A high wear resistant roll ring for a rod and wire mill and a method of manufacturing the same

Abstract

The application relates to the technical field of roller ring preparation, and discloses a high-wear-resistance roller ring suitable for a bar and wire rolling mill and a manufacturing method thereof.The chemical components of the finished product of the high-wear-resistance roller ring suitable for the bar and wire rolling mill include the following components in percentage by weight: C 1.30%-3.50%, Si 0.20%-1.00%, Mn 0.20%-1.20%, Cr 3.75%-6.00%, Ni 1.50%-2.50%, Mo 5.00%-11.00%, V 5.00%-9.00%, W 7.50%-16.00%, Nb 0.20%-3.50%, Co 2.00%-8.00%, P<=0.035%, S<=0.035%, and the balance of Fe and inevitable impurities.The application uses the mutual solubility surface formed by the carbide powder and the molten steel to absorb heat, forcibly reduces the temperature of the molten steel and induces rapid solidification, and overcomes the component segregation defects generated by traditional centrifugal casting under high alloy content.The application realizes firm infiltration of the alloy carbide and the high-speed steel matrix, optimizes the content, form and distribution of the carbide, and significantly improves the hardness uniformity, tempering stability and overall wear resistance of the roller ring.

Description

Technical Field

[0001] This invention relates to the field of roller ring manufacturing technology, and in particular to a high wear-resistant roller ring suitable for bar and wire rod mills and its manufacturing method. Background Technology

[0002] As a core component of bar and wire rod mills, the wear resistance of rolls directly affects the production efficiency and product quality of rolling processes. To meet the ever-increasing demand for wear resistance, roll materials have undergone a continuous upgrade process, from infinitely chilled high-nickel-chromium-molybdenum ductile iron to high-chromium cast iron, high-speed steel, and then to tungsten carbide cemented carbide. Currently, high-speed steel rolls are widely used in industrial production because they can achieve a good balance of hardness, strength, and toughness through quenching and tempering processes.

[0003] Existing high-speed steel rolls are typically formed using induction furnace smelting combined with centrifugal casting technology. Centrifugal casting utilizes centrifugal force to give the workpiece advantages such as high density, refined grains, and high strength and toughness. However, due to the difference in cooling rate and elemental density between the liquid metal and the centrifugal casting process, severe compositional segregation is highly likely to occur.

[0004] In practical applications, high-speed steel rolls need to frequently come into contact with high-temperature red steel, which places higher demands on the carbide content and high tungsten content of the material to ensure sufficient red hardness and wear resistance. However, under the existing centrifugal casting process, attempting to improve performance by further increasing the content of elements such as carbon (C), tungsten (W), and vanadium (V) will only exacerbate component segregation, leading to a significant decline in the overall performance of the product. Therefore, the existing centrifugal casting process has a significant bottleneck in improving the wear resistance of high-speed steel, and there is an urgent need for a manufacturing solution that can retain the advantages of centrifugal casting while effectively suppressing segregation and increasing alloy content. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a high wear-resistant roll ring suitable for bar and wire rod mills and its manufacturing method, which overcomes the compositional segregation defects caused by traditional centrifugal casting under high alloy content, achieves firm wetting of alloy carbides with high-speed steel matrix, optimizes the content, morphology and distribution of carbides, and significantly improves the hardness uniformity, tempering stability and overall wear resistance of the roll ring.

[0006] The present invention solves the above-mentioned technical problems through the following technical means: In a first aspect, the present invention provides a high wear-resistant roll ring suitable for bar and wire rod mills, the chemical composition of which, by weight percentage, comprises: C 1.30%~3.50%, Si 0.20%~1.00%, Mn 0.20%~1.20%, Cr 3.75%~6.00%, Ni 1.50%~2.50%, Mo 5.00%~11.00%, V 5.00%~9.00%, W 7.50%~16.00%, Nb 0.20%~3.50%, Co 2.00%~8.00%, P≤0.035%, S≤0.035%, balance Fe and unavoidable impurities.

[0007] Preferably, the matrix structure of the roller ring is a metal structure formed by the mutual dissolution and infiltration of alloy carbides and high-speed steel matrix.

[0008] Secondly, the present invention provides a method for manufacturing a high wear-resistant roll ring suitable for bar and wire rod mills, for manufacturing the aforementioned high wear-resistant roll ring suitable for bar and wire rod mills, the method comprising: S1. Using scrap steel and alloys as smelting raw materials, the steel is heated and smelted to obtain basic molten steel; S2. Provide tungsten carbide powder and vanadium carbide powder with a particle size of 5μm-10μm, which are dried and weighed before being subjected to plasma cleaning; S3. Mix the base molten steel with the pretreated powder and centrifugally pour it to form a roll ring blank; S4. Perform high-temperature diffusion annealing on the removed roller ring blank; S5. The high wear-resistant roller ring is obtained after spheroidizing annealing, machining and quenching and tempering.

