Method for producing wire rod by adopting bubble tank water bath process

Abstract

The invention relates to the technical field of metal wires, in particular to a method for producing a wire by adopting a bubble tank water bath process. The method comprises the following steps: 1) rolling a wire and spinning; (2) a wire ring formed by spinning is arranged on a roller conveyor and enters an EDC system to be subjected to phase change treatment; (3) a bubble generator is arranged in the EDC water tank, and the cooling speed is controlled; 4) introducing a mixed gas of compressed air and nitrogen with the pressure of 0.6-1.0 MPa into the water by a bubble generator in a phase change early-stage region, and controlling the cooling speed to be 15-30 DEG C / s; compressed air with the pressure of 0.3-0.5 MPa is introduced into the water in the phase change and later stage, and the cooling speed is controlled to be 4-7 DEG C / s; (5) the water temperature of a water tank is 90-100 DEG C, the total in-water time is 20-80 s, and (6) the in-water temperature of the wire rod is 800-880 DEG C, and the water outlet temperature is 560-660 DEG C. Finally, the wire rod with the pearlite lamella thickness being 70-120nm and the sorbite rate being more than 90% is obtained, so that the final performance indexes such as the pearlite lamellas and the sorbite rate of the medium-high carbon steel wire rod are optimal, lead bath can be replaced, energy is saved, and the production cost of steel wires is reduced.

Description

Technical Field

[0001] This invention relates to the field of metal wire technology, specifically to a method for producing wire using a bubble bath process. Background Technology

[0002] EDC (Easy Drawing-Conveyer Process) refers to an online controlled cooling method where hot-rolled wire rod is first water-cooled and then continuously immersed in a hot water bath for further cooling; it is also known as the hot water bath method. EDC is an online heat treatment method primarily used in wire rod production for high-quality carbon steel and high-quality carbon low-alloy steel. It replaces the traditional Stellmor process, allowing the wire rod to directly enter hot water at temperatures above 94°C after hot rolling and drawing to complete the microstructure transformation. Compared to the traditional Stellmor process, EDC offers advantages such as uniform microstructure, less oxidation and decarburization, and higher drawability, making it an ideal replacement for lead bath treatment.

[0003] However, compared to lead bath treatment, the EDC process suffers from a slower cooling rate in the early stages and a faster cooling rate in the later stages. This is reflected in the wire's microstructure and properties, resulting in a higher proportion of proeutectoid phase, poor carbon control in the high-carbon steel mesh, and uneven pearlite lamellar structure, all of which affect the wire's drawability and mechanical properties. Especially for large-diameter wires, insufficient cooling capacity is the most significant factor affecting the final product performance. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a method for producing wire using a bubble bath process, which optimizes the final performance indicators of medium and high carbon steel wire rods, such as pearlite lamellars and sorbitization rate. This method can replace lead baths, saving energy and reducing the production cost of steel wire.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for producing materials using a bubble bath water bath process specifically includes the following steps:

[0007] 1) The wire is rolled and then spun out at a temperature of 840~900℃.

[0008] 2) The wire loops formed by spinning are arranged on a roller conveyor and enter the EDC system for phase change treatment.

[0009] 3) A bubble generator is installed in the EDC water tank. The bubbles in the water are controlled by introducing a mixture of compressed air and nitrogen into the bubble generator, thereby controlling the cooling rate. The number of bubble generators, overlapping points and non-overlapping points are designed differently in the early stage of phase change and the later stage of phase change.

[0010] 4) In the early phase change region, the bubble generator introduces a mixture of compressed air and nitrogen at a pressure of 0.6~1.0MPa into the water to form a steam-water mixture, and controls the cooling rate to 15~30℃ / s.

[0011] During the phase change and later stages, compressed air at a pressure of 0.3~0.5MPa is introduced into the water to form a steam-water mixture, and the cooling rate is controlled at 4~7℃ / s.

