Metallurgical defect-free high-temperature wear-resistant cobalt-based alloy coating as well as preparation method and application thereof

Abstract

The invention discloses a metallurgical-defect-free high-temperature wear-resistant cobalt-based alloy coating and a preparation method and application thereof.The preparation method comprises the following steps that (1) Fe powder, Co powder, Cr powder, Ti powder, Mo powder and Ni powder are accurately weighed according to the stoichiometric equation Co57Fe5Ni5Cr25Ti5Mo3, and (2) the weighed powder is put into a ball milling tank to be subjected to ball milling, so that the powder is evenly mixed, and then drying, sieving and drying storage are conducted; (3) 5NiCrMo hot work die steel is selected as a base material, a sand mill is used for polishing the surface of the base material so as to remove surface oxide skin until a bright surface is exposed, and oil stains on the surface are removed; and (4) a laser directional energy deposition method in laser additive manufacturing is used for continuously depositing the crack-free cobalt-based alloy coating with high temperature resistance, wear resistance and no cracks one by one. The high-temperature wear-resistant alloy shows excellent wear resistance at a high temperature, the alloy has a shallower wear depth and a narrower grinding crack width at the high temperature, and the wear rate at the high temperature of 800 DEG C is reduced from 2.171 * 10 <-4 > mm < 3 > / N.m of a 5CrNiMo base material to 2.45 * 10 < 6 > mm < 3 > / N.m of a coating.

Description

Technical Field

[0001] This invention relates to the field of cobalt-based alloy technology, specifically to a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects, its preparation method, and its application. Background Technology

[0002] Forging is a core process in modern manufacturing, holding an irreplaceable position in aerospace, automotive manufacturing, and energy equipment. Punching, a crucial step in the forging process, involves the punch enduring impact stress on its working surface at gigapascal levels during service. Simultaneously, it experiences instantaneous temperature rises, exceeding 700°C, due to contact with the high-temperature billet. In this thermo-mechanical multi-field coupled environment, the punch surface suffers combined adhesive and oxidative wear damage. Under high temperature and contact stress, the material surface layer locally adheres and tears, while the high-temperature oxidation process intensifies. The surface oxide film continuously cracks and peels off under cyclic loading, resulting in continuous material loss. This wear-oxidation synergistic damage mechanism not only leads to dimensional deviations in the punch but also makes its surface defects a source of fatigue crack initiation, accelerating punch failure. To extend the service life of the punch, applying a reinforcing coating to its surface is an economical and effective method. Iron-based alloys are widely used in routine repairs due to their good economic efficiency and matrix compatibility, but they have poor oxidation resistance. Nickel-based alloys have good toughness, impact resistance, heat resistance, oxidation resistance and high corrosion resistance, but their high-temperature performance is poor.

[0003] Laser Additive Manufacturing (LAM), using high-energy lasers as a heat source, overcomes the limitations of traditional manufacturing technologies through layer-by-layer deposition, demonstrating significant technological advantages. Its high degree of design freedom supports the direct forming of complex geometries, such as lightweight cavities, biomimetic topologies, or functionally integrated components, enabling innovative designs in aerospace, biomedical, and other fields. Simultaneously, material utilization rates exceed 90%, significantly reducing waste of expensive metal raw materials. Combined with short-cycle, moldless, and flexible production characteristics, it effectively shortens R&D cycles and reduces the cost of small-batch customization. Leveraging the high energy density of lasers, this technology can precisely melt difficult-to-machine materials such as titanium alloys and nickel-based superalloys, achieving microstructural densification and mechanical property optimization. It also possesses composite manufacturing potential, enabling damage repair and surface strengthening of critical components while reducing cutting fluid usage and waste emissions, aligning with green and sustainable development principles. It is becoming a core driving force for the transformation of high-end manufacturing towards personalization and high performance in the Industry 4.0 era. Currently, there is considerable research on the mechanical properties of laser additive manufacturing alloys, but less research on their friction and wear properties at high temperatures. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the first objective of this invention is to provide a method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects, the second objective is to provide the high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects prepared therefrom, and the third objective is to provide its application.

[0005] To achieve the first objective mentioned above, the present invention provides the following technical solution: a method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects, characterized by preparation according to the following steps:

[0006] (1) According to the stoichiometric formula Co 57 Fe5Ni5Cr 25 Accurately weigh out Fe, Co, Cr, Ti, Mo, and Ni powders respectively for Ti5Mo3.

