ZG40mn2 guide groove laser repair process based on ultra-thick cladding layer

Abstract

Provided in the present invention is a ZG40Mn2 guide groove laser repair process based on an ultra-thick cladding layer. The process comprises the following content: S1, performing flaw detection on a surface of a guide groove, and performing grinding processing on worn portions to remove defective portions and impurities; S2, by using WGD130 powder as a cladding material, using a laser cladding device to perform laser cladding on a portion to be repaired, wherein the laser operation trajectory laterally advances in a direction perpendicular to an extension direction of the guide groove, and stopping operating once a desired thickness is reached; and S3, inspecting the surface formation of a cladding layer to ensure that there are no crack defects, and performing machining and grinding on the cladding layer to complete the repair. By means of the ZG40Mn2 guide groove laser repair process provided in the present invention, a laser repair experiment is performed on a worn region of a guide rail surface of a guide groove, and related engineering application data such as cracks, hardness, repair effect and repair efficiency of a laser repair layer are studied.

Description

Laser repair technology of ZG40Mn2 guide groove based on ultra-thick cladding layer Technical Field

[0001] The invention belongs to the technical field of hydraulic metal structure repair, and relates to a guide groove laser repair process, in particular to a ZG40Mn2 guide groove laser repair process based on an ultra-thick cladding layer. Background Art

[0002] ZG40Mn2 is a low-alloy cast steel, classified as a medium-carbon quenched and tempered steel, typically used in the quenched and tempered state. Steel castings offer high strength, plasticity, and wear resistance, as well as excellent machinability and heat-treatment processability. Currently, ZG40Mn2 cast steel guide troughs are widely used in hydraulic metal structures. However, due to long-term use under high-frequency, heavy-load conditions, varying degrees of wear on the working surfaces can adversely affect the safe and stable operation of hydraulic metal equipment.

[0003] Laser cladding welding offers advantages such as high strength, low dilution rate, dense, defect-free structure, and minimal deformation. Material composition can be tailored to the specific workpiece requirements, and thickness is controllable. However, the high hardness and deep damage of ZG40Mn2 guide grooves require a thicker cladding layer to repair, making laser cladding layers prone to cracks and defects.

[0004] Summary of the Invention

[0005] The present invention provides a ZG40Mn2 guide groove laser repair process, conducts laser repair experiments on the worn area of ​​the guide groove and guide rail surface, and studies relevant engineering application data such as cracks, hardness, and repair effect and efficiency of the laser repair layer.

[0006] The technical solution of the present invention is a ZG40Mn2 guide groove laser repair process based on an ultra-thick cladding layer, comprising the following steps:

[0007] S1. Detect the surface of the guide groove and grind the worn parts to remove defects and impurities;

[0008] S2. Using WGD130 powder as the cladding material, laser cladding equipment is used to perform laser cladding on the defective parts. The laser operation trajectory is perpendicular to the extension direction of the guide groove and advances horizontally. The operation stops when the expected thickness is reached.

[0009] S3. Check the surface formation of the cladding layer to ensure that there are no crack defects, and then perform mechanical processing and polishing to complete the repair.

[0010] Furthermore, the thickness of the cladding layer is 8 to 16 mm.

[0011] Furthermore, color flaw detection is used in S1, and defective areas are polished away.

[0012] Furthermore, during laser cladding, the base material of the area to be repaired is first preheated until the temperature of the base material reaches 200-360°C before the operation is performed.

[0013] Furthermore, during the laser cladding in S2, 5 to 6 layers are continuously clad after preheating treatment, and then the repaired part and the clad layer are heated to 200 to 360°C, and then multiple layers are further laser clad to the expected thickness.

[0014] Furthermore, using WGD130 powder as the cladding material, laser cladding is performed under normal temperature and normal conditions, with the cladding layer width being less than 90 mm and thickness being less than 10 mm.

[0015] Furthermore, the cladding material also includes WG3130, and the mass ratio of WG3130 to WGD130 is 50-70:30-50.

[0016] Furthermore, WGD130 and WG3130 powders are used as cladding materials, and laser cladding is performed after preheating. The width of the cladding layer is less than 90 mm and the thickness is 8 to 16 mm.

[0017] Furthermore, during laser cladding, the laser power is 2.5-4KW, the spot size is 3-6mm, the scanning speed is 10-20mm / s, the overlap is 1-2mm, the powder feeding is 1-3r / min, and the powder feeding air flow is 3-8L / min.

