Process property evaluation method for laser cladding repair of metal structural member

Abstract

The invention discloses a process property evaluation method for repairing a metal structural part by laser cladding, which comprises the following steps: step 1, after obtaining a metal structural part to be evaluated, carrying out defect analysis for evaluating the repairability and repairing method of the metal structural part to be repaired; 2, the microstructure of the laser cladding repairing test piece is obtained, nondestructive testing is carried out, the tensile property, the impact property, the durability property, the fatigue property, the frictional wear property and the three-dimensional scanning size are compared, and reliability evaluation is carried out on the to-be-repaired metal structural part; thirdly, the metal structural part is repaired; according to the method provided by the invention, the metal structural part is comprehensively analyzed, specifically, the repairability and the repairing method of the metal part to be repaired are judged, and the reliability of the repaired metal structural part is evaluated; safety accidents caused when the repaired metal structural part is put into use are avoided, part production and repairing cost control is achieved, and great economic benefits are brought.

Description

Technical Field

[0001] The invention belongs to the technical field of laser cladding repair, and in particular relates to a process performance evaluation method for laser cladding repair of metal structural parts. Background Art

[0002] Domestic industrial metal structural parts involve some precision parts, which have the characteristics of high material cost, complex structure, high processing precision, long processing cycle, and high value. When damage or processing errors occur, the loss caused by direct scrapping is too great, so laser cladding repair can be used instead of scrapping and replacement.

[0003] At present, the repair of metal structural parts generally only involves simple process verification, lacks a relatively systematic repair process evaluation method, and often involves the destruction of the first piece, resulting in large cost losses. Therefore, the present invention proposes a process performance evaluation method for laser cladding repair of metal structural parts. Summary of the invention

[0004] The purpose of the present invention is to provide a method for evaluating the process performance of laser cladding repair of metal structural parts to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for evaluating the process performance of laser cladding repair of metal structural parts, the specific steps comprising: step 1: after obtaining the metal structural part to be evaluated, performing defect analysis to evaluate the repairability and repair method of the metal structural part to be repaired;

[0006] Step 2: Obtain the microstructure, nondestructive testing, tensile properties, impact properties, endurance properties, fatigue properties, friction and wear properties, and 3D scanning size comparison data of the laser cladding repair test piece, and conduct reliability assessment on the metal structural parts to be repaired;

[0007] Step 3: Repair metal structural parts.

[0008] Preferably, in step 1, the repair part defect analysis and repair method comprises the following steps:

[0009] S11: Perform dimensional and position analysis on part defects to confirm the accessibility of the laser nozzle and the repairability of the defects;

[0010] S12: Grind the defect and the vicinity of the defect, classify the defect type according to the defect morphology after grinding, and confirm the repair method according to the defect type.

[0011] Preferably, in step S12, the following defect type classification and repair method is adopted:

[0012] a: A type of point defect, that is, a point-shaped defect after grinding, with a depth of ≤0.2mm. This type of defect can be filled with one layer of cladding and leave a margin. The repair method is: single-layer overlap with a single pass or less than three passes;

[0013] b: Type II point defects, i.e., point defects after grinding, with a depth of >0.2mm and ≤0.5mm. Such defects cannot be filled by a single layer of cladding and require multi-layer overlap. The repair method is: multi-layer single-pass or multi-layer overlap within three passes;

[0014] c: A type of linear defect, that is, a linear defect after grinding, with a depth of ≤0.2mm and a width of ≤0.8mm. This type of defect can be filled with one layer of cladding and a margin is left. The repair method is: single layer and single pass;

[0015] d: Class II linear defects, i.e. linear defects after grinding, with a width of ≤1.6mm and a depth of >0.2mm and ≤0.5mm. This type of defect is covered with overlap after a single coat of primer. The repair method is: single coat + multiple coats within two coats;

[0016] e: Flaky V-shaped notch, which is located on a thin wall with a thickness of 2-3mm, and presents a V-shaped defect after grinding; there are two sources of flaky V-shaped notch: the thin wall of the part originally has a defect, and the flaky V-shaped notch after grinding is located on the narrow plane of the thin wall. The depth and width dimensions exceed the second type of point and line defects, and the flaky V-shaped notch is formed after grinding. The repair method is: use serpentine reciprocating, increase the distance in the x and y directions layer by layer from bottom to top, until the gap is filled and leave a mechanical margin;

