CN109402355B - 600 MPa-grade hot-rolled TRIP type dual-phase steel and preparation method thereof - Google Patents
600 MPa-grade hot-rolled TRIP type dual-phase steel and preparation method thereof Download PDFInfo
- Publication number
- CN109402355B CN109402355B CN201811639349.4A CN201811639349A CN109402355B CN 109402355 B CN109402355 B CN 109402355B CN 201811639349 A CN201811639349 A CN 201811639349A CN 109402355 B CN109402355 B CN 109402355B
- Authority
- CN
- China
- Prior art keywords
- steel
- hot
- cooling
- type dual
- rolled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
The invention provides 600 MPa-grade hot-rolled TRIP type dual-phase steel and a preparation method thereof, wherein the structure of the hot-rolled TRIP type dual-phase steel is residual austenite, martensite and ferrite, and the surface layer structure of the hot-rolled TRIP type dual-phase steel is as follows: 4-6% of retained austenite, 5-15% of martensite and the balance of ferrite, wherein rod-shaped carbides exist in the ferrite; the main structure of the steel is as follows: 2-5% of retained austenite, 25-40% of martensite and the balance of ferrite, and no carbide is precipitated in the ferrite. The specified plastic elongation strength of the steel is 333-351MPa, the tensile strength is 602-614MPa, and the elongation after fracture (80mm gauge length) is 23-25%. The steel can be applied to complex automobile structural parts and chassis parts, and has better economical efficiency and application prospect.
Description
Technical Field
The invention belongs to the technical field of advanced high-strength steel for hot rolling automobiles, and particularly relates to 600 MPa-grade hot-rolled TRIP type dual-phase steel and a preparation method thereof.
Background
Currently, hot rolled advanced high strength steels for automobiles, such as Dual Phase (DP) steels, transformation induced plasticity (TRIP) steels, have been applied to the preparation of automotive structural members. In the actual production process, the traditional dual-phase steel is difficult to form on a plurality of high-ductility parts and difficult to meet the requirement of complicated stamping structural parts for automobile design. The elongation of the transformation induced plasticity steel is a certain margin, waste is caused, the higher the strength grade is, the poorer the weldability is, but the residual austenite in the TRIP steel can absorb energy when acting as an external force, the transformation of the transformation induced plasticity is generated, namely the TRIP effect is generated, and the safety coefficient is improved.
Therefore, the dual-phase steel with high strength, high ductility and TRIP effect is developed, not only can meet the requirements of complex stamping structural parts, but also has better economic applicability and safety.
Disclosure of Invention
In view of the above, the invention provides 600MPa grade hot-rolled TRIP type dual phase steel and a preparation method thereof, which have the characteristics of high strength, high elongation and TRIP effect through the control of each phase component in the structure.
The invention provides 600 MPa-grade hot-rolled TRIP type dual-phase steel, which comprises a steel main body and a surface layer covering the steel main body, wherein the microstructure of the 600 MPa-grade hot-rolled TRIP type dual-phase steel consists of three phases of ferrite, martensite and retained austenite; the superficial tissues are as follows by volume percentage: 4-6% of retained austenite, 5-15% of martensite, and the balance of ferrite with rod-shaped carbide separated out; the main structure of the steel is as follows: 2-5% of retained austenite, 25-40% of martensite and the balance of ferrite without carbide precipitation.
Preferably, the number of rod-like carbides per 1000 square micrometers on average in the range of 0 to 22 μm thickness from the surface of the 600MPa class hot-rolled TRIP type dual phase steel is 23 to 27; the number of rod-like carbides in the range of 22-43 μm thickness from the surface is 8-10 on average per 1000 square micrometers; at a distance of 43 μm from the surface to half the thickness of the strip, no carbides were precipitated. The carbide precipitation in the thickness range of the surface layer is in a gradually decreasing trend, and the distribution trend of the precipitated carbide directly influences the steel performance and the formation of residual austenite.
