阅读说明：本技术 一种高表面质量热轧钢材的生产方法 (Production method of high-surface-quality hot-rolled steel ) 是由 张华伟 王自强 张勇 于 2020-04-21 设计创作，主要内容包括：本发明公开了一种高表面质量热轧钢材的工艺方法,包括以下步骤,S1,熔铸,坯料经熔铸后得到铸坯；S2,表面清理,采用火焰对铸坯进行表面清理；S3,粗轧,对经过步骤S2后的铸坯进行热轧得到热轧轧件；S4,除鳞,采用高压水除鳞设备对热轧轧件表面进行除鳞；S5,精轧；S6,冷却和卷取。本发明的高表面质量热轧钢材的工艺方法,通过在连铸机与第一架轧机之间增设火焰清理装置,改善板坯表面质量,同时配合轧机间高压水除鳞,实现高表面质量钢材的轧制。(The invention discloses a process method for hot rolling steel with high surface quality, which comprises the following steps of S1, casting, wherein a casting blank is obtained after casting; s2, surface cleaning, wherein flame is adopted to clean the surface of the casting blank; s3, rough rolling, namely, hot rolling the casting blank after the step S2 to obtain a hot rolled piece; s4, descaling, namely descaling the surface of the hot-rolled piece by using high-pressure water descaling equipment; s5, finish rolling; and S6, cooling and coiling. According to the process method for hot rolling the steel with high surface quality, disclosed by the invention, the flame cleaning device is additionally arranged between the continuous casting machine and the first rolling mill, so that the surface quality of the plate blank is improved, and the high-pressure water descaling between the rolling mills is matched, so that the rolling of the steel with high surface quality is realized.)

1. A process method for hot rolling steel with high surface quality is characterized by comprising the following steps:

s1, casting, wherein the blank is cast to obtain a casting blank;

s2, surface cleaning, wherein flame is adopted to clean the surface of the casting blank;

s3, rough rolling, namely rolling the casting blank after the step S2 to obtain a hot rolled piece;

s4, descaling, namely descaling the surface of the hot-rolled piece by using high-pressure water descaling equipment;

s5, finish rolling;

and S6, cooling and coiling.

2. The process of claim 1, wherein heating is provided between the step S1 and the step S2 and/or between the step S3 and the step S4.

3. The process according to claim 2, wherein the heating provided between the step S1 and the step S2 is induction heating, and the slab obtained in the step S1 is heated to a slab surface temperature of 900 ℃ or higher.

4. The process of claim 2, wherein the heating provided between the step S3 and the step S4 is secondary heating, and the hot rolled piece obtained in the step S3 is heated to a surface temperature of the hot rolled piece of not less than 850 ℃.

5. The process method according to claim 1, wherein in the step S2, when surface cleaning is performed, the surface temperature of the cast slab is 900-1000 ℃, the flame cleaning depth is 1-3 mm, and the cleaning speed is 3-40 m/min.

6. The process of claim 1, wherein in step S2, the surface is cleaned using a surface scarfing apparatus.

7. The process according to claim 1, wherein the thickness of the cast slab obtained in the step S1 is 50mm to 400 mm.

8. The process according to claim 1, wherein in step S4, the high-pressure water descaling equipment is charged into at least 1 group, the descaling pressure is 10MPa or more, and the descaling temperature is 850 ℃ or more.

Technical Field

The invention relates to a process method for hot rolling steel, in particular to a process method for hot rolling steel with high surface quality, which is mainly realized by a short-flow continuous casting and rolling hot rolling unit.

Background

A short-process continuous casting and rolling hot rolling unit comprises a plate production line, a bar and wire production line and a hot rolling steel pipe production line, and specifically means that a casting blank does not enter a blank warehouse after being cast out, but is directly fed into a hot rolling unit (or after being subjected to heat compensation) for rolling. Although the short-process continuous casting and rolling has the advantages of compact process, shortened process, energy conservation, consumption reduction and the like compared with the traditional hot continuous rolling, the surface quality of the product produced by the short-process continuous casting and rolling also has some defects, namely various surface defects such as transverse and longitudinal cracks, subcutaneous pinholes, slag inclusion, depression and the like can appear on the surface of the continuous casting billet in the continuous slab casting production process.

