Homogenizing machining method for sorbite of steel wire with specification larger than 2.72 mm

Abstract

The invention relates to a homogenization processing method for sorbite of a steel wire with the specification larger than 2.72 mm. The homogenization processing method for the sorbite of the steel wire with the specification larger than 2.72 mm comprises the steps that the steel wire is heated to the austenitizing temperature and then sequentially passes through a first water tank, an air cooling area and a second water tank to be subjected to segmented cooling, and transformation from austenite to sorbite is completed. Before the steel wire passes through the first water tank, the method further comprises the following steps that the steel wire is pretreated through a low-temperature water tank, the length of the low-temperature water tank is adjustable from 10 cm to 20 cm, the temperature of a solution in the low-temperature water tank is controlled to range from 40 DEG C to 50 DEG C, water outlet holes are evenly distributed in the bottom of the low-temperature water tank, and the solution rises stably and cools the steel wire evenly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal material heat treatment, and specifically relates to a sorbite homogenization processing technology for steel wires with a diameter greater than 2.72 mm, especially suitable for electroplated steel wire production lines. BACKGROUND

[0002] In the steel wire production process, the transformation of austenite to sorbite is a key step in determining the mechanical properties of the steel wire. Traditional processes usually adopt a combination of multiple water tanks and air cooling, for example, first cooling through a first water tank (WT1), then air cooling, and finally cooling in a second water tank (WT2). However, this process has significant defects, mainly in three aspects: uneven grain distribution, low process efficiency, and resource waste. First, due to the different heat dissipation rates of the surface and center of the steel wire during cooling, the cross-sectional temperature gradient is obvious. The edge area forms fine grains due to rapid cooling, while the center area forms coarse grains due to slow heat dissipation. This unevenness significantly reduces the bending performance, fatigue life, and overall mechanical properties of the steel wire. Second, in the traditional process, the steel wire needs to switch between multiple water tanks for cooling, and the temperature and cooling rate of each water tank need to be precisely controlled, resulting in a long cooling period and limiting the production line speed (usually less than 27 m / min). This inefficient production method cannot meet the demand for high yield and high consistency in modern industry. Finally, the use efficiency of the cooling liquid in the traditional process is low, and it is not fully recycled, resulting in high solution consumption and increasing production costs. In addition, frequent replacement of the cooling liquid also increases the complexity and cost of equipment maintenance. In order to solve the above problems, existing technologies have attempted to improve the water tank structure or adjust the cooling liquid formula to improve cooling efficiency and uniformity. For example, some processes improve the cooling effect by increasing the length of the water tank or adjusting the spraying method of the cooling liquid. However, these improvements can only alleviate the problem to a certain extent and cannot fundamentally solve the problem of gradient distribution of grain size in the cross-section of the steel wire. In addition, existing technologies have attempted to control the cooling rate by increasing the length of the air cooling zone or adjusting the temperature of the water tank, but these methods still rely on the traditional multi-stage cooling process and cannot achieve uniformization of the overall temperature of the steel wire. Therefore, the existing process has obvious limitations in improving the quality of the steel wire. In view of the above problems, an innovative process is needed that can achieve uniformization of the overall temperature of the steel wire, shorten the cooling time, and reduce costs. Specifically, a process is needed that can uniformly pretreat the steel wire before it enters the quenching stage to eliminate the cross-sectional temperature gradient, improve the grain size distribution, and increase the production efficiency and resource utilization. Based on this technical need, the present application proposes an innovative sorbite homogenization process for steel wires. By adding a low-temperature water tank pretreatment process before the traditional process, the present application can effectively solve the problem of gradient distribution of grain size in the cross-section of the steel wire, while improving the cooling efficiency and resource utilization. SUMMARY

