A hot-rolled high-speed wire on-line spheroidizing production process

Abstract

The application discloses a hot-rolling high-speed wire rod on-line sorbitizing production process. The process comprises the following steps: heating, rolling, rapid cooling, low-temperature wire laying, on-line sorbitizing, collecting and winding and PF line cooling. The final rolling temperature is 750-1000 DEG C; then multiple rapid cooling is adopted, and the surface temperature is controlled to be not lower than 550 DEG C; the wire laying temperature is 600-650 DEG C, the wire rod product is transformed from austenite to sorbite by keeping the temperature for 30-150 s on the air-cooling roller way; then the wire rod product is air-cooled on the air-cooling roller way and collected and wound, and the PF line continues to cool for not less than 20 min. Through the control of the temperature in the whole process, the material structure is controlled under the optimal undercooling degree and temperature combination condition. The application can be used for producing products with a required sorbite content. The application is simple and easy to implement, has obvious production cost advantages and has wide popularization prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-speed wire and large coil rolling, in particular to a hot-rolling high-speed wire on-line sorbitizing production process and device. BACKGROUND

[0002] With the development of light-weight materials for industrial wire and the increasing environmental protection requirements, the high-strength and high-performance direction is gradually developed. In particular, the cord steel processing procedure is complex, the wire rod is subjected to multi-pass drawing, and the total reduction rate is more than 99.0%, which is close to the limit of the drawing process, so that the sorbitizing rate of the wire rod is required to be extremely high.

[0003] The traditional production process often needs to set a hot-rolling on-line salt bath or off-line salt bath sorbitizing treatment, which increases energy consumption and significantly increases production cost. Or a large air volume cooling process is used on the Stelmor air cooling line, and the product quality stability is not high, especially the control of the wire rod temperature and performance difference often cannot meet the control index.

[0004] Therefore, it is an urgent requirement to further optimize and adjust the hot-rolling high-speed wire and large coil on-line sorbitizing production process, realize the control of the material organization under the optimal supercooling degree and temperature combination condition, improve the production stability, reduce the cost and improve the product competitiveness. SUMMARY

[0005] In order to overcome the above defects, the purpose of the present application is to provide a hot-rolling high-speed wire on-line sorbitizing production process, which can effectively and stably improve the sorbite organization content and control stability.

[0006] In order to achieve the above purpose, the hot-rolling high-speed wire on-line sorbitizing production process of the present application comprises rolling, rapid cooling, low-temperature wire drawing, on-line sorbitizing, coil collecting and PF line cooling.

[0007] The rapid cooling step is to set the cooling capacity of the water tank to be not less than 350℃, control the surface temperature of the rolled piece to be not less than 550℃, the wire drawing or coiling temperature to be 600-650℃, and the temperature difference of the same batch to be ±15℃.

[0008] Further, the rapid cooling refers to reducing the temperature of the rolled piece to the sorbite production temperature range of 600-650℃ within 3s.

[0009] Further, the on-line sorbitizing step is specifically:

[0010] The high-speed wire is cooled for 30-150s on the air-cooling line after being spun or formed into a loop, the front section of the cooling cover is completely closed, and the roller running speed is 0.2-2m / s; the wire product is cooled for 30-150s on the air-cooling roller to complete the transformation from austenite to sorbite, and the sorbite content is greater than or equal to 92%.

[0011] Further, the coiling and PF line cooling are completed to cool in air to below 80 DEG C, which is convenient for inspection sampling, cutting head and tail and warehousing.

[0012] Further, the time for cooling the wire coil on the PF line is not less than 20min.

[0013] Further, the rolling process is as follows: two processes of austenite zone rolling and dual-phase zone rolling are adopted, and the deformation amount of final rolling is controlled to be 30-60%; the rolling temperature difference of the same batch is ± 15 DEG C in the two-phase zone rolling temperature of Ar1-Ar3 or Ar1-Arcm; and the rolling temperature difference of the same batch is ± 15 DEG C in the austenite zone rolling temperature of Ar3-1000 DEG C.

[0014] Further, the rapid cooling process adopts a plurality of annular Venturi nozzles, 6-9 groups of which are arranged in a closed box, and the outlet and the inlet adopt water seal and air seal to prevent steam and water from being taken out of the water tank; 3-5 sets of such water tanks are arranged, and the cooling capacity is not less than 350 DEG C; a surface detection device is arranged in the cooling area to control the surface temperature of the rolled piece to be not less than 550 DEG C, the spinning or loop forming temperature is 600-650 DEG C, and the rolling temperature difference of the same batch is ± 15 DEG C.