Preferably, the surface layer is a thickness range of 43 μm from the surface of the steel sheet.
Preferably, the 600MPa grade hot-rolled TRIP type dual-phase steel comprises the following chemical components: 0.12 to 0.14 percent of C, 0.3 to 0.4 percent of Si, 1.5 to 1.7 percent of Mn, 0.35 to 0.45 percent of Al, less than or equal to 0.014 percent of P, and the balance of Fe and inevitable impurities.
Preferably, the retained austenite is in the form of a thin film. The thin film of retained austenite can increase the elongation of the steel.
Preferably, the specified plastic elongation strength of the 600 MPa-grade hot-rolled TRIP-type dual-phase steel is 333-351MPa, the tensile strength is 602-614MPa, and the elongation after fracture at a gauge length of 80mm is 23-25%.
The invention provides a preparation method of the 600 MPa-grade hot-rolled TRIP-type dual-phase steel, which comprises the following steps:
s1, smelting and casting molten iron to obtain a casting blank meeting the chemical component requirement, and heating and preserving heat of the casting blank under the protection of inert gas;
s2, controlling hot rolling of the heat-preserved casting blank to obtain a hot rolled steel strip;
and S3, controlling and cooling the hot rolled steel strip, and coiling to obtain the product.
The TRIP type dual-phase steel with the specific microstructure is formed through the process flows of heat preservation, hot rolling, cooling and coiling, and particularly the special coiling process after cooling is beneficial to forming of film-shaped residual austenite.
Preferably, in step S1, the heat preservation is to preserve the casting blank at 1150-1250 ℃ for 1.5-2.5h, and 99.99% of high-purity nitrogen protection is adopted. The temperature is kept to be uniform.
Preferably, in step S2, the controlled hot rolling includes 2-3 passes of rough rolling and 3-5 passes of finish rolling, the total reduction of the rough rolling is 82-84%, the finish rolling is carried out at a constant speed of 7-8m/S, and the total reduction of the finish rolling is 72-82%; the thickness of the hot rolled steel strip is 4.3-4.7 mm. The distribution trend of precipitated carbide in steel is influenced in the heat preservation and hot rolling processes.
Preferably, in step S3, the controlling and cooling step includes: water-cooling the steel strip obtained in the step S2 to 690-710 ℃ at an ultra-fast cooling speed of 40-55 ℃/S, then air-cooling for 20-30S, and then water-cooling to 250-285 ℃ at a cooling speed of 25-35 ℃/S; and coiling the cooled steel strip, and then performing stack cooling to room temperature. The cooling process affects the formation of three-phase composite phases on the surface layer and the main body of the steel. The volume fraction of ferrite in the structure is reduced and the elongation of the steel plate is reduced due to overhigh water cooling finishing temperature before air cooling; too low a water cooling finishing temperature may result in too much ferrite volume fraction, reducing the strength of the steel. The water cooling finishing temperature before coiling is too low, so that a large amount of martensite is formed in the structure, and the elongation of the steel plate is greatly reduced; when the temperature is too high after the water cooling, the martensite is insufficiently formed, and the strength of the steel plate is reduced.
Compared with the prior art, the invention has the following advantages: the 600 MPa-grade hot-rolled TRIP-type dual-phase steel provided by the invention has the specified plastic elongation strength of 333-351MPa, the tensile strength of 602-614MPa and the elongation after fracture (80mm gauge length) of 23-25%, can be widely applied to complex automobile structural parts and chassis parts, can solve the complex stamping problem in the stamping forming process, has certain forming advantages in the processes of bending, flanging and bulging, can generate the TRIP effect under the action of external force, improves the safety coefficient, and has better economic applicability and application prospect.