[0017] f: Grooved V-shaped notch, that is, a defect similar to a V-shaped groove after grinding on a horizontal structure with a thickness margin exceeding 5mm. There are two sources of grooved V-shaped notches:

[0018] (1) There is a missing part in the thin wall of the part, forming a V-shaped groove;

[0019] (2) The wall thickness is relatively thick and the thickness margin exceeds 5mm, and the depth and width dimensions exceed the second type of point and line defects, forming a V-shaped groove or a large plane defect after grinding;

[0020] The repair method is: use serpentine reciprocating motion to increase the distance in the x and y directions layer by layer from bottom to top until the gap is filled and a mechanical margin is left.

[0021] Preferably, in step 2, the tissue analysis should include the following steps:

[0022] The specimen sampling should include the substrate, bonding area and laser cladding area. After being etched with the corresponding corrosive agent, it should be photographed with an optical microscope and subjected to tissue analysis.

[0023] Preferably, in step 2, the tensile performance analysis comprises the following steps:

[0024] S21: Obtain a tensile specimen of a plate with a V-shaped groove: Use a serpentine reciprocating motion to increase the distance in the x-direction and y-direction layer by layer from bottom to top until the gap is filled and a mechanical addition margin is left, and sampling is completed. During sampling, the part that has been clad and added is located in the middle of the specimen;

[0025] S22: Obtain a bar tensile specimen having half cladding material and half parent material, and the length of the parent material and the additive material are the same during sampling;

[0026] S23: Obtain a fully additive tensile specimen bar tensile specimen, where the lengths of the parent material and the additive material are consistent during sampling;

[0027] The samples were tested for yield strength, tensile strength, elongation after fracture and section shrinkage, and the tensile strength and yield strength were required to reach 85% of the parent material.

[0028] S24: The size of the repair area of ​​a type of point and line defects is too small to prepare mechanical property specimens by prefabricated defect sampling. Therefore, in the actual repair process, if this type of defect occurs and the bonding performance of the cladding additive and the parent material needs to be verified, the methods described in S21 to S23 should be referred to.

[0029] Preferably, in step 2, the impact performance analysis includes the following steps:

[0030] A21: Obtain an impact specimen with half cladding material and half parent material. The length of the parent material and the additive material is the same during sampling. A V-shaped or U-shaped notch is set at the joint of the specimen.

[0031] A22: Obtain an impact specimen with full cladding additive material. The length of the parent material and the additive material is the same during sampling. The specimen is provided with a V-shaped or U-shaped notch at the joint.

[0032] An impact test is performed on the corresponding bonding surface of the sample; the impact performance of the cladding sample is required to reach 85% of the parent material.

[0033] Preferably, in step 2, the endurance performance analysis includes the following steps: obtaining an endurance sample having half cladding additive and half base material, the base material and the additive being of the same length when sampling; performing an endurance performance test on the sample; obtaining an endurance sample having a full cladding additive, the base material and the additive being of the same length when sampling; performing an endurance performance test on the sample; requiring the endurance performance of the cladding sample to reach 60% of that of the base material.

[0034] Preferably, in step 2, the fatigue analysis includes the following steps: obtaining a fatigue specimen having half cladding additive material and half base material, the base material and the additive material being of the same length when sampling; performing a fatigue performance test on the specimen; obtaining a fatigue specimen having a full cladding additive material, the base material and the additive material being of the same length when sampling; performing a fatigue performance test on the specimen; the fatigue strength limit generally needs to reach 50% of the room temperature tensile strength of the base material, or reach the number of cycles specified in the relevant technical agreement.

[0035] Preferably, in step 2, friction and wear include the following steps: printing a test block of corresponding size according to the test equipment, and performing a friction and wear test on the sample.

[0036] Preferably, an equivalent alternative repair test piece is used to evaluate the performance of the repaired part after repair, and the steps are as follows:

[0037] Ⅰ: Use a substrate made of the same material and the same production method as the metal structure to be repaired, thereby replacing the destructive test of the first repaired part;

[0038] Ⅱ: Processing V-shaped grooves on the substrate;

[0039] III: Sample the defects after processing and complete the tensile test of the plate specimens.