[0007] (2) Place the weighed powder into a ball mill jar for ball milling to make the powder mix evenly, then dry, sieve, and store in a dry place;

[0008] (3) Select 5NiCrMo hot work die steel as the base material, use a sand mill to grind the surface of the base material to remove the surface oxide scale until a bright surface is exposed, and remove the surface oil.

[0009] (4) Using the laser directional energy deposition method in laser additive manufacturing, dry powder is placed in the powder feeding tank of the laser system, and high-purity Ar gas is used to send the powder to the circular spot laser head for melting and deposition, and a crack-free, high-temperature wear-resistant, crack-free cobalt-based alloy coating is continuously deposited.

[0010] In the above scheme: in step (1), the particle size of Fe, Co, Cr, Ti, Mo and Ni powder is 45-105μm, and the purity is ≥99.5%.

[0011] In the above scheme: In step (2), the ball milling parameters are: ball-to-material ratio of 4:1, ball milling speed of 260 rpm / min, forward rotation for 1 hour, reverse rotation for 1 hour, with an interval of 5 minutes in between; and sieving through a 100-200 mesh sieve.

[0012] In the above scheme: In step (3), the oil stains on the surface of 5NiCrMo steel are cleaned with alcohol and then air-dried.

[0013] In the above scheme: the laser model is RC-LMS-6000-R fiber laser, the laser power P is 1000-1700W, the scanning rate v is 10mm / s, the circular spot diameter is 3mm, the defocusing amount is 35mm, and the powder filling speed is 2r / min.

[0014] In the above scheme, the laser power is 1500-1700W.

[0015] A method for preparing a high-temperature wear-resistant cobalt-based alloy coating free of metallurgical defects, as described above, yields a high-temperature wear-resistant cobalt-based alloy coating free of metallurgical defects.

[0016] In the above scheme, the coating thickness is 1-2mm.

[0017] The application of the aforementioned metallurgically defect-free, high-temperature wear-resistant cobalt-based alloy coating in the manufacture of forging punches.

[0018] Beneficial effects:

[0019] This invention employs laser-directed energy deposition (LDED) technology for laser remanufacturing to prepare Co without metallurgical defects (such as pores and cracks). 57 Fe5Ni5Cr 25 Ti5Mo3 cobalt-based alloy coating. The addition of Ti primarily enhances the coating's hardness and wear resistance by forming a hard ceramic phase within the coating. Mo, on the other hand, effectively strengthens the overall mechanical properties of the substrate through solid solution strengthening, grain refinement, and the promotion of new phase formation. The synergistic effect of these two elements significantly optimizes the overall performance of the coating. Furthermore, the fine grain structure of the coating and the dense Cr2O3 oxide film formed on its surface at high temperatures jointly ensure excellent high-temperature wear resistance in components such as punches. This invention uses laser-directed energy deposition technology to prepare alloy samples, eliminating the need for subsequent heat treatment, resulting in excellent wear and impact resistance in the deposited alloy at high temperatures. The alloy prepared by this invention exhibits shallower wear depth and narrower wear track width at high temperatures, with the wear rate at 800℃ decreasing from 2.171 × 10⁻⁶ for the 5CrNiMo substrate. -4 mm 3 / N·m decreased to 2.45×10⁻⁶ for the coating. -6 mm 3 / N·m. Attached Figure Description

[0020] Figure 1. Co 57 Fe5Ni5Cr 25 Microstructure of Ti5Mo3 coating under different processes.

[0021] Figure 2 Co at different power levels at a scan speed of 0.01 m / s 57 Fe5Ni5Cr 25 Microhardness of Ti5Mo3 coating.

[0022] Figure 3 Co under different processes 57 Fe5Ni5Cr 25 Macroscopic morphology and microscopic wear marks of Ti5Mo3 coating under high temperature friction and wear.

[0023] Figure 4. Co under different processes 57 Fe5Ni5Cr 25 Volumetric wear rate diagram of Ti5Mo3 coating and substrate. Detailed Implementation

[0024] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0025] Example 1

[0026] (1) Powder selection: The selected Fe, Co, Cr, Ti, Mo, and Ni powder alloys are spherical with a size of 45-105 μm and a purity of ≥ 99.5%. According to the stoichiometric formula Co... 57 Fe5Ni5Cr 25 Ti5Mo3 was weighed using an FA224 electronic balance with an accuracy of 0.0001g.