[0018] Furthermore, during laser cladding, multi-layer cladding is performed, wherein the thickness of a single layer is 0.7 to 1.2 mm.

[0019] The present invention has the following beneficial effects:

[0020] 1. When repairing the ZG40Mn2 guide groove, due to severe wear and high thickness of the cladding layer, crack defects are likely to occur between the substrate to be repaired and the cladding layer, causing repair failure. Analysis of the reasons is mainly due to uneven local heating during the cladding process. The substrate and the molten material have different shrinkage rates during solidification and cooling, resulting in tensile stress. When the strength of the repair material is greater than that of the substrate, cracks are likely to occur on the side of the substrate near the bonding surface between the repair layer and the substrate. Therefore, the present invention should try to ensure that the mechanical properties of the repair layer are close to the properties of the substrate in order to reduce the possibility of cracks. The present invention selects WGD130 as the cladding material, which can ensure that its toughness is good based on the hardness of hrc22-27, and the cladding layer is not easily torn from the substrate during the cooling process. In the experimental plan, a certain proportion of WG3130 powder is added. The powder has better toughness and helps to eliminate the structural defects between the cladding material and the substrate.

[0021] 2. The inventors have found that cracks in the repair layer often appear on both sides of the rapid movement direction of the cladding processing track. Therefore, the length of the walking track during cladding should avoid the edge of the guide rail by about 3-5 mm to minimize the tensile stress between the edges of the substrate and the cladding layer.

[0022] 3. The ZG40Mn2 guide groove has a high carbon content, and the cladding layer cools quickly, which easily produces hardened structures in the bonding layer and heat-affected zone, leading to cracks. Large workpieces are difficult to deform and offset stress during the cladding process. Preheating the substrate and slowing down the cooling process can effectively release some of the stress during the cooling process and prevent cracks. The present invention effectively prevents cracks in the guide groove repair layer by preheating the guide groove and rail surface, especially by controlling the preheating temperature to 200°C to 360°C before laser cladding.

[0023] 4. The laser cladding method is used to repair the guide groove. Its repair efficiency is high and it can be repaired on site. The total working time for each piece is about 120 hours, including 40 hours of grinding and measurement, 48 hours of cladding, 16 hours of grinding and testing, and 16 hours of equipment preparation. The good repair effect will help promote the application of this process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 shows the wear condition of the guide groove in Example 1, wherein FIG1-1 shows the wear condition of the outer side surface, and FIG1-2 shows the wear condition of the inner side surface.

[0025] Figure 2 is a layout diagram of the guide groove repair equipment.

[0026] FIG3 shows the cladding condition of the horizontal laser cladding specimen at room temperature in Example 1-1.

[0027] FIG4 shows the cladding condition of the horizontal laser cladding specimen at room temperature in Example 1-2.

[0028] FIG5 shows the cladding conditions of the horizontal laser cladding specimens at room temperature in Examples 1-3.

[0029] FIG6 shows the cladding conditions of the horizontal laser cladding specimens at room temperature in Examples 1-4.

[0030] FIG7 shows the cladding conditions of the horizontal laser cladding specimens at room temperature in Examples 1-5.

[0031] FIG8 shows the cladding condition of the horizontal laser cladding specimen at room temperature in Example 1-6, where the cladding material is 50% WG3130+50% WGD130.

[0032] FIG9 shows the cladding condition of the horizontal laser cladding specimen at room temperature in Example 1-6, where the cladding material is 66% WG3130+34% WGD130.

[0033] FIG10 shows the cladding conditions of the room temperature transverse laser cladding specimens in Example 1-7.

[0034] FIG11 shows the cladding conditions of the room temperature transverse laser cladding specimens in Example 1-8.

[0035] Figure 12 is a photo of the sample in Example 2.

[0036] Figure 13 shows the cross-sectional microstructure analysis of the sample after cladding.

[0037] Figure 14 shows the cross-sectional microstructure analysis of the sample after cladding. DETAILED DESCRIPTION

[0038] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0039] Example 1

[0040] The ZG40Mn2 guide groove to be repaired had been in service for over 20 years. Measurements revealed wear primarily on the two outer rail surfaces, with wear depths ranging from 11-13mm, sometimes reaching 16mm. The inner surface showed wear depths of 0.5-2mm, primarily due to light wear and corrosion. Figures 1-1 and 1-2 show the wear on the outer surface.