[0040] Preferably, in step 2, the nondestructive testing should include the following steps:

[0041] Ⅰ: Conduct penetration testing on the repair area;

[0042] II: Perform X-ray inspection on the repaired area.

[0043] It is required that there are no defects such as inclusions and cracks in the cladding area and joints.

[0044] Preferably, in step 3, the three-dimensional scanning should include the following steps:

[0045] Ⅰ: 3D scanning of the repaired parts before repair;

[0046] II: 3D scanning of the repaired parts;

[0047] III: Compare the dimensions of the repaired part before and after scanning to confirm the deformation.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows: the method proposed in the present invention conducts a more comprehensive analysis of metal structural parts, specifically, the repairability and repair methods of the metal parts to be repaired are judged, and the reliability of the repaired metal structural parts is evaluated according to the laser cladding additive layer structure, non-destructive testing, tensile properties, impact properties, and three-dimensional scanning size comparison of the repaired test pieces; a method of replacing the parts to be repaired with an equivalent repair test piece is adopted, and the performance of the repaired test piece after repair is truly and objectively reflected, thereby avoiding the destructive test of the first piece with the repaired part. Through defect analysis, the repairability and repair methods of metal structural parts can be evaluated; through reliability evaluation, safety accidents caused by metal structural parts during use can be avoided, and the cost control of parts production and repair can be achieved, bringing greater economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic diagram of point defects and line defects in a method for evaluating process performance of laser cladding repair of metal structural parts according to an embodiment of the present invention:

[0050] Figure 2 A schematic diagram of a sheet V-notch plate tensile test specimen of a method for evaluating process performance of laser cladding repair of a metal structural component according to an embodiment of the present invention;

[0051] Figure 3 A schematic diagram of a V-groove notch plate tensile test specimen of a method for evaluating process performance of laser cladding repair of a metal structural component according to an embodiment of the present invention;

[0052] Figure 4 This is a schematic diagram of sampling longitudinal bar tensile specimens in a method for evaluating process performance of laser cladding repair of metal structural parts according to an embodiment of the present invention, which can also be used as a sampling method for fatigue and endurance specimens;

[0053] Figure 5 This is a schematic diagram of sampling a transverse bar tensile specimen in a method for evaluating the process performance of laser cladding repair of metal structural parts according to an embodiment of the present invention; it can also be used as a sampling method for fatigue and endurance specimens;

[0054] Figure 6 A schematic diagram of longitudinal impact specimen sampling for a method for evaluating process performance of laser cladding repair of metal structural parts according to an embodiment of the present invention:

[0055] Figure 7 A schematic diagram of transverse impact specimen sampling for a method for evaluating process performance of laser cladding repair of metal structural parts according to an embodiment of the present invention:

[0056] Figure 8A schematic diagram of a fatigue specimen of a method for evaluating process performance of laser cladding repair of a metal structural component according to an embodiment of the present invention;

[0057] Fig. 9 A schematic diagram of a friction and wear sample of a method for evaluating process performance of laser cladding repair of a metal structural part according to an embodiment of the present invention;

[0058] Fig.10 For Example 1 of the present invention Figure 2 Schematic diagram of hardness test results of each area of ​​the specimen. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] The present invention provides a method for evaluating the process performance of laser cladding repair of metal structural parts. Figures 1 to 7 , specifically including the following steps:

[0061] After obtaining the metal structural parts to be evaluated, defect analysis is performed to evaluate the repairability and repair methods of the metal repair parts;

[0062] Embodiment 1:

[0063] In one embodiment, the part to be repaired is a thin-walled part made of titanium alloy; the defect types and sizes need to be classified and repaired using corresponding laser cladding processes. The defect type classification method is as follows:

[0064] A type of point defect, that is, a point-shaped defect after grinding, can be used Figure 1 The mark 1 indicates that the depth is ≤0.2mm. This type of defect can be filled with one layer of cladding and leave a margin. The repair method is: single-layer overlap within three layers;

[0065] The second type of point defects, that is, the defects that appear in point shape after grinding, can be used Figure 1 The mark 1 indicates that the defect is different from the point defect in that its size is larger: the depth is greater than 0.2mm and less than 0.5mm. This type of defect cannot be filled by a single layer of cladding and requires multi-layer overlap. The repair method is: multi-layer single-pass or multi-layer overlap within three passes;

