Laser repair method for ZG40Mn2 guide grooves based on ultra-thick cladding layer

Abstract

The present invention provides a laser repair method for ZG40Mn2 guide grooves based on an ultra-thick cladding layer, comprising: S1 inspecting the surface of the guide groove, polishing the worn portion, and removing defects and impurities; S2 using WGD130 powder as the cladding material, performing laser cladding on the area to be repaired with a laser cladding device, advancing the laser's trajectory perpendicular to the extension direction of the guide groove, and stopping the operation after reaching a predetermined thickness; and S3 detecting the formation of the cladding layer surface to ensure that no crack defects have occurred, and completing the repair by machining and polishing. The present invention provides a laser repair method for ZG40Mn2 guide grooves, and conducts laser repair experiments on the worn area of ​​the guide rail surface of the guide groove to study relevant engineering application data such as cracks in the laser-repaired layer, hardness, repair effect, and efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of the repair of metal structures used in hydraulic engineering, relates to a laser repair method for a guide groove, and specifically relates to a laser repair method for a ZG40Mn2 guide groove based on an ultra-thick clad layer.

Background Art

[0002] ZG40Mn2 is a low-alloy cast steel, belonging to medium-carbon quenched and tempered steel, and is generally used in a quenched and tempered state. The strength, plasticity and wear resistance of cast steel products are all relatively high, the cutting performance and heat treatment processability are good. At present, the ZG40Mn2 cast steel guide groove is widely applied in the field of hydraulic metal structures. However, because it needs to be used for a long time under high-frequency and heavy-load conditions, different degrees of wear appear on its working surface, which will have an adverse impact on the safe and smooth operation of hydraulic metal equipment.

[0003] Laser cladding welding has characteristics such as high strength, low dilution rate, dense structure without defects, and small deformation. It is possible to design the composition of the material according to various use requirements of the workpiece and control the thickness at the same time. However, because the hardness of the ZG40Mn2 guide groove is high and the depth of damage is large, the thickness of the clad layer that needs to be repaired is large, and cracks and defects are likely to occur in the laser clad layer.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention provides a laser repair method for a ZG40Mn2 guide groove, which conducts laser repair experiments on the worn area of the guide rail surface of the guide groove and studies relevant engineering application data such as cracks, hardness, repair effect, and efficiency of the laser repair layer.

Means for Solving the Problems

[0005] The technical proposal of the present invention is as follows: A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer, comprising: S1 inspecting the surface of the guide groove for defects, polishing worn areas, and removing defects and impurities; S2 using WGD130 powder as the cladding material, performing laser cladding on the defective areas with a laser cladding device, advancing the laser trajectory perpendicular to the extension direction of the guide groove in a lateral direction, and stopping the operation after reaching a predetermined thickness; and S3 detecting the formation of the cladding layer surface to ensure that no crack defects have occurred, and completing the repair by machining and polishing.

[0006] Furthermore, the cladding layer is 8-16 mm thick.

[0007] Furthermore, S1 employs colored flaw detection, and areas with defects are polished away.

[0008] Furthermore, during laser cladding, the substrate of the area to be repaired is first preheated, and the operation is performed after the substrate temperature reaches 200-360°C.

[0009] Furthermore, in S2, during laser cladding, after preheating, 5 to 6 layers are first clad consecutively, then the area to be repaired and the clad layers are heated to 200 to 360°C, and then multi-layer laser cladding is performed until the predetermined thickness is reached.

[0010] Furthermore, WGD130 powder was used as the cladding material, and laser cladding was performed at room temperature and under normal conditions, resulting in a cladding layer with a width of 90 mm or less and a thickness of 10 mm or less.

[0011] Furthermore, the cladding material further contains WG3130, with a mass ratio of 50-70:30-50 with respect to WGD130.

[0012] Furthermore, WGD130 and WG3130 powders were used as cladding materials, and after preheating, laser cladding was performed. The cladding layer was less than 90 mm in width and 8 to 16 mm in thickness.

[0013] Furthermore, during laser cladding, the laser power is 2.5-4KW, the light spot size is 3-6mm, the scan speed is 10-20mm / s, the overlap amount is 1-2mm, the powder transport speed is 1-3r / min, and the powder transport flow rate is 3-8L / min.

