阅读说明：本技术 一种单机架炉卷轧机宽薄规格x60钢级管线钢及轧制方法 (Wide and thin X60 steel grade pipeline steel of single-stand steckel mill and rolling method ) 是由 殷杰 吴俊平 姜金星 杜海军 翟冬雨 贠强鹏 刘帅 赵显鹏 王凡 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种单机架炉卷轧机宽薄规格X60钢级管线钢及轧制方法,成分按重量百分比为C 0.04～0.07%,Si 0.10～0.40%,Mn 1.30～1.80%,P≤0.015%,S≤0.0050%,Nb 0.040～0.070%,V≤0.10%,Ti 0.006～0.020%,Cr 0.10～0.30%,Ni≤0.30%,Mo≤0.10%,Cu≤0.10%,Al 0.015～0.050%,余量为Fe和杂质。该轧制工艺用厚度为150mm的坯料生产成品规格(6～8)mm×(>2800)mmX60级别的宽薄规格管线钢板,通过控制出钢温度、卷取炉温度、二阶段开轧温度、粗轧末道次压下率、终轧速度、ACC冷却等,得到性能与板形符合要求的宽薄规格X60钢级管线钢板,提高了轧机产能,成材率、性能合格率高。(The invention discloses a single-stand steckel mill wide and thin X60 steel-grade pipeline steel and a rolling method, wherein the components in percentage by weight are 0.04-0.07% of C, 0.10-0.40% of Si, 1.30-1.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.0050% of S, 0.040-0.070% of Nb, less than or equal to 0.10% of V, 0.006-0.020% of Ti, 0.10-0.30% of Cr, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Mo, less than or equal to 0.10% of Cu, 0.015-0.050% of Al, and the. According to the rolling process, a finished product specification (6-8) mmX (>2800) mmX 60-grade wide and thin pipeline steel plate is produced by using a blank with the thickness of 150mm, and the wide and thin specification X60 steel-grade pipeline steel plate with the performance meeting the plate shape requirement is obtained by controlling the tapping temperature, the coiling furnace temperature, the second-stage rolling temperature, the rough rolling final pass reduction rate, the final rolling speed, ACC cooling and the like, so that the rolling mill capacity is improved, and the yield and the performance qualified rate are high.)

1. The wide and thin X60 steel grade pipeline steel for single-stand steckel mill is characterized by comprising the following components in percentage by weight: 0.04-0.07% of C, 0.10-0.40% of Si, 1.30-1.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.0050% of S, less than or equal to 0.040-0.070% of Nb0.040-0.070%, less than or equal to 0.10% of V, 0.006-0.020% of Ti, 0.10-0.30% of Cr, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Mo, less than or equal to 0.10% of Cu, 0.015-.

2. The single-stand steckel mill wide and thin gauge X60 steel grade pipeline steel as claimed in claim 1, wherein the steel plate has a thickness of 6-8 mm and a width of >2800 mm.

3. The single housing steckel mill wide and thin gauge X60 steel grade pipeline steel as claimed in claim 1, wherein the steel sheet structure is ferrite and bainite.

4. The method for rolling the wide and thin X60 steel grade pipeline steel of the single-stand steckel mill as claimed in claim 1, wherein the wide and thin X60 steel grade pipeline steel plate with the performance meeting the plate shape requirement is obtained by controlling the tapping temperature, the temperature of a coiling furnace, the second-stage starting temperature, the final reduction rate of rough rolling, the final rolling speed and ACC cooling, and specifically comprises the following steps:

1) the tapping temperature is more than or equal to 1190 ℃, the temperature uniformity of the plate blank is less than 10 ℃, and the temperature of the coiling furnace before and after the machine is more than or equal to 910 ℃;

2) the rolling passes are 13, the reduction of each pass is less than or equal to 25mm in 4 passes before rough rolling, and the reduction of the last pass of rough rolling is more than or equal to 18%;

3) the initial rolling temperature in the finish rolling stage is 1000-1030 ℃, and the thickness of a blank to be heated in the finish rolling stage is 40-50 mm;

4) the final rolling speed is more than 1.50 m/s;

5) the ACC cooling system is separated from boiling water, and the cooling rate is 5-15 ℃/s.

