CN109022734B - Online heat treatment device and method for strip steel - Google Patents
Online heat treatment device and method for strip steel Download PDFInfo
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- CN109022734B CN109022734B CN201811030454.8A CN201811030454A CN109022734B CN 109022734 B CN109022734 B CN 109022734B CN 201811030454 A CN201811030454 A CN 201811030454A CN 109022734 B CN109022734 B CN 109022734B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
Abstract
The invention belongs to the technical field of strip steel manufacturing, and particularly relates to an online strip steel heat treatment device and a heat treatment method. The device comprises a strip steel production assembly, a heat treatment assembly and a coiling assembly which are sequentially arranged according to a production line. When different types of strip steel are subjected to online heat treatment, required components can be selected to perform online heat treatment on the strip steel, so that the method can meet the individual requirements of different high-performance steels on tissues and processes through a set of device, and the flexible post-rolling heat treatment equipment configuration is adopted to regulate and control the post-rolling phase change process of the strip steel, namely the flexibility meets the complex tissue regulation and control requirements of the high-performance steels, and the applicability is strong.
Description
Technical Field
The invention belongs to the technical field of strip steel manufacturing, and particularly relates to an online strip steel heat treatment device and a heat treatment method.
Background
With the development of hot rolling technology, especially thin slab continuous casting and rolling technology, the product breaks through the limit of the traditional hot rolled product as an intermediate product, and directly enters the application field of cold rolled products, namely end products. The method has the obvious effects of greatly shortening the manufacturing process and reducing the manufacturing cost. Meanwhile, the structure performance regulation and control process which can be realized by cold rolling and heat treatment originally needs to be synchronously completed in the hot rolling process, which puts higher requirements on the existing hot rolling process equipment, particularly the controlled cooling equipment after rolling.
For example, the existing post-rolling cooling control equipment can only realize one-way cooling and cannot meet the requirement of certain high-performance products such as martensitic steel, Q & P steel, medium manganese steel and the like on structure regulation, and then heating treatment is carried out after cooling.
In addition, for high performance steels having metastable retained austenite as the main plastic phase, such as TRIP steels, Q & P steels, etc., too long bainite isothermal time or partitioning time causes decomposition of the retained austenite. Because the steel coil cooling is a slow cooling process, if the cooling process of the high-performance steel coil is not interfered, the performance of the high-performance steel coil is deteriorated, and the material structure performance of different parts can generate large fluctuation.
Namely, the process and equipment of the existing hot continuous rolling production line can not meet the complex structure regulation and control requirement of high-performance steel, and only one steel with simple process can be subjected to heat treatment.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides an online strip steel heat treatment device and a heat treatment method, which flexibly meet the complex structure regulation and control requirement of high-performance steel.
The invention realizes the purpose through the following technical scheme:
on one hand, the invention provides an online strip steel heat treatment device which comprises a strip steel production assembly, a heat treatment assembly and a coiling assembly which are sequentially arranged according to a production line, wherein the heat treatment assembly is arranged between the strip steel production assembly and the coiling assembly, and consists of a cooling first section, an induction heating section, a cooling second section, an isothermal section and a post-treatment section which are sequentially arranged according to the production line.
Furthermore, a first temperature detector is arranged between the cooling section and the strip steel production assembly, a second temperature detector is arranged between the cooling section and the induction heating section, a third temperature detector is arranged between the induction heating section and the cooling section, and a fourth temperature detector is arranged between the cooling section and the isothermal section.
Further, the strip steel production assembly comprises a high-speed continuous casting machine, a first high-pressure water descaling machine, a roughing mill, a pendulum shear, an induction heating furnace, a second high-pressure water descaling machine and a finishing mill set which are sequentially arranged according to a production line.
Further, the coiling assembly comprises a flying shear and a coiling unit which are sequentially arranged according to a production line, the coiling unit comprises a first coiling machine and a second coiling machine, and the first coiling machine and the second coiling machine are both connected with the flying shear.
In another aspect, the present invention provides an online heat treatment method for strip steel, which is based on the above apparatus and is used for heat treatment of strip steel, and the method includes:
the strip steel production assembly produces strip steel;
selecting components in the heat treatment assembly to carry out online heat treatment on the produced strip steel according to the type of the strip steel;
and the coiling assembly coils the strip steel subjected to the online heat treatment into a steel coil.
