A preparation process of directional high-speed steel band saw blade wire

Abstract

This invention discloses a manufacturing process for oriented high-speed steel band saw blade wire, comprising: electric furnace smelting, oriented electroslag remelting, two-stage directional forging, and wire rolling. This invention employs a combination of oriented electroslag remelting and two-stage directional forging steps. The oriented electroslag remelting step, through a combination of water circulation cooling in a crystallizer and bottom water tank extraction, increases the solidification rate to a certain extent, achieving directional grain growth in the oriented high-speed steel strip and refining the carbide microstructure. The two-stage directional forging step, through specific ratio round bar cutting and multiple directional forging processes, eliminates the difference in carbide composition between the surface and core of the high-speed steel ingot. Subsequently, high-speed steel wire can be successfully produced using traditional manufacturing processes, filling a domestic technological gap.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, specifically to a process for preparing directional high-speed steel band saw blade wire. Background Technology

[0002] Bimetal band saw blades are metal cutting tools made of high-speed steel for the teeth and low-alloy spring steel for the backing material. They are widely used in sawing structural steel, stainless steel, titanium alloys, and other metal materials. The band saw wire is the core tooth material of the bimetal band saw blade, and its quality directly determines the blade's lifespan. There is an urgent need for a high-performance, cost-effective domestic band saw wire material with a lifespan comparable to imported products and a price similar to domestic brands to improve the overall cost-effectiveness of bimetal band saw blades.

[0003] Currently, the production method for domestically produced M42 band saw blade wire is: electric furnace smelting, electroslag remelting, forging and drawing, hot rolling, drawing, and wire rolling. However, due to the coarse micro-carbide particles in the steel after electroslag remelting and insufficient uniformity during forging, this method can only produce materials with an upper limit of 25% alloy element ratio for high-speed steel. Further increasing the alloy composition ratio will cause cracking. Therefore, it is impossible to produce high-end band saw blade wires with higher alloy element content such as M51 (31% alloy element ratio), P30 (28% alloy element ratio), and HS90 (28% alloy element ratio). To address this, we propose a preparation process for oriented high-speed steel band saw blade wire. Summary of the Invention

[0004] The purpose of this invention is to provide a process for preparing directional high-speed steel band saw blade wire, so as to solve the problems that need to be solved in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a process for preparing oriented high-speed steel band saw blade wire, the process comprising the following steps:

[0006] Step 1: Electric furnace smelting: The directional high-speed steel is melted using an electric furnace to obtain directional high-speed steel melt;

[0007] Step 2: Directional electroslag remelting: The directional high-speed steel melt is rapidly directionally electroslag remelted using a combined crystallizer to obtain high-speed steel ingots with directionally grown grains and uniform fine carbide structure;

[0008] Step 3: Two-stage forging process: The high-speed steel ingot is cut and forged multiple times to ensure that the carbides inside the high-speed steel ingot are evenly distributed to obtain a forged steel billet.

[0009] Step 4: Hot rolling of the forged steel billet from Step 3: Hot rolling is performed to obtain a coiled steel billet.

[0010] Step 5: Wire rolling process: The coiled steel billet obtained in Step 4 is sequentially drawn and rolled to obtain oriented high-speed steel band saw blade wire with a size of not less than 0.94*1.20mm.

[0011] Currently, the production method for domestically produced M42 band saw blade steel wire is as follows: electric furnace smelting, electroslag remelting, forging and drawing, hot rolling into coils, drawing, and wire rolling. However, due to the coarse microscopic carbide particles in the steel after electroslag remelting and insufficient uniformity during forging, this method can only produce high-speed steel with an alloy element ratio of up to 25%. Further increasing the alloy composition ratio will cause cracking. Therefore, it is impossible to produce M51 (31% alloy element ratio), P30 (28% alloy element ratio), and HS90 (28% alloy element ratio) with higher alloy element content. For high-end band saw blade wire, this invention employs a combination of directional electroslag remelting and two-stage directional forging blanking steps. The directional electroslag remelting step, through combined crystallizer water circulation cooling and bottom water tank extraction, improves the solidification speed to a certain extent, achieving directional growth of high-speed steel strip grains and refining the carbide structure. The two-stage directional forging blanking steps, through specific ratio round bar cutting and multiple directional forging, can eliminate the difference in carbides between the surface and core of the high-speed steel ingot. Subsequently, high-speed steel wire can be successfully produced using traditional production processes, filling a domestic technological gap.