[0027] (2) Powder ball milling: The prepared powder is placed in a stainless steel ball mill jar and ball milled in a planetary ball mill. The ball milling parameters are: ball-to-powder ratio of 4:1, ball milling speed of 260 rpm / min, ball milling for 1 hour in the forward direction and 1 hour in the reverse direction, with a 5-minute pause between the forward and reverse directions to ensure that the powder is fully mixed and uniform. After ball milling, the powder is passed through a 100-200 mesh stainless steel sieve and then placed in a vacuum drying oven at 60℃ for drying and later use.

[0028] (3) Substrate selection: 5CrNiMo hot work die steel with a diameter of 100mm and a thickness of 10mm was selected as the substrate. The oxide scale on the surface of the substrate was removed using a grinding wheel to prevent pores from forming at the bottom of the sample during the deposition process. The surface oil was cleaned with alcohol and dried with a hair dryer for later use.

[0029] (4) Sample preparation: Laser-directed energy deposition (LDED) was used in laser additive manufacturing. The laser model was RC-LMS-6000-R fiber laser. The dried powder was placed in the powder feeding tank of the laser powder feeding system. High-purity argon gas with a purity of 99.999% was used to transport the powder raw material to the substrate. At the same time, the laser beam was focused to form a small molten pool. A 1-2 mm thick coating was gradually deposited on the substrate through an S-shaped path cladding strategy. The laser-directed energy deposition process parameters were set as follows: laser power P = 1000W, 1200W, 1400W, 1500W, 1600W, 1700W, scanning rate v = 10 mm / s, circular spot diameter 3 mm, defocusing amount 35 mm, and powder filling speed 2 r / min.

[0030] (5) High-temperature wear test: Co with no metallurgical defects was clad... 57 Fe5Ni5Cr25 Ti5Mo3 cobalt-based alloy samples were prepared into 20mm×10mm×2mm friction and wear specimens using wire cutting. The experiments were conducted using an HT-1000 high-temperature friction and wear testing machine. The temperature was raised to 800℃ in a heating furnace for the friction and wear test, with a load of 1000N and a rotation speed of 1000rpm. The friction and wear performance of the laser-clad cobalt-based alloy coating at 800℃ was studied.

[0031] like Figure 1 Co is given 57 Fe5Ni5Cr 25 Microstructures of Ti5Mo3 coatings under different processes: (a) 1000W & 0.01 m / s, (b) 1200W & 0.01 m / s, (c) 1400W & 0.01 m / s, (d) 1600W & 0.01 m / s, (e) 1500W & 0.01 m / s, (f) 1700W & 0.01 m / s. As shown in the figure, the coating microstructure consists of cellular crystals, dendrites, and intergranular carbides, with no cracks and extremely low porosity. All samples were processed using a double-layer cladding process, indicating good controllability of coating thickness and the absence of metallurgical defects. Further observation revealed that the first three samples had poor microstructure uniformity, while the latter three samples showed more uniform microstructure distribution.

[0032] Figure 2 Co at different powers at a scanning speed of 0.01 m / s 57 Fe5Ni5Cr 25 The microhardness of the Ti5Mo3 coating was measured. As shown in the figure, the microhardness values ​​of the coatings prepared under different process parameters were generally close to those of the substrate material, indicating good mechanical compatibility between the two. The hardness of the latter three groups of samples remained stable at 520 HV. 0.2 Approximately; under process conditions of 1500W & 0.01m / s, the coating hardness reaches its maximum value of 527.29HV. 0.2 The small hardness difference between the coating and the substrate helps to avoid interfacial delamination or premature failure caused by stress abrupt changes under extreme service conditions of high temperature and high impact (such as punching punch conditions). Meanwhile, the coating itself has a high hardness (>520 HV). 0.2 It provides it with the necessary high-temperature wear resistance and resistance to plastic deformation.