[0066] A type of linear defect, that is, a linear defect after grinding, can be Figure 1The mark 2 indicates that the depth is ≤0.2mm and the width is ≤0.8mm. This type of defect can be filled with one layer of cladding and leave a margin. The repair method is: single layer and single pass;

[0067] The second type of linear defects, that is, the linear defects after grinding, can be used Figure 1 The mark 2 indicates that the difference from the first type of linear defects is that its size is larger: width ≤1.6mm, depth >0.2mm and ≤0.5mm. This type of defect is covered with overlapping after single-pass primer. The repair method is: single-pass + multiple-layer overlap within two passes;

[0068] The V-shaped notch is located on a thin wall with a thickness of 2-3 mm. After grinding, the shape is close to the shape of a thin sheet, such as Figure 2 As shown in the mark 3; there are two sources of lamellar V-notch:

[0069] (1) There is a missing part in the thin wall of the part, and after grinding, a V-shaped notch appears;

[0070] (2) Located on a thin-walled narrow plane, the depth and width dimensions exceed the second-class point and line defects, and a flake V-shaped notch is formed after grinding. The repair method is: use serpentine reciprocating to increase the distance in the x and y directions layer by layer from bottom to top until the notch is filled and a mechanical margin is left;

[0071] Grooved V-notch, that is, located on the horizontal structure with a thickness margin exceeding 5mm, after grinding, it presents a defect similar to a V-groove, such as Figure 3 As shown in the mark 4; there are two sources of V-groove notches:

[0072] (1) There is a missing part in the thin wall of the part, forming a V-shaped groove;

[0073] (2) The wall thickness is relatively thick and the thickness margin exceeds 5mm, and the depth and width dimensions exceed the second type of point and line defects, which form V-groove notches or large plane defects after grinding.

[0074] The repair method is: using a multi-pass, multi-layer and serpentine reciprocating cladding method, increasing the distance in the x-direction and y-direction layer by layer from bottom to top until the gap is filled and a mechanical margin is left;

[0075] In one embodiment, after obtaining the cross-sectional sample of the repaired test piece, the sample is prepared by a metallographic grinder, and the microstructures of the substrate, heat-affected zone, joint, and laser cladding zone are observed under an optical microscope. Similar to welding, the laser cladding structure is formed by solidification of liquid metal and belongs to a cast structure; and the heat-affected zone is formed when it is combined with the substrate. The heat affected zone must have remelting zone, overheating zone and phase change zone. The size of these zones will have an important influence on the metallurgical bonding performance of the cladding layer and the substrate. After etching with the corresponding corrosive agent, the joint is photographed with an optical microscope. The photographing magnification can be selected from one to three combinations of 25×, 50×, 100×, 200×, and 500×, generally composed of low magnification and high magnification, such as 25× and 200×. If necessary, a higher magnification can be used. If the heat affected zone is very narrow (usually it is believed that it should not exceed 0.5mm) and the two ends close to the substrate and the cladding layer are similar to the substrate or the cladding layer in morphology, and there are no cracks, unfused and pores exceeding the size specified in the corresponding technical requirements, it is considered that the cladding layer and the substrate have formed a good metallurgical bond.

[0076] In one embodiment, Figure 2 to Figure 5 As shown, the tensile performance analysis includes the following steps:

[0077] Get thin plates and medium and thick plates with V-grooves, such as Figure 2 and Figure 3 As shown, three-dimensional scanning is performed to record dimension data;

[0078] Obtain a thin plate with a V-groove filled with laser cladding, the size of which is 100 mm × 20 mm × 3 mm. The middle part of the processed tensile specimen must be completely filled with laser cladding; the V-groove depth is 10 mm, and the notch angle is 45°;

[0079] A medium-thick plate with a laser cladding filled V-groove is obtained, the size of which is 100 mm×50 mm×5 mm, the depth of the V-groove is 3 mm, and the notch angle is 45°;

[0080] Get the laser cladding sample, including the longitudinal ( Figure 4 shown) and horizontally ( Figure 5 Specimens shown);