Because the short-process continuous casting and rolling mill set has higher pulling speed, low surface burning loss, less descaling pass, small reduction rate and other factors, the defects of surface slag inclusion, iron scale, cracks, scratches, non-rolling combination and the like are far higher than those of the traditional hot rolling, so that products with high surface quality cannot be produced, and the variety, the profit and the competitiveness of the short-process continuous casting and rolling mill set are severely restricted; although the surface quality of the product can be improved to a certain extent by means of measures of increasing the pressure of descaling water, increasing the descaling pass and the like, the temperature drop of the corner part of a casting blank can be greatly increased at the same time, so that the rolling defect is caused, and the rolled product still has surface quality difference compared with the traditional hot continuous rolling; thereby affecting the quality of the final product, including high quality automobile panels, household electrical panels, silicon steel, sheet products such as cold rolled thin sheets and ultra thin sheets, rod and wire products such as gears, bearings, cold heading, springs, gas valves, hot rolled steel pipes and other related products.

In view of the above circumstances, there is an urgent need to develop a method for improving the surface quality of products, which can overcome the defects of the surface quality of products in the rolling process of a short-process continuous casting and rolling hot rolling unit.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a process method for hot rolling steel with high surface quality.

In order to achieve the above purpose, the invention adopts the following technical scheme,

a process for hot rolling a steel product with high surface quality, comprising the steps of,

s1, casting, wherein the blank is cast to obtain a casting blank;

s2, surface cleaning, wherein flame is adopted to clean the surface of the casting blank;

s3, rough rolling, namely rolling the casting blank after the step S2 to obtain a hot rolled piece;

s4, descaling, namely descaling the surface of the hot-rolled piece by using high-pressure water descaling equipment;

s5, finish rolling;

and S6, cooling and coiling.

Preferably, heating is provided between the step S1 and the step S2 and/or between the step S3 and the step S4.

Preferably, the heating set between the step S1 and the step S2 is induction heating, and the casting blank obtained in the step S1 is heated until the surface temperature of the casting blank is not less than 900 ℃.

Preferably, the heating set between the step S3 and the step S4 is secondary heating, and the hot rolled piece obtained in the step S3 is heated until the surface temperature of the hot rolled piece is equal to or higher than 850 ℃.

Preferably, in the step S2, when surface cleaning is performed, the surface temperature of the casting blank is 900 to 1000 ℃, the flame cleaning depth is 1mm to 3mm, and the cleaning speed is 3 to 40 m/min.

Preferably, in step S2, a surface scarfing apparatus is used for surface cleaning.

Preferably, the thickness of the cast slab obtained in the step S1 is 50mm to 400 mm.

Preferably, in step S4, the high-pressure water descaling equipment is added in at least 1 group, the descaling pressure is greater than or equal to 10MPa, and the descaling temperature is greater than or equal to 850 ℃.

The invention has the beneficial effects that:

the technological method of the invention for hot rolling the steel with high surface quality fully removes various surface defects of surface transverse and longitudinal cracks, subsurface pinholes, slag inclusion, depression, iron scale and the like by additionally arranging the flame cleaning device between the continuous casting machine and the first rolling mill and matching with high-pressure water descaling after multi-pass rolling.

Drawings

Other features, objects and advantages of the present invention will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings.

FIG. 1 is a schematic process flow diagram of a process for hot rolling a high surface quality steel product according to the present invention;

FIG. 2 is a schematic view showing a part of the structure of an apparatus for a process of hot rolling a steel product with high surface quality according to the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way.

As shown in FIGS. 1 to 2, the process for hot rolling a steel product with high surface quality according to the present invention comprises the following steps,

and S1, casting, wherein the blank is subjected to a continuous casting machine 1 to obtain a casting blank 8, the casting blank 8 can be a plate blank or a square blank or a rectangular blank or a round blank, and the like, and the width (or the diameter) of the casting blank 8 is 100 mm-3000 mm, and the thickness of the casting blank is 50 mm-400 mm.

And S2, surface cleaning, namely, performing surface cleaning on the casting blank 8 prepared in the step S1 by using flame cleaning equipment 2, wherein the surface cleaning is performed at a temperature of 950-1000 ℃, a surface cleaning depth of 1-3 mm and a surface cleaning speed of 3-40 m/min, and the surface is flame cleaned by using the upper surface, the lower surface or the circumferential surface.