The first embodiment of the invention is: an online heat treatment method for strip steel, which is based on the device for online heat treatment of Q & P steel, and comprises the following steps:
the strip steel production assembly produces strip steel, the thickness of the strip steel is 1.0-2.0 mm, and the finishing temperature is 820-850 ℃;
cooling the produced strip steel to a quenching temperature through a cooling section of a heat treatment assembly, wherein the quenching temperature is 240-260 ℃, rapidly heating the cooled strip steel through an induction heating section of the heat treatment assembly by 370-400 ℃, entering an isothermal section, preserving heat for 3min, finally cooling to 100-120 ℃ through a post-treatment section, and removing residual cooling water on the upper plate surface and the lower plate surface of the strip steel;
the coiling assembly coils the strip steel processed by the post-processing section into a steel coil.
The second embodiment of the present invention is: the online heat treatment method for the strip steel is based on the device for online heat treatment of the medium manganese steel, and comprises the following steps:
the strip steel production assembly produces strip steel, the thickness of the strip steel is 1.0-2.0 mm, and the finishing temperature is 820-850 ℃;
cooling the produced strip steel to 200 ℃ through a cooling section of a heat treatment assembly, rapidly heating the cooled strip steel to 620-650 ℃ through an induction heating section of the heat treatment assembly, entering an isothermal section, preserving heat for 4min, finally cooling to 100-120 ℃ through a post-treatment section, and removing residual cooling water on the upper plate surface and the lower plate surface of the strip steel;
the coiling assembly coils the strip steel processed by the post-processing section into a steel coil.
The third embodiment of the present invention is: an online hot treatment method for strip steel, which is based on the device for performing online hot treatment on DP steel, and comprises the following steps:
the strip steel production assembly produces strip steel, the thickness of the strip steel is 1.0-2.0 mm, and the finishing temperature is 800-820 ℃;
cooling the produced strip steel to an intermediate temperature through a cooling section of the heat treatment assembly, wherein the intermediate temperature is 690-710 ℃, performing air cooling for 4-6 s before entering the cooling section of the heat treatment assembly, cooling to below 200 ℃ through the cooling section, passing through an isothermal section, and finally removing residual cooling water on the upper plate surface and the lower plate surface of the strip steel through a post-treatment section;
the coiling assembly coils the strip steel processed by the post-processing section into a steel coil.
The fourth embodiment of the present invention is: an online heat treatment method for strip steel, which is based on the device for carrying out online heat treatment on TRIP steel, and comprises the following steps:
the strip steel production assembly produces strip steel, the thickness of the strip steel is 1.0-2.0 mm, and the finishing temperature is 820-850 ℃;
cooling the produced strip steel to an intermediate temperature through a first cooling section of a heat treatment assembly, wherein the intermediate temperature is 680-700 ℃, performing air cooling for 5-8 s before the strip steel enters a second cooling section of the heat treatment assembly, cooling to 380-400 ℃ through the second cooling section, keeping the temperature of the strip steel in an isothermal section for 5min, finally cooling to 100-120 ℃ through a post-treatment section, and removing residual cooling water on the upper plate surface and the lower plate surface of the strip steel;
the coiling assembly coils the strip steel processed by the post-processing section into a steel coil.
The fifth embodiment of the present invention is: an online heat treatment method for strip steel, which is based on the device for online heat treatment of MS steel, and comprises the following steps:
the strip steel production assembly produces strip steel, the thickness of the strip steel is 1.0-2.0 mm, and the finishing temperature is 800-820 ℃;
cooling the produced strip steel to below 200 ℃ through a cooling section of the heat treatment assembly, and removing residual cooling water on the upper plate surface and the lower plate surface of the strip steel through a post-treatment section;
the coiling assembly coils the strip steel processed by the post-processing section into a steel coil.
The invention has the beneficial effects that:
according to the strip steel online heat treatment device provided by the invention, the heat treatment assembly is arranged on the production line between the strip steel production assembly and the coiling assembly, and when different types of strip steel are subjected to online heat treatment, the required components can be selected to perform online heat treatment on the strip steel, so that the device can meet the individual requirements of different high-performance steels on the structure and the process through one set of device, the flexible post-rolling heat treatment equipment configuration is adopted to regulate and control the post-rolling phase change process of the strip steel, namely the flexibility meets the complex structure regulation and control requirements of the high-performance steel, and the applicability is strong.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural view of an in-line heat treatment apparatus for strip steel according to an embodiment of the present invention;
FIG. 2 is a schematic structural view of the heat treatment assembly of FIG. 1;
FIG. 3 is a schematic flow chart of an on-line heat treatment method for strip steel according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an on-line heat treatment of hot-rolled high-performance steel (Q & P steel, medium manganese steel) requiring heating in a cooling phase transformation process according to an embodiment of the present invention;
FIG. 5 is a schematic view of post-rolling controlled cooling and phase transition of hot-rolled high-performance steel (DP steel, TRIP steel, MS steel) and other steel types that do not require heating in the cooling phase transition process according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Firstly, the embodiment of the invention provides an online heat treatment device for strip steel.
