CN116213454A - A rolling method for avoiding round drawing and breaking of steel discs caused by mixed crystals - Google Patents

Abstract

The invention provides a rolling method for avoiding drawing breakage of a steel disc circle caused by mixed crystal, which comprises the following steps: the composition of the steel is optimized, and narrow composition control of C, si and Mn is ensured, so that the stability of mechanical properties is ensured; and a second step of: controlling the ring difference of the steel disc; and a third step of: optimizing a cooling process, and rolling at 980-1020 ℃ in a high-line rolling start temperature; in the air cooling stage, the length of a stelmor air cooling line is 97 m; the stability of chemical components of the product is improved through narrow component control, and the performance difference caused by large component fluctuation is reduced; the fan is additionally provided with a jialing device, so that the air quantity distribution is optimized, the cooling effect at the wire rod lap joint point is improved, and the wire rod performance and the drawing performance are improved; the cooling uniformity of the steel disc circle is improved by optimizing the process temperature control and the air-cooled roller way cooling process, the same circle difference of the steel disc circle is within 20MPa, the grain size difference is within 0.5 level, the performance temperature is high, the drawing breaking problem caused by mixed crystal is solved, and the use requirement of a user is met.

Description

A rolling method for avoiding round drawing and breaking of steel discs caused by mixed crystals

technical field

The invention relates to the technical field of metal rolling, in particular to a rolling method for avoiding round drawing and breaking of steel discs caused by mixed crystals.

Background technique

Panyuan, also known as wire rod, is a commonly used name in construction engineering, which means steel bars with a diameter of less than 10 mm. Because steel bars less than 10 mm are easy to bend, in order to reduce the length before transportation, manufacturers roll very long steel bars into circular rings. On construction sites, such steel bars are referred to as coils for short.

The existing production of 45# steel 6.5 discs is broken during the drawing process of the user. During the process of handling quality objections, the broken sample of the light round during the drawing process was retrieved. Through electron microscope and metallographic analysis, the steel billet Inclusions (silicates) and the coarse grain size or mixed crystals of the finished steel structure are the main reasons for the fracture of 45# steel during the drawing process. The slag inclusions in the steel billet are removed through protective pouring and argon blowing during the steelmaking process to ensure the purity of molten steel. Therefore, there is a need for a rolling method that avoids the round drawing and breaking of the steel disc caused by mixed crystals, so as to solve the above technical problems.

Contents of the invention

The object of the present invention is to provide a rolling method that avoids the steel disc round drawing and breaking caused by mixed crystals, so as to solve the above-mentioned problems in the background technology.

In order to achieve the above object, the present invention provides the following technical solution: a rolling method for avoiding the round drawing and breaking of steel discs caused by mixed crystals, comprising the following steps:

The first step: optimize the composition of the steel to ensure the narrow composition control of C, Si and Mn, so as to ensure the stability of mechanical properties;

The second step: Control the circle difference of the steel plate circle, through the technical transformation of the air-cooled track and the installation of a Jialing device, optimize the air volume distribution, increase the cooling air volume at the lap joint, and evenly cool the wire rod in the same circle, and solve the problem of the steel plate During the cooling process of the circle in the air-cooled track, there is a problem of mixed crystals at the overlapping points of the same circle;

The third step: optimize the cooling process. In the rolling stage, the high-wire rolling start temperature is 980-1020°C; the inlet temperature of the finishing mill is 850-880°C; the inlet temperature of the reducing sizing mill is 800-850°C; the spinning temperature is 720°C -780°C; the final rolling exit speed is 105m/s; the diameter of the finished steel disc is 6.5mm;

In the air-cooling stage, the Stelmo air-cooling line is 97 meters long, and there are 7 groups of fans in total. The air volume of 1-3# fans is 240000m3/h, the air volume of 4-7# fans is 180000m3/h, and the 1-7# fans are on ( %) is 95%, 95%, 95%, 95%, 95%, 95%, 95%; the insulation cover is fully opened.

Preferably, the composition of the steel includes C, Si, Mn, P, S, Cr, Ni and Cu, wherein the content of C is 0.44-0.48%, the content of Si is 0.18-0.30%, and the content of Mn is 0.50% -0.70%, P content≤0.030%, S content≤0.030%, S content≤0.25%, Ni content≤0.30%, Cu content≤0.25%.

Preferably, the Stelmo air-cooled line also includes 13 sets of roller tables, the initial speed of the roller tables is 0.93m/s, and two-stage control is adopted. The front stage adopts a certain extreme difference to gradually accelerate, and the rear stage rollers The road adopts a certain range and gradually decelerates.

Preferably, in the two-stage control, the front stage adopts a certain extreme difference to gradually accelerate, so as to ensure that the wire rod is pulled apart, the overlapping points are not fixed, the same-turn difference is reduced, the cooling rate is increased, and abnormal precipitation of ferrite is avoided; In the back section of the roller table, a certain extreme difference is adopted to gradually decelerate to ensure that the wire rod forms a stacking effect and slowly cools down, reducing the residual stress of the wire rod.

Compared with the prior art, the beneficial effect of the present invention is: the rolling method avoids the steel disc round drawing and breaking caused by the mixed crystal, through the narrow composition control, the stability of the chemical composition of the product is improved, and the fluctuation of the composition is reduced. The performance difference caused by the large size is large; the fan is equipped with a Jialing device to optimize the air volume distribution, improve the cooling effect at the lap joint of the wire rod, solve the defects such as high temperature tissue growth and mixed crystals caused by the lap joint, and improve the uniformity of the structure, thereby Improve passability and drawing performance; by optimizing process temperature control and air-cooled roller table cooling process, the cooling uniformity of the steel disc circle is improved. The difference between the same circle of the steel disc circle is within 20MPa, the structure is uniform, and the grain size difference is within 0.5 grade range Within the performance temperature, it solves the problem of pulling and breaking caused by mixed crystals, and meets the requirements of users.

Description of drawings

Fig. 1 is that the present invention uses the table of every parameter change table of steel disc circle after using this method;

Fig. 2 is a steel composition optimization table of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The present invention provides an embodiment: a rolling method for avoiding the round drawing and breaking of steel discs caused by mixed crystals, comprising the following steps:

The first step: optimize the composition of the steel to ensure the narrow composition control of C, Si, and Mn, so as to ensure the stability of mechanical properties; the stability of the drawing force during the drawing process of the user reduces the uneven wear of the drawing abrasive and causes fractures occur.

The second step: Control the circle difference of the steel plate circle, through the technical transformation of the air-cooled track and the installation of a Jialing device, optimize the air volume distribution, increase the cooling air volume at the lap joint, and evenly cool the wire rod in the same circle, and solve the problem of the steel plate During the cooling process of the circle in the air-cooled track, there is a problem of mixed crystals at the overlapping points of the same circle;

The third step: optimize the cooling process. In the rolling stage, the high-wire rolling start temperature is 980-1020°C; the inlet temperature of the finishing mill is 850-880°C; the inlet temperature of the reducing sizing mill is 800-850°C; the spinning temperature is 720°C -780°C; the final rolling exit speed is 105m/s; the diameter of the finished steel disc is 6.5mm;

In the air-cooling stage, the Stelmo air-cooling line is 97 meters long, and there are 7 groups of fans in total. The air volume of 1-3# fans is 240000m3/h, the air volume of 4-7# fans is 180000m3/h, and the 1-7# fans are on ( %) is 95%, 95%, 95%, 95%, 95%, 95%, 95%; the insulation cover is fully opened.

In this implementation: the second step is to control the ring difference of the steel disc circle. During the production process of the 45# steel 6.5 disc circle, samples are taken to analyze and compare the mechanical properties and metallographic structure of the same circle, and it is found that the mechanical properties of the same circle of 45 steel The difference in performance is large, and the comparative analysis of the metallographic structure found that the mechanical properties of the lap joints on the air-cooled rails are low. Through the technical transformation of the air-cooled rails and the installation of Jialing devices, the air volume distribution is optimized to improve the cooling of the lap points. The air volume and the uniform cooling speed of the wire rod in the same circle solve the problem of mixed crystals at the lap joints of the 45# steel in the cooling process of the air-cooled track. The performance difference between the disk and the circle is reduced from more than 50MPa to less than 20MPa, and the uniform grain size of the structure is about 0.5 grades.

Further, the composition of the steel includes C, Si, Mn, P, S, Cr, Ni and Cu, wherein the content of C is 0.44-0.48%, the content of Si is 0.18-0.30%, and the content of Mn is 0.50- 0.70%, P content ≤ 0.030%, S content ≤ 0.030%, S content ≤ 0.25%, Ni content ≤ 0.30%, Cu content ≤ 0.25%.

In this implementation: the components of the steel are controlled to ensure the stability of the mechanical properties; the stability of the drawing force during the user's drawing process reduces the occurrence of fractures caused by uneven wear of the drawing abrasives.

Further, the Stelmore air-cooled line also includes 13 sets of roller tables. The initial speed of the roller tables is 0.93m/s, and two-stage control is adopted. Use a certain range to gradually decelerate.

Further, in the two-stage control, the front stage adopts a certain extreme difference to gradually accelerate to ensure that the wire rod is pulled apart, the overlapping point is not fixed, the same circle difference is reduced, the cooling rate is increased, and the abnormal precipitation of ferrite is avoided; The rear section of the roller table adopts a certain extreme difference to gradually decelerate to ensure that the wire rod forms a stacking effect and cools slowly, reducing the residual stress of the wire rod.

In this implementation: by optimizing the process temperature control and the cooling process of the air-cooled roller table, the cooling uniformity of the product is improved. Thereby improving the cleaning rod performance.

This application: through narrow composition control, improve the stability of the chemical composition of the product, reduce the large performance difference caused by the large fluctuation of the composition; install the Jialing device through the fan, optimize the air volume distribution, and improve the cooling effect at the overlapping point of the wire rod. Solve defects such as high temperature tissue growth and mixed crystals caused by lap joints, improve the uniformity of the structure, thereby improving the passability and drawing performance; by optimizing the process temperature control and the cooling process of the air-cooled roller table, the cooling uniformity of the steel disc circle is improved High performance, the difference between the circle and the circle of the steel plate is within 20MPa, the structure is uniform, the difference in grain size is within 0.5 grades, and the performance temperature solves the problem of pulling and breaking caused by mixed crystals and meets the requirements of users.

Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or perform equivalent replacements for some of the technical features. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (4)

1. A rolling method for avoiding drawing breakage of a steel disc circle caused by mixed crystal is characterized by comprising the following steps: the method comprises the following steps:

the first step: the composition of the steel is optimized, and narrow composition control of C, si and Mn is ensured, so that the stability of mechanical properties is ensured;

and a second step of: the method comprises the steps of controlling the ring difference of the steel disc, improving the cooling air quantity distribution of the lap joint points by adding a Jialing device to the air-cooled rail through technical improvement, and solving the problem that mixed crystals appear in the lap joint points of the steel disc in the cooling process of the air-cooled rail, wherein the cooling air quantity distribution of the lap joint points is improved, and the cooling speed of the steel disc is uniform;

and a third step of: optimizing a cooling process, and rolling at 980-1020 ℃ in a high-line rolling start temperature; the inlet temperature of the finishing mill is 850-880 ℃; the inlet temperature of the reducing sizing mill is 800-850 ℃; the spinning temperature is 720-780 ℃; the final rolling outlet speed is 105m/s; the diameter of the steel disc round finished product is 6.5mm;

in the air cooling stage, the length of a Steyr air cooling line is 97 meters, 7 groups of fans are provided, the air quantity of 1-3# fans is 240000m < 3 >/h, the air quantity of 4-7# fans is 180000m < 3 >/h, and the starting states (%) of 1-7# fans are 95%, 95% and 95%; the heat preservation cover is fully opened.

2. The rolling method for avoiding drawing breakage of the steel disc circle caused by mixed crystal according to claim 1, wherein the rolling method comprises the following steps: the steel comprises C, si, mn, P, S, cr, ni and Cu, wherein the content of C is 0.44-0.48%, the content of Si is 0.18-0.30%, the content of Mn is 0.50-0.70%, the content of P is less than or equal to 0.030%, the content of S is less than or equal to 0.25%, the content of Ni is less than or equal to 030%, and the content of Cu is less than or equal to 0.25%.

3. The rolling method for avoiding drawing breakage of the steel disc circle caused by mixed crystal according to claim 2, wherein the rolling method comprises the following steps: the Steyr air cooling line also comprises 13 groups of roller ways, the initial speed of the roller ways is 0.93m/s, two-stage control is adopted, the front stage is gradually accelerated by a certain range, and the rear stage is gradually decelerated by a certain range.

4. A rolling method for avoiding breakage of a steel disc round by mixed crystal according to claim 3, characterized in that: the two-stage control is carried out, the front stage is gradually accelerated by a certain range, the wire rod is pulled open, the lap joint is not fixed, the same-circle difference is reduced, the cooling speed is increased, and abnormal precipitation of ferrite is avoided; and the rear roller way is gradually decelerated by a certain range, so that the coil is guaranteed to form a stacking effect and be slowly cooled, and the residual stress of the coil is reduced.

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