[0012] 5) Maintain the water temperature in the tank at 90-100℃, and the total time spent in the water is 20-80 seconds.

[0013] 6) The water temperature of the wire is 800~880℃ and the water temperature of the wire is 560~660℃; finally, a wire with a pearlite lamellar thickness of 70~120nm and a sorbitization rate of more than 90% is obtained.

[0014] Furthermore, in 5), the total time spent in the water is 30~60s.

[0015] Furthermore, in 6), the wire has a uniform sorbitic structure, tensile strength ≥1200MPa, elongation ≥10%, and shrinkage of area ≥30%.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. This invention significantly improves the microstructure and properties of wire rods. Through a bubble-controlled EDC cooling process, high-pressure bubbles (0.6~1.0MPa) are used in the early phase transformation stage to break the vapor film, increasing the cooling rate (15~30℃ / s) and suppressing the formation of proeutectoid ferrite and coarse pearlite. In the later stages of the phase transformation, low-pressure bubbles (0.3~0.5MPa) form a vapor-water isolation layer, reducing the cooling rate (4~7℃ / s) and avoiding low-temperature structures such as martensite, ultimately resulting in a uniform sorbite microstructure (pearlite lamellae 70~120nm, sorbitization rate ≥90%). Simultaneously, by introducing a mixture of compressed air and nitrogen, a vapor-water mixture is created, controlling the condition of the wire rod scale. This avoids the problem of yellow rust formation on the wire rod surface caused by simple water baths or compressed air alone, which would otherwise require pickling before downstream processing. This patented mixed gas process ensures excellent scale condition, allowing for mechanical peeling to remove the scale, saving on acidic processing costs.

[0018] 2. This invention has environmental and cost advantages. It can completely or partially replace traditional lead bath treatment, eliminating the risk of lead pollution and meeting the requirements of green manufacturing; it simplifies the production process, reduces energy consumption and the production costs of downstream steel wire and steel wire rope; and in downstream reprocessing, it uses mechanical peeling to remove iron scale instead of acid washing, saving costs.

[0019] 3. This invention achieves a breakthrough in cooling capacity. By dynamically controlling bubbles to achieve zoned cooling, it solves the problem of uneven cooling of large-diameter wires (especially at the splice points). The cooling efficiency at the splice points is further improved by increasing the number of bubble generators. The cooling rate has a wide controllable range (1~30℃ / s), and the overall performance is close to or reaches the level of lead bath cooling, which is significantly better than conventional EDC and water circulation processes.

[0020] 4. The process of this invention has outstanding versatility. It is applicable to high-quality carbon steel and low-alloy steel wire rods, and is especially suitable for the production of large-diameter wire rods of medium and high carbon steel, improving their drawing performance and final wire strength (tensile strength ≥1200MPa, elongation ≥10%, reduction of area ≥30%, sorbitization ≥90%, pearlite lamellars 70~120nm).

[0021] In summary, this invention is applicable to high-quality carbon steel and low-alloy high-quality carbon steel wire rods. After rolling, the wire rod undergoes a cooling phase transformation in an EDC (Electrostatic Discharge) bath with added air bubbles. Because the bubbles break the vapor film in the early cooling stage, the cooling rate is increased, eliminating proeutectoid phases and coarse pearlite. In the later cooling stage, the bubbles isolate the wire rod from the hot water, reducing the cooling rate and eliminating excessively fine pearlite and martensite, etc., at low temperatures. This results in wire rods with uniform microstructure and excellent performance, optimizing the final performance indicators such as pearlite lamellars and sorbitization rate of medium- and high-carbon steel wire rods. Simultaneously, by partially or completely replacing lead bath treatment in the steel wire production process, it is beneficial for environmental protection, saving process energy and other consumption, and reducing the production costs of downstream products such as steel wire and wire rope. Attached Figure Description

[0022] Figure 1 This is a metallographic diagram of the wire rod in Embodiment 1 of the present invention.