Drawings
FIG. 1 is a photograph of the morphology and a spectrum of the carbide in example 3 of the present invention.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following specific examples.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
The invention provides 600 MPa-grade hot-rolled TRIP type dual-phase steel in a first aspect, which comprises a steel main body and a surface layer covering the steel main body, wherein the thickness of the surface layer is 43 mu m. The microstructure of the 600 MPa-grade hot-rolled TRIP type dual-phase steel consists of three phases of ferrite, martensite and film-shaped residual austenite; the superficial tissues are as follows by volume percentage: 4-6% of film-like retained austenite, 5-15% of martensite, and the balance of ferrite, and rod-like carbides are present in the ferrite; the main structure of the steel is as follows: 2-5% of film-like retained austenite, 25-40% of martensite, and the balance of ferrite, and no carbide is precipitated in the ferrite. Specifically, the number of rod-like carbides in the range of 0 to 22 μm in thickness from the surface per 1000 square micrometers on average is 23 to 27; the number of rod-like carbides in the range of 22-43 μm thickness from the surface is 8-10 on average per 1000 square micrometers; at a distance of 43 μm from the surface to half the thickness of the strip, no carbides were precipitated. The chemical components of the TRIP type dual-phase steel comprise: 0.12 to 0.14 percent of C, 0.3 to 0.4 percent of Si, 1.5 to 1.7 percent of Mn, 0.35 to 0.45 percent of Al, less than or equal to 0.014 percent of P, and the balance of Fe and inevitable impurities.
The specified plastic elongation strength of the 600 MPa-grade hot-rolled TRIP-type dual-phase steel is 333-351MPa, the tensile strength is 602-614MPa, and the elongation after fracture at a gauge length of 80mm is 23-25%.
The invention provides a preparation method of the 600 MPa-grade hot-rolled TRIP-type dual-phase steel, which comprises the following steps:
s1, smelting and casting molten iron to obtain a casting blank meeting the requirements of chemical components, heating the casting blank to 1150-1250 ℃ under the protection of 99.99% high-purity nitrogen, and preserving heat for 1.5-2.5 h;
s2, controlling hot rolling of the heat-preserved casting blank, wherein the controlled hot rolling comprises 2-3 times of rough rolling and 3-5 times of finish rolling, the total reduction of the rough rolling is 82-84%, the finish rolling is carried out at a constant speed of 7-8m/S, and the total reduction of the finish rolling is 75-82%, so that a hot-rolled steel strip with the thickness of 4.3-4.7mm is obtained;
s3, cooling the hot rolled steel strip to 690-720 ℃ at a cooling speed of 40-55 ℃/S, then air-cooling for 20-30S, and then cooling to 250-280 ℃ at a cooling speed of 35-35 ℃/S; and coiling the cooled steel strip, and then performing stack cooling to room temperature to obtain the product.
The 600MPa grade hot rolled TRIP type dual phase steel of the present application and the method for manufacturing the same will be described in detail with reference to five specific examples.
Example 1
The embodiment provides a preparation method of 600 MPa-grade hot-rolled TRIP type dual-phase steel, which comprises the following steps:
heating the casting blank to 1200 ℃ under the protection of 99.99% high-purity nitrogen, preserving heat for 2h, and protecting the casting blank by using nitrogen with the purity of 99.99% during heating. The casting blank comprises the following chemical components: and C, calculated by mass percent: 0.124%, Si: 0.39%, Mn: 1.67%, Alt: 0.42%, P: 0.014%, the balance being Fe and unavoidable impurities.
Starting hot rolling the heated and insulated casting blank at 1180 ℃, and controlling a hot rolling process as follows: carrying out 3-pass rough rolling with the total reduction of 83%, and then carrying out 4-pass finish rolling at a constant speed of 7.5m/s, wherein the last entry temperature of the finish rolling is 880 ℃, and the total reduction of the finish rolling is 79%, so as to obtain a hot-rolled steel strip with the thickness of 4.5 mm;
and controlling the obtained hot rolled steel strip to be cooled, and controlling the structure of the hot rolled steel strip to be a ferrite, martensite and retained austenite three-phase structure. The specific cooling control process comprises the following steps: cooling the steel strip to 700 ℃ at a cooling speed of 50 ℃/s, then cooling the steel strip in air for 25s, and then cooling the steel strip to 275 ℃ at a cooling speed of 30 ℃/s; and coiling the cooled steel strip, and then performing stack cooling to room temperature to obtain the product.