5. The rolling method according to claim 4, wherein the reduction speed in the middle of the finish rolling is 5.0m/s or more.

6. The rolling method according to claim 1, wherein the temperature control time in the finish rolling stage is less than 30 seconds.

7. The rolling method according to claim 1, wherein a penultimate reduction ratio of the finish rolling is less than 18% and a last reduction ratio is less than 12.5%.

Technical Field

The invention belongs to the field of steel rolling, relates to a rolling process, and particularly relates to a rolling process of wide and thin X60 steel grade pipeline steel of a single-stand steckel mill.

Background

When a 150mm thick blank is adopted by a 3500mm steckel mill to roll a (6-8) mmX (>2800) mmX60 wide and thin pipeline steel plate, the length of the blank is not more than 4.3m, the yield of the product is low, and the production efficiency is low. If the rolled piece is too long, especially when the length of the rolled piece is more than 150m, even by increasing the heating temperature and the rolling speed, the temperature of the steel plate is reduced more and more quickly along with the increase of the length of the rolled piece due to the gradual reduction of the thickness of the rolled piece in the rolling process, especially the temperature of the head and the tail of the rolled piece is reduced more and more quickly. The process temperature difference of the steel plate in the rolling direction is larger and larger, and the uniformity of the rolled plate shape and the performance of the whole plate are directly influenced. Because the strength grade of the X60 steel grade pipeline steel is higher, the head and tail temperature of a rolled piece is low in the rolling process, the difference between the head and tail rolling force and the body is larger, the rolling force of the rolling mill is abnormal, the plate shape quality is poor, the rolling is stopped quickly, the steel plate is wasted, and the production is influenced. Particularly, when the length of the rolled piece exceeds 150m, a series of problems of plate shape, performance and the like caused by overlarge temperature difference and too fast temperature drop of the rolled piece can occur. Therefore, it is a necessary matter to develop a wide and thin specification X60 steel grade pipeline steel plate.

Disclosure of Invention

The invention aims to solve the problems of improper performance and quick stop caused by poor plate shape and the like caused by too fast temperature drop and too large temperature difference of rolled pieces in a wide and thin long rolled piece pipeline steel plate in the prior art, and provides a rolling process of wide and thin X60 steel grade pipeline steel of a single-stand steckel mill. When the rolling process is used for producing wide and thin pipeline steel plates, particularly when the length of rolled pieces exceeds 150m, the heat preservation effect of a front-machine rear-crimping furnace is utilized, steel plates with wide and thin specifications (6-8) mmX (>2800) mmX60 are rolled by controlling the tapping temperature, the temperature of a coiling furnace, the temperature of a two-stage initial rolling temperature, the rolling reduction rate of the last pass of rough rolling, the final rolling speed, ACC cooling and the like, and the obtained plate shape and performance meet the requirements of related technical standards.

The purpose of the invention is realized by the following technical scheme.

The wide and thin X60 steel grade pipeline steel for single-stand steckel mill is characterized by comprising the following components in percentage by weight: 0.04-0.07% of C, 0.10-0.40% of Si, 1.30-1.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.0050% of S, less than or equal to 0.040-0.070% of Nb0.040-0.070%, less than or equal to 0.10% of V, 0.006-0.020% of Ti, 0.10-0.30% of Cr, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Mo, less than or equal to 0.10% of Cu, 0.015-.

According to the rolling method, a blank with the thickness of 150mm is adopted to produce a finished product specification (6-8) mmX (>2800) mmX 60-grade pipeline steel plate, and the wide-thin specification X60 steel-grade pipeline steel plate with the performance meeting the plate shape requirement is obtained by controlling the tapping temperature, the coiling furnace temperature, the second-stage initial rolling temperature, the rough rolling final pass reduction rate, the final rolling speed, ACC cooling and the like. The specific requirements are as follows:

1) the tapping temperature is more than or equal to 1190 ℃, the temperature uniformity of the plate blank is less than 10 ℃, and the temperature of the coiling furnace before and after the machine is more than or equal to 910 ℃;

2) the rolling passes are 13, the reduction of each pass is less than or equal to 25mm in 4 passes before rough rolling, and the reduction of the last pass of rough rolling is more than or equal to 18%;

3) the initial rolling temperature in the finish rolling stage is 1000-1030 ℃, and the thickness of a blank to be heated in the finish rolling stage is 40-50 mm;

4) the final rolling speed is more than 1.50 m/s;

5) the ACC cooling system is separated from boiling water, and the cooling rate is 5-15 ℃/s.