[0023] Figure 2 This is a metallographic diagram of a standard wire rod. Detailed Implementation

[0024] This invention discloses a method for producing materials using a bubble bath process. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention.

[0025] The methods and applications of the present invention have been described through preferred embodiments. Those skilled in the art will be able to make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention, so as to realize and apply the technology of the present invention.

[0026] A method for producing materials using a bubble bath water bath process specifically includes the following steps:

[0027] 1) The wire is rolled and then spun out at a temperature of 840~900℃.

[0028] 2) The wire rings are laid on the roller conveyor, and the wire rings are fed into the EDC system for phase change treatment.

[0029] 3) Install bubble generators in the EDC tank. The number of bubble generators varies depending on the position of the phase change in the early stage, the phase change stage, the phase change stage, and the position of the coil overlap and non-overlap.

[0030] For example, the number of bubble generators should be more at the overlap point in the early stage of phase transformation, and less at non-overlap points, phase transformation locations, and the later stage of phase transformation. This is because, firstly, the cooling rate at the overlap point in the early stage of phase transformation should be increased, and secondly, the cooling rate in the later stage of phase transformation should be slowed down to avoid the formation of low-temperature structures such as martensite.

[0031] 4) The EDC device is about 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, compressed air of 0.6~1.0MPa or higher is introduced into the water to make the hot water in the EDC water tank a mixture of steam and water. The cooling rate before phase change is 15~30℃ / s. In the phase change and after phase change, i.e., 15~30m, compressed air of 0.3~0.5MPa or higher is introduced to make the hot water in the EDC water tank a mixture of steam and water. The cooling rate in the later stage of phase change is 4~7℃ / s.

[0032] 5) Water temperature 90~100℃, total time in water 20~80s.

[0033] 6) The wire immersion temperature is 800~880℃, and the wire outlet temperature is 560~660℃. After cooling in the EDC water tank, the wire has a pearlite lamellar layer of 70~120nm and a sorbitization rate of 90%, meeting the final performance requirements of the product.

[0034] Example 1:

[0035] A method for producing wire rod using a bubble bath process, steel grade: SWRH62A, wire rod specification φ5.0mm:

[0036] 1) The wire is rolled and then spun into strands at a temperature of 840℃;

[0037] 2) The wire loops are laid on the roller conveyor, and then the wire loops that have been spun out enter the EDC system for phase change treatment;

[0038] 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators varies depending on the location of the phase change in the early stage, the phase change stage, the late stage, and the overlapping and non-overlapping points of the coil. For example, there should be more bubble generators at the overlapping points in the early stage of the phase change, and fewer bubble generators at the non-overlapping points, the phase change stage, and the late stage of the phase change. This is to increase the cooling rate at the overlapping points in the early stage of the phase change and to slow down the cooling rate in the late stage of the phase change to avoid the formation of low-temperature structures such as martensite.

[0039] 4) The EDC device is about 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, a mixture of compressed air and nitrogen with a pressure of more than 0.6MPa is introduced into the water to make the hot water in the EDC tank a steam-water mixture. The cooling rate before phase change is 26℃ / s. In the later stage of phase change, i.e., 15~30m, compressed air with a pressure of more than 0.3MPa is introduced to make the hot water in the EDC tank a steam-water mixture. The cooling rate in the later stage of phase change is 4℃ / s.

[0040] 5) Water temperature 90℃, total time in water 20s;

[0041] 6) The wire enters the water at 820℃ and exits at 560℃; the pearlite layer of the wire after cooling in the EDC water tank is 80nm, which meets the final performance requirements of the product.

[0042] Results: SWRH62A wire with a diameter of 5.0mm, after being cooled in the bubble-filled EDC water bath described in this invention, can be directly drawn to a diameter of 0.8mm; while when using conventional EDC water bath cooling, it can only be drawn to a diameter of 1.2mm, or it needs to undergo lead bath treatment when drawn to a diameter of 1.85mm before being drawn to a diameter of 0.8mm. This eliminates the need for lead bath treatment, saving processing costs.