Fig. 1 is a schematic structural view of an on-line heat treatment apparatus for strip steel according to an embodiment of the present invention, and referring to fig. 1, the apparatus includes a strip steel production assembly, a heat treatment assembly, and a coiling assembly arranged in sequence according to a production line, wherein: the heat treatment assembly consists of a cooling section 8, an induction heating section 9, a cooling section 10, an isothermal section 11 and a post-treatment section 12 which are sequentially arranged according to a production line.
FIG. 2 is a schematic structural diagram of the heat treatment assembly shown in FIG. 1, and referring to FIG. 2, the cooling section 8 in the embodiment of the present invention may be composed of an ultrafast cooling section 8a and a laminar flow section 8b, wherein the ultrafast cooling section 8a may be composed of 5 ultrafast cooling header groups, and the cooling water flow rate is 10000m3H, the maximum pressure of cooling water is 4bar, and the maximum cooling speed is 500 ℃/s; the laminar flow section 8b can be composed of 3 sets of laminar cooling header groups with cooling water flow of 2000m3/h。
Referring to fig. 2, the induction heating section 9 of the embodiment of the present invention may be composed of 10 sets of induction heaters with a total installed capacity of 40MW and a maximum heating rate of 350 ℃/s.
Referring to fig. 2, the cooling section 10 according to the embodiment of the present invention may be composed of 3 sets of laminar flow-encrypted cooling headers with a total flow rate of cooling water of 4000m3The maximum cooling rate is 200 ℃/s.
Referring to FIG. 2, the isothermal section 11 according to the embodiment of the present invention comprises a main body of a vertical loop holding furnace, the maximum loop amount is 800m, and the protective atmosphere in the furnace is N2。
Referring to FIG. 2, the aftertreatment section 12 of an embodiment of the invention is comprised of 2 sets of laminar flow cooling headers 12a and air purge components 12 b.
In order to measure the temperature of the strip steel in real time, with reference to fig. 2, a first temperature detector 15a is arranged between the cooling section 8 and the strip steel production assembly, a second temperature detector 15b is arranged between the cooling section 8 and the induction heating section 9, a third temperature detector 15c is arranged between the induction heating section 9 and the cooling section 10, and a fourth temperature detector 15d is arranged between the cooling section 10 and the coiling assembly.
Referring to fig. 1, a strip production assembly according to an embodiment of the present invention includes a high-speed continuous casting machine 1, a first high-pressure water descaler 2, a roughing mill 3, a pendulum shear 4, an induction heating furnace 5, a second high-pressure water descaler 6, and a finishing mill group 7, which are sequentially arranged in a production line, and produces a strip having a specific dimensional specification through the strip production assembly.
Referring to fig. 1, the winding assembly according to the embodiment of the present invention includes a flying shear 13 and a winding unit sequentially arranged according to a production line, the winding unit includes a first winding machine 14a and a second winding machine 14b, the first winding machine 14a and the second winding machine 14b are both connected to the flying shear 13, and the first winding machine 14a and the second winding machine 14b are both connected to the flying shear 13.
In the embodiment of the present invention, the raw material may be sequentially conveyed among the members by a roller conveyor.
On the other hand, the embodiment of the invention also provides an online strip steel heat treatment method, which is based on the device for carrying out heat treatment on the strip steel. Fig. 3 is a schematic flow chart of an on-line heat treatment method for strip steel according to an embodiment of the invention, which, in conjunction with fig. 3, includes:
step S1: the strip steel production assembly produces strip steel;
step S2: selecting components in the heat treatment assembly to carry out online heat treatment on the produced strip steel according to the type of the strip steel;
step S3: the coiling assembly coils the strip steel subjected to the online heat treatment into a steel coil.
