron treated with Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4, with the abrasive hardness of 260HBS, the rotation speed of 400r / min, the contact load of 6kg, and the total wear test time of 25min. The weight of the ductile iron was recorded before and after the wear test, and the wear amount data of the ductile iron treated with Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were obtained.

[0066] It can be seen that the wear resistance and hardness data of the laser repaired surface of the ductile iron after treatment in comparative examples 1, 2, 3 and 4 are lower than those in experiments 1, 2 and 3; this shows that: in the surface laser repair process of ductile iron, the graphite powder is evenly attached to the position to be repaired on the surface of the ductile iron through the pre-coating treatment of the ductile iron. When the ductile iron is clad, the paraffin wax used as a binder will be gasified, and the graphite powder can be supplemented with an additional carbon source to ensure the formation and uniform distribution of graphite balls, so that the metallurgical bonding between the cladding layer and the substrate is better and the bonding strength is improved. At the same time, the good thermal conductivity of graphite powder can be used to improve the temperature distribution of the ductile iron during the laser cladding process, so that the cladding repair layer is evenly combined and generated, thereby improving the repair effect of the ductile iron.

[0067] By comparing and analyzing the relevant data in the table, it can be seen that the ductile iron laser repair surface treated by the ductile iron surface laser repair method of the present invention not only has good wear resistance, but also has excellent hardness performance. This shows that the ductile iron surface laser repair method provided by the present invention has a broader market prospect and is more suitable for promotion.

[0068] In the description of this specification, the description with reference to the terms "an experiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the experiment or example are included in at least one experiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same experiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more experiments or examples in a suitable manner.

[0069] The preferred experiments of the present invention disclosed above are only used to help explain the present invention. The preferred experiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these experiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only 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; 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 raw materials of the coating material are 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 meshes.

4. The laser repair method for the surface of ductile iron according to claim 3, characterized in that: 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 rotation speed is 120-160r / min, the heat preservation and stirring treatment is carried out for 8-12min, then graphite powder is added, and the heat preservation and stirring treatment is continued for 16-20min to obtain the coating material.

5. 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.

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

7. 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.

8. 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.

9. The laser repair method for the surface of ductile iron according to claim 8, 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.

10. 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.

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