[0043] Example 2:

[0044] A method for producing wire rod using a bubble bath process, steel grade: SWRH72A, wire rod specification φ5.0mm:

[0045] 1) The wire is rolled and then spun into strands at a temperature of 860℃;

[0046] 2) The wire loops are laid on the roller conveyor, and then the wire loops that have been spun out enter the EDC system for phase change treatment;

[0047] 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators varies depending on the location of the phase change in the early stage, the phase change stage, the late stage, and the overlapping and non-overlapping points of the coil. For example, there should be more bubble generators at the overlapping points in the early stage of the phase change, and fewer bubble generators at the non-overlapping points, the phase change stage, and the late stage of the phase change. This is to increase the cooling rate at the overlapping points in the early stage of the phase change and to slow down the cooling rate in the late stage of the phase change to avoid the formation of low-temperature structures such as martensite.

[0048] 4) The EDC device is about 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, a mixture of compressed air and nitrogen with a pressure of more than 0.7MPa is introduced into the water to make the hot water in the EDC tank a steam-water mixture. The cooling rate before phase change is 27℃ / s. In the later stage of phase change, i.e., 15~30m, compressed air with a pressure of more than 0.35MPa is introduced to make the hot water in the EDC tank a steam-water mixture. The cooling rate in the later stage of phase change is 5℃ / s.

[0049] 5) Water temperature 90~100℃, total time in water 20s;

[0050] The wire's water inlet temperature is 845℃, and its water outlet temperature is 565℃. After being cooled in the EDC water tank, the wire's pearlite layer is 100nm, meeting the final performance requirements of the product.

[0051] Results: SWRH72A wire with a diameter of 5.0mm, after being cooled in the bubble-filled EDC water bath described in this invention, can be directly drawn to a diameter of 0.96mm, allowing for direct production of finished tire bead wire. In contrast, when using a conventional EDC water bath, a lead bath treatment is required when drawing to a diameter of 3.4mm, followed by further drawing to 0.96mm. Eliminating the lead bath treatment saves processing costs.

[0052] Example 3:

[0053] A method for producing wire rods using a bubble bath process, steel grade: SWRH62A, wire rod specification φ6.5mm:

[0054] 1) The wire is rolled and then spun into strands at a temperature of 850℃;

[0055] 2) The wire loops are laid on the roller conveyor, and then the wire loops that have been spun out enter the EDC system for phase change treatment;

[0056] 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators varies depending on the location of the phase change in the early stage, the phase change stage, the late stage, and the overlapping and non-overlapping points of the coil. For example, there should be more bubble generators at the overlapping points in the early stage of the phase change, and fewer bubble generators at the non-overlapping points, the phase change stage, and the late stage of the phase change. This is to increase the cooling rate at the overlapping points in the early stage of the phase change and to slow down the cooling rate in the phase change and late stage to avoid the formation of low-temperature structures such as martensite.

[0057] 4) The EDC device is approximately 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, a mixture of compressed air and nitrogen at a pressure of 0.8MPa or higher is introduced into the water to make the hot water in the EDC tank a steam-water mixture. The cooling rate before phase change is 25℃ / s. In the later stage of phase change, i.e., 15~30m, compressed air at a pressure of 0.4MPa or higher is introduced to make the hot water in the EDC tank a steam-water mixture. The cooling rate in the later stage of phase change is 5.5℃ / s.

[0058] 5) Water temperature 90~100℃, total time in water 30s;

[0059] 6) The wire enters the water at 840℃ and exits at 570℃; the pearlite layer of the wire after cooling in the EDC water tank is 95nm, which meets the final performance requirements of the product.