[0033] Figure 3 Co under different processes 57 Fe5Ni5Cr 25Macroscopic morphology and microscopic wear track images of Ti5Mo3 coatings under high-temperature friction and wear. As shown in the figure, under experimental conditions of 1000 N load, 1000 rpm rotation speed, and 800 ℃ high temperature, the wear morphology of coatings prepared by different processes showed significant differences. Macroscopic wear morphology showed that the wear tracks corresponding to the first three process parameters (1000W & 0.01m / s, 1200W & 0.01m / s, 1400W & 0.01m / s) were deeper and irregular in morphology; in contrast, the wear tracks of the latter three processes (1500W & 0.01m / s, 1600W & 0.01m / s, 1700W & 0.01m / s) were shallower and more regular. Further measurements of the wear track width yielded the following results (unit: μm): 1000W & 0.01m / s: 1392.85, 1200W & 0.01m / s: 1456.65, 1400W & 0.01m / s: 1442.92, 1500W & 0.01m / s: 1070.07, 1600W & 0.01m / s: 1066.63, 1700W & 0.01m / s: 812.89. Among these, the coating with the 1700W & 0.01m / s process exhibited the smallest wear track width, at only 812.89 μm, demonstrating the best wear resistance.

[0034] Figure 4 Co under different processes 57 Fe5Ni5Cr 25 Comparison of volumetric wear rates between Ti5Mo3 coating and substrate. Based on the volumetric wear rate calculation formula:

[0035]

[0036] Among them, V loss This represents the volume loss due to wear, where F is the load value and L represents the sliding distance (i.e., the product of rotational speed, sliding time, and wear track circumference).

[0037] As shown in the figure, by analyzing Co 57 Fe5Ni5Cr 25 A comparative analysis of the volumetric wear rate of the Ti5Mo3 coating (group af) and the substrate showed that all coatings significantly improved the wear resistance of the materials. The overall volumetric wear rate of the coatings was in the low range (2.40 × 10⁻⁶). -6 ~ 5.00×10 -6 mm³ / N·m), where the values ​​for groups a, b, and c are similar (approximately 5.00 × 10⁻⁶). -6 Groups d and e are in the middle (approximately 3.40 × 10⁻⁶). -6 Group f had the lowest wear rate, at only 2.45 × 10⁻⁶. -6 mm3 / N·m. In comparison, the wear rate of the substrate reached 2.171×10⁻⁶. -4 mm 3 The wear resistance of the coating group is more than 88 times that of the group f coating, indicating that the Co-based coating can effectively reduce wear. In different processes, the group f coating (i.e., 1700W & 0.01m / s) exhibits the best wear resistance.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects, characterized in that, Prepare according to the following steps: (1) According to the stoichiometric formula Co 57 Fe5Ni5Cr 25 Accurately weigh out Fe, Co, Cr, Ti, Mo, and Ni powders respectively for Ti5Mo3. (2) Place the weighed powder into a ball mill jar for ball milling to make the powder mix evenly, then dry, sieve, and store in a dry place; (3) Select 5NiCrMo hot work die steel as the base material, use a sand mill to grind the surface of the base material to remove the surface oxide scale until the bright surface is exposed, and remove the surface oil. (4) Using the laser directional energy deposition method in laser additive manufacturing, dry powder is placed in the powder feeding tank of the laser system, and high-purity Ar gas is used to send the powder to the circular spot laser head for melting and deposition, and a crack-free, high-temperature wear-resistant, crack-free cobalt-based alloy coating is continuously deposited.

2. The method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects according to claim 1, characterized in that: In step (1), the Fe, Co, Cr, Ti, Mo and Ni powders have a particle size of 45-105 μm and a purity of ≥ 99.5%.

3. The method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects according to claim 2, characterized in that: In step (2), the ball milling parameters are: ball-to-material ratio of 4:1, ball milling speed of 260 rpm / min, forward rotation for 1 hour, reverse rotation for 1 hour, with a 5-minute interval in between; and sieving through a 100-200 mesh sieve.

4. The method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects according to claim 3, characterized in that: In step (3), the oil stains on the surface of 5NiCrMo steel are cleaned with alcohol and then air-dried.

5. The method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects according to claim 4, characterized in that: The laser model is RC-LMS-6000-R fiber laser, with a laser power P of 1000-1700W, a scanning rate v of 10mm / s, a circular spot diameter of 3mm, a defocusing amount of 35mm, and a powder filling speed of 2r / min.

6. The method for preparing a high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects according to claim 5, characterized in that: The laser power is 1500-1700W.

7. A high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects prepared by the method of any one of claims 1-6.

8. The high-temperature wear-resistant cobalt-based alloy coating without metallurgical defects according to claim 7, characterized in that: The coating thickness is 1-2mm.

9. The application of the metallurgically defect-free, high-temperature wear-resistant cobalt-based alloy coating of claim 7 in the manufacture of forging punches.

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