[0041] The guide groove is in a vertical position during on-site repair. During workshop testing, the repair equipment and the guide groove entity are placed on the ground. The small welding and cladding robot has an arm span of 1700mm and requires three equipment platforms to ensure accessibility to all repair positions. To accommodate laser cladding on the inner side of the guide groove, a 360° rotatable processing head is used. The product uses fiber optic access and a fully sealed design. It is equipped with a rotation adjustment device to adjust the laser incident posture. The posture of the rotating laser head can be applied to the processing of two parallel guide rail surfaces, which improves work efficiency. It is equipped with a double-headed powder hose that can be extended and rotated to adjust the powder delivery position. The specific layout of the guide groove repair equipment is shown in Figure 2.

[0042] The cladding materials involved in the repair are WG3130, WGD130 and WG6125, and their specific compositions are shown in Table 1 below.

[0043] Table 1

[0044] The laser repair process parameters are shown in Table 2.

[0045] Table 2

[0046] When repairing, use the following methods:

[0047] 1-1. Room temperature transverse laser cladding experiment

[0048] WG3130 powder is used as the cladding material, the cladding layer is 1600mm long and 80mm wide, and the designed total thickness of the cladding layer is 9mm. No preheating is performed, the laser operation trajectory is horizontal advancement, and the construction is continuous.

[0049] When the cladding test reached the 4th to 6th layers, there began to be a cracking sound; when the cladding test reached the 8th layer, large-scale cracks appeared on the outside of the guide rail fusion surface, and the test failed, as shown in Figure 3.

[0050] 1-2. Room temperature longitudinal laser cladding experiment

[0051] WG3130 powder is used as the cladding material, the cladding layer is 700 mm long and 80 mm wide, and the designed total thickness of the cladding layer is 9 mm. No preheating is performed, the laser operation trajectory is longitudinal advancement, and the construction is continuous.

[0052] When the cladding experiment reached the 7th layer, long cracks appeared on the surface of the cladding layer, making it difficult to overlap the cladding layers in adjacent areas, and the experiment failed, as shown in Figure 4.

[0053] 1-3. Room temperature transverse segmented and layered laser cladding experiments

[0054] WG3130 powder was used as the cladding material. Each cladding layer was 250 mm long and 80 mm wide. No preheating was performed. The laser operation trajectory was horizontal advancement. Each layer was stopped until it reached a natural state before welding the next layer.

[0055] When the cladding test reached the sixth layer, a large number of small cracks appeared on the surface of the cladding layer, and the experiment failed, as shown in Figure 5.

[0056] 1-4. Preheating and insulation transverse laser cladding experiment

[0057] WG3130 powder is used as the cladding material. Each cladding layer is 300 mm long and 80 mm wide. After preheating the substrate to 200-230°C, 6 layers are applied continuously. Then, the substrate is heated again and multi-layer cladding is applied. The laser operation trajectory is horizontal advancement.

[0058] When the cladding thickness reached 7.5 mm, a large number of fine cracks appeared on the surface of the cladding layer and the experiment failed, as shown in Figure 6.

[0059] 1-5. Transverse laser cladding experiments with various powders

[0060] The experiment used WG6125 powder as the base (2mm thickness) and WG3130 powder as the cover. Each cladding layer was 500mm long and 80mm wide. After preheating the substrate to 200-230℃, 6 layers were applied continuously, then heated and multi-layer cladding was performed. The laser operation trajectory was horizontal advancement.

[0061] When the cladding thickness reached 11 mm, a large number of fine cracks appeared on the surface of the cladding layer and the experiment failed, as shown in Figure 7.

[0062] 1-6 Room temperature multi-powder mixed transverse laser cladding experiment

[0063] In the experiment, WG3130 powder and WGD130 powder were mixed to obtain two cladding materials (66% WG3130 + 34% WGD130 powder, 50% WG3130 + 50% WGD130). The two proportions of cladding materials were clad separately. Each cladding layer was 300 mm long and 80 mm wide. The laser was operated at room temperature and the trajectory was horizontal advancement.