According to the strip steel online heat treatment device provided by the invention, the heat treatment assembly is arranged on the production line between the strip steel production assembly and the coiling assembly, the second cooling assembly is arranged on the production line behind the coiling assembly, and when different types of strip steel are subjected to online heat treatment, required components can be selected to perform online heat treatment on the strip steel, so that the strip steel online heat treatment device can meet the personalized requirements of different high-performance steels on tissues and processes through one set of device, the rolled phase change process of the strip steel is regulated and controlled by adopting flexible rolled heat treatment equipment configuration, namely the flexibility meets the complex tissue regulation and control requirements of the high-performance steels, and the applicability is strong.
The first embodiment is as follows:
embodiment one discloses a pair Q&P steel on-line heat treatment method, FIG. 4 shows a hot rolled high performance steel (Q) to be heated in a cooling transformation process according to an embodiment of the present invention&P steel and medium manganese steel) on-line heat treatment schematic diagram. With reference to FIG. 4, Q&The heat treatment process of the P steel comprises the following steps: quickly cooling the strip steel after finish rolling to a martensite transformation starting point Ms and a martensite transformation finishing point MfAt the intermediate quenching temperature QT, a large amount of austenite is transformed into martensite, then the temperature is quickly raised to the distribution temperature PT for heat preservation, and the residual austenite is gradually enriched with carbon to form stable austenite. The final structure is lath martensite + retained austenite. Decomposition of the retained austenite may occur with an increase in partition time. The QP980 steel is produced by a sheet billet continuous casting and rolling production line of the device, and the method mainly comprises the following steps:
QP980 molten steel with the components shown in the table 1 is cast into a continuous casting blank with the thickness of 100mm through a high-speed continuous casting machine 1, the drawing speed is 5.5m/min, the casting blank temperature is 1050 ℃, the continuous casting blank is descaled through a first high-pressure descaler 2 with the pressure of 20MPa and then enters a roughing mill 3 to be rolled into an intermediate blank with the thickness of 12mm, the surface temperature of the intermediate blank is about 960 ℃, the intermediate blank is subjected to pendulum shear 4 treatment, the temperature is raised to 1130 ℃ through an induction heating furnace 5, then the intermediate blank is rolled into strip steel with the thickness of 1.0-2.0 mm through a second high-pressure descaler 6 with the pressure of 40MPa and a finishing mill group 7;
after strip steel enters a run-out Roller (ROT), the strip steel is subjected to temperature measurement through a temperature meter and fed back to a cooling model, the strip steel is rapidly cooled to a quenching temperature QT (240-260 ℃) through a cooling section 8, then is rapidly heated to a temperature PT (370-400 ℃) through an induction heating section 9, a cooling section 10 is not started, then the strip steel enters a vertical loop heat preservation furnace of an isothermal section 11 for heat preservation for 3min, then the strip steel is cooled to 100-120 ℃ through a cooling header group 12a in a post-treatment section 12, and residual cooling water on the upper plate surface and the lower plate surface is removed through an air purging component 12 b;
the steel is cut by the flying shear 13 and then wound by the first winding machine 14a and the second winding machine 14b to form a finished steel coil.
The process and the performance of the QP980 steel are shown in tables 2-3.
| Steel grade | C | Si | Mn | P | S | Als |
| QP980 | 0.18 | 1.6 | 1.8 | 0.03 | 0.005 | 0.033 |
TABLE 1
TABLE 2
TABLE 3
Example two:
the second embodiment discloses an online heat treatment method for medium manganese steel, and with reference to fig. 4, the post-rolling controlled cooling and heat treatment process for hot-rolled medium manganese steel comprises the following steps: quick cooling of strip steel after finish rolling to martensite end point MfThe method comprises the following steps of transforming austenite into lath martensite, rapidly heating to a gamma + α two-phase region for annealing, and transforming the martensite into ultra-fine grained ferrite and residual austenite, wherein the MMn1200 steel is produced by a thin slab continuous casting and rolling production line of the online heat treatment device, and the method mainly comprises the following steps:
the MMn1200 molten steel with the components shown in the table 4 is cast into a continuous casting blank with the thickness of 100mm through a high-pulling-speed continuous casting machine 1, the pulling speed is 5.5m/min, the temperature of the casting blank is 1040 ℃, the continuous casting blank enters a roughing mill 3 after being descaled by a first high-pressure descaler 2 with the pressure of 20MPa, the casting blank is rolled into an intermediate blank with the thickness of 10mm, the surface temperature of the intermediate blank is 940 ℃, the intermediate blank is subjected to pendulum shear 4 treatment, the temperature is raised to 1160 ℃ through an induction heating furnace 5, the intermediate blank is rolled into strip steel with the thickness of 1.0-2.0 mm through a second high-pressure descaler 6 with the pressure of 40MPa and a finishing mill;
after the strip steel enters a run-out roller table (ROT), the strip steel is subjected to temperature measurement through a temperature measuring meter, the strip steel is rapidly cooled to a temperature below a martensite phase change end point (200 ℃) through a cooling section 8, then is rapidly heated to a temperature 620-650 ℃ with a two-phase region slightly higher than Ac1 through an induction heating section 9 through temperature feedback, a cooling section 10 is not started, then the strip steel enters a vertical loop heat preservation furnace of an isothermal section 11 for heat preservation for 4min, then is cooled to 100-120 ℃ through a cooling header group 12a in a post-treatment section 12, and residual cooling water on the upper plate surface and the lower plate surface is removed through an air purging component 12 b;
the strip steel is cut by the flying shear 13 and then coiled into a finished steel coil by the first coiling machine 14a and the second coiling machine 14 b.