[0060] Example 4:

[0061] A method for producing wire rod using a bubble bath process, steel grade: SWRH82A, wire rod specification φ6.5mm:

[0062] 1) The wire is rolled and then spun into strands at a temperature of 860℃;

[0063] 2) The wire loops are laid on the roller conveyor, and then the wire loops that have been spun out enter the EDC system for phase change treatment;

[0064] 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators varies depending on the location of the phase change in the early stage, the phase change stage, the late stage, and the overlap and non-overlap points of the coil. For example, there should be more bubble generators at the overlap points in the early stage of the phase change, and fewer bubble generators at the non-overlap points, the phase change stage, and the late stage of the phase change. This is to increase the cooling rate at the overlap points in the early stage of the phase change and to slow down the cooling rate in the late stage of the phase change to avoid the formation of low-temperature structures such as martensite.

[0065] 4) The EDC device is about 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, a mixture of compressed air and nitrogen with a pressure of more than 0.9MPa is introduced into the water to make the hot water in the EDC tank a steam-water mixture. The cooling rate before phase change is 26℃ / s. In the later stage of phase change, i.e., 15~30m, compressed air with a pressure of more than 0.43MPa is introduced to make the hot water in the EDC tank a steam-water mixture. The cooling rate in the later stage of phase change is 6℃ / s.

[0066] 5) Water temperature 90~100℃, total time in water 30s;

[0067] 6) The wire enters the water at 850℃ and exits at 575℃; after being cooled in the EDC water tank, the wire has a pearlite layer of 90nm and a sorbitization rate of 95%, meeting the final performance requirements of the product.

[0068] Example 5:

[0069] A method for producing wire rod using a bubble bath process, steel grade: SWRH92A, wire rod specification φ14.0mm:

[0070] 1) The wire is rolled and then spun into strands at a temperature of 890℃;

[0071] 2) The wire loops are laid on the roller conveyor, and then the wire loops that have been spun out enter the EDC system for phase change treatment;

[0072] 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators varies depending on the location of the phase change in the early stage, the phase change stage, the late stage, and the overlapping and non-overlapping points of the coil. For example, there should be more bubble generators at the overlapping points in the early stage of the phase change, and fewer bubble generators at the non-overlapping points, the phase change stage, and the late stage of the phase change. This is to increase the cooling rate at the overlapping points in the early stage of the phase change and to slow down the cooling rate in the late stage of the phase change to avoid the formation of low-temperature structures such as martensite.

[0073] 4) The EDC device is approximately 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, a mixture of compressed air and nitrogen at a pressure of 0.95MPa or higher is introduced into the water to make the hot water in the EDC tank a steam-water mixture. The cooling rate before phase change is 24℃ / s. In the later stage of phase change, i.e., 15~30m, compressed air at a pressure of 0.45MPa or higher is introduced to make the hot water in the EDC tank a steam-water mixture. The cooling rate in the later stage of phase change is 6.5℃ / s.

[0074] 5) Water temperature 90~100℃, total time in water 70s;

[0075] 6) The wire enters the water at 870℃ and exits at 600℃; after being cooled in the EDC water tank, the wire has 80nm pearlite lamellars and a sorbitization rate of 95%, meeting the final performance requirements of the product.

[0076] Example 6:

[0077] A method for producing wire rod using a bubble bath process, steel grade: SWRH92A, wire rod specification φ16.0mm:

[0078] 1) The wire is rolled and then spun into strands at a temperature of 900℃;

[0079] 2) The wire loops are laid on the roller conveyor, and then the wire loops that have been spun out enter the EDC system for phase change treatment;

[0080] 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators varies depending on the location of the phase change in the early stage, the phase change stage, the late stage, and the overlapping and non-overlapping points of the coil. For example, there should be more bubble generators at the overlapping points in the early stage of the phase change, and fewer bubble generators at the non-overlapping points, the phase change stage, and the late stage of the phase change. This is to increase the cooling rate at the overlapping points in the early stage of the phase change and to slow down the cooling rate in the late stage of the phase change to avoid the formation of low-temperature structures such as martensite.