[0009] Preferably, the chemical composition of the base molten steel in step S1, by weight percentage, includes: C 1.60%–2.00%, Si 0.20%–0.80%, Mn 0.20%–0.80%, Cr 3.75%–6.00%, Ni 1.50%–2.50%, Mo 5.00%–11.00%, V 3.50%–4.50%, W 5.00%–6.00%, Co 2.00%–8.00%, Nb 0.20%–3.50%, P ≤ 0.035%, and S ≤ 0.035%.

[0010] Preferably, in step S1, the smelting temperature is controlled at 1600℃, and the smelting slag needs to be removed before pouring out the molten steel.

[0011] Preferably, in step S2, the specific operation method of plasma cleaning is as follows: adjust the vacuum degree to ≤10Pa, introduce inert gas such as argon, and maintain the working pressure at 25-30Pa for 3-5 minutes.

[0012] Preferably, in step S3, the mixing and casting process is specifically controlled as follows: after the centrifuge reaches the predetermined speed of 800-900 rpm, the base molten steel is injected into the centrifuge through a special pouring cup, and at the same time, the carbide powder located in the vacuum chamber is injected into the molten steel flow with a radio frequency power of 100-150W for mixing and casting. The centrifugal rotation time after the casting is completed is set to 20 minutes.

[0013] Preferably, in step S4, the high temperature is set to 1250°C for homogenization quenching.

[0014] Preferably, the parameters for the spheroidizing annealing are set as follows: first, hold at 880 degrees Celsius; then, hold at 740 degrees Celsius; and finally, slowly cool to below 600 degrees Celsius before removing from the furnace. The parameters for the quenching are set as follows: first, quench at 1050 degrees Celsius; then, temper at 560 degrees Celsius three times.

[0015] The core technical principle of this invention lies in the deep coupling of powder metallurgy and centrifugal casting processes. By redesigning the chemical composition of high-speed steel, the content of key elements such as carbon (C), tungsten (W), and vanadium (V) is significantly increased, achieving a composite material structure of "high alloy content matrix and a large number of dispersed alloy carbide phases." Under this design, the alloying elements are composed of the original components in the base molten steel and the added WC and VC powders. This synergistic effect of dual sources breaks through the technical bottleneck that increases in alloy content in traditional processes inevitably lead to severe component segregation, providing a solid material foundation for improving the red hardness and wear resistance of rolls.

[0016] Pretreatment and activity control of the powder surface are crucial for ensuring a strong bond between the reinforcing phase and the matrix. WC and VC powders with particle sizes controlled between 5μm and 10μm require plasma cleaning before spraying. This process utilizes active particles (ions, electrons, etc.) in the plasma to physically impact and chemically react with the powder surface, thoroughly removing impurities such as oxides and organic matter. This process significantly improves the activity of the powder surface, enabling it to rapidly form a miscible surface upon entering the high-temperature molten steel. This ensures high-quality metallurgical bonding between the reinforcing phase powder and the high-speed steel matrix, rather than simple physical deposition.

[0017] Utilizing the "cold source" effect of powder to achieve rapid solidification is the core physical mechanism for overcoming centrifugal segregation. After the centrifuge reaches a predetermined speed of 800-900 rpm, molten steel at 1600℃ is injected. Simultaneously, activating powder is sprayed into the molten steel stream using 100-150W of radio frequency power. The powder's large specific surface area absorbs heat and forcibly lowers the temperature of the molten steel, enabling rapid solidification of the molten steel as a whole within the centrifugal force field. This instantaneous heat exchange mechanism significantly shortens the residence time of the liquid metal, effectively suppressing the migration and segregation of alloying elements under centrifugal force, and ensuring the uniformity of the roll ring's microstructure and hardness.

[0018] Multi-stage heat treatment-driven microstructure optimization is crucial for achieving the final performance goals. Immediately after centrifugation for 20 minutes, high-temperature diffusion annealing utilizes thermodynamic forces to further wet the matrix and carbides, forming a novel metallic structure of stable alloy carbides and a high-speed steel matrix. Subsequently, spheroidizing annealing improves machinability, and finally, quenching and tempering processes finely control the matrix microstructure, resulting in a finished product with a microstructure composed of tempered martensite and dispersed carbides. Ultimately, this allows the roller ring to possess excellent wear resistance while also exhibiting a good balance of hardness, strength, and toughness. The beneficial effects of this invention are: The invention utilizes the miscible surface formed between carbide powder after plasma cleaning and molten steel, effectively leveraging the heat absorption and cooling effect of the powder as a "cold source," thus forcibly shortening the solidification time of the molten steel. This physical mechanism fundamentally solves the compositional segregation defects that are difficult to avoid in traditional centrifugal casting processes with high alloy content. While retaining the advantages of high density, grain refinement, and high strength and toughness of centrifugal casting, it significantly improves the uniformity of the roll ring structure and properties.