[0003] The technical problem solved by the present application is to provide a sorbite homogenization process for steel wires with a diameter greater than 2.72 mm, which solves the technical problems existing in the current sorbite homogenization process for steel wires: the traditional process causes different heat dissipation rates on the surface and center of the steel wire, resulting in a gradient distribution of cross-sectional grain size, with fine edge grains and coarse center grains, reducing the bending performance and fatigue life of the steel wire; the multi-section water tank cooling process has low efficiency and limited production line speed (usually less than 27 m / min), making it difficult to meet the demand for efficient production; the cooling liquid is not fully recycled, resulting in resource waste and cost increase; the process stability is insufficient, making it difficult to accurately control the temperature distribution of the steel wire, affecting the uniformity of the transformation of austenite to sorbite. The present application adds a low-temperature water tank pretreatment process, achieving overall temperature homogenization of the steel wire, improving grain distribution, and improving cooling efficiency and resource utilization, effectively solving the above problems.

[0004] Technical scheme: A sorbite homogenization process for steel wires with a diameter greater than 2.72 mm, including heating the steel wire to an austenitizing temperature, then sequentially passing through a first water tank, an air cooling zone and a second water tank to complete the transformation of austenite to sorbite, before the steel wire passes through the first water tank, the following steps are included: pretreating the steel wire through a low-temperature water tank, the length of the low-temperature water tank is adjustable between 10 cm and 20 cm, the solution temperature in the tank is controlled between 40℃ and 50℃, and water outlets are uniformly arranged at the bottom of the tank to make the solution rise smoothly and cool the steel wire uniformly.

[0005] The solution in the above-mentioned low-temperature water tank is a mixture of water and Aqua Quench 110.

[0006] The diameter of the water outlets of the above-mentioned low-temperature water tank is 2-5 mm, and the spacing between the outlets is 10-15 cm.

[0007] The solution in the above-mentioned low-temperature water tank is circulated to a water tank to be cooled by a water pump, and then returned to the low-temperature water tank after cooling.

[0008] The above-mentioned pretreatment process adjusts the cooling length to make the temperature difference between the surface and center of the steel wire ≤50℃.

[0009] The length of the above-mentioned first water tank is 200 cm-300 cm, and the cooling temperature is 630℃-660℃, the length of the above-mentioned second water tank is 180 cm-200 cm, and the cooling temperature is 610℃-630℃.

[0010] The length of the above-mentioned air cooling zone is 65 cm-75 cm, and the residence time of the steel wire in the air cooling zone is 3-5 seconds.

[0011] A device for the method comprises a low-temperature water tank, a first water tank (WT1), a second water tank (WT2) and a solution circulation system connected in sequence; an air cooling zone is arranged between the first water tank and the second water tank; the low-temperature water tank is provided with uniformly distributed water outlets, and a water tank to be cooled is arranged outside the low-temperature water tank, and the water tank to be cooled is connected with the water outlets in the low-temperature water tank through a water pump and a pipeline.

[0012] The solution circulation system comprises a water pump, a cooler and a flow control valve, and the solution circulation system controls the liquid flow direction and flow between the low-temperature water tank, the first water tank (WT1) and the second water tank (WT2) in the device.

[0013] The solution spraying direction of the low-temperature water tank forms an angle of 30-60° with the movement direction of the steel wire, the flow is controlled to be 100L / H-120L / H, and the pressure is adjusted to be 0.45Pa-0.55Pa.

[0014] Beneficial effects: the low-temperature water tank pretreatment process is additionally arranged before the traditional steel wire sorbite homogenization process, and multiple synergistic effects are achieved. First, the low-temperature water tank pretreatment makes the steel wire obtain uniform temperature distribution before entering the AQ quenching process, significantly improves the gradient distribution problem of the grain size of the steel wire cross section, controls the temperature difference between the surface and the center of the steel wire to be within 10℃ through accurate temperature control (50℃) and uniformly arranged water outlets at the bottom, ensures the uniformity of the transformation of austenite to sorbite, and thus improves the bending performance of the steel wire by 10%. Second, the pretreatment process significantly shortens the subsequent cooling time, makes the production line speed increase from the traditional 27m / min to more than 30m / min, and greatly improves the production efficiency. In addition, through the design of the solution circulation system, the cooling liquid flows out from the low-temperature water tank, is recovered through the water tank to be cooled, is recycled through the water pump, the solution utilization rate is increased by 20%, and the production cost is reduced by 15%. The present application further optimizes the spraying direction of the water outlet (forms an angle of 30-60° with the movement direction of the steel wire), and further improves the cooling uniformity and process stability. This synergistic process design is not only suitable for steel wires of different specifications (such as 2.72mm to 3.0mm), but also provides reliable performance guarantee for subsequent process processing and product use, and has significant industrialization popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a process flow diagram of the present application.