The flame cleaning equipment 2 utilizes the heat generated by oxygen-gas thermochemical oxidation reaction to clean the surface of the casting blank on line, thereby integrally improving the surface quality of the casting blank, improving the surface quality of a rolled product and obtaining higher benefit. The scarfing apparatus 2 may be a slab scarfing machine or other apparatus that achieves the same result.

S3, rough rolling, namely, passing the casting blank 8 obtained in the step S2 through a first rolling unit 4 to obtain a hot rolled piece 9; the number of rolling stands of the first rolling train 4 is determined as required.

S4, descaling by high-pressure water, namely descaling the upper surface and the lower surface of the hot rolled piece 9 in the step S3 by high-pressure water descaling equipment 6; the high-pressure water descaling equipment 6 is at least added into 1 group, for example, 2 groups or 3 groups, and the like, the descaling pressure is more than or equal to 10MPa, and the descaling temperature is more than or equal to 850 ℃.

S5, finish rolling, in which the hot rolled product 9 obtained in step S4 is rolled by the second rolling mill 7; wherein the number of rolling stands of the second rolling mill train 7 is determined as required.

S6, cooling and coiling, and obtaining the hot rolled steel through on-line cooling and coiling.

Heating is also provided between step S1 and step S2 and/or step S3 and step S4;

wherein the heating set between the step S1 and the step S2 is induction heating, namely the casting blank 8 prepared in the step S1 is heated by the induction heating device 3 until the surface temperature of the casting blank 8 is more than or equal to 900 ℃, so that the surface cleaning in the step S2 is facilitated; the induction heating device 3 can induce the surface temperature of the casting blank 8 in real time and heat the casting blank;

the heating set between the step S3 and the step S4 is secondary heating, that is, the hot rolled piece 9 obtained in the step S3 is heated by the induction heating device 5 until the surface temperature of the hot rolled piece 9 is not less than 850 ℃, so that the step S4 is convenient for descaling.

The induction heating device 3 and the induction heating device 5 may be a medium frequency induction heating apparatus or a high frequency induction heating apparatus or the like which can achieve the above-described effects.

The above production method is further described below by referring to specific examples.

Example 1

A process for hot rolling a steel product with high surface quality, comprising the steps of,

and S1, casting, wherein the blank is subjected to a continuous casting machine 1 to obtain a casting blank 8, and the casting blank 8 is a plate blank with the width of 1500mm and the thickness of 70 mm.

S2, surface cleaning, namely, performing surface cleaning on the casting blank 8 prepared in the step S1 by using flame cleaning equipment 2, wherein the surface temperature of the casting blank 8 is 950 ℃, the surface cleaning depth is 2mm, and the surface cleaning speed is 4 m/min;

induction heating is arranged between the step S1 and the step S2, and the surface temperature of the casting blank 8 is 950 ℃ and is more than 900 ℃, so that the casting blank does not need to be heated by the induction heating device 3.

S3, rough rolling, namely, passing the casting blank 8 obtained in the step S2 through a first rolling unit 4 to obtain a hot rolled piece 9; the number of rolling stands of the first rolling train 4 is determined as required.

S4, descaling by high-pressure water, namely descaling the upper surface and the lower surface of the hot rolled piece 9 in the step S3 by high-pressure water descaling equipment 6; the high-pressure water descaling equipment 6 is put into 1 group, and the descaling pressure is 30 MPa.

The secondary heating is provided between the step S3 and the step S4, and the hot rolled sheet 9 obtained in the step S3 is heated to 1000 ℃ by the second induction heating device 5, so that the high-pressure water descaling in the step S4 is facilitated.

And S5, finish rolling, in which the hot rolled product 9 obtained in the step S4 is rolled by the second rolling mill 7.

S6, cooling and coiling, and obtaining the hot rolled steel through on-line cooling and coiling.

The rolled steel reaches the high surface quality standard, the defects of slag inclusion, iron scale and the like on the surface of the rolled steel are removed completely, and the surface quality is high.

Example 2

A process for hot rolling a steel product with high surface quality, comprising the steps of,

and S1, casting, wherein the blank is subjected to a continuous casting machine 1 to obtain a casting blank 8, and the casting blank 8 is a square blank with the width of 1300mm and the thickness of 70 mm.