The 600 MPa-grade hot-rolled TRIP type dual-phase steel prepared by the preparation method has a microstructure consisting of three phases of ferrite, martensite and film-shaped residual austenite. The percentage of each phase (volume percentage,%) of the surface layer tissue is as follows: 4.8% of retained austenite, 8.6% of martensite, and the balance being ferrite in which rod-like carbides are present. The main body structure of the steel except the surface structure comprises the following phases in percentage: 2.5 percent of retained austenite, 31 percent of martensite and the balance of ferrite, and no carbide is precipitated; the number of rod-like carbides in the range of 0-22 μm thickness from the surface is 23 on average per 1000 square micrometers; the number of rod-like carbides in the range of 22-343 μm thickness from the surface is 10 on average per 1000 square micrometers; at 43 μm-half of the total thickness from the surface, no carbide precipitates; the retained austenite in the structure is thin film.
The hot-rolled dual-phase steel obtained in this example was measured to have a predetermined plastic elongation of 351MPa, a tensile strength of 614MPa, and an elongation after fracture (80mm gauge length) of 23.5%.
Example 2
This example provides a hot-rolled TRIP type dual phase steel of 600MPa class, using substantially the same preparation steps as example 1, with the difference that: the casting blank comprises the following chemical components: and C, calculated by mass percent: 0.131%, Si: 0.36%, Mn: 1.55%, Alt: 0.45%, P: 0.012%, and the balance of Fe and inevitable impurities.
The microstructure of the obtained 600 MPa-grade hot-rolled TRIP type dual-phase steel consists of three phases of ferrite, martensite and film-shaped residual austenite. The percentage of each phase (volume percentage,%) of the surface layer tissue is as follows: 5.2% of retained austenite, 11% of martensite and the balance of ferrite, wherein rod-shaped carbides exist in the ferrite. The main body structure of the steel except the surface structure comprises the following phases in percentage: 3.5 percent of retained austenite, 38 percent of martensite and the balance of ferrite, and no carbide is precipitated; the number of rod-like carbides in the range of 0-22 μm thickness from the surface is 26 on average per 1000 square micrometers; the number of rod-like carbides in the thickness range of 22-343 μm from the surface is 8 on average per 1000 square micrometers; at 43 μm-half of the total thickness from the surface, no carbide precipitates; the retained austenite in the structure is thin film.
The hot-rolled dual-phase steel obtained in this example was measured to have a predetermined plastic elongation of 337MPa, a tensile strength of 613MPa, and an elongation after fracture (80mm gauge length) of 24.5%.
Example 3
This example provides a hot-rolled TRIP type dual phase steel of 600MPa class, using substantially the same preparation steps as example 1, with the difference that: the casting blank comprises the following chemical components in percentage by mass: 0.136%, Si: 0.34%, Mn: 1.61%, Alt: 0.37%, P: 0.014%, the balance being Fe and unavoidable impurities.
The microstructure of the obtained 600 MPa-grade hot-rolled TRIP type dual-phase steel consists of three phases of ferrite, martensite and film-shaped residual austenite. The percentage of each phase (volume percentage,%) of the surface layer tissue is as follows: 4.4% of retained austenite, 9% of martensite and the balance of ferrite, wherein rod-shaped carbides exist in the ferrite. The main body structure of the steel except the surface structure comprises the following phases in percentage: 2.5 percent of retained austenite, 29 percent of martensite and the balance of ferrite, and no carbide is precipitated; the number of rod-like carbides in the range of 0-22 μm thickness from the surface is 27 on average per 1000 square micrometers; the number of rod-like carbides in the range of 22-343 μm thickness from the surface is 10 on average per 1000 square micrometers; no rod-like carbides are precipitated at a distance of 43 μm to one-half of the entire thickness from the surface; the retained austenite in the structure is thin film.