[0016] Figure 2 It is a device diagram of the present application, wherein 1 is a low-temperature water tank, 2 is a first water tank (WT1), 3 is an air cooling zone, and 4 is a second water tank (WT2).

[0017] Figure 3Figure 1 is a schematic diagram of a water tank to be cooled, wherein 5 is a water tank to be cooled, and 6 is a solution inlet area.

[0018] Figure 4 Figure 4 is a schematic diagram of a low-temperature water tank structure, wherein 11 is a solution outlet hole, and 12 is a solution discharge hole in the area to be cooled.

[0019] Figure 5 Figure 5 is a schematic diagram of a segmented cooling device, wherein 21 is a solution outlet hole of a first water tank (WT1), 41 is a solution outlet hole of a second water tank (WT2), and 51 is a solution discharge hole in the area to be cooled.

[0020] Figure 6 Figure 6 is a comparison of cooling curves.

[0021] Figure 7 Figure 7 is a schematic diagram of a steel wire grain size detection site, wherein 71, 72, 73, and 74 are peripheral grain detection points, 81, 82, 83, and 84 are middle grain detection points, and 91, 92, 93, and 94 are central grain detection points. DETAILED DESCRIPTION

[0022] The following examples further illustrate the present application, but should not be construed as limiting the present application. Modifications and substitutions of the methods, steps or conditions described herein are considered to be within the scope of the present application, without departing from the spirit and the scope of the present application.

[0023] Example 1

[0024] A pretreatment process was added before the conventional AQ process: after the steel wire with a size of 3 mm was cleaned, it was preheated to 500°C, and then heated to 900°C and kept for 2 hours. The steel wire passed through a low-temperature water tank with a length of 10 cm and a temperature controlled at 50°C, and holes were uniformly drilled at the bottom of the water tank to ensure that the liquid surface rose smoothly when the solution circulated, and to ensure uniform cooling of the steel wire. The low-temperature water tank parameters were: length 10 cm, temperature 50°C, hole diameter 3 mm, and hole spacing 12 cm. The temperature of the mixed solution was 85°C-95°C, after the steel wire was cooled in the water tank, the temperature of the mixed solution was 95°C-105°C, and after passing through the heat exchanger, the temperature of the mixed solution was 42°C-45°C, flowed into the water tank to be cooled, and then was transported to the low-temperature water tank by the water pump to realize continuous cooling. This pretreatment process made the steel wire obtain a uniform temperature distribution before entering the AQ quenching process, thereby effectively improving the phenomenon of uneven grain in the cross section of the steel wire, realizing the homogenization of the grain structure, and at the same time, improving the solution utilization rate and reducing the cost. According to the AQ process, the steel wire was heated to 900°C and kept for 2 hours, and then was cooled in the low-temperature water tank, and then was cooled in the air to room temperature. The cooling rate of the steel wire was 10°C / s, and the cooling rate of the solution was 0.5°C / s. Figure 6The comparison of cooling curves shows that the cooling time of the present invention is significantly shorter than that of the prior art. The grain size of the steel wire was detected using a Leica microscope (500x magnification), with the detection points distributed as follows: peripheral (71, 72, 73, 74), middle (81, 82, 83, 84), and outer (91, 92, 93, 94). The detection results in Table 1 show that the uniformity of grain size has been significantly improved.

[0025] The solution in the tank from Figure 4 The water is ejected from hole 11, cooling the steel wire, and then flows into the cooling tank from both sides. Figure 4 The solution enters the cooling zone through hole 12. Subsequently, a water pump delivers the solution from the bottom of the tank, allowing it to pass through the bottom of the tank... Figure 4 The pore 11 in the middle achieves circulation, thereby realizing uniform cooling of the steel wire and improving solution utilization.