The structure of the pipeline steel plate rolled by the process is ferrite and bainite, and the structure ensures that the low-temperature drop hammer DWTT performance and the tensile property are qualified.

According to the invention, the equipment load of the rolling mill and the slab reheating austenitizing degree in the rough rolling stage are integrated, the slab reheating temperature is increased to be more than or equal to 1190 ℃ from 1180 ℃, and the temperature uniformity of the slab is controlled to be less than 10 ℃; the rolling adopts two-stage rolling, and the nucleation point in the austenite recrystallization process is increased by controlling the final pass reduction rate of the rough rolling, so as to achieve the effect of refining grains; in order to reduce the rolling force in the finish rolling stage, the invention adopts the steps of increasing the initial rolling temperature of the two stages from 900-980 ℃ under the normal condition to 1000-1030 ℃, increasing the temperature of the curling furnace from 850-900 ℃ of the conventional rolling process to not less than 910 ℃, and simultaneously increasing the final rolling speed of the rolling process from about 1.45m/s to more than 1.50m/s so as to achieve the effect of improving the temperature uniformity of the whole plate process and improve the mechanical property uniformity of the length of the whole rolled piece.

The invention increases rolling passes, reduces equipment load, reduces the reduction of 4 passes before rough rolling, increases the reduction rate of the last pass of the rough rolling, increases austenite nucleation points, and provides time for austenite nucleation recrystallization by adopting a weak controlled rolling process with the temperature control time of less than 30 seconds in the two-stage rolling and finish rolling stages so as to uniformly refine grains.

The rolling mill can roll the pipeline steel plate with the length of 150-200 m and the width specification (6-8) mmX (>2800) mmX60 grade by using the heat preservation function of the curling furnaces on two sides of the inlet and the outlet of the rolling mill when the pipeline steel plate with the width specification (6-8) mmX (>2800) mmX60 grade is rolled by using a blank with the thickness of 150mm, and simultaneously, the reheating temperature (tapping temperature) of the plate blank and the initial rolling temperature of the second stage (finish rolling stage) are improved on the premise of ensuring the mechanical property, and meanwhile, the property and the plate shape of the pipeline steel with the width specification (6-8) mmX (>2800) mmX60 grade are comprehensively ensured by considering the plate shape condition, reasonably arranging procedures, the final pass reduction rate of the.

The invention overcomes the defects of large fluctuation of the whole plate performance, high head-tail tensile performance, low body tensile performance, quick stop of rolling caused by poor plate shape and the like due to the fact that the temperature drop is too fast and the temperature difference between the head and the tail is too large when a 150mm blank is rolled into a pipeline steel plate with the width specification of (6-8) mmX (>2800) mmX60 grade. The single-stand steckel mill is used for rolling pipeline steel plates with wide and thin specifications (6-8) mmX (>2800) mmX60 levels in a mode of increasing the heating temperature, increasing the initial rolling temperature of the two stages, increasing the temperature of the coiling furnace, manually controlling the final pass reduction rate and the like.

The invention successfully solves the problems of quick stop of rolling of pipeline steel with the width and thickness specification of (6-8) mmX (>2800) mmX60 grade, large performance fluctuation of the whole plate and the like, can roll 150-200 m long rolled pieces, improves the production efficiency of a rolling mill, improves the productivity, and simultaneously improves the primary qualified rate of plate shape, the performance qualified rate and other indexes.

Drawings

FIG. 1 is a typical structural morphology graph and the whole tensile property of a pipeline steel plate obtained in example 1 after hot rolling under a metallographic microscope;

FIG. 2 is a typical microstructure and morphology diagram and the whole tensile property of the hot rolled pipe steel plate obtained in example 2 under a metallographic microscope.

Detailed Description