Methods for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel
By spraying a high-temperature resistant insulating coating onto the surface of YG8 tungsten carbide rods and adding boron to molten high-manganese steel to form a barrier layer, combined with precise temperature control casting and pre-alloying modification, the problems of cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel were solved, achieving a composite material with high bonding strength and high performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 杜炜
- Filing Date
- 2026-05-27
- Publication Date
- 2026-07-31
AI Technical Summary
Existing technologies are insufficient to effectively address the issues of poor bonding and performance degradation of YG8 tungsten carbide rods in molten high-manganese steel due to cobalt segregation, embrittlement, and pulverization, especially at high temperatures where failure is likely to occur.
A high-temperature resistant insulating coating is sprayed onto the surface of YG8 tungsten carbide rods, and boron is added to high-manganese steel melt to form a dense Fe-B barrier layer. Combined with precise temperature control casting, the melting point of the cobalt phase is increased through pre-alloying modification, and a stable interface transition layer is generated on the surface of YG8 to suppress the formation of brittle phases.
It achieves high bonding strength between YG8 tungsten carbide rods and high manganese steel, avoids cobalt segregation and embrittlement, maintains high hardness and bending strength, and is suitable for high-temperature environments without failure.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of mining machinery technology, and relates to the field of wear-resistant metal material preparation technology, specifically to an integral composite casting process of tungsten carbide hard alloy rod and high manganese steel. Background Technology
[0002] High manganese steel inherently possesses properties such as high strength, good plasticity, good low-temperature toughness, work hardening properties, and good impact resistance. As a wear-resistant material, its resistance to abrasive or gouging wear under strong impact and high pressure is unparalleled by other materials under high impact stress conditions. Wear-resistant products for mining machinery, such as liners, hammers, screen bars, and jaw plates, made of high manganese steel, are widely used in machinery and equipment in metallurgy, mining, building materials, railways, power, and coal industries.
[0003] However, the wear resistance of high-manganese steel is limited. Its high wear resistance is only realized under conditions of high impact, high stress, and hard abrasive. Under significant impact, the austenitic surface layer of high-manganese steel deforms into martensite, rapidly increasing the surface hardness from HB180-220 to HB500-550, thus achieving high wear resistance. However, under low-impact or no-impact conditions, the work hardening effect of high-manganese steel is not significant, resulting in lower surface hardness and poor wear resistance. Furthermore, due to its low yield strength and poor shear resistance, high-manganese steel is prone to deformation and shear failure during initial use, leading to significant wear. To overcome these limitations, a process for preparing tungsten carbide-reinforced high-manganese steel-based composite materials has been developed.
[0004] Due to its high hardness and wear resistance, YG8 cemented carbide (WC8Co) can be used as a core component embedded in a high-manganese steel matrix through composite casting to manufacture various wear-resistant parts for mining machinery. In composite casting, the YG8 core component must withstand immersion in molten high-manganese steel at 1400℃ for 30 minutes. Conventional YG8 is prone to the following three major failure defects: A. Cobalt segregation and loss: At temperatures above 1200℃, cobalt, as a binder phase, is in a viscous flow state and will migrate along the gaps in the WC lattice framework, resulting in melting and loss, causing the WC framework to lose adhesion and pulverize. B. Interface embrittlement: C and Mn in high manganese steel react with WC to form various brittle phases such as WC2 and M7C3, which causes a sharp drop in bending strength. C. Continuous wetting of high-manganese steel liquid will accelerate the disintegration of the crystal lattice framework structure.
[0005] For example, Chinese patent application CN101705413A, entitled "Preparation Process of Tungsten Carbide Reinforced High Manganese Steel Matrix Composite Material," discloses a preparation process for tungsten carbide reinforced high manganese steel matrix composite material. This process mainly includes the following steps: weaving tungsten wire into a tungsten wire mesh, cutting, multi-layering, or stacking it to form a mesh-like three-dimensional skeleton structure; preparing a mold according to casting process requirements, and pre-placing the tungsten wire mesh skeleton in the mold cavity; smelting high manganese steel and pouring it into the mold, then cooling and cleaning to obtain a tungsten wire-high manganese steel binary material preform; placing the tungsten wire-high manganese steel binary material preform into a heat treatment furnace, heating it to the carbide formation temperature, and holding it at that temperature to obtain a tungsten carbide particle-reinforced high manganese steel matrix composite material. The composite material prepared by this method fully utilizes the high wear resistance of the tungsten carbide hard phase and the good toughness of high manganese steel. It is easy to control, the process is reliable, and it solves problems such as incomplete reaction of the composite material, uneven distribution of reinforcing phase particles, and weakening of the reinforcing phase interface due to contamination.