[0012] As a further description of the above technical solution:

[0013] The raw materials for manufacturing the oriented high-speed steel include carbon, tungsten, molybdenum, chromium, vanadium, cobalt and iron. The mass percentage of the oriented high-speed steel is 1.3% carbon, 6.5% tungsten, 5.2% molybdenum, 4% chromium, 3% vanadium, 8% cobalt, and the balance is iron.

[0014] As a further description of the above technical solution:

[0015] The two-stage forging process in step three includes the following steps: sawing high-speed steel ingots into round steel billets with a diameter-to-height ratio of 1:2.5; chamfering the top and bottom of the round steel billets; forging the chamfered round steel billets into round disc steel billets by changing their direction by 90°; forging the round disc steel billets into square shapes and drawing them out to obtain drawn steel billets; sawing the drawn steel billets again into billets with a diameter-to-length ratio not greater than 1:2.5; repeating the above steps once to obtain forged steel billets.

[0016] As a further description of the above technical solution:

[0017] In the two-stage forging and billet opening in step three, the billet used in the second forging and billet opening step is obtained by sawing the elongated steel billet after the first forging and drawing again. The ratio of the diameter to the height of the elongated steel billet after the first forging and drawing is not greater than 1:2.5.

[0018] As a further description of the above technical solution:

[0019] The combined crystallizer includes an upper processing mechanism, a bottom water tank, and a consumable electrode. The bottom water tank is fitted below the upper processing mechanism, and the consumable electrode is disposed inside the upper processing mechanism. The upper processing mechanism and the bottom water tank are cooled by circulating water.

[0020] As a further description of the above technical solution:

[0021] The upper treatment mechanism includes an upper water jacket, an insulating layer, and a lower water jacket, which are sequentially arranged from top to bottom.

[0022] As a further description of the above technical solution:

[0023] The internal circulating water flow rate of the upper and lower water jackets is 8-10 m³ / h; the circulating water temperature is 25-32℃; and the bottom water tank is pulled out at a speed of 5-8 mm / min.

[0024] As a further description of the above technical solution:

[0025] The top and bottom of the round steel billet are chamfered at 45° angles, with a chamfer depth of 2-3cm.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention employs a combination of directional electroslag remelting and two-stage forging steps. The directional electroslag remelting step, through combined crystallizer water circulation cooling and bottom water tank extraction, improves the solidification rate to a certain extent, thereby achieving directional growth of high-speed steel strip grains and refining the carbide structure.

[0028] The two-stage forging process involves cutting round bars to a specific ratio and performing multiple forging operations. Figure 5 The microscopic metallographic comparison shows that this application can eliminate the difference in carbides between the surface and core of high-speed steel ingots, and then high-speed steel wire can be successfully produced using traditional production processes, filling a domestic technological gap.

[0029] 2. The raw materials for manufacturing the directional high-speed steel of this invention are 1.3% carbon, 6.5% tungsten, 5.2% molybdenum, 4% chromium, 3% vanadium, and 8% cobalt, with the balance being iron. After the vanadium reaches 3%, the directional electroslag remelting and two-stage forging blanking steps are optimized, which can make the minimum wire size of the directional high-speed steel band saw blade reach 0.94*1.20mm. The service life of this invention is close to that of other products, and it can meet the sawing needs of difficult-to-machine metal materials such as structural steel, stainless steel, and titanium alloys. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the production process of the present invention;

[0031] Figure 2 This is a schematic diagram of the front view of the combined crystallizer of the present invention;

[0032] Figure 3 This is a schematic diagram of the two-direction forging process of the present invention;

[0033] Figure 4 This is a schematic diagram of the tensile test data testing structure of the present invention;

[0034] Figure 5 This is a schematic diagram comparing the microscopic metallographic images of the present invention and a comparative product. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1:

[0037] Please see Figure 1 This invention provides a technical solution: a process for preparing oriented high-speed steel band saw blade wire, the process comprising the following steps:

[0038] Step 1: Electric furnace smelting: The directional high-speed steel is melted using an electric furnace to obtain directional high-speed steel melt;

[0039] Step 2: Directional electroslag remelting: The directional high-speed steel melt is rapidly directionally electroslag remelted using a combined crystallizer to obtain high-speed steel ingots with directionally grown grains and uniform fine carbide structure;

[0040] Step 3: Two-stage forging process: The high-speed steel ingot is cut and forged multiple times to ensure that the carbides inside the high-speed steel ingot are evenly distributed to obtain a forged steel billet.