[0081] 4) The EDC device is about 30m long. In the early stage of phase change, i.e., 15m before entering the EDC, a mixture of compressed air and nitrogen with a pressure of more than 1.0MPa is introduced into the water to make the hot water in the EDC tank a steam-water mixture. The cooling rate before phase change is 22℃ / s. In the later stage of phase change, i.e., 15~30m, compressed air with a pressure of more than 0.5MPa is introduced to make the hot water in the EDC tank a steam-water mixture. The cooling rate in the later stage of phase change is 7℃ / s.

[0082] 5) Water temperature 90~100℃, total time in water 80s;

[0083] 6) The wire enters the water at 885℃ and exits at 620℃; after being cooled in the EDC water tank, the wire has a pearlite lamellar layer of 75nm and a sorbitization rate of 95%, meeting the final performance requirements of the product.

[0084] The wire rod produced using this invention achieves optimal final performance indicators such as pearlite lamellars and sorbitization rate. Simultaneously, it partially or completely replaces lead bath treatment in the wire production process, which is beneficial for environmental protection, saves energy and other consumption in the process, and reduces the production costs of downstream products such as steel wire and wire rope. Furthermore, by introducing a mixture of compressed air and nitrogen to create a gas-water mixture, the condition of the wire rod's iron scale is controlled, avoiding the yellow rust problem caused by a simple water bath or a mixture of compressed air alone. In such cases, the wire rod must undergo pickling before downstream processing to remove the rust, while this patented mixed gas process ensures excellent iron scale condition, allowing for mechanical peeling to remove the oxide scale, thus saving on acidic process costs.

[0085] Table 1 Comparison of the microstructure and properties of wires produced by the present invention and conventional EDC processes.

[0086]

[0087] As shown in Table 1, the microstructure and properties of the wire produced using the present invention are compared with those produced using conventional EDC processes (SWRH92A wire with a diameter of 14.0 mm): tensile strength, reduction of area, and sorbite content are significantly increased, and the lamellar structure is dense and uniform. Figure 1 As shown, the wire rod produced by this invention has better uniformity of structure than that produced by conventional methods.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing materials using a bubble bath water bath process, characterized in that, Specifically, the steps include the following: 1) The wire is rolled and then spun into strands at a temperature of 840–900℃; 2) The wire loops formed by spinning are arranged on a roller conveyor and enter the EDC system for phase change treatment; 3) Install bubble generators in the EDC water tank. Control the bubbles in the water by introducing a mixture of compressed air and nitrogen into the bubble generators, thereby controlling the cooling rate. The number of bubble generators and the number of overlapping and non-overlapping points are designed differently in the early stage of phase change compared to the phase change and the later stage of phase change. 4) In the early phase change region, the bubble generator introduces a mixture of compressed air and nitrogen at a pressure of 0.6~1.0MPa into the water to form a steam-water mixture, and controls the cooling rate to 15~30℃ / s. During the phase change and later stages, compressed air at a pressure of 0.3~0.5MPa is introduced into the water to form a steam-water mixture, and the cooling rate is controlled at 4~7℃ / s. 5) Maintain the water temperature in the tank at 90–100℃, with a total water time of 20–80 seconds; 6) The water temperature of the wire is 800~880℃ and the water temperature of the wire is 560~660℃; finally, a wire with a pearlite lamellar thickness of 70~120nm and a sorbitization rate of more than 90% is obtained.

2. The method for producing materials using a bubble bath process according to claim 1, characterized in that, 5) The total time spent in the water is 30~60s.

3. The method for producing materials using a bubble bath process according to claim 1, characterized in that, 6) The wire has a uniform sorbitic structure, tensile strength ≥1200MPa, elongation ≥10%, and shrinkage of area ≥30%.

Images