S2, surface cleaning, namely, performing surface cleaning on the casting blank 8 prepared in the step S1 by using flame cleaning equipment 2, wherein the surface temperature of the casting blank 8 is 950 ℃, the surface cleaning depth is 2mm, and the surface cleaning speed is 5 m/min;

induction heating is arranged between the step S1 and the step S2, and the surface temperature of the casting blank 8 is 950 ℃ and is more than 900 ℃, so that the casting blank does not need to be heated by the induction heating device 3.

S3, rough rolling, namely, passing the casting blank 8 obtained in the step S2 through a first rolling unit 4 to obtain a hot rolled piece 9; the number of rolling stands of the first rolling train 4 is determined as required.

S4, descaling by high-pressure water, namely descaling the upper surface and the lower surface of the hot rolled piece 9 in the step S3 by high-pressure water descaling equipment 6; the high-pressure water descaling equipment 6 is put into 1 group, and the descaling pressure is 30 MPa.

Secondary heating is arranged between the step S3 and the step S4, and the hot rolled plate 9 obtained in the step S3 is heated to 950 ℃ through the second induction heating device 5, so that high-pressure water descaling in the step S4 is facilitated.

And S5, finish rolling, in which the hot rolled product 9 obtained in the step S4 is rolled by the second rolling mill 7.

S6, cooling and coiling, and obtaining the hot rolled steel through on-line cooling and coiling.

The rolled steel reaches the high surface quality standard, the defects of slag inclusion, iron scale and the like on the surface of the rolled steel are removed completely, and the surface quality is high.

Example 3

A process for hot rolling a steel product with high surface quality, comprising the steps of,

and S1, casting, wherein the blank is subjected to a continuous casting machine 1 to obtain a casting blank 8, and the casting blank 8 is a square blank with the width of 1500mm and the thickness of 50 mm.

S2, surface cleaning, namely, performing surface cleaning on the casting blank 8 prepared in the step S1 by using flame cleaning equipment 2, wherein the surface temperature of the casting blank 8 is 950 ℃, the surface cleaning depth is 1.2mm, and the surface cleaning speed is 6 m/min;

induction heating is arranged between the step S1 and the step S2, and the surface temperature of the casting blank 8 is 950 ℃ and is more than 900 ℃, so that the casting blank does not need to be heated by the induction heating device 3.

And S3, rough rolling, namely, passing the casting blank 8 obtained in the step S2 through a first rolling mill unit 4 to obtain a hot rolled product 9.

S4, descaling by high-pressure water, namely descaling the upper surface and the lower surface of the hot rolled piece 9 in the step S3 by high-pressure water descaling equipment 6; 2 groups of high-pressure water descaling equipment 6 are put into the device, and the descaling pressure is 30 MPa.

The secondary heating is provided between the step S3 and the step S4, and the hot rolled sheet 9 obtained in the step S3 is heated to 1000 ℃ by the second induction heating device 5, so that the high-pressure water descaling in the step S4 is facilitated.

And S5, finish rolling, in which the hot rolled product 9 obtained in the step S4 is rolled by the second rolling mill 7.

S6, cooling and coiling, and obtaining the hot rolled steel through on-line cooling and coiling.

The rolled steel reaches the high surface quality standard, the defects of slag inclusion, iron scale and the like on the surface of the rolled steel are removed completely, and the surface quality is high.

Example 4

A process for hot rolling a steel product with high surface quality, comprising the steps of,

and S1, casting, wherein the blank is subjected to a continuous casting machine 1 to obtain a casting blank 8, and the casting blank 8 is a square blank with the width of 1300mm and the thickness of 70 mm.

S2, surface cleaning, namely, performing surface cleaning on the casting blank 8 prepared in the step S1 by using flame cleaning equipment 2, wherein the surface temperature of the casting blank 8 is 950 ℃, the surface cleaning depth is 2mm, and the surface cleaning speed is 5 m/min;

induction heating is provided between step S1 and step S2, and the surface temperature of the cast slab 8 is 880 ℃.

S3, rough rolling, namely, passing the casting blank 8 obtained in the step S2 through a first rolling unit 4 to obtain a hot rolled piece 9; the number of rolling stands of the first rolling train 4 is determined as required.