[0081] Carry out penetration test and X-ray test on the above samples to ensure that the cladding layer has no cracks, unfused or pores that do not meet the size specified in the relevant technical requirements;

[0082] The tensile test should be carried out under the same conditions using substrates of the same size;

[0083] Carry out tensile test on the above samples and record the tensile strength σ b , yield strength σ 0.2 , elongation δ5, section shrinkage ψ;

[0084] Analyze the fracture surface in each state to confirm the fracture type;

[0085] In one embodiment, Figure 6 As shown, the impact toughness analysis includes the following steps:

[0086] Get the laser cladding sample, including the longitudinal ( Figure 6 shown) and horizontally ( Figure 7 Specimens shown);

[0087] Carry out penetration test and X-ray test on the above samples to ensure that the cladding layer has no cracks, unfused or pores that do not meet the size specified in the relevant technical requirements;

[0088] The impact test should be carried out under the same conditions using substrates of the same size;

[0089] Carry out impact toughness test on the above specimens and record the impact energy. The impact toughness shall be at least 85% of the parent material.

[0090] In one embodiment, fatigue performance analysis includes the following steps:

[0091] Obtain laser cladding samples, including longitudinal and transverse samples; perform penetration test and X-ray test on the above samples to ensure that the cladding layer has no cracks, unfused layers, or pores that do not meet the specified size requirements of relevant technical requirements; the samples can be cut into plates, such as Figure 8 As shown;

[0092] The fatigue test should be carried out under the same conditions using the same size substrate;

[0093] Perform fatigue tests on the above specimens and record the number of stress cycles;

[0094] In one embodiment, the friction and wear performance analysis includes the following steps:

[0095] Get the laser cladding sample, and then take out the square test block with a thickness of 5mm. The outline size can be selected by yourself, and 15mm×15mm is recommended. Fig. 9 As shown;

[0096] The above samples are subjected to penetrant inspection and X-ray inspection to ensure that the cladding layer has no cracks, unfused layers, or pores that do not meet the size requirements of the relevant technical requirements; the samples can be cut into plates, such as Figure 8 As shown;

[0097] The friction and wear test should be carried out under the same conditions using substrates of the same size;

[0098] Conduct friction and wear tests on the above samples and record the friction coefficient;

[0099] It should be noted that after laser cladding repair, residual stress will be generated inside the cladding structure. In order to avoid deformation or cracking of parts caused by residual stress release during the use of parts, stress relief annealing is generally performed after laser cladding; the annealing system should be determined according to the base material of the parts;

[0100] The same type of specimens with the same specifications shall be prepared. After stress relief annealing, tensile test, impact test, fatigue test, endurance test, friction and wear test shall be carried out under the same conditions to obtain the mechanical properties of the repaired parts after annealing. The mechanical properties evaluation method shall still comply with the above provisions.

[0101] In one embodiment, the dimensional reliability of the repaired metal structural part is verified based on the dimensional inspection and nondestructive inspection of the prepared specimen;

[0102] Specifically, the structural parts should be 3D scanned before repair to record the original dimensions;

[0103] Specifically, the process method should be selected according to the type of structural defect before repair;

[0104] Specifically, the structural parts should be cleaned before repair to avoid defects such as inclusions, cracks and unfused structures caused by oil, dust, metal attachments, etc.;

[0105] Specifically, during repair, the structural parts should be kept under good inert gas protection to avoid excessive contact of the red-hot metal with air and oxidation, which will affect the structure and performance;

[0106] Specifically, during repair, it should be ensured that the cladding layer has sufficient machining allowance;

[0107] Specifically, a second 3D scan should be performed after restoration to record the dimensions of the restoration;

[0108] Specifically, stress relief annealing should be performed after repair to eliminate the residual stress generated by laser cladding;

[0109] Specifically, the risk of heat deformation of parts should be fully assessed according to their structure, and thin-walled structures or structures with sudden changes in wall thickness without rib support should be fixed with tooling to avoid deformation after heat treatment;

[0110] Specifically, the heat-treated parts were subjected to a third 3D scan to record the dimensions after repair;

[0111] Specifically, set the machining program according to the part drawing; remove the excess cladding layer;

[0112] Specifically, the machined parts are subjected to a fourth three-dimensional scan, the dimensions after repair are recorded, and compared with the initial dimensions to confirm that they meet the dimensions specified in the relevant technical requirements;

[0113] From the performance evaluation data of some titanium alloy thin-walled parts, it can be seen that the tensile and impact properties of all samples have reached more than 85% of the parent material properties: according to the technical agreement requirements, fatigue reached 1.0×10 5 , all samples can meet the requirements.