[0019] 2. By redesigning the chemical composition of high-speed steel, this invention significantly increases the content of key alloying elements such as carbon, tungsten, and vanadium, achieving a scientific combination of more carbide phases and a matrix with higher alloy content. This novel material structure directly leads to a significant improvement in wear resistance, giving the roll ring excellent red hardness, hardness, and tempering stability, better meeting the wear resistance requirements of roll materials in rolling processing.

[0020] 3. Plasma cleaning technology is used to pretreat the carbide powder, which thoroughly removes surface oxides and organic impurities through the physical impact and chemical reaction of active particles, greatly improving the interfacial activity of the powder surface. Combined with a high-temperature diffusion annealing process performed immediately after molding, deep metallurgical wetting is achieved between the matrix and the carbide, constructing an extremely robust new metallic structure of "alloy carbide and high-speed steel matrix", ensuring the structural reliability of the material under harsh working conditions.

[0021] 4. This invention combines centrifugal casting and powder spraying technologies to significantly improve macroscopic hardness and wear resistance while also achieving excellent overall mechanical properties. Subsequent spheroidizing annealing, rough machining, and final quenching and tempering further optimize the morphology and distribution of carbides, achieving a good balance of hardness, strength, and toughness. Attached Figure Description

[0022] Figure 1 This is a 100x magnification metallographic structure diagram of the present invention; Figure 2 It is a metallographic image of ordinary high-speed steel, magnified 100 times. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example 1 This embodiment describes a high wear-resistant roll ring suitable for bar and wire rod rolling mills and its manufacturing method. 1. Raw material preparation and chemical composition control In embodiments of the present invention, the final chemical composition of the high wear-resistant roller ring, by weight percentage, is set as follows: C: 1.30%–3.50%, Si: 0.20%–1.00%, Mn: 0.20%–1.20%, Cr: 3.75%–6.00%, Ni: 1.50%–2.50%, Mo: 5.00%–11.00%, V: 5.00%–9.00%, W: 7.50%–16.00%, Nb: 0.20%–3.50%, Co: 2.00%–8.00%, P≤0.035%, S≤0.035%, balance being Fe and unavoidable impurities.

[0024] To achieve the above composition, the raw materials are divided into two parts: basic smelting material and external reinforcing phase powder. Basic smelting feedstock: including scrap steel and various ferroalloys, used for smelting basic molten steel. Its composition is set as follows: C 1.60%~2.00%, W 5.00%~6.00%, V 3.50%~4.50%, Cr 3.75%~6.00%, Ni 1.50%~2.50%, etc.

[0025] Reinforcing phase powder: Tungsten carbide (WC) and vanadium carbide (VC) metal powders are used, and the particle size is strictly controlled between 5μm and 10μm.

[0026] 2. Manufacturing process steps The specific manufacturing process of this embodiment is as follows: S1. Basic steelmaking Scrap steel and alloy materials are added to an induction furnace for heating and smelting. The smelting temperature is controlled to reach 1600℃. After the composition is homogeneous, the slag is removed, and the molten steel is poured into a ladle for casting.

[0027] S2. Powder Pretreatment After drying and weighing tungsten carbide and vanadium carbide powders according to the formula, the pretreated powders are placed in a plasma cleaning device. The vacuum degree is adjusted to ≤10Pa, and inert gases such as argon are introduced. The working pressure is maintained at 25-30Pa for 3-5 minutes to ionize the gas and generate plasma. The active particles such as ions and electrons in the plasma will undergo physical collisions or chemical reactions with contaminants on the powder surface, thereby removing impurities such as oxides and organic matter from the surface, while improving the activity of the powder surface.

[0028] S3. Mixed centrifugal casting molding The cleaned powder is placed into a special pouring cup with a vacuum chamber and protected with argon gas.

[0029] Start the centrifuge and, once the speed reaches the predetermined 800-900 rpm, pour the 1600℃ base steel into the centrifuge through a specially made pouring cup.

[0030] At the same time, using 100-150W of radio frequency power, the carbide powder in the vacuum chamber is sprayed into the molten steel flow in an atomized state, and then enters the centrifuge along with the molten steel to rotate and form.

[0031] By utilizing the miscible surface formed by the powder and molten steel to absorb heat, the molten steel solidifies rapidly, thereby suppressing element segregation caused by centrifugal force.

[0032] S4. Homogenization and Diffusion Treatment After the centrifuge rotates for 20 minutes, the bottom cover plate is removed, and the roller ring blank is taken out. The blank is immediately placed into a heat treatment furnace for high-temperature diffusion annealing. The residual heat and external heating are used to further wet the matrix and carbides, achieving a strong new metal structure of "alloy carbides and high-speed steel matrix".