The process and the performance of the MMn1200 steel are shown in tables 5-6.
| Steel grade | C | Si | Mn | P | S | Als |
| MMn1200 | 0.17 | 0.5 | 6.0 | 0.03 | 0.005 | 0.033 |
TABLE 4
TABLE 5
TABLE 6
Example three:
the third embodiment discloses an online heat treatment method for DP steel, and fig. 5 is a post-rolling cooling and phase change control schematic diagram of hot-rolled high-performance steel (DP steel, TRIP steel and MS steel) and other steel types which do not need to be heated in the cooling phase change process. With reference to fig. 5, the post-rolling controlled cooling process of the hot-rolled DP steel comprises: after the strip steel is taken out of the finishing mill and quickly cooled to the intermediate temperature (two-phase region), about 80 percent of austenite structure is converted into ferrite after a period of air cooling, the rest austenite is converted into martensite after the quick cooling, and the final structure is a ferrite F + martensite M two-phase structure.
The production line for producing DP590 steel by utilizing the sheet billet continuous casting and rolling of the online heat treatment device of the invention mainly comprises the following steps:
DP590 molten steel with the components shown in the table 7 is cast into a continuous casting blank with the thickness of 100mm by a high-speed casting machine 1, the drawing speed is 6.0m/min, the casting blank temperature is 1030 ℃, the continuous casting blank is descaled by a first high-pressure descaler 2 with the pressure of 20MPa, then the continuous casting blank enters a roughing mill 3 to be rolled into an intermediate blank with the thickness of 12mm, the surface temperature of the intermediate blank is about 930 ℃, the intermediate blank is subjected to pendulum shear 4 treatment, the temperature is increased to 1100 ℃ by an induction heating furnace 5, and then the intermediate blank is rolled into strip steel with the thickness of 1.0-2.0 mm by a second high-pressure descaler 6 with the pressure of 40MPa and a finishing mill;
after the strip steel is discharged from a finishing mill unit 7 and enters a run-out table (ROT), the strip steel is rapidly cooled to an intermediate temperature of 690-710 ℃ through a cooling section 8, at the moment, an induction heating section 9 is not started, the strip steel is subjected to temperature measurement through a temperature meter, the opening and closing of a collecting pipe of the cooling section 8 and a cooling section 10 are controlled through temperature feedback, the length of the air cooling roller table meets the air cooling time of the strip steel for 4-6 s, then the strip steel is rapidly cooled to a temperature below a martensite phase transition end point (200 ℃) through the cooling section 10, a vertical loop holding furnace of an isothermal section 11 is not started; the strip steel is subjected to air purging by an air purging component 12b in the post-treatment section 12 to remove residual cooling water on the upper plate surface and the lower plate surface;
the strip is then cut by flying shears 13 and wound by a first winder 14a and a second winder 14b into finished coils.