[0114] (1) Stretching:

[0115] Table 1 Longitudinal tensile results of titanium alloy samples (temperature: 24°C)

[0116]

[0117] Table 2 Transverse tensile results of titanium alloy samples (temperature: 24°C)

[0118]

[0119]

[0120] (2) Impact:

[0121] Table 3 Longitudinal impact results of titanium alloy samples (temperature: 24°C)

[0122]

[0123] Table 4 Transverse impact results of titanium alloy samples (temperature: 24°C)

[0124]

[0125] (3) High cycle fatigue:

[0126] Test parameters: Fatigue test requirements: high cycle fatigue, 400MPa stress, sine wave, r=-1, frequency 120Hz, until breaking.

[0127] Table 5 High cycle fatigue test results of titanium alloy specimens

[0128]

[0129] (4) Microhardness

[0130] Microhardness data see Fig.10 .

[0131] Embodiment 2:

[0132] In one embodiment, the part to be repaired is a stainless steel shaft part; the defect type and size need to be classified and repaired by using the corresponding laser cladding process, and most of the steps performed are similar to those in Example 1 and will not be repeated; the difference is that fatigue test and impact test are not required according to technical requirements, and because it is a shaft part, the equivalent replacement damage form is a groove-shaped V-shaped notch instead of a sheet-shaped V-shaped notch, and hardness testing and friction and wear tests are performed;

[0133] Some performance evaluation data of stainless steel shaft parts and some experimental data are as follows. It can be seen that the tensile properties of all samples have reached more than 85% of the parent material performance:

[0134] Table 6 Stainless steel sample tensile test results (temperature: 24°C)

[0135]

[0136]

[0137] Table 7 Friction and wear test data of stainless steel samples

[0138]

[0139] Embodiment 3:

[0140] In one embodiment, the part to be repaired is a high-temperature alloy special-shaped part; the defect type and size need to be classified and repaired by using a corresponding laser cladding process. The steps performed are similar to those in Example 1 and will not be repeated here; the difference is that:

[0141] (1) Special-shaped parts have thin walls and thick walls, so it is necessary to carry out cladding tests on both sheet-shaped and grooved V-shaped specimens. The impact performance requirements of these parts are not high, but they need to be subjected to longitudinal high-temperature tensile, high-temperature endurance, and low-cycle high-temperature fatigue tests;

[0142] (2) According to the service conditions and service time of the high-temperature alloy repair parts, restorative heat treatment is required: first, solution heat treatment is performed, then stress relief annealing is performed after laser cladding repair, and finally aging is completed.

[0143] Some performance evaluation data of high-temperature alloy special-shaped parts are as follows: the tensile properties of all samples have reached more than 85% of the parent material properties, and the endurance properties of all samples have reached more than 60% of the parent material; the fatigue cycle under specified conditions has reached 1.0×10 5 , all samples met the requirements.

[0144] Table 8 Longitudinal tensile results of high temperature alloy samples (temperature: 24°C)

[0145]

[0146] Table 9 Longitudinal tensile results of high temperature alloy samples (temperature: 650°C)

[0147]

[0148]

[0149] Table 10 Longitudinal rupture results of high temperature alloy samples (temperature: 650℃)

[0150]

[0151] Table 11 Low cycle fatigue test results of high temperature alloy specimens (temperature: 650°C)

[0152]

[0153] It should be noted that since the repair test piece is made of the same process conditions and the defects and repairs are artificially prepared, it is believed that the repair of metal structural parts is based on complete process verification, thus replacing the traditional first-piece destructive test; saving the economic losses caused by the scrapping and destruction of parts;

[0154] It should be noted that the corresponding heat treatment system should be determined according to the type of material of the repaired parts; and the order of heat treatment in the entire repair process should be reasonably arranged.