[0033] S5. Subsequent heat treatment and processing Spheroidizing annealing: The blank after diffusion annealing is spheroidized to reduce hardness and facilitate subsequent cutting.

[0034] Rough machining: Machining the blank to the predetermined size.

[0035] Final heat treatment: Through the "quenching and tempering" process, the material obtains a tempered martensitic matrix and dispersed composite carbides, and is finally machined into a high wear-resistant roll ring suitable for bar and wire rod mills.

[0036] The parameters for the spheroidizing annealing are set as follows: first, hold at 880 degrees Celsius; then, hold at 740 degrees Celsius; and finally, slowly cool to below 600 degrees Celsius before removing from the furnace. The parameters for the quenching are set as follows: first, quench at 1050 degrees Celsius; then, temper at 560 degrees Celsius three times.

[0037] Performance tests were conducted on the roller rings compared to ordinary high-speed steel rollers, and the test results are shown in Table 1.

[0038] Table 1 Performance Comparison As shown in Table 1, Figure 1 and Figure 2 As shown, the high wear-resistant roll ring of the present invention exhibits a significantly increased number of carbide phases in its microstructure, with uniform distribution and no obvious segregation. In tests, its hardness, compressive strength, and fracture toughness are superior to those of ordinary high-speed steel rolls manufactured using traditional processes, demonstrating a significant improvement in wear resistance.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A high wear-resistant roll ring suitable for bar and wire rod rolling mills, characterized in that, Its chemical composition, by weight percentage, includes: C 1.30%~3.50%, Si 0.20%~1.00%, Mn 0.20%~1.20%, Cr 3.75%~6.00%, Ni 1.50%~2.50%, Mo 5.00%~11.00%, V 5.00%~9.00%, W 7.50%~16.00%, Nb 0.20%~3.50%, Co 2.00%~8.00%, P≤0.035%, S≤0.035%, balance Fe and unavoidable impurities.

2. The high wear-resistant roller ring according to claim 1, characterized in that, The base structure of the roller ring is a metallic structure formed by the mutual dissolution and infiltration of alloy carbides and high-speed steel matrix.

3. A method for manufacturing a high wear-resistant roll ring suitable for bar and wire rod mills, used to manufacture the high wear-resistant roll ring suitable for bar and wire rod mills as described in claim 1 or 2, characterized in that, The preparation method includes, S1. Using scrap steel and alloys as smelting raw materials, the steel is heated and smelted to obtain basic molten steel; S2. Provide tungsten carbide powder and vanadium carbide powder with a particle size of 5μm-10μm, which are dried and weighed before being subjected to plasma cleaning; S3. Mix the base molten steel with the pretreated powder and centrifugally pour it to form a roll ring blank; S4. Perform high-temperature diffusion annealing on the removed roller ring blank; S5. The high wear-resistant roller ring is obtained after spheroidizing annealing, machining and quenching and tempering.

4. The manufacturing method according to claim 3, characterized in that, The chemical composition of the base molten steel mentioned in step S1, by weight percentage, includes: C 1.60%–2.00%, Si 0.20%–0.80%, Mn 0.20%–0.80%, Cr 3.75%–6.00%, Ni 1.50%–2.50%, Mo 5.00%–11.00%, V 3.50%–4.50%, W 5.00%–6.00%, Co 2.00%–8.00%, Nb 0.20%–3.50%, P≤0.035%, and S≤0.035%.

5. The manufacturing method according to claim 3, characterized in that, In step S1, the smelting temperature is controlled at 1600℃, and the smelting slag needs to be removed before pouring out the molten steel.

6. The manufacturing method according to claim 3, characterized in that, In step S2, the specific operation method of plasma cleaning is as follows: adjust the vacuum degree to ≤10Pa, introduce inert gas such as argon, and maintain the working pressure at 25-30Pa for 3-5 minutes.

7. The manufacturing method according to claim 3, characterized in that, In step S3, the mixing and casting process is specifically controlled as follows: after the centrifuge reaches the predetermined speed of 800-900 rpm, the base molten steel is injected into the centrifuge through a special pouring cup. At the same time, the carbide powder located in the vacuum chamber is injected into the molten steel flow with a radio frequency power of 100-150W for mixing and casting. The centrifugal rotation time after the casting is completed is set to 20 minutes.

8. The manufacturing method according to claim 3, characterized in that, In step S4, the high temperature is set to 1250℃ for homogenization quenching.

9. The manufacturing method according to claim 3, characterized in that, The parameters for the spheroidizing annealing are set as follows: first, hold at 880 degrees Celsius; then, hold at 740 degrees Celsius; and finally, slowly cool to below 600 degrees Celsius before removing from the furnace. The parameters for the quenching are set as follows: first, quench at 1050 degrees Celsius; then, temper at 560 degrees Celsius three times.

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