[0015] The present application controls the generation of internal sorbite structure by controlling the heating, rolling, rapid cooling, online sorbite treatment and PF line cooling processes in the production process of high-speed wire, and improves the strength, plasticity, toughness and drawing performance of the material. The hot-rolled wire rod produced by the present application has a sorbite rate of greater than or equal to 92%, no large network cementite and pro-eutectoid ferrite, and high purity, which can meet the requirements of high-strength steel cord drawing and low-alloy components for building steel. DETAILED DESCRIPTION

[0016] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0017] The terms "first", "second", "third", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an ordered ranking of the indicated technical features. Thus, features defined with "first", "second" etc. can explicitly or implicitly include one or more of such features. In the description of the application, the meaning of "a plurality of" is two or more, unless otherwise specified or limited.

[0018] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0019] The purpose of the rolling process of the present application is to obtain a fine and uniform rolled structure by rolling the steel material in the finish rolling pass at low temperature austenite zone or dual phase zone. The rolling deformation temperature is reduced, which reduces the stability of the supercooled austenite, and prepares the structure for sorbite formation. Therefore, the deformation amount of the final rolling is controlled at 30-60%; the rolling temperature in the two-phase zone is Ar1-Ar3 or Ar1-Arcm, and the rolling temperature difference of the same batch is ±15℃; the austenite zone rolling temperature is Ar3-1000℃, and the rolling temperature difference of the same batch is ±15℃.

[0020] The online sorbitizing treatment is designed in three stages: the first stage is rapid cooling, the cooling capacity of the water tank is not less than 350℃, the surface temperature of the rolled piece is controlled to be not less than 550℃, the spinning or looping temperature is 600-650℃, and the rolling temperature difference of the same batch is ±15℃. The temperature of the rolled piece is rapidly reduced to the sorbite production temperature range of 600-650℃ within 3s, and the surface temperature is controlled to prevent the generation of other organizational states.

[0021] The second stage is to complete the sorbite transformation in the range of 600-650℃. The high-speed wire is cooled on the air cooling line for 30-150s after spinning or looping, the front section of the heat preservation cover is completely closed, and the roller running speed is 0.2-2m / s. The wire product is transformed from austenite to sorbite by keeping the temperature on the air cooling roller for 30-150s, and the sorbite content is ≥92%.

[0022] The third stage is the collection of the coil and the cooling of the PF line, which completes the cooling in the air to below 80℃, facilitating inspection, sampling, cutting of head and tail, and storage. The coil is cooled on the PF line after being collected, and the cooling time is not less than 20min.

[0023] The above-mentioned hot rolling high-speed wire on-line sorbitizing production process is a hot rolling high-speed wire or large coil with a diameter of Φ4.0-45mm.

[0024] Specifically, the hot-rolled high-speed wire in-line sorbitizing production process of the application comprises the following steps: heating, rolling, rapid cooling, low-temperature wire drawing, in-line sorbitizing, coil collecting and PF line cooling.

[0025] The rolling process adopts two processes of austenite zone rolling and dual-phase zone rolling, and the final rolling deformation is controlled at 30-60%; the final rolling pass is at a two-phase zone rolling temperature of Ar1-Ar3 or Ar1-Arcm, and the rolling temperature difference of the same batch is ±15℃; the final rolling pass is at an austenite zone rolling temperature of Ar3-1000℃, and the rolling temperature difference of the same batch is ±15℃.

[0026] The rapid cooling process adopts multiple-section ring-shaped Venturi nozzles, 6-9 groups of which are placed in a closed box, and the outlet and inlet are provided with water seal and air seal to prevent steam and water from being taken out of the water tank; 3-5 sets of such water tanks are provided, and the cooling capacity is not less than 350℃; a surface detection device is arranged in the cooling zone to control the surface temperature of the rolled piece to be not less than 550℃, the wire drawing or looping temperature is 600-650℃, and the rolling temperature difference of the same batch is ±15℃.

[0027] The in-line sorbitizing process is characterized in that: the high-speed wire is kept for 30-150s on the air-cooling line after looping by the wire drawing machine, the front section 25-45m of the heat preservation cover is completely closed, and the roller running speed is 0.2-2m / s.

[0028] After the coil is collected, the wire is cooled in the PF line for not less than 20min.

[0029] Example 1

[0030] The hot-rolled high-speed wire in-line sorbitizing production process of the embodiment comprises the following steps.

[0031] (1) Rolling: The rolling process adopts continuous untwisted rolling, and the final rolling pass is 4 stands, including 2 stands of reducing mill and 2 stands of sizing mill; the cross-sectional size before rolling is Φ12.5mm, the finished product size after rolling is Φ10.0mm, and the final rolling temperature is 850-880℃.

[0032] (2) On-line spheroidizing treatment: after rolling, open the water tank with 3 sets of water tank, control the surface temperature of the rolled piece to be not lower than 550°C, send it to the wire rod laying machine within 3s, the wire rod laying temperature is 630-650°C; after the high-speed wire rod is formed into a coil by the wire rod laying machine, keep it on the air cooling line for 60s, close the front 40m of the heat preservation cover, gradually raise the speed of the first to ninth roller beds, the speed is 0.2-0.8m / s.

[0033] (3) The diameter of the rod in this embodiment is Φ10.0mm, the chemical composition is C: 0.85-0.90%, Mn: 0.40-0.60%, Si: 0.15-0.30%, P: ≤0.012%, S: ≤0.012%, O ≤0.0020%, [N] ≤0.0045%, the balance is Fe and inevitable impurities. The hot-rolled state organization is mainly sorbite, the content is ≥92%, the grain size is 9.0 level.

[0034] Example 2

[0035] The hot-rolled high-speed wire rod in this embodiment is produced by the on-line spheroidizing process, which includes the following steps.

[0036] (1) Rolling: continuous untwisted rolling is adopted in the whole rolling process, the final rolling pass is 4 stands, including 2 stands of reducing mill and 2 stands of sizing mill; the cross-sectional size before rolling is Φ11.5mm, the finished product size is Φ8.0mm, and the final rolling temperature is 750-780°C.

[0037] (2) On-line spheroidizing treatment: after rolling, open the water tank with 2 sets of water tank, control the surface temperature of the rolled piece to be not lower than 550°C, send it to the wire rod laying machine within 3s, the wire rod laying temperature is 600-630°C; after the high-speed wire rod is formed into a coil by the wire rod laying machine, keep it on the air cooling line for 30s, close the front 24m of the heat preservation cover, gradually raise the speed of the first to sixth roller beds, the speed is 0.5-1.2m / s.

[0038] (3) The diameter of the rod in this embodiment is Φ8.0mm, the chemical composition is C: 0.20-0.25%, Mn: 0.8-0.95%, Si: 0.15-0.30%, P: ≤0.013%, S: ≤0.020%, O ≤0.0020%, [N] ≤0.0045%, the balance is Fe and inevitable impurities. The hot-rolled state organization is ferrite-sorbite, the grain size is 9.0 level, the yield strength is 510-530MPa, the tensile strength is 600-630MPa, and the elongation is 1.25.

[0039] In the description of this specification, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0040] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An in-line martensitic production process for hot-rolled high-speed wire rod, characterized in that, The process includes: rolling, rapid cooling, low-temperature spinning, in-line martensitization, coiling, and PF line cooling. The rapid cooling steps are as follows: the cooling capacity of the water tank is set to be no less than 350℃, the surface temperature of the rolled piece is controlled to be no less than 550℃, the wire drawing or coiling temperature is 600-650℃, and the temperature difference between rolling batches is ±15℃. The rapid cooling mentioned above refers to reducing the temperature of the rolled piece to the sorbite production temperature range of 600-650℃ within 3 seconds; The specific steps of the in-line steatidization are as follows: After the high-speed wire is coiled or rolled, it is kept warm on the air-cooled line for 30-150 seconds. The front 25-45m of the heat preservation cover is completely closed, and the roller conveyor runs at a speed of 0.2-2m / s. The heat preservation time on the air-cooled roller conveyor is 30-150 seconds, so that the wire product can complete the transformation from austenitic to sorbite, with a sorbite content of ≥92%. The aforementioned winding and PF line cooling process completes the cooling to below 80°C in air, facilitating inspection, sampling, head and tail trimming, and warehousing. After the wire is coiled, the cooling time on the PF wire should be no less than 20 minutes. The rolling process is as follows: two processes are used: austenitic rolling and two-phase rolling. The final rolling deformation is controlled at 30-60%. The rolling temperature in the two-phase region of the final rolling pass is Ar1-Ar3 or Ar1-Arcm, with a rolling temperature difference of ±15℃ within the same batch. The rolling temperature in the austenitic region of the final rolling pass is Ar3-1000℃, with a rolling temperature difference of ±15℃ within the same batch. The rapid cooling process employs multi-segment annular venturi nozzles, with 6-9 sets placed inside a closed chamber. Water and air seals are used at the outlet and inlet to prevent steam and water from being carried out of the water tank. 3-5 such water tanks are installed, with a cooling capacity of not less than 350℃. A surface detection device is installed in the cooling zone to control the surface temperature of the rolled piece to be not lower than 550℃, the wire drawing or coiling temperature to be 600-650℃, and the temperature difference within the same batch of rolling to be ±15℃.