(Ti, W) C reinforced Ni-based remelting coating and in-situ generation method and application thereof

Abstract

The invention provides a preparation method for in-situ generation of a (Ti, W) C strengthened Ni-based remelting coating, and belongs to the technical field of metal surface strengthening. The method comprises the following steps: mixing Ni60 powder, W powder, C powder and Ti powder in proportion; under the protection of argon, the mixed powder is subjected to synchronous laser cladding on the surface of the pretreated H13 hot work die steel, and a cladding layer is formed; and after powder feeding is stopped, the cladding layer is subjected to laser remelting according to the original path under the same protective atmosphere. Through a two-step process of optimizing component design and combining cladding with remelting, a cladding layer structure is remarkably refined and compact, a hard phase is uniformly distributed, the cracking tendency is effectively reduced, the microhardness is improved by 5.8% compared with that of a single cladding layer, and the average friction coefficient is reduced to 0.33. The method is controllable in process and suitable for preparation of the high-performance wear-resistant cladding layer.

Description

Technical Field

[0001] This invention relates to surface strengthening technology for metallic materials, and more particularly to a (Ti,W)C-reinforced Ni-based remelted coating, its in-situ generation method, and its application. Background Technology

[0002] H13 hot work die steel is widely used in aerospace engines, automotive manufacturing, and industrial chemicals due to its excellent wear resistance and corrosion resistance. However, the harsh service conditions of hot work dies, such as high-intensity thermal fatigue and mechanical fatigue, can cause defects such as pitting and thermal fatigue cracking on their surfaces, severely limiting their service life and leading to overall part failure. Applying a high-performance alloy coating to the surface can modify the metal's surface properties to extend its service life, or perform localized repair and strengthening of failed parts. In the field of mechanical engineering materials, nickel-based alloys exhibit excellent wear resistance and corrosion resistance even at high temperatures, integrating good oxidation resistance, wettability, corrosion resistance, and tribological properties, making them a preferred material for laser surface modification. Laser cladding technology can be used to prepare Ni-based coatings on the die surface for repair and strengthening.

[0003] However, with the continuous development of manufacturing technology, the requirements for the comprehensive performance of component surfaces are becoming increasingly stringent. Single nickel-based alloy coatings have limited performance under harsh conditions. Ceramic reinforcing phase particles can be added to nickel-based powders. By leveraging the complementary properties of the high hardness and wear resistance of the ceramic phase with the toughness of the metallic phase, the overall performance of the coating can be significantly improved, including key indicators such as hardness, wear resistance, and fatigue resistance. Currently, WC and TiC are commonly used. However, TiC has a lower density and tends to float on top of the coating, while WC has a higher density and mostly sinks to the bottom. Both distributions result in uneven coating performance, hindering its widespread application.

[0004] Solid solutions of WC and TiC possess the same crystal structure as TiC, inheriting not only the stable crystal structure of TiC but also integrating the advantages of both ceramic phases through compositional control. Their overall performance, including hardness, wear resistance, and chemical stability, surpasses that of WC or TiC alone. However, analysis of the coating's microstructure reveals an uneven distribution of the generated (Ti,W)C hard phase particles. Furthermore, the TiC generated during the cladding process has a lower density than WC, leading to delamination when preparing thicker cladding layers. This results in significant differences in microstructure across different regions of the coating, increasing the probability of crack formation. Therefore, exploring new processes and methods to improve the microstructure and morphological defects in (Ti,W)C / Ni cladding layers is crucial. Summary of the Invention

[0005] The purpose of this invention is to address the problems of uneven distribution of WC and TiC hard phase particles, delamination during the preparation of thick cladding layers, and significant differences in microstructure in different regions of the coating. This invention proposes a method for preparing an in-situ (Ti,W)C-reinforced Ni-based remelted coating. This method optimizes the composition of the cladding powder and combines laser cladding and continuous laser remelting processes to obtain a cladding layer with a fine microstructure and no obvious elemental segregation.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing an in-situ generated (Ti,W)C reinforced Ni-based remelted coating, comprising the following steps:

[0007] Step 1: Mix Ni60 powder, W powder, C powder and Ti powder to obtain cladding layer powder;

[0008] Step 2: Use pretreated H13 hot work die steel as the base material;

[0009] Step 3: Under argon protection, the cladding powder is fed to the substrate surface through the cladding head using a powder feeder. Simultaneously, a laser is used for synchronous laser cladding to form the cladding layer.

[0010] Step 4: Stop powder feeding, maintain argon protection conditions, and use a laser to scan and remelt the cladding layer along the original cladding path.

[0011] Furthermore, the chemical composition of the Ni60 powder is shown in Table 1.