The components, the process and the actual performance of the DP590 steel are shown in tables 8-9.
| Steel grade | C | Si | Mn | P | S | Als | Cr |
| DP590 | 0.06 | 0.25 | 1.30 | 0.03 | 0.005 | 0.033 | 0.50 |
TABLE 7
TABLE 8
TABLE 9
Example four:
the fourth embodiment discloses an online heat treatment method for TRIP steel. With reference to fig. 5, the post-rolling controlled cooling process of the hot-rolled TRIP steel comprises: the strip steel is quickly cooled to an intermediate temperature (a two-phase region) after being discharged from a finishing mill, 50% -60% of austenite structure is converted into ferrite after a period of air cooling, then the strip steel is quickly cooled and enters a bainite region for heat preservation, part (30% -40%) of the rest austenite generates bainite conversion, the unconverted austenite is gradually enriched with carbon, the stability is increased, and the final structure is a multi-phase structure of ferrite F + bainite B + residual austenite RA. However, as the holding time of the strip in the bainite region increases, the residual austenite may decompose. The invention relates to a production line for producing TRIP780 steel by utilizing a thin slab continuous casting and rolling production line of an online heat treatment device, which mainly comprises the following steps:
TRIP780 molten steel having a composition shown in Table 10 was cast by a high casting speed caster 1 into a continuous casting slab having a thickness of 100mm at a casting speed of 5.5m/min and a casting slab temperature of 1050 ℃. After descaling by a first high-pressure descaler 2 at 20MPa, feeding the ingot into a roughing mill 3 to roll the ingot into an intermediate billet with the thickness of 12mm, wherein the surface temperature of the intermediate billet is about 950 ℃, after treatment by pendulum shear 4, heating the intermediate billet to 1120 ℃ by an induction heating furnace 5, then rolling the intermediate billet into a strip steel with the thickness of 1.0-2.0 mm by a second high-pressure descaler 6 at 40MPa and a finishing mill unit 7, and the final rolling temperature is 820-850 ℃;
after the strip steel is discharged from the finishing mill unit 7 and enters a run-out table (ROT), the strip steel is rapidly cooled to an intermediate temperature of 680-700 ℃ through a first cooling section 8, at the moment, an induction heating section 9 is not started, the temperature of the strip steel is measured through a temperature meter, the opening and closing of a collecting pipe of the first cooling section 8 and a second cooling section 10 are controlled through temperature feedback, the length of the air cooling roller table meets the air cooling time of the strip steel for 5-8 s, then the strip steel is rapidly cooled to a bainite transformation temperature of 380-400 ℃ through the second cooling section 10, then the strip steel enters a vertical loop heat preservation furnace of an isothermal section 11 for heat preservation for 5min, then the strip steel is cooled to 100-120 ℃ through a cooling collecting pipe group 12a in a post-;
finally, the strip steel is cut off by a flying shear 13, and the first coiling machine 14a and the second coiling machine 14b are coiled into a finished steel coil.
The components, the process and the actual performance of the TRIP780 steel are shown in the following tables 10 to 12.
| Steel grade | C | Si | Mn | P | S | Als |
| TRIP780 | 0.17 | 1.55 | 1.55 | 0.03 | 0.005 | 0.03 |
TABLE 11
TABLE 12
Example five:
the fifth embodiment discloses an online heat treatment method for MS steel, and with reference to FIG. 5, the post-rolling controlled cooling process for hot-rolled MS steel comprises the following steps: rapid cooling to martensite transformation after strip steel finish rollingEnd point temperature MfThereafter, austenite is transformed into martensite by rapid cooling, and the final structure is a lath martensite structure. The MS1200 steel is produced by a thin slab continuous casting and rolling production line of the online heat treatment device, and the method mainly comprises the following steps:
MS1200 molten steel with the components shown in the table 13 is cast into continuous casting billets with the thickness of 100mm through a high-speed casting machine 1, the drawing speed is 5.8m/min, the temperature of the casting billets is 1030 ℃, the continuous casting billets are descaled through a first high-pressure descaler 2 with the pressure of 20MPa and then enter a roughing mill 3, the casting billets are rolled into intermediate billets with the thickness of 12mm, the surface temperature of the intermediate billets is about 930 ℃, the pendulum shear 4 is treated, the temperature is increased to 1100 ℃ through an induction heating furnace 5, the intermediate billets are rolled into strip steel with the thickness of 1.0-2.0 mm through a second high-pressure descaler 6 with the pressure of 40MPa and a finishing mill group 7, and the finishing temperature is 800;
after entering a run-out table (ROT), the strip steel is rapidly cooled to a temperature below a martensite phase transition end point (200 ℃) through a cooling section 8, at the moment, an induction heating section 9, a cooling section 10 and an isothermal section 11 are not started, and the strip steel is subjected to air purging devices 12b of a post-treatment section to remove residual cooling water on the upper plate surface and the lower plate surface of the strip steel;
the strip steel is cut off by a flying shear 13 and then coiled into a finished steel coil by a first coiling machine 14a and a second coiling machine 14 b.