[0041] Step 4: Hot rolling of the forged steel billet from Step 3: Hot rolling is performed to obtain a coiled steel billet.

[0042] Step 5: Wire rolling process: The coiled steel billet obtained in Step 4 is sequentially drawn and rolled to obtain oriented high-speed steel band saw blade wire with a size of not less than 1.94*1.20mm.

[0043] Example 2:

[0044] Please see Figures 1-5The raw materials for manufacturing the oriented high-speed steel include carbon, tungsten, molybdenum, chromium, vanadium, cobalt and iron. The mass percentage of the oriented high-speed steel is 1.3% carbon, 6.5% tungsten, 5.2% molybdenum, 4% chromium, 3% vanadium, 8% cobalt, and the balance is iron.

[0045] Among them, the vanadium content is set at 3% to refine the grains and generate high-hardness VC carbides, which further improves wear resistance and impact toughness, solving the pain point of "easy breakage" in the production of high alloy steel wire by traditional processes; while the cobalt content of 8% can enhance the high-temperature strength and carbide stability of the steel, and synergistically improve the red hardness with tungsten and molybdenum, making the steel wire less prone to tooth breakage or deformation during long-term high-intensity sawing, and can be directly benchmarked against the performance of high-performance products.

[0046] Please see Figure 3 The two-stage forging process in step three includes the following steps: sawing high-speed steel ingots into round billets with a diameter-to-height ratio of 1:2.5; chamfering the top and bottom of the round billets at 45° angles with a chamfering depth of 2-3cm; forging the chamfered round billets at a 90° angle into round disc billets; forging the round disc billets into square shapes and drawing them out to obtain drawn billets; sawing the drawn billets again into billets with a diameter-to-length ratio not greater than 1:2.5; repeating the above steps once to obtain forged billets; in the two-stage forging process in step three, the billet used in the second forging process is obtained by sawing the drawn billet after the first forging and drawing process again, and the diameter-to-height ratio of the drawn billet after the first forging and drawing process is not greater than 1:2.5.

[0047] The process involves sawing steel ingots into short, wide round billets to ensure uniform stress during forging and sufficient deformation of the core. This allows the forging pressure to penetrate the core of the billet and break down the coarse carbide structure. The 90° directional forging, which transfers the billet from a round bar to a disc, changes the force direction from axial to radial, causing the surface of the billet to intersect with the metal flow path in the core. This forcibly disrupts the original uneven structure and reduces carbide segregation. The secondary forging process involves sawing the first-drawn billet again and repeating the entire process. This is equivalent to performing bidirectional, multi-dimensional deformation on the billet, completely eliminating any residual microstructural differences after the first forging. The final result is a forged billet with consistent surface and core carbide particle size and no obvious segregation.

[0048] Furthermore, the chamfering pretreatment can chamfer the top and bottom of the round bar billet, avoiding micro-cracks caused by stress concentration at the billet edges during forging, and reducing the risk of fracture in subsequent processing; and the multi-form forging process of the entire two-stage forging process, using different forging actions to continuously break and recrystallize the internal grains of the billet, generating finer grains, can significantly improve the toughness of the material, ensuring that it can be successfully hot-rolled into coils and drawn into 1.15*1.40mm fine steel wires. (See Tables 1, 2, and 3 below.) Figure 4 You can refer to Table 1, Table 2, Table 3 and Figure 4 The data shows that the product produced by this method has a tensile strength of 799 MPa and an elongation after fracture of 17.0%, so it will not break due to insufficient toughness. This breaks through the production limitations of traditional processes. Furthermore, the entire forging process relies on a conventional hydraulic forging machine, eliminating the need for imported special equipment or powder metallurgy equipment, thus avoiding additional equipment investment and controlling production costs. In addition, the billet ratio, angle of change, and number of repetitions in the entire two-stage forging process are all clear and controllable parameters, which facilitates stable replication during mass production and reduces the scrap rate caused by process fluctuations.