[0012] Table 1 Chemical composition (wt%) of Ni60 powder

[0013]

[0014] Further, the molar ratio of W powder, C powder and Ti powder in step 1 is 1-1.25:1-1.25:0.75-1, preferably 1:1:1, and the Ni60 accounts for 70-90% of the total mass of the cladding layer powder, preferably 80%.

[0015] Furthermore, the purity of the Ni60 powder, W powder, C powder, and Ti powder is 99%.

[0016] Furthermore, the particle size of the Ni60 powder, W powder, C powder and Ti powder is 10-200 μm, preferably 56-75 μm.

[0017] Furthermore, the powder feeding rate of the cladding layer powder in step 3 is 8-10 g / min, preferably 9.8 g / min.

[0018] Furthermore, the argon gas purity in step 3 is ≥99.9%.

[0019] Furthermore, the pretreatment described in step 3 includes polishing to remove stains and oxide layers, and then wiping the substrate surface with anhydrous ethanol.

[0020] Furthermore, in step 3, powder is conveyed through a cladding head and laser cladding is performed. An argon gas nozzle is installed inside the cladding head.

[0021] Furthermore, in step 3, when the cladding head is working, its axis forms an angle of 75-90° with the surface of the substrate, preferably 90°.

[0022] Furthermore, the cladding path in step 3 can take various forms, such as an arc shape (multiple parallel straight lines) or a zigzag path.

[0023] Furthermore, in step 3, the laser power of the laser cladding is 1100W-1500W, the scanning speed is 0.5-2mm / s, the spot diameter is 1-3mm, and the powder feeding voltage is 6V-10V.

[0024] Furthermore, the argon gas purity in step 4 is ≥99.9%.

[0025] Furthermore, the laser power in the remelting process described in step 3 is 800W-1300W, and the scanning speed is 0.5-2mm / s. The laser power in the remelting process is lower than that in the initial cladding to reduce the laser energy density.

[0026] Furthermore, the number of remelting cycles is 1-3.

[0027] Another objective of this invention is to disclose a (Ti,W)C reinforced Ni-based remelted coating, which is prepared using the method described above.

[0028] Furthermore, the microhardness of the (Ti,W)C reinforced Ni-based remelted coating is 800-950 HV. 0.5 The coefficient of friction is 0.3-0.35. The preferred microhardness is 931.36-950 HV. 0.5 The preferred friction coefficient is 0.3-0.33.

[0029] Furthermore, the (Ti,W)C reinforced Ni-based remelted coating has no obvious pores or cracks, the coating and the substrate are well bonded, and the dilution rate is around 10%.

[0030] Another objective of this invention is to disclose the application of a (Ti,W)C reinforced Ni-based remelted coating in the fields of aerospace engines and automobiles.

[0031] Another object of the present invention discloses a steel, including H13 hot work die steel, and a (Ti,W)C reinforced Ni-based remelted coating on its surface.

[0032] The (Ti,W)C reinforced Ni-based remelted coating, its in-situ generation method, and its application, compared with the prior art, have the following advantages:

[0033] 1) This invention effectively refines the internal structure of the (Ti,W)C-reinforced Ni-based remelted coating through laser remelting, making its surface smoother and more even. At the same time, the internal structure is significantly refined and denser, effectively reducing the probability of crack formation.

[0034] 2) The (Ti,W)C reinforced Ni-based remelted coating of the present invention exhibits excellent microhardness. For example, the microhardness of a single (Ti,W)C / Ni laser cladding layer is 880 HV. 0.5 After remelting, the microhardness of the cladding layer significantly increased to 931.36 HV. 0.5 Compared to a single laser cladding layer, the microhardness is increased by 5.8%.

[0035] 3) The (Ti,W)C reinforced Ni-based remelted coating of the present invention has excellent wear resistance and low friction coefficient. For example, the average friction coefficient of a single (Ti,W)C / Ni laser cladding layer is 0.47, while the average friction coefficient of the (Ti,W)C / Ni coating after remelting is reduced to 0.33. Moreover, in the wear test, it only shows slight abrasive wear and adhesive wear, without obvious peeling or grooves.

[0036] 4) The preparation method described in this invention can also be used for the preparation of WC / Ni-based cladding layers. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the laser cladding process;

[0038] Figure 2 This is a schematic diagram of the laser remelting process;

[0039] Figure 3 This is a schematic diagram of the scanning path during the laser remelting process. Detailed Implementation

[0040] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0041] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0042] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0043] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0044] Example

[0045] This embodiment discloses a method for preparing an in-situ (Ti,W)C reinforced Ni-based remelted coating, such as... Figure 1-3 As shown, it includes the following steps:

[0046] like Figure 1 As shown, a piece of H13 hot work die steel with a diameter of 50mm×40mm×8mm was used as the experimental substrate. The substrate was repeatedly sanded with 500-grit, 600-grit and 800-grit sandpaper to remove rust and oxide layer. After that, the surface of the substrate was wiped with anhydrous ethanol and then dried with a hair dryer for later use.