The components, the process and the performance of the MS1200 steel are shown in the following tables 14-15.
| Steel grade | C | Si | Mn | P | S | Als | Nb+Ti | Cr |
| MS1200 | 0.18 | 0.20 | 1.80 | 0.03 | 0.005 | 0.033 | 0.04 | 0.40 |
TABLE 14
Watch 15
From the above, the present invention has the following advantages:
1. the on-line heat treatment device provided by the invention can be used for regulating and controlling the phase change process of the strip steel after rolling by adopting flexible configuration of the heat treatment equipment after rolling according to the personalized requirements of high-performance steel on the structure and the process.
2. For high-performance steel taking metastable retained austenite as a main plastic phase, the online heat treatment device and the method provided by the invention can accurately control the isothermal quenching time or the distribution time of the strip steel, and avoid the decomposition of the retained austenite in a steel structure caused by long-time heat preservation and distribution, thereby influencing the final performance of the strip steel.
3. The hot-rolled high-performance steel coil produced by the on-line heat treatment device and the method provided by the invention has good structure and performance uniformity, and the structure performance is basically equivalent to that of cold-rolled steel with the same specification.
4. The online heat treatment device and the online heat treatment method provided by the invention shorten the manufacturing process of high-performance steel, save energy, realize the replacement of cold by heat, and accord with the development trend of energy conservation, emission reduction and green manufacturing.
The following embodiments are provided for the purpose of illustrating the present invention and are not to be construed as limiting the present invention in any way, and it will be apparent to those skilled in the art that the technical features of the present invention can be modified or changed in some ways without departing from the scope of the present invention.
Claims (4)
1. The strip steel online heat treatment method is characterized in that the strip steel is subjected to heat treatment based on a strip steel online heat treatment device, the device comprises a strip steel production assembly, a heat treatment assembly and a coiling assembly which are sequentially arranged according to a production line, and the heat treatment assembly consists of a cooling section (8), an induction heating section (9), a cooling section (10), an isothermal section (11) and a post-treatment section (12) which are sequentially arranged according to the production line; the method comprises the following steps:
the strip steel production assembly produces strip steel, the thickness of the strip steel is 1.0-2.0 mm, and the finishing temperature is 820-850 ℃;
according to the type of the strip steel, selecting components in the heat treatment assembly to carry out online heat treatment on the produced strip steel, and specifically comprising the following steps: the strip steel is TRIP steel, the produced strip steel is cooled to an intermediate temperature through a cooling section (8) of a heat treatment assembly, the intermediate temperature is 680-700 ℃, air cooling is carried out for 5-8 s before the strip steel enters a cooling section (10) of the heat treatment assembly, then the strip steel is cooled to 380-400 ℃ through the cooling section (10), the strip steel enters an isothermal section (11) for heat preservation for 5min, and finally the strip steel is cooled to 100-120 ℃ through a post-treatment section (12), and residual cooling water on the upper plate surface and the lower plate surface of the strip steel is removed;
and the coiling assembly coils the strip steel subjected to the online heat treatment into a steel coil.
2. The on-line heat treatment method of the strip steel as claimed in claim 1, characterized in that a first temperature detector (15a) is arranged between the cooling section (8) and the strip steel production assembly, a second temperature detector (15b) is arranged between the cooling section (8) and the induction heating section (9), a third temperature detector (15c) is arranged between the induction heating section (9) and the cooling section (10), and a fourth temperature detector (15d) is arranged between the cooling section (10) and the isothermal section (11).
3. The on-line heat treatment method of strip steel according to claim 1, wherein the strip steel production assembly comprises a high-speed continuous casting machine (1), a first high-pressure water descaling machine (2), a roughing mill (3), a pendulum shear (4), an induction heating furnace (5), a second high-pressure water descaling machine (6) and a finishing mill group (7) which are arranged in sequence according to a production line.
4. The on-line heat treatment method of the strip steel according to claim 1, wherein the coiling assembly comprises a flying shear (13) and a coiling unit which are arranged in sequence according to a production line, the coiling unit comprises a first coiling machine (14a) and a second coiling machine (14b), and the first coiling machine (14a) and the second coiling machine (14b) are both connected with the flying shear (13).
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