Method for rapidly preparing metallographic structure of hard alloy and steel brazing part

Abstract

The invention discloses a method for rapidly preparing a metallographic structure of a hard alloy and steel brazed part, which comprises the following steps: welding hard alloy and steel, linearly cutting along a direction vertical to a welding trace, and taking the welded hard alloy and steel as a preparation sample; the first abrasive paper and the second abrasive paper are sequentially divided into three concentric circular ring areas including an abrasive paper outer ring, an abrasive paper middle ring and an abrasive paper inner ring from the edge to the center according to different rotating speeds of the first abrasive paper and the second abrasive paper in all the areas of the grinding machine. According to the method, the hard alloy and the steel are cut after being welded, and the cut sample is polished and washed after being polished for multiple times, so that the problem that metallographic structures are difficult to prepare from two welding samples with great hardness difference is solved; and common metallographic preparation materials and equipment are adopted, so that the microstructure of the welded part of the hard alloy and the steel can be rapidly prepared. And the problems of serious unclear structure and false phase in the metallographic phase preparation process can also be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of metallographic preparation, in particular to a method for rapidly preparing the metallographic structure of a hard alloy and a steel brazing part. Background Art

[0002] Cemented carbide and steel welded parts have wide application prospects in many fields. Brazing cemented carbide with steel is to take advantage of the advantages of both and improve the overall performance of the materials. Cemented carbide has high hardness and wear resistance, while steel has good toughness and impact resistance. By welding these two materials, cemented carbide can be used in parts that require high hardness and wear resistance, while steel can be used in parts that require toughness and impact resistance, thus achieving the best combination of materials. Some industrial enterprises use the welding technology of cemented carbide YG8 and 45 steel when manufacturing machine tools and cutting tools to improve the wear resistance and service life of the products. In addition, the automotive manufacturing industry also widely uses this welding technology to ensure the strength and durability of vehicle parts.

[0003] At present, during the cutting and polishing process of samples after welding of cemented carbide and steel brazing parts, the hardness of cemented carbide is much higher than that of steel, resulting in inconsistent wear speed, which in turn easily leads to uneven wear of samples and easy fracture; when selecting abrasives, it is difficult to find abrasives suitable for both materials, and most of them are expensive; due to the difference in hardness between cemented carbide and steel, grinding parameters such as speed, pressure and lubrication method are difficult, and improper operation may cause damage to the sample surface and affect metallographic observation. Therefore, in order to solve the above technical deficiencies, it is necessary to design a method for quickly preparing the metallographic structure of cemented carbide and steel brazing parts. Summary of the invention

[0004] The object of the present invention is to provide a method for rapidly preparing the metallographic structure of a cemented carbide and steel brazing component, so as to solve the technical problems raised in the background technology.

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

[0006] S1. After welding the cemented carbide and the steel, a wire cutting is performed along a direction perpendicular to the welding trace and the wire cutting is used as a prepared sample, wherein the prepared sample includes the cemented carbide, the steel, the welding trace and the cutting trace;

[0007] S2, dividing the first sandpaper and the second sandpaper into three concentric ring areas, namely, a sandpaper outer ring area, a sandpaper middle ring area, and a sandpaper inner ring area, from the edge to the center according to the different rotation speeds of the respective areas on the grinding machine;

[0008] S3, applying W40 water-soluble diamond powder grinding paste at any position on the outer circle of the first sandpaper, installing the first sandpaper on a grinder, placing the prepared sample on the outer circle of the first sandpaper for grinding to form a primary grinding sample;

[0009] S4, installing the second sandpaper on the grinding machine, placing the first ground sample on the middle circle of the second sandpaper for grinding to form a second ground sample;

[0010] S5, dividing the polishing cloth into three concentric ring areas, namely, a polishing outer ring, a polishing middle ring, and a polishing inner ring, from the edge to the center according to the different rotation speeds of the polishing cloth in each area on the polishing machine;

[0011] S6. Apply W2.5 water-soluble diamond powder grinding paste at any position of the polishing middle circle of the polishing cloth, install the polishing cloth on the polishing machine, place the secondary grinding sample on the polishing middle circle of the polishing cloth for polishing to form the final polished sample;

[0012] S7. The surface of the final polished sample is rinsed with alcohol for the first time, and then quickly blown dry and then corroded. The surface of the final polished sample is rinsed with alcohol for the second time, and then quickly blown dry. Finally, the microstructure of the final polished sample after the second rinse is observed.