[0049] Table 1

[0050] Material Sample shape Sample size (mm) Original cross-sectional area (mm^2) Original gauge length (mm) Gauge length after break (mm) Elongation A (%) Dimensions after fracture (mm) ZDF-P30 Bar stock (diameter) 1.82 2.602 100 117.55 18.0 1.43 ZDF-P30 Bar stock (diameter) 1.82 2.602 100 116.55 17.0 1.46 ZDF-P30 Bar stock (diameter) 1.82 2.602 100 117 17.0 1.45

[0051] Table 2

[0052]

[0053] Table 3

[0054]

[0055] Example 3:

[0056] Please see Figure 1 and Figure 2 The combined crystallizer includes an upper processing mechanism, a bottom water tank, and a consumable electrode. The bottom water tank is sleeved below the upper processing mechanism, and the consumable electrode is disposed inside the upper processing mechanism. The upper processing mechanism and the bottom water tank are cooled by circulating water. The upper processing mechanism includes an upper water jacket, an insulating layer, and a lower water jacket, which are arranged sequentially from top to bottom.

[0057] Here, the consumable electrode is cast from the high-speed steel melt after electric furnace smelting in step one. The consumable electrode is hoisted above the upper processing mechanism. At this time, the bottom water tank rises to the highest position and is embedded in the bottom of the inner cavity of the upper processing mechanism to form a closed molten pool space. Then, pre-melted slag is added to the temporal part of the combined crystallizer to cover the surface of the bottom water tank. Then, the circulating cooling water system of the upper water jacket, lower water jacket and bottom water tank is connected, and different circulating water flow rates are set. The circulating water flow rates of the bottom water tank, lower water jacket and upper water jacket increase in sequence. The sealing and insulation of the insulation layer are tested to ensure that there is no risk of current short circuit.

[0058] Subsequently, the consumable electrode slowly descends and comes into contact with the surface of the pre-melted slag. After being energized, an arc is ignited. The current passes through the molten slag and generates Joule heat, which melts the end of the consumable electrode and forms a metal droplet. The metal droplet and the molten slag fall onto the surface of the bottom water tank and begin to solidify to form the initial layer of the steel ingot. At this time, the strong cooling effect of the bottom water tank causes the first layer of metal to nucleate rapidly, laying the foundation for subsequent directional growth.

[0059] As the electrodes continue to melt, molten steel accumulates on top of the solidified steel ingot.

[0060] The bottom water tank moves slowly downwards at a constant speed, while the upper processing mechanism remains stationary, with heat dissipation controlled solely by water cooling of the side walls. Circulating water passing through the bottom water tank quickly removes heat from the bottom, maintaining the solidification front a few millimeters above the tank. Circulating water in the lower water jacket cools the lower side walls of the strongly cooled steel ingot, inhibiting lateral grain growth. Finally, circulating water in the upper water jacket prevents premature crusting below the slag pool. The insulating layer blocks the electrical connection between the upper and lower water jackets and creates thermal resistance, resulting in a "stronger at the bottom, weaker at the top" gradient distribution of cooling intensity. This allows the steel ingot to solidify under conditions of extreme axial temperature gradient from bottom to top, with grains growing directionally along the drawing direction and carbides becoming fine and uniform.

[0061] Once the consumable electrode has melted completely and the steel ingot has reached the target length, the power supply is cut off and the electrode feeding is stopped. At this time, the bottom water tank continues to descend and detach from the upper processing mechanism, bringing out the complete steel ingot. Then, the slag on the surface of the steel ingot can be cleaned, the skin peeled off, and it can be sawn into forged round steel billets with a height-to-diameter ratio of 1:2.5 to enter the two-stage forging and billet opening steps.