The morphology photograph and the energy spectrum of the carbide in the present example are shown in fig. 1, and the specific data corresponding to the energy spectrum in fig. 1 are shown in table 1.
Table 1 carbide spectra in example 3
The hot-rolled dual-phase steel obtained in this example was measured to have a predetermined plastic elongation of 333MPa, a tensile strength of 602MPa, and an elongation after fracture (80mm gauge length) of 24%.
Comparative example 1
The chemical components of the dual-phase steel casting blank provided by the comparative example are the same as those of the dual-phase steel casting blank provided by the example 3, and the preparation steps are basically the same as those of the dual-phase steel casting blank provided by the example 3, except that: the hot rolling adopts 2-pass rough rolling and 5-pass finish rolling, the total reduction of the rough rolling is 60%, the total reduction of the finish rolling is 77.5%, the entry temperature of the last pass of the finish rolling is 860 ℃, air cooling is carried out to 670 ℃ after the finish rolling is finished, then water cooling is carried out to 450 ℃, coiling is carried out, and the stack cooling is carried out to the room temperature after the coiling.
The dual-phase steel provided in this comparative example had a structure composed of 55% ferrite and 45% bainite, and the hot-rolled dual-phase steel had a specified plastic elongation of 449MPa, tensile strength of 592MPa, and elongation after fracture (80mm gauge length) of 20%.
The chemical component preparation process and the mechanical property can be obtained by combining the embodiment of the invention and the comparison: the performance of all embodiments of the invention is better, the specified plastic elongation strength of the obtained 600 MPa-grade hot-rolled TRIP type dual-phase steel is 333-351MPa, the tensile strength is 602-614MPa, and the elongation after fracture (80mm gauge length) is 23-25%. The structure is a ferrite, martensite and retained austenite three-phase structure, and the surface layer ferrite structure contains rod-like carbides. The chemical composition of the comparative example was the same as that of the example, but the structure control was different, and the obtained structure was ferrite and bainite, and the ferrite had insufficient carbon removal, no retained austenite was formed, a lower specific plastic elongation, a higher tensile strength and a higher elongation were not obtained, and the TRIP effect was not further developed.
Example 4
The embodiment provides a preparation method of 600 MPa-grade hot-rolled TRIP type dual-phase steel, which comprises the following steps:
heating the casting blank to 1180 ℃, preserving heat for 2.5 hours, and protecting by using nitrogen with the purity of 99.99% during heating. The casting blank comprises the following chemical components: and C, calculated by mass percent: 0.124%, Si: 0.39%, Mn: 1.67%, Alt: 0.42%, P: 0.014%, the balance being Fe and unavoidable impurities.
Starting hot rolling the heated and heat-preserved casting blank at 1150 ℃, and controlling a hot rolling process as follows: carrying out 3-pass rough rolling with the total reduction of 83%, and then carrying out 4-pass finish rolling at a constant speed of 7m/s, wherein the last entry temperature of the finish rolling is 850 ℃, and the total reduction of the finish rolling is 76%, so as to obtain a hot-rolled steel strip with the thickness of 4.7 mm;
and controlling the obtained hot rolled steel strip to be cooled, and controlling the structure of the hot rolled steel strip to be a ferrite, martensite and retained austenite three-phase structure. The specific cooling control process comprises the following steps: cooling to 690 ℃ at a cooling speed of 52 ℃/s, then air-cooling for 20s, and then cooling to 265 ℃ at a cooling speed of 25 ℃/s; and coiling the cooled steel strip, and then performing stack cooling to room temperature to obtain the product. The properties of the product obtained were essentially identical to those of example 1.