[0155] It should be noted that due to the small size of the repair area of ​​a type of point and line defects, it is impossible to prepare mechanical properties samples by sampling the prefabricated defects. Therefore, in the actual repair process, if such defects occur and the bonding performance of the cladding additive and the parent material needs to be verified, reference should be made to Figure 2 to Figure 7 The method of preparing samples and testing them;

[0156] It should be noted that the mechanical property data provided in the embodiments are data completed according to the technical conditions during actual repair. The mechanical property related steps of the present invention do not need to be performed in full, but all or part of the experiments are selectively performed according to the performance requirements specified in the corresponding technical conditions, including the environmental requirements for the experiments, such as selecting room temperature or high temperature, or performing all of them;

[0157] The process performance evaluation method for laser cladding repair of metal structural parts provided in the embodiment conducts a relatively comprehensive analysis of metal structural parts, specifically, the repairability and repair method of metal repair parts are judged, and the reliability of the repaired metal structural parts is evaluated according to the laser cladding additive layer structure, non-destructive testing, tensile properties, and impact properties of the prepared test pieces. An equivalent test piece is used to replace the part to be repaired, and the performance of the repaired simple test piece is used to truly and objectively reflect the performance of the repaired structural part. Through defect analysis, the repairability and repair method of metal structural parts can be evaluated; through reliability evaluation, safety accidents caused by metal structural parts during use can be avoided, and cost control of parts production and repair can be achieved, bringing greater economic benefits.

[0158] Although embodiments of the present invention have been shown and described (see the above detailed description for details), it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the process performance of laser cladding repair of metal structural parts, characterized in that: The specific steps include: Step 1: After obtaining the metal structure to be evaluated, a defect analysis is performed to evaluate the repairability and repair method of the metal structure to be repaired; Step 2: Obtain the microstructure, nondestructive testing, tensile properties, impact properties, endurance properties, fatigue properties, friction and wear properties, and 3D scanning size comparison data of the laser cladding repair test piece, and conduct reliability assessment on the metal structural parts to be repaired; Step 3: Repair metal structural parts.

2. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized in that: In step 1, the repair part defect analysis and repair method includes the following steps: S11: Perform dimensional and position analysis on part defects to confirm the accessibility of the laser nozzle and the repairability of the defects; S12: Grind the defect and the vicinity of the defect, classify the defect type according to the defect morphology after grinding, and confirm the repair method according to the defect type.

3. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 2 is characterized in that: In step S12, the following defect type classification and repair method is adopted: a: A type of point defect, that is, a point-shaped defect after grinding, with a depth of ≤0.2mm. This type of defect can be filled with one layer of cladding and leave a margin. The repair method is: single-layer overlap with a single pass or less than three passes; b: Type II point defects, i.e., point defects after grinding, with a depth of >0.2mm and ≤0.5mm. Such defects cannot be filled by a single layer of cladding and require multi-layer overlap. The repair method is: multi-layer single-pass or multi-layer overlap within three passes; c: A type of linear defect, that is, a linear defect after grinding, with a depth of ≤0.2mm and a width of ≤0.8mm. This type of defect can be filled with one layer of cladding and a margin is left. The repair method is: single layer and single pass; d: Class II linear defects, i.e. linear defects after grinding, with a width of ≤1.6mm and a depth of >0.2mm and ≤0.5mm. This type of defect is covered with overlap after a single coat of primer. The repair method is: single coat + multiple coats within two coats; e: Flaky V-shaped notch, which is located on a thin wall with a thickness of 2-3mm, and presents a V-shaped defect after grinding; there are two sources of flaky V-shaped notch: the thin wall of the part originally has a defect, and the flaky V-shaped notch after grinding is located on the narrow plane of the thin wall. The depth and width dimensions exceed the second type of point and line defects, and the flaky V-shaped notch is formed after grinding. The repair method is: use serpentine reciprocating, increase the distance in the x and y directions layer by layer from bottom to top, until the gap is filled and leave a mechanical margin; f: Grooved V-notch, that is, located on the horizontal structure with a thickness margin exceeding 5mm, after grinding, it presents a V-shaped groove morphology; there are two sources of grooved V-notch: (1) There is a missing part in the thin wall of the part, forming a V-shaped groove; (2) The wall thickness is relatively thick and the thickness margin exceeds 5mm, and the depth and width dimensions exceed the second type of point and line defects, forming a V-shaped groove or a large plane defect after grinding; The repair method is: use serpentine reciprocating motion to increase the distance in the x and y directions layer by layer from bottom to top until the gap is filled and a mechanical margin is left.

4. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized in that: In step 2, the organizational analysis should include the following steps: The specimen sampling should include the substrate, bonding area and laser cladding area. After being etched with the corresponding corrosive agent, it should be photographed with an optical microscope and subjected to tissue analysis.

5. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized in that: In the step 2, the tensile performance analysis includes the following steps: S21: Obtain a tensile specimen of a plate with a V-shaped groove: Use a serpentine reciprocating motion to increase the distance in the x-direction and y-direction layer by layer from bottom to top until the gap is filled and a mechanical addition margin is left, and sampling is completed. During sampling, the part that has been clad and added is located in the middle of the specimen; S22: Obtain a bar tensile specimen having half cladding material and half parent material, and the length of the parent material and the additive material are the same during sampling; S23: Obtain a fully additive tensile specimen bar tensile specimen, where the lengths of the parent material and the additive material are consistent during sampling; The samples were tested for tensile strength, yield strength, elongation after fracture and section shrinkage respectively, and the tensile strength and yield strength were required to reach 85% of the parent material; S24: The size of the repair area of ​​a type of point and line defects is too small to prepare mechanical property specimens by prefabricated defect sampling. Therefore, in the actual repair process, if this type of defect occurs and the bonding performance of the cladding additive and the parent material needs to be verified, the methods described in S21 to S23 should be referred to.

6. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized in that: In the step 2, the impact performance analysis includes the following steps: A21: Obtain an impact specimen with half cladding material and half parent material. The length of the parent material and the additive material is the same during sampling. A V-shaped or U-shaped notch is set at the joint of the specimen. A22: Obtain an impact specimen with full cladding additive material. The length of the parent material and the additive material is the same during sampling. The specimen is provided with a V-shaped or U-shaped notch at the joint. An impact test is performed on the corresponding bonding surface of the sample; the impact performance of the cladding sample is required to reach 85% of the parent material.

7. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized in that: In the step 2, the endurance performance analysis includes the following steps: obtaining an endurance sample having half cladding additive material and half parent material, wherein the parent material and the additive material have the same length when sampling; performing an endurance performance test on the sample; obtaining an endurance sample having a full cladding additive material, wherein the parent material and the additive material have the same length when sampling; Carry out endurance performance test on the sample; the endurance performance of the cladding sample is required to reach 60% of the parent material; In the step 2, the fatigue analysis includes the following steps: obtaining a fatigue specimen having half cladding additive material and half parent material, wherein the parent material and the additive material have the same length when sampling; performing a fatigue performance test on the specimen; obtaining a fatigue specimen having full cladding additive material, wherein the parent material and the additive material have the same length when sampling; performing a fatigue performance test on the specimen; the fatigue strength limit generally needs to reach 50% of the room temperature tensile strength of the parent material, or reach the number of cycles specified in the relevant technical agreement; In the step 2, the friction and wear test includes the following steps: printing a test block of corresponding size according to the test equipment, and performing a friction and wear test on the sample.

8. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized by: The performance of the repaired part after repair is evaluated by using an equivalent replacement repair test piece, and the steps are as follows: Ⅰ: Use a substrate made of the same material and the same production method as the metal structure to be repaired, thereby replacing the destructive test of the first repaired part; Ⅱ: Artificially process V-shaped grooves on the substrate; III: Sample the defects after processing and complete the tensile test of the plate specimens.

9. The process performance evaluation method for laser cladding repair of metal structural parts according to claim 1 is characterized in that: In step 2, the non-destructive testing should include the following steps: Ⅰ: Conduct penetration testing on the repair area; II: X-ray inspection of the repaired area; It is required that there are no inclusions or cracks in the cladding area and joints.

10. According to the method for evaluating the process performance of laser cladding repair of metal structural parts in claim 1, in step 3, the three-dimensional scanning should include the following steps: Ⅰ: 3D scanning of the repaired parts before repair; II: 3D scanning of the repaired parts; III: Compare the dimensions of the repaired part before and after scanning to confirm the deformation.

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