[0006] The preparation process of tungsten carbide reinforced high-manganese steel matrix composites using this technology only employs conventional binary material composites and conventional heat treatment. Such conventional processes cannot simultaneously and effectively solve the three core problems of isolating the tungsten carbide core embedded in the high-manganese steel matrix, suppressing segregation, and stabilizing the interface. It has defects such as relatively high production costs, insufficient bonding between tungsten carbide and high-manganese steel matrix, difficulty in mass production, and significant performance degradation. The application effect is not ideal. Summary of the Invention
[0007] To overcome the shortcomings of the prior art, the present invention provides a method for resisting cobalt segregation, embrittlement and pulverization of YG8 tungsten carbide rods in high manganese steel melt, which can effectively overcome the three major failure defects.
[0008] The technical solution adopted by the present invention to achieve the above-mentioned technical objectives is: a method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in high-manganese steel liquid, comprising the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.05wt%~0.1wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1380~1390℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 10~15min.
[0009] The YG8 tungsten carbide rod is pre-alloyed before forming; 0.5wt%~1wt% of Cr or Ta is added to the preform, and Cr / Ta forms Co-Cr / Co-Ta intermetallic compound with Co, raising the high-temperature melting point of the cobalt phase to above 1550℃; ultrafine WC is used, and a pre-oxidation treatment at 500℃ for 1 hour is performed. The pre-oxidation treatment generates a WCxOy oxide film on the YG8 surface, forming a stable interface transition layer.
[0010] The high-temperature insulating coating is an Al2O3-ZrO2 composite ceramic coating or a NiCrAlY-WC cermet coating; the volume ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite ceramic coating is 7:3; when the coating is prepared by plasma spraying, the coating thickness is 50~80μm; when the coating is prepared by sol-gel method, the coating thickness is 20~30μm; the coating is dried at 200℃ for 2h, and the inspection ensures that there are no pinholes or cracks and that it covers the entire surface.
[0011] By employing the above technical solutions, this invention effectively overcomes three major failure defects compared to traditional technologies. The treated YG8 achieves the following performance indicators: hardness HRA≥89, bending strength≥1400MPa, interfacial bonding strength with high manganese steel≥200MPa, and no cobalt segregation, no embrittlement, and no pulverization. The application effect is more ideal.
[0012] The present invention will be further described below through specific embodiments. Detailed Implementation
[0013] Example 1, a method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel, includes the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.05 wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1380℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 10 minutes.
[0014] The YG8 tungsten carbide rod is pre-alloyed before forming; 0.5wt% of Cr or Ta is added to the preform, and Cr / Ta forms Co-Cr / Co-Ta intermetallic compound with Co, raising the high-temperature melting point of the cobalt phase to above 1550℃; ultrafine WC is used, and a pre-oxidation treatment at 500℃ for 1 hour is performed. The pre-oxidation treatment generates a WCxOy oxide film on the YG8 surface, forming a stable interface transition layer.
[0015] The high-temperature insulating coating is an Al2O3-ZrO2 composite ceramic coating or a NiCrAlY-WC cermet coating; the volume ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite ceramic coating is 7:3; when the coating is prepared by plasma spraying, the coating thickness is 50 μm; when the coating is prepared by sol-gel method, the coating thickness is 20 μm; the coating is dried at 200℃ for 2 hours, and the inspection ensures that there are no pinholes or cracks, and that it covers the entire surface.
[0016] Example 2, a method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel, includes the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.1 wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1390℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 15 minutes.
[0017] The YG8 tungsten carbide rod is pre-alloyed before forming; 1 wt% Cr or Ta is added to the preform, and Cr / Ta forms Co-Cr / Co-Ta intermetallic compound with Co, raising the high-temperature melting point of the cobalt phase to above 1550℃; ultrafine WC is used, and a pre-oxidation treatment at 500℃ for 1 hour is performed. The pre-oxidation treatment generates a WCxOy oxide film on the YG8 surface, forming a stable interface transition layer.
[0018] The high-temperature insulating coating is an Al2O3-ZrO2 composite ceramic coating or a NiCrAlY-WC cermet coating; the volume ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite ceramic coating is 7:3; when the coating is prepared by plasma spraying, the coating thickness is 80 μm; when the coating is prepared by sol-gel method, the coating thickness is 30 μm; the coating is dried at 200℃ for 2 hours, and the inspection ensures that there are no pinholes or cracks, and that it covers the entire surface.
[0019] Example 3, a method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel, includes the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.075 wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1385℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 13 minutes.