Example 5
The embodiment provides a preparation method of 600 MPa-grade hot-rolled TRIP type dual-phase steel, which comprises the following steps:
heating the casting blank to 1250 ℃, preserving heat for 1.5h, and protecting by nitrogen with the purity of 99.99 percent during heating. The casting blank comprises the following chemical components: and C, calculated by mass percent: 0.124%, Si: 0.39%, Mn: 1.67%, Alt: 0.42%, P: 0.014%, the balance being Fe and unavoidable impurities.
Starting hot rolling the heated and heat-preserved casting blank at 1220 ℃, and controlling a hot rolling process as follows: carrying out 3-pass rough rolling with the total reduction of 83%, and then carrying out 4-pass finish rolling at a constant speed of 8m/s, wherein the last entry temperature of the finish rolling is 860 ℃, and the total reduction of the finish rolling is 82%, so as to obtain a hot-rolled steel strip with the thickness of 4.3 mm;
and controlling the obtained hot rolled steel strip to be cooled, and controlling the structure of the hot rolled steel strip to be a ferrite, martensite and retained austenite three-phase structure. The specific cooling control process comprises the following steps: cooling the steel strip to 710 ℃ at a cooling speed of 45 ℃/s, then air-cooling for 20s, and then cooling the steel strip to 275 ℃ at a cooling speed of 28 ℃/s; and coiling the cooled steel strip, and then performing stack cooling to room temperature to obtain the product. The properties of the product obtained were essentially identical to those of example 1.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (3)
1. A preparation method of 600 MPa-grade hot-rolled TRIP type dual-phase steel comprises the following steps:
s1, smelting and casting molten iron to obtain a casting blank meeting the chemical component requirement, heating the casting blank under the protection of inert gas and preserving heat; wherein, by mass percent, the casting blank comprises the following chemical components: 0.12 to 0.14 percent of C, 0.3 to 0.4 percent of Si, 1.5 to 1.7 percent of Mn, 0.35 to 0.45 percent of Al0.014 percent of P, and the balance of Fe and inevitable impurities; the heat preservation is to preserve the heat of the casting blank for 1.5 to 2.5 hours at 1150-1250 ℃ under the protection of 99.99 percent of high-purity nitrogen;
s2, controlling hot rolling of the heat-preserved casting blank to obtain a hot rolled steel strip; the controlled hot rolling comprises 2-3 times of rough rolling and 3-5 times of finish rolling, the total reduction of the rough rolling is 82-84%, the finish rolling is carried out at a constant speed of 9m/s, and the total reduction of the finish rolling is 75-82%; the thickness of the hot rolled steel strip is 4.3-4.7 mm;
s3, controlling and cooling the hot rolled steel strip, and coiling to obtain a product; the step of controlling cooling comprises: water-cooling the steel strip obtained in the step S2 to 690-720 ℃ at a cooling speed of 40-55 ℃/S, then air-cooling for 20-30S, and then water-cooling to 250-285 ℃ at a cooling speed of 25-35 ℃/S; coiling the cooled steel strip, and then stacking and cooling to room temperature;
the 600 MPa-grade hot-rolled TRIP-type dual-phase steel comprises a steel main body and a surface layer covering the steel main body, wherein the microstructure of the 600 MPa-grade hot-rolled TRIP-type dual-phase steel consists of three phases of ferrite, martensite and retained austenite; the superficial tissues are as follows by volume percentage: 4-6% of retained austenite, 5-15% of martensite, and the balance of ferrite with rod-shaped carbide separated out; the main structure of the steel is as follows: 2-5% of retained austenite, 25-40% of martensite and the balance of ferrite without carbide precipitation; the residual austenite is in a thin film shape; wherein the surface layer is a thickness range of 43 μm from the surface of the steel sheet.