[0064] The cladding thickness of 50% WG3130 + 50% WGD130 material is 14.5 mm, and no cladding layer defects are generated, as shown in Figure 8. When the cladding thickness of 66% WG3130 + 34% WGD130 material is 15.2 mm, no cladding layer defects are generated. When the cladding thickness reaches 16.0 mm, cladding defects are generated, as shown in Figure 9.

[0065] 1-7. Room temperature WGD130 powder transverse laser cladding experiment

[0066] The experiment used WGD130 powder, and the cladding layer was 1000 mm long, 60 mm wide, and 8 mm thick. No preheating was performed, and the laser operation trajectory was horizontal advancement. The cladding test surface was well formed without crack defects. The average hardness at this time was (HB) 210, which has theoretical significance. See Figure 10 for details.

[0067] 1-8. Preheating of various powder mixtures for transverse laser cladding experiments

[0068] The experiment used a mixture of WG3130 powder and WGD130 powder at a ratio of 66% WG3130 + 34% WGD130 powder. Each cladding layer was 400 mm long and 80 mm wide. After preheating the substrate to 250-350°C, 6 layers were applied continuously. The substrate was then heated to above 250°C and cladding was performed in multiple layers until the thickness reached 16.2 mm. The laser operation trajectory was horizontal advancement.

[0069] When the cladding layer reaches 16.2 mm, the surface of the cladding experiment is well formed without crack defects. At this time, the average hardness is (HB) 225, as shown in Figure 11, which has theoretical significance.

[0070] Example 2:

[0071] For methods 1-7 in Example 1, laser cladding of WGD130 powder was performed on a ZG40Mn2 test block at room temperature and normal conditions. The resulting sample is shown in Figure 12. Hardness gradient testing of the material revealed an effective hardened layer ≥ 3.8 mm, with 4 mm representing the base material hardness. Cross-sectional microstructure analysis of the ZG40Mn2 test block after cladding (GB / T 13298-2015) is shown in Figures 13 and 14.

[0072] The above embodiments are merely illustrative of the technical concepts and features of the present invention. The contents described are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Within the technical scope disclosed by the present invention, equivalent changes or improvements based on the technical solutions and inventive concepts of the present invention are all encompassed within the scope of protection of the present invention.

Claims

1. A ZG40Mn2 guide groove laser repair process based on ultra-thick cladding layer, characterized in that: Includes the following: S1. Detect the surface of the guide groove and grind the worn parts to remove defects and impurities; S2, using WGD130 powder as cladding material, laser cladding equipment is used to perform laser cladding on the defective parts, and the laser operation trajectory is to advance horizontally perpendicular to the extension direction of the guide groove, and the operation is stopped after the expected thickness is reached; S3. Check the surface formation of the cladding layer to ensure that there are no crack defects, and then perform mechanical processing and polishing to complete the repair.

2. The process according to claim 1, characterized in that: The thickness of the cladding layer is 8 to 16 mm.

3. The process according to claim 1, characterized in that: In S1, color flaw detection is used and defective areas are polished away.

4. The process according to claim 1, characterized in that: During laser cladding, the base material to be repaired is first preheated until the temperature of the base material reaches 200-360°C before the operation.

5. The process according to any one of claim 4, characterized in that: During laser cladding in S2, 5 to 6 layers are clad continuously after preheating treatment, and then the repaired area and the clad layer are heated to 200 to 360°C, and then multiple layers are further laser clad to the expected thickness.

6. The process according to any one of claims 1 to 5, characterized in that: Using WGD130 powder as cladding material, laser cladding is performed under normal temperature and conditions, with a cladding layer width of less than 90 mm and a thickness of less than 10 mm.

7. The process according to any one of claims 1 to 5, characterized in that: The cladding material also includes WG3130, and the mass ratio of WG3130 to WGD130 is 50-70:30-50.

8. The process according to claim 7, characterized in that: WGD130 and WG3130 powders are used as cladding materials, the cladding layer width is less than 90 mm, and the thickness is 8 to 16 mm.

9. The process according to claim 1, characterized in that: During laser cladding, the laser power is 2.5-4KW, the spot size is 3-6mm, the scanning speed is 10-20mm / s, the overlap is 1-2mm, the powder feeding is 1-3r / min, and the powder feeding airflow is 3-8L / min.

10. The process according to claim 1, characterized in that: During laser cladding, multi-layer cladding is performed, in which the thickness of a single layer is 0.7 to 1.2 mm.

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