[0026] Using the apparatus of this invention, steel wire is rapidly cooled to above 400°C at a cooling rate of 80°C / s, and then slowly cooled to 350°C at a cooling rate of 10°C / h. It is then subjected to isothermal quenching at 350°C for 4 hours, and finally tempered. The production speed is 30 m / min, and the resulting steel wire exhibits a sorbite uniformity of 95%. Results show that the standard deviation of grain size decreased from 0.8 μm to 0.3 μm, bending performance improved by 12%, and both strength and toughness were significantly enhanced.

[0027] Table 1

[0028]

[0029] Example 2

[0030] The 3mm steel wire was processed according to the steps in Example 1, with the low-temperature water bath temperature adjusted to 45℃, and other parameters the same as in Example 1. Results: The grain refinement in the central region increased by 5%, and the solution circulation efficiency increased by 10%.

[0031] Example 3

[0032] The 3mm steel wire was processed according to the steps in Example 1, with the water outlet spray direction at a 45° angle to the steel wire movement direction. Results: The surface cooling uniformity of the steel wire improved by 8%, and the production line speed was further increased to 32m / min.

Claims

1. A method for homogenizing sorbite in steel wire with a diameter greater than 2.72 mm, comprising heating the steel wire to the austenitizing temperature, and then sequentially cooling it in stages through a first water tank, an air-cooling zone, and a second water tank to complete the transformation of austenite into sorbite, characterized in that... Before the steel wire passes through the first water tank, the following steps are further included: pretreating the steel wire by passing through a low-temperature water tank, the low-temperature water tank having a length of 10 cm to 20 cm and being adjustable, the solution in the low-temperature water tank being controlled at a temperature of 40 DEG C to 50 DEG C, and the bottom of the low-temperature water tank being uniformly provided with water outlet holes so that the solution rises smoothly and uniformly cools the steel wire.

2. The method of claim 1, wherein, The solution in the low-temperature water tank is a mixture of water and AquaQuench 110.

3. The method of claim 1, wherein, The water outlet holes of the low-temperature water tank have a hole diameter of 2-5 mm and a hole spacing of 10-15 cm.

4. The method of claim 1, wherein, The solution of the low-temperature water tank is circulated to the water tank to be cooled by a water pump and then back-flushed to the low-temperature water tank after cooling.

5. The method of claim 1, wherein, In the pretreatment process, the surface and center temperature difference of the steel wire is less than or equal to 50 DEG C by adjusting the cooling length.

6. The method of claim 1, wherein, The first water tank has a length of 200 cm to 300 cm and is cooled to 630 DEG C to 660 DEG C, and the second water tank has a length of 180 cm to 200 cm and is cooled to 610 DEG C to 630 DEG C.

7. The method of claim 1, wherein, The air cooling zone has a length of 65 cm to 75 cm, and the steel wire stays in the air cooling zone for 3-5 seconds.

8. A device for use in the method of any one of claims 1 to 7, characterized in that The low-temperature water tank, the first water tank (WT1), the second water tank (WT2) and the solution circulation system are sequentially connected, an air cooling zone is arranged between the first water tank and the second water tank, the low-temperature water tank is provided with uniformly distributed water outlet holes, and a water tank to be cooled is arranged outside the low-temperature water tank, the water tank to be cooled is connected with the water outlet holes in the low-temperature water tank by a water pump and a pipeline.

9. The apparatus of claim 8, wherein, The solution circulation system includes a water pump, a cooler and a flow control valve, and the solution circulation system controls the liquid flow direction and flow rate between the low-temperature water tank, the first water tank (WT1) and the second water tank (WT2) in the control device.

10. The apparatus of claim 8, wherein, The solution of the low-temperature water tank is sprayed at an angle of 30-60 DEG with respect to the movement direction of the steel wire, the flow rate is controlled at 100 L / H to 120 L / H, and the pressure is adjusted at 0.45 Pa to 0.55 Pa.

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