[0014] Furthermore, during laser cladding, the cladding is multi-layered, with each layer having a thickness of 0.7 to 1.2 mm. [Effects of the Invention]

[0015] This invention offers the following beneficial effects.

[0016] 1. When repairing ZG40Mn2 guide grooves, severe wear and a large cladding layer thickness make it easy for cracks and other defects to occur between the substrate and the cladding layer, leading to repair failure. Analysis of the cause revealed that localized heating non-uniformity occurs mainly during the cladding process, and the substrate and cladding material shrink at different 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 one side of the joint surface between the repair layer and the substrate, closer to the substrate. Therefore, in this invention, in order to reduce the possibility of crack formation, it is necessary to make the mechanical properties of the repair layer as close as possible to those of the substrate. In this invention, WGD130 was selected as the cladding material, and a hardness of hrc22-27 was guaranteed, while its toughness was relatively good, making the cladding layer less likely to tear from the substrate during the cooling process. In the test plan, WG3130 powder was added at a certain ratio, and the toughness of this powder was even better, helping to eliminate structural defects between the cladding material and the substrate.

[0017] 2. The inventors found that cracks in the repair layer tend to occur on both sides of the high-speed movement direction of the cladding process trajectory. Therefore, the length of the travel trajectory during cladding is kept approximately 3-5 mm away from the edge of the guide rail, minimizing the tensile stress between the edges of the base material and the cladding layer on both sides.

[0018] 3. The ZG40Mn2 guide groove has a relatively high carbon content, and the cooling rate of the cladding layer is relatively fast, making it easy for quenching to occur in the bonding layer and heat-affected zone, leading to crack formation. Due to the large size of the workpiece, deformation is less likely to occur in order to offset stress during the cladding process. By preheating the substrate and slowing down the cooling, some of the stress during the cooling process can be effectively relieved, preventing crack formation. In this invention, by preheating the guide rail surface of the guide groove, and in particular controlling the preheating temperature to 200°C to 360°C before performing laser cladding, it is possible to effectively prevent crack formation in the repair layer of the guide groove.

[0019] 4. Using the laser cladding method to repair guide grooves offers high repair efficiency, allows for on-site repair, and requires approximately 120 hours of work per case (including 40 hours for polishing and measurement, 48 hours for cladding, 16 hours for polishing and detection, and 16 hours for equipment preparation). Furthermore, it provides good repair results and contributes to the widespread adoption of this method. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1-1 shows the wear condition of the guide groove in Example 1, and Figure 1-2 shows the wear condition of the inner surface. [Figure 2] This is a diagram showing the layout of the equipment used for repairing guide grooves. [Figure 3] This shows the cladding conditions in Example 1-1, where the test specimen is laser-cladded in the lateral direction at room temperature. [Figure 4] Examples 1-2 show the cladding conditions when the test specimen is laser-cladded in the lateral direction at room temperature. [Figure 5]In Examples 1-3, it is the cladding situation where the test piece is laser clad horizontally at room temperature. [Figure 6] In Examples 1-4, it is the cladding situation where the test piece is laser clad horizontally at room temperature. [Figure 7] In Examples 1-5, it is the cladding situation where the test piece is laser clad horizontally at room temperature. [Figure 8] In Examples 1-6, it is the cladding situation where the test piece is laser clad horizontally at room temperature, and the cladding material is 50% WG3130 + 50% WGD130. [Figure 9] In Examples 1-6, it is the cladding situation where the test piece is laser clad horizontally at room temperature, and the cladding material is 66% WG3130 + 34% WGD130. [Figure 10] In Examples 1-7, it is the cladding situation where the test piece is laser clad horizontally at room temperature. [Figure 11] In Examples 1-8, it is the cladding situation where the test piece is laser clad horizontally at room temperature. [Figure 12] It is a photograph of the sample in Example 2. [Figure 13] It is the analysis situation of the cross-sectional structure after the sample is clad. [Figure 14] It is the analysis situation of the cross-sectional structure after the sample is clad.