S4, descaling by high-pressure water, namely descaling the upper surface and the lower surface of the hot rolled piece 9 in the step S3 by high-pressure water descaling equipment 6; the high-pressure water descaling equipment 6 is put into 1 group, and the descaling pressure is 30 MPa.

The secondary heating is provided between the step S3 and the step S4, and the hot rolled sheet 9 obtained in the step S3 is heated to 950 ℃ by the induction heating device 3, so that the high-pressure water descaling in the step S4 is facilitated.

And S5, finish rolling, in which the hot rolled product 9 obtained in the step S4 is rolled by the second rolling mill 7.

S6, cooling and coiling, and obtaining the hot rolled steel through on-line cooling and coiling.

The rolled steel reaches the high surface quality standard, the defects of slag inclusion, iron scale and the like on the surface of the rolled steel are removed completely, and the surface quality is high.

Comparative example 1

The process conditions in the other steps were the same as in example 3, and only when the surface cleaning depth was 0mm in step S2, the surface cleaning was not performed, and the surface of the produced steel was dark and poor in surface quality.

Comparative example 2

The process conditions in the other steps were the same as in example 3, and only when the surface cleaning depth was 0.3mm in step S2, the surface of the produced steel was dark and the surface quality was relatively poor.

Comparative example 3

When the process conditions in the other steps are the same as those in example 2, the surface temperature of the hot-rolled product 9 is 800 ℃ before the descaling is performed in step S4, and heating is not performed; the surface temperature of the hot rolled piece 9 is 800 ℃ when the high-pressure water is used for descaling, and is less than the lower limit 850 ℃ of the descaling temperature. At this time, the produced hot rolled steel has iron scale on the surface, and has darker color and poorer surface quality.

Comparative example 4

When the process conditions in the other steps are the same as those in example 2, in step S4, the hot rolled product 9 is not subjected to high-pressure water descaling, and the produced hot rolled steel has scale on the surface, dark surface color, and poor surface quality.

Comparative example 5

When the process conditions in the other steps are the same as those in example 2, in step S2, the surface temperature of the cast slab 8 is 870 ℃ before surface cleaning, and heating is not performed; the surface temperature of the casting blank 8 is 800 ℃ during surface cleaning, and is less than the lower limit 900 ℃ of the surface cleaning temperature. Because the rolling temperature of the casting blank is lower, iron scales are broken, so that the iron scales exist on the surface of the steel produced under the condition, the color is darker, and the surface quality is poorer.

In summary, in the embodiments 1 to 3, when the casting blank 8 is subjected to flame cleaning, the surface temperature reaches 900 to 1000 ℃, the surface cleaning depth is 1 to 3mm when the flame surface is cleaned, the surface cleaning speed is 3 to 40m/min, the steel produced in the embodiments 1 to 3 has no slag inclusion and iron scale on the surface, and the surface quality is high; in the comparative example 1, the casting blank 8 is not subjected to surface cleaning, so that the produced steel has dark surface and relatively poor surface quality; when the casting blank 8 in the comparative example 2 is subjected to flame cleaning, the surface cleaning depth is 0.3mm and is smaller than the lower limit of the flame surface cleaning depth in the process method, and the produced steel has iron scale on the surface, is darker in color and poor in surface quality; compared with the prior art, when the hot-rolled piece 9 is descaled in the comparative example 3, the surface temperature is 800 ℃, which is less than the lower limit of the descaling temperature in the process method, and the produced steel has iron scales on the surface, darker color and poor surface quality; compared with the prior art, the hot-rolled product 9 in the comparative example 4 is not descaled by high pressure water, and the produced steel has the defects of iron scale on the surface, darker surface color and poor surface quality; in the comparative example 5, when the surface of the casting blank 8 is cleaned, the surface temperature is 800 ℃, which is less than the lower limit of the surface cleaning temperature in the process method, and the produced steel has iron scale on the surface, darker color and poorer surface quality.

According to the process method for hot rolling the steel with high surface quality, disclosed by the invention, the flame surface cleaning equipment is additionally arranged between the continuous casting machine and the first rolling mill, and the high-pressure water descaling equipment between the rolling mills is matched, so that slag inclusion, iron scale, cracks, depressions and the like on the surface of the steel can be removed, and the rolling of the steel with high surface quality is realized.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.