[0013] Furthermore, the specific grinding process of step S3 is: placing the prepared sample on the sandpaper outer ring area of ​​the first sandpaper, so that the cemented carbide of the prepared sample is close to the outer edge of the sandpaper outer ring and the cutting mark is perpendicular to the movement direction of the first sandpaper, applying a first grinding pressure to the prepared sample, starting the grinder for grinding and adding water in small amounts multiple times during the grinding process, repeating this step until the scratch direction after grinding with the first sandpaper is consistent, and the prepared sample has no obvious cross-section to form a first grinding sample.

[0014] Furthermore, the specific grinding process of step S4 is: placing the first ground sample on the middle circle of the second sandpaper, and making the scratches after the first sandpaper is polished perpendicular to the movement direction of the second sandpaper, applying the second grinding pressure to the first ground sample, starting the grinder for grinding and adding water in small amounts multiple times during the grinding process, repeating this step until the scratches after the second sandpaper are fine and uniform and the first ground sample has no obvious cross section to form a second ground sample.

[0015] Furthermore, the specific polishing process in step S6 is: placing the secondary ground sample on the polishing middle circle of the polishing cloth, so that the cemented carbide of the secondary ground sample is close to the inner edge of the polishing middle circle and the scratches after the second sandpaper polishing are perpendicular to the movement direction of the polishing cloth, applying polishing pressure to the secondary ground sample, starting the polishing machine and continuously adding a small amount of water during the polishing process, repeating this step until there are basically no scratches to form a final polished sample.

[0016] Furthermore, the particle sizes of the first sandpaper and the second sandpaper are both 1000#, the polishing cloth is red velvet, and the amounts of W40 water-soluble diamond powder grinding paste and W2.5 water-soluble diamond powder grinding paste correspond to the wire cutting sizes of the prepared samples and the secondary grinding samples, respectively.

[0017] Furthermore, in step S3, the speed of the grinder is set to 800 r / min, the first grinding pressure is 30 N, and the grinding time is 5 min. In step S4, the speed of the grinder is set to 1000 r / min, the second grinding pressure is 20 N, and the grinding time is 3 min. The speed of the polisher is set to 800 r / min, the polishing pressure is 20 N, and the polishing time is 2 min.

[0018] Beneficial effects:

[0019] 1. The present invention solves the problem that it is difficult to prepare the metallographic structure of two welding samples with huge hardness differences by cutting the cemented carbide and steel after welding, and polishing and rinsing the cut samples after multiple grinding. In addition, the present invention adopts common metallographic preparation materials and equipment to quickly prepare the microstructure of the welded parts of cemented carbide and steel. It can also avoid the serious unclear structure and false phase problems in the metallographic preparation process.

[0020] 2. In the process of grinding and polishing the sample, the first sandpaper, the second sandpaper and the polishing cloth are divided into an outer circle, a middle circle and an inner circle according to the different rotation speeds of each area on the grinder and the polisher, so as to facilitate grinding and polishing of the sample according to the needs, avoid the situation that scratches and polishing do not meet the requirements and the occurrence of cross-sections, which affect the preparation of metallographic structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions implemented in the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 A flow chart of the method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts according to the present invention;

[0023] Figure 2 The microstructure of the brazing piece of YG8 cemented carbide and 45 steel of the present invention;

[0024] Figure 3 It is a schematic diagram of cutting after welding of cemented carbide and steel according to the present invention;

[0025] Figure 4 This is a schematic diagram of the initial grinding with the first sandpaper of the present invention;

[0026] Figure 5 This is a schematic diagram of secondary grinding with the second sandpaper of the present invention;

[0027] Figure 6 It is a schematic diagram of polishing of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] like Figure 1-Figure 6 As shown, the present invention provides a method for rapidly preparing the metallographic structure of a cemented carbide and steel brazing part, and the specific steps are as follows:

[0030] S1. After welding the cemented carbide and the steel, a wire cutting is performed along a direction perpendicular to the welding trace and the prepared sample is used as the prepared sample, wherein the prepared sample includes the cemented carbide, the steel, the welding trace and the cutting trace. In this embodiment, the cemented carbide is YG8, the steel is 45 steel, and the size of the prepared sample is 20mm*20mm*10mm. Figure 3 As shown, the size of the prepared sample cut out can be convenient for hand-holding, or it can be cut according to the size specified by the automatic polishing machine;

[0031] S2, such as Figure 4 and Figure 5 As shown, the first sandpaper and the second sandpaper are divided into three concentric ring areas, namely, a sandpaper outer ring, a sandpaper middle ring and a sandpaper inner ring, from the edge to the center according to the different rotation speeds of the respective areas on the grinding machine;

[0032] S3, such as Figure 4As shown, W40 water-soluble diamond powder grinding paste is applied at any position of the sandpaper outer circle of the first sandpaper, and the first sandpaper is installed on the grinder, and the prepared sample is placed in the sandpaper outer circle area of ​​the first sandpaper, so that the cemented carbide of the prepared sample is close to the outer edge of the sandpaper outer circle and the cutting mark is perpendicular to the movement direction of the first sandpaper, and the first grinding pressure is applied to the prepared sample, and the grinder is started for grinding and water is added in small amounts multiple times during the grinding process. This step can be repeated until the scratch direction after grinding with the first sandpaper is consistent, and the prepared sample has no obvious cross-section to form a first grinding sample, and overheating is avoided by adding water in small amounts multiple times, wherein the particle size of the first sandpaper and the second sandpaper used are both 1000#, the rotation speed of the grinder in this step is set to 800r / min, the first grinding pressure is 30N, the grinding time is 5min, and the amount of W40 water-soluble diamond powder grinding paste corresponds to the wire cutting size of the prepared sample. In this embodiment, 0.2cm of W40 water-soluble diamond powder grinding paste is applied at any position of the sandpaper outer circle of the first sandpaper;

[0033] The outer ring, middle ring and inner ring of the first and second sandpapers on the grinder are divided based on the different rotation speeds of each area. The outer ring of the sandpaper has the largest rotation speed, and the inner ring of the sandpaper has the smallest rotation speed. Grinding with the first sandpaper requires quickly grinding away the wire cutting marks, so the outer ring of the sandpaper will be faster. Carbide has a higher hardness and needs to be placed close to the outer edge of the outer ring of the sandpaper, while steel has a lower hardness and can be placed close to the inner edge of the outer ring of the sandpaper to avoid cross-sections.

[0034] S4, such as Figure 5 As shown, the second sandpaper is installed on the grinder, the first grinded sample is placed on the middle circle of the second sandpaper, and the scratches after the first sandpaper is grinded are perpendicular to the movement direction of the second sandpaper, and the second grinding pressure is applied to the first grinded sample, the grinder is started for grinding, and water is added in small amounts multiple times during the grinding process. This step can be repeated until the scratches after the second sandpaper is grinded are fine and uniform and the first grinded sample has no obvious cross section to form a second grinded sample, and overheating is avoided by adding water in small amounts multiple times. In this step, the grinder speed is set to 1000r / min, the second grinding pressure is 20N, and the grinding time is 3min. The second grinding is performed through the middle circle of the second sandpaper to make the scratches on the sample finer and smaller.

[0035] S5, such as Figure 6 As shown, the polishing cloth is divided into three concentric ring areas, namely, the polishing outer ring, the polishing middle ring and the polishing inner ring, from the edge to the center according to the different rotation speeds of the polishing cloth in each area on the polishing machine. The polishing cloth is red flannel.

[0036] S6. Apply W2.5 water-soluble diamond powder grinding paste to any position of the polishing middle circle of the polishing cloth, and install the polishing cloth on the polishing machine. Place the secondary ground sample on the polishing middle circle of the polishing cloth, so that the carbide of the secondary ground sample is close to the inner edge of the polishing middle circle and the scratches after the second sandpaper is polished are perpendicular to the movement direction of the polishing cloth. Apply polishing pressure to the secondary ground sample, start the polishing machine and continue to add a small amount of water during the polishing process. Repeat this step until there is basically no scratch to form the final polished sample. By continuing to add a small amount of water to remove the ground particles, the polishing machine speed is set to 8 00r / min, polishing pressure is 20N, polishing time is 2min, the speed of the polishing outer circle is too large, which easily causes scratches on the surface of the secondary ground sample during the polishing process, the speed of the polishing inner circle is too small, and a longer polishing time is required. The polishing middle circle is selected for polishing to reduce the polishing time and avoid scratches on the surface of the secondary ground sample. The amount of W2.5 water-soluble diamond powder grinding paste corresponds to the wire cutting size of the secondary ground sample. In this embodiment, 0.2 cm of W2.5 water-soluble diamond powder grinding paste is applied at any position of the polishing middle circle of the polishing cloth;

[0037] S7. The surface of the final polished sample is rinsed with alcohol for the first time, and then quickly blown dry and then corroded. The surface of the final polished sample is rinsed with alcohol for the second time, and then quickly blown dry. Finally, the microstructure of the final polished sample after the second rinse is observed. Figure 2 As shown, after two rinses with alcohol, you need to blow dry quickly to avoid leaving water stains.

[0038] The hardness of cemented carbide is mostly around 1500 HV, and the hardness of steel is mostly around 600 HV. The present invention discloses a method for quickly preparing the metallographic structure of cemented carbide and steel brazing parts. The method solves the problem that it is difficult to prepare the metallographic structure of two welding samples with huge hardness differences by cutting the cemented carbide and steel after welding, and polishing and rinsing the cut samples after multiple grinding. In addition, the common metallographic preparation materials and equipment can be used to quickly prepare the microstructure of the welded parts of cemented carbide and steel. It can also avoid serious unclear organization and false phase problems in the metallographic preparation process.

[0039] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0040] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts, characterized in that: The following steps are involved: S1. After welding the cemented carbide and the steel, a wire cutting is performed along a direction perpendicular to the welding trace and the wire cutting is used as a prepared sample, wherein the prepared sample includes the cemented carbide, the steel, the welding trace and the cutting trace; S2, dividing the first sandpaper and the second sandpaper into three concentric ring areas, namely, a sandpaper outer ring area, a sandpaper middle ring area, and a sandpaper inner ring area, from the edge to the center according to the different rotation speeds of the respective areas on the grinding machine; S3, applying W40 water-soluble diamond powder grinding paste at any position on the outer circle of the first sandpaper, installing the first sandpaper on a grinder, placing the prepared sample on the outer circle of the first sandpaper for grinding to form a primary grinding sample; S4, installing the second sandpaper on the grinding machine, placing the first ground sample on the middle circle of the second sandpaper for grinding to form a second ground sample; S5, dividing the polishing cloth into three concentric ring areas, namely, a polishing outer ring, a polishing middle ring, and a polishing inner ring, from the edge to the center according to the different rotation speeds of the polishing cloth in each area on the polishing machine; S6. Apply W2.5 water-soluble diamond powder grinding paste at any position of the polishing middle circle of the polishing cloth, install the polishing cloth on the polishing machine, place the secondary grinding sample on the polishing middle circle of the polishing cloth for polishing to form the final polished sample; S7. The surface of the final polished sample is rinsed with alcohol for the first time, and then quickly blown dry and then corroded. The surface of the final polished sample is rinsed with alcohol for the second time, and then quickly blown dry. Finally, the microstructure of the final polished sample after the second rinse is observed.

2. The method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts according to claim 1, characterized in that: The specific grinding process of step S3 is as follows: placing the prepared sample on the outer ring area of ​​the first sandpaper, so that the cemented carbide of the prepared sample is close to the outer edge of the outer ring of the sandpaper and the cutting mark is perpendicular to the movement direction of the first sandpaper, applying a first grinding pressure to the prepared sample, starting the grinder for grinding and adding water in small amounts multiple times during the grinding process, and repeating this step until the scratch directions after grinding with the first sandpaper are consistent and the prepared sample has no obvious cross section to form a first grinding sample.

3. The method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts according to claim 1, characterized in that: The specific grinding process of step S4 is: placing the first grinding sample on the middle circle of the second sandpaper, and making the scratches after the first sandpaper grinding perpendicular to the movement direction of the second sandpaper, applying the second grinding pressure to the first grinding sample, starting the grinder for grinding and adding water in small amounts multiple times during the grinding process, and repeating this step until the scratches after the second sandpaper grinding are fine and uniform and the first grinding sample has no obvious cross section to form a second grinding sample.

4. The method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts according to claim 1, characterized in that: The specific polishing process in step S6 is: placing the secondary ground sample on the polishing middle circle of the polishing cloth, so that the cemented carbide of the secondary ground sample is close to the inner edge of the polishing middle circle and the scratches after the second sandpaper is polished are perpendicular to the movement direction of the polishing cloth, applying polishing pressure to the secondary ground sample, starting the polishing machine and continuously adding a small amount of water during the polishing process, and repeating this step until there are basically no scratches to form a final polished sample.

5. The method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts according to claim 1, characterized in that: The particle sizes of the first sandpaper and the second sandpaper are both 1000#, the polishing cloth is red flannel, and the amounts of W40 water-soluble diamond powder grinding paste and W2.5 water-soluble diamond powder grinding paste correspond to the wire cutting sizes of the prepared sample and the secondary grinding sample, respectively.

6. The method for rapidly preparing the metallographic structure of cemented carbide and steel brazing parts according to claim 1, characterized in that: In step S3, the speed of the grinder is set to 800 r / min, the first grinding pressure is 30 N, and the grinding time is 5 min. In step S4, the speed of the grinder is set to 1000 r / min, the second grinding pressure is 20 N, and the grinding time is 3 min. The speed of the polisher is set to 800 r / min, the polishing pressure is 20 N, and the polishing time is 2 min.

Images