Modes for Carrying Out the Invention

[0021] Hereinafter, the implementation plan of the present invention will be described in detail while referring to the examples. However, those skilled in the art can understand that the following examples are merely for explaining the present invention and should not be regarded as limiting the scope of the present invention.

[0022] (Example 1) The guide grooves made of ZG40Mn2 material to be repaired have been in service for over 20 years. Measurements of the actual parts showed that wear on the guide rail surfaces of the guide grooves was mainly concentrated on the two outer guide rail surfaces, with a wear depth of 11-13 mm, and locally reaching 16 mm. The wear depth on the inner surfaces was 0.5-2 mm, mainly consisting of light wear and rust. Specifically, this is shown in Figures 1-1 and 1-2, with Figure 1-1 showing the wear condition of the outer surfaces.

[0023] When repairing on-site, the guide groove is positioned vertically. When testing in the factory, both the repair equipment and the guide groove itself are placed on the ground. The arm length of the small welding / welding robot is 1700 mm, and it is necessary to mount three equipment platforms so that it can reach all repair positions. A 360° rotatable processing head is used to laser cladding the inner surface of the guide groove, and the product is connected using optical fiber and has a completely sealed design. A rotation adjustment device is provided to adjust the laser incidence position. By rotating the position of the optical head, it can be adapted to processing two parallel guide rail surfaces, resulting in high work efficiency. A double-head powder tube is provided, and the powder transport position can be adjusted by extending, retracting, and rotating. The specific arrangement of the guide groove repair equipment is shown in Figure 2.

[0024] The cladding materials used during restoration are WG3130, WGD130, and WG6125, and their specific compositions are shown in Table 1 below. [Table 1]

[0025] The parameters for the laser repair method are shown in Table 2 below. [Table 2]

[0026] Specifically, the following methods will be used during the repair process.

[0027] (Example 1-1) Laser cladding experiment in the lateral direction at room temperature Using WG3130 powder as the cladding material, the cladding layer was designed to be 1600mm long, 80mm wide, and have a total thickness of 9mm. No preheating was performed, the laser trajectory was advanced laterally, and continuous construction was carried out.

[0028] When the cladding experiment reached layers 4-6, a sound of collapse began to be heard, and when the cladding experiment reached layer 8, a large-area crack occurred on the outside of the fusion surface of the guide rail, and the experiment failed. This is shown in detail in Figure 3.

[0029] (Examples 1-2) Laser cladding experiment in the longitudinal direction at room temperature Using WG3130 powder as the cladding material, the cladding layer was designed to be 700 mm long, 80 mm wide, and have a total thickness of 9 mm. No preheating was performed, the laser path was advanced in the vertical direction, and continuous construction was carried out.

[0030] When the cladding experiment reached the seventh layer, long cracks formed on the surface of the cladding layer, making it difficult to overlap the cladding layers in adjacent regions, and the experiment failed. This is shown in detail in Figure 4.

[0031] (Examples 1-3) Laser cladding experiment in the lateral direction for each segment and layer at room temperature Using WG3130 powder as the cladding material, the cladding layer of each segment is 250 mm long and 80 mm wide. No preheating is performed, the laser path is advanced laterally, and after welding one layer, the surface is returned to its natural state before welding the next layer.

[0032] When the cladding experiment reached the sixth layer, a large number of microcracks appeared on the surface of the cladding layer, and the experiment failed. This is shown specifically in Figure 5.

[0033] (Examples 1-4) Laser cladding experiment in the lateral direction by preheating and heat retention WG3130 powder was used as the cladding material, with each segment having a cladding layer length of 300 mm and a width of 80 mm. After preheating the substrate to 200-230°C, six layers were continuously laser-cladded and heated, followed by further multi-layer cladding, with the laser trajectory moving laterally.

[0034] When the cladding thickness reached 7.5 mm, a large number of microcracks appeared on the surface of the cladding layer, and the experiment failed. This is shown specifically in Figure 6.

[0035] (Examples 1-5) Lateral laser cladding experiment using various powders In the experiment, WG6125 powder was used as a base coat (2 mm thick), and WG3130 powder was used as a top coat. The length of the cladding layer for each segment was 500 mm and the width was 80 mm. After preheating the substrate to 200-230°C, six layers were continuously laser cladded and heated, and then multiple layers of cladding were performed, with the laser trajectory moving laterally.