2. The method of manufacturing hot-rolled TRIP type dual phase steel of 600MPa grade according to claim 1, characterized in that: the number of the rodlike carbides in the range of 0-22 μm thickness from the surface of the 600MPa grade hot-rolled TRIP type dual-phase steel is 23-27 on average per 1000 square micrometers; the number of rod-like carbides in the range of 22-43 μm thickness from the surface is 8-10 on average per 1000 square micrometers; at a distance of 43 μm from the surface to half the thickness of the strip, no carbides were precipitated.
3. The method of manufacturing hot-rolled TRIP type dual phase steel of 600MPa grade according to claim 1, characterized in that: the specified plastic elongation strength of the 600 MPa-grade hot-rolled TRIP-type dual-phase steel is 333-351MPa, the tensile strength is 602-614MPa, and the elongation after fracture at a gauge length of 80mm is 23-25%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811639349.4A CN109402355B (en) | 2018-12-29 | 2018-12-29 | 600 MPa-grade hot-rolled TRIP type dual-phase steel and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811639349.4A CN109402355B (en) | 2018-12-29 | 2018-12-29 | 600 MPa-grade hot-rolled TRIP type dual-phase steel and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109402355A CN109402355A (en) | 2019-03-01 |
| CN109402355B true CN109402355B (en) | 2020-12-15 |
Family
ID=65462162
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811639349.4A Active CN109402355B (en) | 2018-12-29 | 2018-12-29 | 600 MPa-grade hot-rolled TRIP type dual-phase steel and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109402355B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118639115A (en) * | 2024-08-16 | 2024-09-13 | 鞍钢股份有限公司 | Steel for 375 MPa-level cold stamping automobile axle housing and production method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5585626A (en) * | 1978-11-14 | 1980-06-27 | Nisshin Steel Co Ltd | Manufacture of low alloy steel sheet or hoop for precise punching |
| CN102321845A (en) * | 2011-09-21 | 2012-01-18 | 首钢总公司 | A kind of high-strength hot-rolled dual-phase steel and method of manufacture thereof |
| KR20140018580A (en) * | 2012-08-02 | 2014-02-13 | 주식회사 포스코 | Hot-rolled steel sheet for steel pipe having excellent surface integrity and method for manufacturing the same |
| CN106119703A (en) * | 2016-06-21 | 2016-11-16 | 宝山钢铁股份有限公司 | A kind of 980MPa level hot-rolled dual-phase steel and manufacture method thereof |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102517496A (en) * | 2011-12-23 | 2012-06-27 | 首钢总公司 | Hot rolled ferrite/martensite double phase steel and production method thereof |
| TWI468534B (en) * | 2012-02-08 | 2015-01-11 | Nippon Steel & Sumitomo Metal Corp | High-strength cold rolled steel sheet and manufacturing method thereof |
| CN102650017A (en) * | 2012-05-25 | 2012-08-29 | 宝山钢铁股份有限公司 | Hot-rolled steel plate and manufacturing method thereof |
| CN102719732A (en) * | 2012-06-28 | 2012-10-10 | 宝山钢铁股份有限公司 | Hot-rolled high-strength dual phase steel plate and manufacturing method thereof |
| CN103233161B (en) * | 2013-04-09 | 2016-01-20 | 宝山钢铁股份有限公司 | A kind of low yield strength ratio high-strength hot-rolled Q & P steel and manufacture method thereof |
| BR102014005015A8 (en) * | 2014-02-28 | 2017-12-26 | Villares Metals S/A | martensitic-ferritic stainless steel, manufactured product, process for producing forged or rolled bars or parts of martensitic-ferritic stainless steel and process for producing all seamless martensitic-ferritic stainless steel |
| CN108950383B (en) * | 2018-06-25 | 2020-08-28 | 敬业钢铁有限公司 | Cold-rolled steel plate for high-strength high-plasticity reinforced guard plate and production process thereof |
-
2018