[0062] The internal circulating water flow rate of the upper and lower water jackets is 8-10 m³ / h; the circulating water temperature is 25-32℃; and the bottom water tank is pulled out at a speed of 5-8 mm / min.

[0063] The internal circulating water flow rate of the upper and lower water jackets is 8-10 m³ / h, which is relatively fast and can ensure sufficient cooling intensity, prevent overheating of the side walls of the upper and lower water jackets, and avoid the formation of coarse equiaxed crystal defects on the side walls of the upper and lower water jackets. Moreover, sufficient water flow ensures that the cooling of the lower water jacket is stronger than that of the upper water jacket, which helps the grains to grow preferentially along the drawing direction and inhibits the development of transverse dendrites. The relatively fast bottom water tank drawing speed can enable the high vanadium content (3% V) oriented high-speed steel to solidify quickly and avoid damaging the toughness of the oriented high-speed steel. The slag pool here is shallow and flat, and the slag material is reduced by 20% compared with traditional electroslag remelting. By strictly controlling the current and voltage and cooling rate of oriented remelting, the grains of high-speed steel can be forced to grow in an oriented manner, and the carbide structure can be refined.

[0064] 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 process for preparing directional high-speed steel band saw blade wire, characterized in that: The manufacturing process of the directional high-speed steel band saw blade wire includes the following steps: Step 1: Electric furnace smelting: The directional high-speed steel is melted using an electric furnace to obtain directional high-speed steel melt; Step 2: Directional electroslag remelting: The directional high-speed steel melt is rapidly directionally electroslag remelted using a combined crystallizer to obtain high-speed steel ingots with directionally grown grains and uniform fine carbide structure; Step 3: Two-stage forging process: The high-speed steel ingot is cut and forged multiple times to ensure that the carbides inside the high-speed steel ingot are evenly distributed to obtain a forged steel billet. Step 4: Hot rolling of the forged steel billet from Step 3: Hot rolling is performed to obtain a coiled steel billet. Step 5: Wire rolling process: The coiled steel billet obtained in Step 4 is sequentially drawn and rolled to obtain oriented high-speed steel band saw blade wire with a size of not less than 0.94*1.20mm; The two-stage forging process in step three includes the following steps: sawing high-speed steel ingots into round steel billets with a diameter-to-height ratio of 1:2.5; chamfering the top and bottom of the round steel billets; forging the chamfered round steel billets into round disc steel billets by changing their direction by 90°; forging the round disc steel billets into square shapes and drawing them out to obtain drawn steel billets; sawing the drawn steel billets again into billets with a diameter-to-length ratio of no more than 1:2.5; repeating the above steps once to obtain forged steel billets. In the two-stage forging and billet opening in step three, the billet used in the second forging and billet opening step is obtained by sawing the elongated steel billet after the first forging and drawing again. The ratio of the diameter to the height of the elongated steel billet after the first forging and drawing is not greater than 1:2.

5. The top and bottom chamfers of the round steel billet are 45°, and the chamfer depth is 2-3cm; The raw materials for manufacturing the oriented high-speed steel include carbon, tungsten, molybdenum, chromium, vanadium, cobalt and iron. The mass percentage of the oriented high-speed steel is 1.3% carbon, 6.5% tungsten, 5.2% molybdenum, 4% chromium, 3% vanadium, 8% cobalt, and the balance is iron.

2. The manufacturing process of the directional high-speed steel band saw blade wire according to claim 1, characterized in that: The combined crystallizer includes an upper processing mechanism, a bottom water tank, and a consumable electrode. The bottom water tank is fitted below the upper processing mechanism, and the consumable electrode is disposed inside the upper processing mechanism. The upper processing mechanism and the bottom water tank are cooled by circulating water.

3. The manufacturing process of the directional high-speed steel band saw blade wire according to claim 2, characterized in that: The upper treatment mechanism includes an upper water jacket, an insulating layer, and a lower water jacket, which are sequentially arranged from top to bottom.

4. The manufacturing process of the directional high-speed steel band saw blade wire according to claim 3, characterized in that: The internal circulating water flow rate of the upper and lower water jackets is 8-10 m³ / h; the circulating water temperature is 25-32℃; and the bottom water tank is pulled out at a speed of 5-8 mm / min.

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