[0036] When the cladding thickness reached 11 mm, a large number of microcracks appeared on the surface of the cladding layer, and the experiment failed. This is shown specifically in Figure 7.

[0037] (Examples 1-6) Lateral laser cladding experiment using a mixture of various powders at room temperature In the experiment, WG3130 powder and WGD130 powder were mixed to obtain two types of cladding materials (66% WG3130 + 34% WGD130 powder, and 50% WG3130 + 50% WGD130). Cladding was performed using two proportional amounts of these cladding materials, with each segment having a cladding layer length of 300 mm and a width of 80 mm. At room temperature, the laser trajectory was propelled laterally.

[0038] The cladding thickness of the 50%WG3130+50%WGD130 material was 14.5 mm, and no defects occurred in the cladding layer. This is shown in detail in Figure 8. When the cladding thickness of the 66%WG3130+34%WGD130 material was 15.2 mm, no defects occurred in the cladding layer, but when the cladding thickness reached 16.0 mm, defects occurred in the cladding. This is shown in detail in Figure 9.

[0039] (Examples 1-7) Lateral laser cladding experiment using WGD130 powder at room temperature In the experiment, WGD130 powder was used, with a cladding layer length of 1000 mm, a width of 60 mm, and a thickness of 8 mm. No preheating was performed, and the laser trajectory was advanced laterally. The surface shaping of the cladding experiment was good, and no crack defects occurred. The average hardness at this time was (HB)210, which has theoretical significance. Specifically, this is shown in Figure 10.

[0040] (Examples 1-8) Laser cladding experiment in the lateral direction by preheating and mixing of various powders In the experiment, WG3130 powder and WGD130 powder were mixed in a ratio of 66% WG3130 + 34% WGD130 powder. The length of the cladding layer of each segment was 400 mm and the width was 80 mm. After preheating the substrate to 250-350°C, six layers were laser cladded consecutively, and then heated to over 250°C. Multilayer cladding was performed until the thickness reached 16.2 mm, with the laser trajectory moving laterally.

[0041] When the cladding layer reached 16.2 mm, the surface formation in the cladding experiment was good, and no crack defects occurred. The average hardness at this point was (HB) 225, which is specifically shown in Figure 11 and has theoretical significance.

[0042] (Example 2) Based on the procedures of Examples 1-7 in Example 1, laser cladding was performed on a ZG40Mn2 test specimen substrate with WGD130 powder at room temperature and under normal conditions. The obtained sample is shown in Figure 12. The hardness gradient of the material was detected, and the hardness of the substrate was determined when the effective hardened layer was ≥3.8 mm and 4 mm. The microstructure of the cross-section after cladding the ZG40Mn2 block was analyzed (GB / T 13298-2015), specifically shown in Figures 13 and 14.

[0043] The above embodiments are merely for the purpose of explaining the technical concept and features of the present invention, and the content described is merely a preferred embodiment of the present invention; the scope of protection of the present invention is not limited to these embodiments. Within the technical scope disclosed in the present invention, equivalent changes or improvements based on the technical proposals of the present invention and the inventive concept thereof are all covered within the scope of protection of the present invention.

[0044] (Note) (Note 1) A laser repair method for ZG40Mn2 guide grooves based on an ultra-thick cladding layer, S1 involves inspecting the surface of the guide groove for defects, polishing the worn areas, and removing defects and impurities. Using WGD130 powder as the cladding material, laser cladding is performed on the defective area using a laser cladding device, and the laser's movement trajectory is advanced laterally perpendicular to the extension direction of the guide groove, and the operation is stopped after a predetermined thickness is reached (S2). A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer, comprising S3, which involves detecting the formation of the cladding layer surface to ensure that no crack defects occur, and then completing the repair by machining and polishing.

[0045] (Note 2) A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in Appendix 1, characterized in that the cladding layer has a thickness of 8 to 16 mm.

[0046] (Note 3) A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in Appendix 1, characterized in that S1 employs colored flaw detection and polishes away areas where defects exist.

[0047] (Note 4) A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in Appendix 1, characterized in that, during laser cladding, the substrate of the area to be repaired is first preheated, and the operation is performed after the temperature of the substrate reaches 200 to 360°C.