[0020] The YG8 tungsten carbide rod is pre-alloyed before forming; 0.75wt% of Cr or Ta is added to the preform, and Cr / Ta forms Co-Cr / Co-Ta intermetallic compound with Co, raising the high-temperature melting point of the cobalt phase to above 1550℃; ultrafine WC is used, and a pre-oxidation treatment at 500℃ for 1 hour is performed. The pre-oxidation treatment generates a WCxOy oxide film on the YG8 surface, forming a stable interface transition layer.
[0021] The high-temperature insulating coating is an Al2O3-ZrO2 composite ceramic coating or a NiCrAlY-WC cermet coating; the volume ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite ceramic coating is 7:3; when the coating is prepared by plasma spraying, the coating thickness is 65μm; when the coating is prepared by sol-gel method, the coating thickness is 25μm; the coating is dried at 200℃ for 2h, and the inspection ensures that there are no pinholes or cracks, and that it covers the entire surface.
[0022] Example 4, a method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel, includes the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.08 wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1385℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 12 minutes.
[0023] The high-temperature insulating coating is an Al2O3-ZrO2 composite ceramic coating; the volume ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite ceramic coating is 7:3; the coating is prepared by plasma spraying and has a thickness of 60μm; the coating is dried at 200℃ for 2 hours and inspected to ensure that there are no pinholes or cracks and that it covers the entire surface.
[0024] This embodiment is applicable to the mass production of cost-sensitive workpieces.
[0025] Product performance: Co is uniformly distributed and there is no brittle phase; HRA=89.5, flexural strength=1480MPa; interfacial bonding strength=230MPa; no pulverization.
[0026] Example 5, a method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel, includes the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.1 wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1400℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 10 minutes.
[0027] The YG8 tungsten carbide rod is pre-alloyed and modified before forming; 0.8 wt% Cr is added during preforming; ultrafine WC is used, and it is pre-oxidized at 500℃ for 1 hour.
[0028] The high-temperature insulating coating is a NiCrAlY-WC cermet coating; the coating is prepared by plasma spraying and has a thickness of 70μm; the coating is dried at 200℃ for 2 hours and inspected to ensure that there are no pinholes or cracks and that it covers the entire surface.
[0029] This embodiment is applicable to the production of high-end workpieces for mining and processing ultra-high hardness ores.
[0030] Product performance: HRA=90, bending strength=1550MPa; interface bonding strength=260MPa; YG8 core component can withstand high temperature of 1400℃ and immersion in high manganese steel liquid for 30 minutes without failure.
[0031] The YG8 tungsten carbide rod produced by the method of this invention, combined with high-manganese steel liquid, is suitable for crushing ultra-high hardness ores with a Protodyakonov hardness >15.
Claims
1. A method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel, comprising the following steps: Step A, spraying a high-temperature resistant insulating coating onto the surface of the YG8 tungsten carbide rod: a high-temperature resistant insulating coating is prepared by spraying onto the surface of the pre-formed YG8 rod; Step B: After the YG8 tungsten carbide rod has been sprayed, it is placed in the composite casting cavity and positioned. Step C, microalloying of high manganese steel melt: 0.05wt%~0.1wt% boron is added to the high manganese steel melt during the smelting process; boron forms a dense Fe-B barrier layer at the YG8 interface, inhibiting the formation of WC2 and M7C3 brittle phases; Step D, precise temperature control during casting: The casting temperature of high manganese steel is controlled at 1380~1390℃, and the gating system is optimized to control the high temperature residence time above 1400℃ to 10~15min.
2. The method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel according to claim 1, characterized in that: The YG8 tungsten carbide rod is pre-alloyed before forming; 0.5wt%~1wt% of Cr or Ta is added to the preform, and Cr / Ta forms Co-Cr / Co-Ta intermetallic compound with Co, raising the high-temperature melting point of the cobalt phase to above 1550℃; ultrafine WC is used, and a pre-oxidation treatment at 500℃ for 1 hour is performed. The pre-oxidation treatment generates a WCxOy oxide film on the YG8 surface, forming a stable interface transition layer.
3. The method for preventing cobalt segregation, embrittlement, and pulverization of YG8 tungsten carbide rods in molten high-manganese steel according to claim 2, characterized in that: The high-temperature insulating coating is an Al2O3-ZrO2 composite ceramic coating or a NiCrAlY-WC cermet coating; the volume ratio of Al2O3 to ZrO2 in the Al2O3-ZrO2 composite ceramic coating is 7:3; when the coating is prepared by plasma spraying, the coating thickness is 50~80μm; when the coating is prepared by sol-gel method, the coating thickness is 20~30μm; the coating is dried at 200℃ for 2h, and the inspection ensures that there are no pinholes or cracks and that it covers the entire surface.