[0047] Ni60 powder, W powder, C powder and Ti powder are mixed in a certain proportion to obtain cladding powder. The molar ratio of W powder, C powder and Ti powder is 1:1:1. Ni60 accounts for 80% of the total mass of the mixed powder. The prepared cladding powder and grinding balls are added to a planetary ball mill at a mass ratio of 1:2. After mixing and grinding at a speed of 120 r / min for 2 hours, the ground mixed powder is added to the powder feeder.

[0048] The laser cladding equipment uses a German 6-axis KUKA robotic arm equipped with a PERCITECYC52 powder feeder, and is equipped with an FHPF-10 synchronous powder feeder manufactured by Beijing Feihong Laser and a YLR-3000 fiber laser manufactured by IPG of Germany. The cladding head is equipped with a protective gas nozzle with a diameter of 8mm.

[0049] The process parameters for laser cladding were set as follows: laser power 1500W, scanning speed 1.5mm / s, spot diameter 1mm, powder feed rate 9.8g / min, and the angle between the cladding head axis and the substrate surface 90°. The cladding head continuously fed powder and performed laser cladding. After the laser contacted the powder and the substrate surface, a molten pool was formed. After solidification, a cladding layer was formed on the substrate. The powder feeding path was parallel to one of the edges of the substrate surface. After scanning one path, the next adjacent path was immediately scanned in the opposite direction to the previous path. To prevent the mixed powder from contacting oxygen and causing oxidation of the molten pool, the protective gas nozzle continuously supplied 99.9% pure argon gas to the molten pool as a protective gas during the laser cladding process, with a gas flow rate of 15L / min.

[0050] like Figure 2 and Figure 3 As shown, after the laser cladding is completed, the powder feeding is stopped, the laser power is set to 1300W, the scanning speed is set to 1mm / s, and the cladding layer formed in the previous step is scanned and remelted according to the original cladding path.

[0051] The remelted coating has a smooth surface, fine structure, and no obvious elemental segregation. The microhardness of the remelted coating reaches 931.36 HV. 0.5 The microhardness value was increased by 5.82% compared to a single laser cladding layer. The average coefficient of friction of the remelted coating was 0.33, and the worn surface showed only slight abrasive wear and adhesive wear, with no obvious peeling, oxidation, grooves, or other wear phenomena.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coatings, characterized in that, Includes the following steps: Step 1: Mix Ni60 powder, W powder, C powder and Ti powder to obtain cladding layer powder; Step 2: Use pretreated H13 hot work die steel as the base material; Step 3: Under argon protection, the cladding powder is fed to the substrate surface through the cladding head using a powder feeder. Simultaneously, a laser is used for synchronous laser cladding to form the cladding layer. Step 4: Stop powder feeding, maintain argon protection conditions, and use a laser to scan and remelt the cladding layer along the original cladding path.

2. The method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coating according to claim 1, characterized in that, The molar ratio of W powder, C powder and Ti powder in step 1 is 1-1.25:1-1.25:0.75-1, and the Ni60 powder accounts for 70-90% of the total mass of the cladding layer powder.

3. The method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coating according to claim 1, characterized in that, The pretreatment described in step 3 includes sanding to remove stains and oxide layers, and then wiping the substrate surface with anhydrous ethanol.

4. The method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coating according to claim 1, characterized in that, The argon gas purity mentioned in steps 3 and 4 is ≥99.9%.

5. The method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coating according to claim 1, characterized in that, In step 3, when the cladding head is working, its axis forms an angle of 75-90° with the surface of the substrate.

6. The method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coating according to claim 1, characterized in that, The laser power in the cladding process described in step 3 is 1100W-1500W, the scanning speed is 0.5-2mm / s, the spot diameter is 1-3mm, and the powder feeding voltage is 6V-10V.

7. The method for in-situ generation of (Ti,W)C reinforced Ni-based remelted coating according to claim 1, characterized in that, The laser power for the remelting process described in step 4 is 800W-1300W, and the scanning speed is 0.5-2mm / s.

8. A (Ti,W)C reinforced Ni-based remelted coating, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The application of the (Ti,W)C reinforced Ni-based remelted coating of claim 8 in the fields of aerospace engines and automobiles.

10. A type of steel, characterized in that, Including H13 hot work die steel, and the (Ti,W)C reinforced Ni-based remelted coating on its surface as described in claim 8.

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