[0048] (Note 5) In S2, a laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in any one of Appendix 1 to 4, characterized in that, during laser cladding, after preheating treatment, 5 to 6 layers are first cladded continuously, then the area to be repaired and the cladded layers are heated to 200 to 360°C, and further multi-layer laser cladding is performed until a predetermined thickness is reached.

[0049] (Note 6) A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in any one of the appendices 1 to 5, characterized in that WGD130 powder is used as the cladding material, laser cladding is performed at room temperature and under normal conditions, and the width of the cladding layer is 90 mm or less and the thickness is 10 mm or less.

[0050] (Note 7) A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in any one of appendices 1 to 5, characterized in that the cladding material further contains WG3130, and the mass ratio of WGD130 is 50 to 70:30 to 50.

[0051] (Note 8) A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in Appendix 7, characterized in that WGD130 and WG3130 powders are used as cladding materials, and the cladding layer has a width of 90 mm or less and a thickness of 8 to 16 mm.

[0052] (Note 9) A laser repair method for ZG40Mn2 guide grooves based on an ultra-thick cladding layer as described in Appendix 1, characterized in that, during laser cladding, the laser power is 2.5 to 4 kW, the optical spot size is 3 to 6 mm, the scan speed is 10 to 20 mm / s, the overlap amount is 1 to 2 mm, the powder transport speed is 1 to 3 r / min, and the powder transport flow rate is 3 to 8 L / min.

[0053] (Note 10) A laser repair method for ZG40Mn2 guide grooves based on an ultra-thick cladding layer as described in Appendix 1, characterized in that multi-layer cladding is performed during laser cladding, with each layer having a thickness of 0.7 to 1.2 mm.

Claims

1. A laser repair method for ZG40Mn2 guide grooves based on an ultra-thick cladding layer, S1 involves inspecting the surface of the guide groove for defects, polishing the worn areas, and removing defects and impurities. Using WGD130 powder as the cladding material, laser cladding is performed on the defective area using a laser cladding device, and the laser's movement trajectory is advanced laterally perpendicular to the extension direction of the guide groove, and the operation is stopped after a predetermined thickness is reached (S2). A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer, comprising S3, which involves detecting the formation of the cladding layer surface to ensure that no crack defects occur, and then completing the repair by machining and polishing.

2. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in claim 1, characterized in that the cladding layer has a thickness of 8 to 16 mm.

3. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in claim 1, characterized in that in S1, color inspection is employed and areas where defects exist are polished away.

4. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in claim 1, characterized in that, during laser cladding, the substrate of the area to be repaired is first preheated, and the operation is performed after the temperature of the substrate reaches 200 to 360°C.

5. In step S2, the laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in any one of claims 1 to 4, characterized in that, after preheating treatment during laser cladding, first, 5 to 6 layers are cladded continuously, then the area to be repaired and the cladded layers are heated to 200 to 360°C, and further, multi-layer laser cladding is performed until a predetermined thickness is reached.

6. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer according to any one of claims 1 to 5, characterized in that WGD130 powder is used as the cladding material, laser cladding is performed at room temperature and under normal conditions, and the width of the cladding layer is 90 mm or less and the thickness is 10 mm or less.

7. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer according to any one of claims 1 to 5, characterized in that the cladding material further comprises WG3130, with a mass ratio of 50 to 70:30 to 50 with respect to WGD130.

8. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer according to claim 7, characterized in that WGD130 and WG3130 powders are used as cladding materials, and the cladding layer has a width of 90 mm or less and a thickness of 8 to 16 mm.

9. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in claim 1, characterized in that, during laser cladding, the laser power is 2.5 to 4 kW, the optical spot size is 3 to 6 mm, the scan speed is 10 to 20 mm / s, the overlap amount is 1 to 2 mm, the powder transport speed is 1 to 3 r / min, and the powder transport flow rate is 3 to 8 L / min.

10. A laser repair method for a ZG40Mn2 guide groove based on an ultra-thick cladding layer as described in claim 1, characterized in that multi-layer cladding is performed during laser cladding, and the thickness of each layer is 0.7 to 1.2 mm.

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