- 2018-12-29 CN CN201811639349.4A patent/CN109402355B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5585626A (en) * | 1978-11-14 | 1980-06-27 | Nisshin Steel Co Ltd | Manufacture of low alloy steel sheet or hoop for precise punching |
| CN102321845A (en) * | 2011-09-21 | 2012-01-18 | 首钢总公司 | A kind of high-strength hot-rolled dual-phase steel and method of manufacture thereof |
| KR20140018580A (en) * | 2012-08-02 | 2014-02-13 | 주식회사 포스코 | Hot-rolled steel sheet for steel pipe having excellent surface integrity and method for manufacturing the same |
| CN106119703A (en) * | 2016-06-21 | 2016-11-16 | 宝山钢铁股份有限公司 | A kind of 980MPa level hot-rolled dual-phase steel and manufacture method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109402355A (en) | 2019-03-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107119228B (en) | A kind of 700~800MPa of tensile strength grades of hot rolling high-strength light dual phase steels and its manufacturing method | |
| CN108018503B (en) | Layered superfine crystal dual-phase ferrite/martensite steel and preparation method thereof | |
| CN104593674B (en) | Galvanizing ultra-low carbon baking hardening steel and its production method | |
| CN103215516A (en) | 700MPa high strength hot rolling Q&P steel and manufacturing method thereof | |
| JP2006509912A (en) | Steel product manufacturing method | |
| CN111218620B (en) | High-yield-ratio cold-rolled dual-phase steel and manufacturing method thereof | |
| CN109680129A (en) | A kind of 500MPa grades of cold rolling micro-alloy high-strength steel and preparation method thereof | |
| CN103233161A (en) | Low-yield-ratio high-strength hot-rolled Q&P steel and manufacturing method thereof | |
| CN108707823A (en) | Ultrahigh-strength steel plates and preparation method thereof and unimach slab products | |
| CN109554615A (en) | A kind of tensile strength 900MPa grades of analysis of producing hot rolled TRIP and preparation method thereof | |
| CN111118397A (en) | 980 MPa-grade quenching distribution steel and preparation method thereof | |
| CN107326276B (en) | A kind of 500~600MPa of tensile strength grades of hot rolling high-strength light dual phase steels and its manufacturing method | |
| CN105695870A (en) | thick hot rolled sheet steel with 450MPa grade yield strength and manufacturing method thereof | |
| CN107794452A (en) | A kind of thin strap continuous casting superelevation strength and ductility product continuously surrenders automobile steel and its manufacture method | |
| WO2019107042A1 (en) | High-strength cold-rolled steel sheet and method for manufacturing same | |
| WO2007000954A1 (en) | Process for manufacture of cold-rolled high-carbon steel plate | |
| CN106636925B (en) | A kind of high strength and ductility Cold-Rolled TRIP Steel and preparation method thereof | |
| CN116288021A (en) | High-strength and high-toughness dual-phase low-density steel and preparation method and application thereof | |
| KR101568519B1 (en) | Hot rolled steel sheet having excellent deformation anisotropy in sheared edge and anti fatigue property and method for manufacturing the same | |
| CN109554616B (en) | 700 MPa-grade hot-rolled TRIP auxiliary type dual-phase steel and preparation method thereof | |
| CN109402355B (en) | 600 MPa-grade hot-rolled TRIP type dual-phase steel and preparation method thereof | |
| CN109735768A (en) | A kind of 650MPa level low alloy high-strength steel and its production method | |
| CN107794453A (en) | A kind of thin strap continuous casting medium managese steel and its manufacture method | |
| CN108411200B (en) | Hot-rolled Q & P steel plate with high work hardening rate and preparation method thereof | |
| CN107217209A (en) | Delamination resistance and the excellent high-yield-ratio type cold-rolled steel sheet of collision characteristic and its manufacture method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |