CN114032467A - Cold-rolled high-strength steel plate and preparation method thereof - Google Patents

Cold-rolled high-strength steel plate and preparation method thereof Download PDF

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CN114032467A
CN114032467A CN202111360817.6A CN202111360817A CN114032467A CN 114032467 A CN114032467 A CN 114032467A CN 202111360817 A CN202111360817 A CN 202111360817A CN 114032467 A CN114032467 A CN 114032467A
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strength steel
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徐接旺
郭太雄
董学强
冉长荣
罗嘉庆
赵平平
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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    • 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
    • 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
    • C21D1/26—Methods of annealing
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • 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
    • 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
    • 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
    • C21D8/0236—Cold rolling
    • 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
    • C21D8/0242—Flattening; Dressing; Flexing
    • 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
    • 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
    • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • 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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • 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

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  • Crystallography & Structural Chemistry (AREA)
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  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The invention discloses a cold-rolled high-strength steel plate and a preparation method thereof, belonging to the field of surface treatment of metal materials. The cold-rolled high-strength steel plate comprises the following casting blank chemical components in percentage by mass: 0.1 to 0.2 percent of C, 1.5 to 2.5 percent of Mn1, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of P, 0.5 to 2.0 percent of Si, 0.015 to 0.06 percent of AlsN, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities. The preparation method comprises the process flows of smelting and casting → hot rolling and coiling → acid pickling and cold rolling → continuous annealing → leveling. The phosphating film layer on the surface of the cold-rolled automobile plate prepared by the method has the advantages of compact structure, uniform crystallization, granular shape, smaller porosity and higher coatability, and can effectively solve the problem of poorer phosphating performance of the existing cold-rolled high-strength steel plate with high formability.

Description

Cold-rolled high-strength steel plate and preparation method thereof
Technical Field
The invention belongs to the field of surface treatment of metal materials, and particularly relates to a cold-rolled high-strength steel plate and a preparation method thereof.
Background
With the continuous development of automobile lightweight technology, high-strength steel is used as one of key materials for automobile lightweight, has obvious application effects on the aspects of reducing automobile weight, saving energy and improving safety performance, is widely applied to the automobile industry, and is mainly used as an automobile structural part, a safety part and a reinforcing part. However, as the strength of the material increases, the formability of the material decreases sharply, which leads to an increasingly prominent problem of cracking of the part during the stamping process, limiting the application of high-strength steel sheets to complex parts of automobile bodies. Therefore, there is an urgent need to develop a steel sheet having both high strength and high formability.
In order to improve the formability of high-strength steel sheets, silicon is generally added. However, in the annealing process, alloying elements such as silicon and manganese are enriched and selectively oxidized on the surface of the steel plate, so that the surface reaction activity is not uniform, the surface phosphating reaction process of the steel plate is not uniform, the structure of a phosphating film layer at a local position is abnormal, and the problem that the phosphating performance of a cold-rolled high-strength steel plate with high formability is poor is increasingly highlighted in recent years.
2016, 3, 23 and CN105420607A disclose a method for controlling the surface quality of cold-rolled automobile sheet coating performance, which is only suitable for IF steel cold-rolled automobile sheet, and the cold-rolled automobile sheet coating performance is improved by controlling the element distribution, oxidation state, surface roughness and the like of the cold-rolled automobile sheet. CN111647733A of 9/11/2020 discloses a method for improving the phosphating performance of a low-carbon aluminum killed steel automobile plate and the automobile plate, wherein the phosphating performance of the low-carbon aluminum killed steel automobile plate is improved by controlling the components of a casting blank, hot rolling, cold rolling, annealing and flattening processes, and the method is obviously not suitable for cold rolling of a high-strength steel plate. CN106244923A on 21/12/2016 discloses a cold-rolled high-strength steel plate with excellent phosphatization and forming performances and a manufacturing method thereof, wherein in the method, the external oxidation is converted into the internal oxidation by controlling the dew point temperature of the atmosphere in a heating section and a soaking section in the continuous annealing process, thereby reducing the enrichment of surface elements and improving the quality of a phosphatization film; however, the control of the surface cleanliness and surface roughness of the cold rolled plate and the reactivity of the substrate in the phosphating solution is neglected.
Therefore, it is necessary to develop a new cold-rolled high-strength steel sheet having excellent phosphatability and formability.
Disclosure of Invention
The invention aims to solve the technical problem that the existing cold-rolled high-strength steel plate with high formability has poor phosphating performance.
The technical scheme adopted by the invention for solving the technical problems is as follows: the cold-rolled high-strength steel plate comprises the following casting blank chemical components in percentage by mass: 0.1 to 0.2 percent of C, 1.5 to 2.5 percent of Mn, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of P, 0.5 to 2.0 percent of Si, 0.015 to 0.06 percent of Als, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
The preparation method of the cold-rolled high-strength steel plate comprises the following steps:
a. smelting and casting: smelting and pouring according to chemical components of a cold-rolled high-strength steel plate casting blank;
b. a hot rolling coiling process: controlling the temperature of a steel billet of the hot-rolled strip steel to be 1200-1300 ℃, and controlling the finish rolling temperature to be 840-900 ℃; rolling and then coiling;
c. acid pickling and cold rolling: controlling the pickling speed to be 80-120m/min, the cold rolling reduction rate to be 40-80%, and the saponification value of the emulsion to be 100-200 mgKOH/g;
d. a continuous annealing process: heating to 800-;
e. leveling: controlling the surface roughness Ra value of the flat strip steel to be 1.0-1.3 mu m, the Rpc value to be 80-130 and the surface energy to be 1.2-1.8J/m2。
In the step a, the chemical components of the cold-rolled high-strength steel plate casting blank comprise, by mass, 0.1-0.2% of C, 1.5-2.5% of Mn, less than or equal to 0.005% of S, less than or equal to 0.015% of P, 0.5-2.0% of Si, 0.015-0.06% of Als, less than or equal to 0.005% of N, and the balance Fe and inevitable impurities.
In the step b, the steel tapping billet temperature of the hot-rolled strip steel is 1220-1250 ℃, and the finish rolling temperature is 850-880 ℃.
In the step b, the coiling temperature is 400-600 ℃.
In the step c, the pickling speed is 80-100m/min, the cold rolling reduction is 60-80%, and the saponification value of the emulsion is 150-200 mgKOH/g.
Further, the corrosion inhibitor in the emulsion is at least one of urotropine, thiourea and thiourea-aluminum sulfate in the acid washing solution.
Furthermore, the mass fraction of the corrosion inhibitor in the emulsion is 0.5-1.5%.
In the step c, the total amount of the residual oil on the double surfaces of the cold-hard strip steel after cold rolling is controlled to be less than or equal to 200mg/m2The surface reflectivity is more than or equal to 80 percent.
In the step d, the atmosphere of the annealing furnace is N2-H2In which H is2The content is 2-10%, and the dew point temperature of the annealing atmosphere is-25-10 ℃.
In the step e, the specific value of the roughness is based on controlling the initial potential of the cold rolled plate in the phosphating solution to be-450- (-520) mV.
The invention has the beneficial effects that: the yield strength of the cold-rolled high-strength steel plate provided by the invention is more than or equal to 600MPa, the tensile strength is more than or equal to 700MPa, and the elongation A50 is 20-40%. According to the preparation method of the cold-rolled high-strength steel plate, the retained austenite induces and generates martensite phase transformation under the action of plastic deformation, and the provided cold-rolled automobile plate has high strength and excellent forming performance and phosphating performance; according to the invention, the internal oxidation replaces the external oxidation process, and no obvious element enrichment phenomenon exists on the surface of the steel plate, so that the high strength and the formability of the cold-rolled plate are ensured, and the cold-rolled plate has excellent phosphatability, and meets the technical requirements of light weight of automobiles; the surface cleanliness of the cold-rolled automobile plate provided by the invention is higher, the surface is almost free of any residue pollution, the surface reflectivity after acid rolling is more than or equal to 80%, the pit size of the surface after leveling is smaller and is uniformly distributed, the surface phosphating active points are more in number and are uniformly distributed, and the surface phosphating active points are tightly combined with a phosphating film and have strong adhesive force; the cold-rolled automobile sheet provided by the invention has the advantages of low initial potential and high surface activity in the phosphating solution, can quickly generate phosphating reaction, and is suitable for priming before coating and corrosion prevention.
Drawings
FIG. 1 is a diagram showing the appearance of a phosphating film on the surface of a cold-rolled automobile plate manufactured in example 1 of the invention;
FIG. 2 is a topographic map of the phosphating film on the surface of the cold-rolled automobile plate prepared in the embodiment 2 of the invention.
Detailed Description
The technical solution of the present invention can be specifically implemented as follows.
The cold-rolled high-strength steel plate comprises the following casting blank chemical components in percentage by mass: 0.1 to 0.2 percent of C, 1.5 to 2.5 percent of Mn, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of P, 0.5 to 2.0 percent of Si, 0.015 to 0.06 percent of Als, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
The preparation method of the cold-rolled high-strength steel plate comprises the following steps:
a. smelting and casting: smelting and pouring according to chemical components of a cold-rolled high-strength steel plate casting blank;
b. a hot rolling coiling process: controlling the temperature of a steel billet of the hot-rolled strip steel to be 1200-1300 ℃, and controlling the finish rolling temperature to be 840-900 ℃; rolling and then coiling;
c. acid pickling and cold rolling: controlling the pickling speed to be 80-120m/min, the cold rolling reduction rate to be 40-80%, and the saponification value of the emulsion to be 100-200 mgKOH/g;
d. a continuous annealing process: heating to 800-;
e. leveling: controlling the surface roughness Ra value of the flat strip steel to be 1.0-1.3 mu m, the Rpc value to be 80-130 and the surface energy to be 1.2-1.8J/m2。
In the step a, the chemical components of the cold-rolled high-strength steel plate casting blank comprise, by mass, 0.1-0.2% of C, 1.5-2.5% of Mn1, less than or equal to 0.005% of S, less than or equal to 0.015% of P, 0.5-2.0% of Si, 0.015-0.06% of Als, less than or equal to 0.005% of N, and the balance Fe and inevitable impurities.
If the temperature of the hot-rolled strip steel tapping steel billet is too high, not only can the crystal grains in the steel billet be abnormally large and the hot processing performance be reduced, but also the surface of the plate blank can be seriously decarburized; if the temperature is too low, the deformation resistance of the plate blank is increased, and the plasticity is reduced; if the finish rolling temperature is too low, the deformation resistance of the plate blank is increased, a steel plate with a specified thickness is difficult to produce, and the plate shape is poor; therefore, in the step b, the steel tapping temperature of the hot-rolled strip steel is 1220-.
In the pickling process, if the pickling speed is too high, the iron oxide scales on the surface of the steel plate cannot be completely cleaned, so that surface defects are easily formed, and if the pickling speed is too low, the speed of a rolling mill is reduced, so that the plate shape control and the production efficiency are influenced; the formation rate of austenite in the annealing process can be improved by a larger reduction ratio, which is beneficial to improving the uniformity and ductility of the steel plate structure after annealing, but if the reduction ratio of cold rolling is too large, the deformation resistance of the material is very high due to work hardening, and the cold-rolled steel plate which meets the specified thickness and has good plate shape is difficult to prepare; therefore, in step c, the pickling speed is 80-100m/min, the cold rolling reduction is 60-80%, and the saponification value of the emulsion is 150-200 mgKOH/g; the corrosion inhibitor in the emulsion is at least one of urotropine, thiourea and thiourea-aluminum sulfate in a pickling solution, and the mass fraction of the corrosion inhibitor in the emulsion is 0.5-1.5%; more preferably, the total amount of residual oil on the double surfaces of the cold-hard strip steel after cold rolling is controlled to be less than or equal to 200mg/m2The surface reflectivity is more than or equal to 80 percent.
The soaking temperature and soaking time of the invention are selected mainly by considering their influence on the structure and performance of the strip steel matrix and their influence on the thickness of the oxide layer in the steel plate. The content of the retained austenite in the structure is controlled by means of rapid cooling, reheating temperature and heat preservation, and the performance of the steel strip is further influenced.
If the temperature of the soaking section is too low and the heat preservation time is too short, the austenite phase transformation of the cold-rolled steel plate is insufficient, a sufficient amount of residual austenite cannot be formed, and the problems of low strip steel strength, insufficient elongation and the like caused by uneven austenite structure can also occur; if the temperature of the soaking section is too high and the heat preservation time is too long, the matrix structure of the annealed steel plate is subjected to complete austenite transformation, so that the stability of austenite is reduced, the content of residual austenite in the matrix of the annealed steel plate is reduced, ferrite disappears, the strength of the steel plate is increased, and the formability is reduced. Therefore, the control parameters of the designed annealing process of the invention are that the temperature is raised to 800-. Meanwhile, in order to obtain a steel strip having high strength and good formability, it is preferable that the annealing furnace atmosphere in the step d is N2-H2In which H is2The content is 2-10%, and the dew point temperature of the annealing atmosphere is-25-10 ℃.
If the roughness and the surface activity are too low, the number of nucleation points in the phosphating reaction process is small, the phosphating film forming rate is slow, the formed phosphating film is sparse and even has no film, because in the step e, the surface roughness Ra value of the strip steel after being controlled to be flat is 1.0-1.3 mu m, the Rpc value is 80-130, and the surface energy is 1.2-1.8J/m2The specific value of the roughness is based on controlling the initial potential of the cold rolled plate in the phosphating solution to be-450- (-520) mV.
The technical solution and effects of the present invention will be further described below by way of practical examples.
Examples
The invention provides two groups of examples for preparing cold-rolled automobile plates by adopting the method, and the main chemical components of the casting blanks of the examples 1 and 2 are shown in the table 1.
TABLE 1 example billet chemical composition%
C Si Mn P S Als N
Example 1 0.15 1.55 2.41 0.01 0.005 0.02 0.005
Example 2 0.11 0.55 2.61 0.01 0.005 0.02 0.005
The specific experimental procedures of examples 1 and 2 were as follows:
a. smelting and casting: smelting and pouring according to chemical components of the cold-rolled high-strength steel plate casting blank in the table 1;
b. a hot rolling coiling process: the steel billet temperature of the hot-rolled strip steel of example 1 was controlled to 1200 ℃, the hot-rolling finishing temperature was controlled to 840 ℃, and the coiling temperature was controlled to 600 ℃; controlling the temperature of a steel billet discharged from the hot-rolled strip steel of example 2 to 1250 ℃, the hot-rolling finishing temperature to 880 ℃ and the coiling temperature to 500 ℃;
c. acid pickling and cold rolling: carrying out acid pickling on the hot rolled plate, and then carrying out cold rolling, wherein the specific process parameters are shown in table 2, so as to obtain cold-hard strip steel; example 1 Total amount of residual oil on the surface of a cold-hard strip after acid rolling (both sides) was 100mg/m2Surface reflectance was 92%; example 2 Total amount of residual oil (on both sides) on the surface of the cold-hard strip after acid rolling was 50mg/m2Surface reflectance is 95%;
TABLE 2 Cold Rolling Process for pickling
Figure BDA0003359176670000051
d. A continuous annealing process: carrying out continuous annealing treatment on the cold-hard strip steel, wherein the specific process parameters are shown in table 3, and obtaining an annealed steel plate;
TABLE 3 annealing procedure
Figure BDA0003359176670000052
The annealed steel sheet obtained in example 1 had a tensile strength of 780MPa, a yield strength of 600MPa, an elongation a50 of 35%, a residual austenite content of about 5% in a room temperature structure, a ferrite content of about 50%, and an inner oxide film layer thickness of 5 μm;
the annealed steel sheet obtained in example 2 had a tensile strength of 980MPa, a yield strength of 750MPa, an elongation a50 of 30%, a residual austenite content of about 10%, a ferrite content of about 40%, and an inner oxide film layer thickness of 8 μm in a room temperature structure;
e. leveling: after the flattening of the steel strip of the embodiment 1, the surface roughness Ra value is controlled to be 1.0 mu m, the Rpc value is controlled to be 100, and the surface energy is controlled to be 1.7J/m2The initial potential of the Zn-Mn-Ni phosphating solution for the automobile is-480 mV; after the flattening of the steel strip is carried out by controlling the Ra value of the surface roughness of the steel strip to be 1.2 mu m, the Rpc value to be 110 and the surface energy to be 1.8J/m2The initial potential of the Zn-Mn-Ni phosphating solution for the automobile is-500 mV.
The surface phosphating films of the cold-rolled automobile plates obtained in the examples 1 and 2 are detected:
as can be seen from the figure, the average grain size of the phosphating film layer prepared by the method is 3 microns, and the phosphating film layer has a compact structure, uniform crystallization, granular shape, small porosity and high coatability.

Claims (10)

1. The cold-rolled high-strength steel plate is characterized in that the casting blank comprises the following chemical components in percentage by mass: 0.1 to 0.2 percent of C, 1.5 to 2.5 percent of Mn, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of P, 0.5 to 2.0 percent of Si, 0.015 to 0.06 percent of Als, less than or equal to 0.005 percent of N, and the balance of Fe and inevitable impurities.
2. The preparation method of the cold-rolled high-strength steel plate is characterized by comprising the following steps of:
a. smelting and casting: smelting and pouring according to chemical components of a cold-rolled high-strength steel plate casting blank;
b. a hot rolling coiling process: controlling the temperature of a steel billet of the hot-rolled strip steel to be 1200-1300 ℃, and controlling the finish rolling temperature to be 840-900 ℃; rolling and then coiling;
c. acid pickling and cold rolling: controlling the pickling speed to be 80-120m/min, the cold rolling reduction rate to be 40-80%, and the saponification value of the emulsion to be 100-200 mgKOH/g;
d. a continuous annealing process: heating to 800-;
e. leveling: controlling the surface roughness Ra value of the flat strip steel to be 1.0-1.3 mu m, the Rpc value to be 80-130 and the surface energy to be 1.2-1.8J/m2。
3. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2, characterized in that: in the step a, the chemical components of the cold-rolled high-strength steel plate casting blank comprise, by mass, 0.1-0.2% of C, 1.5-2.5% of Mn, less than or equal to 0.005% of S, less than or equal to 0.015% of P, 0.5-2.0% of Si, 0.015-0.06% of Als, less than or equal to 0.005% of N, and the balance Fe and inevitable impurities.
4. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2, characterized in that: in the step b, the steel tapping billet temperature of the hot-rolled strip steel is 1220-1250 ℃, and the finish rolling temperature is 850-880 ℃.
5. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2, characterized in that: in the step b, the coiling temperature is 400-600 ℃.
6. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2, characterized in that: in the step c, the pickling speed is 80-100m/min, the cold rolling reduction is 60-80%, and the saponification value of the emulsion is 150-200 mgKOH/g.
7. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2 or 6, characterized in that: the corrosion inhibitor in the emulsion is at least one of urotropine, thiourea and thiourea-aluminum sulfate in the acid washing solution.
8. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 7, characterized in that: the mass fraction of the corrosion inhibitor in the emulsion is 0.5-1.5%.
9. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2, characterized in that: in the step c, the total amount of the residual oil on the two sides of the cold-hard strip steel after cold rolling is controlled to be less than or equal to 200mg/m2The surface reflectivity is more than or equal to 80 percent.
10. The method of manufacturing a cold-rolled high-strength steel sheet according to claim 2, characterized in that: in step d, the atmosphere of the annealing furnace is N2-H2In which H is2The content is 2-10%, and the dew point temperature of the annealing atmosphere is-25-10 ℃.
CN202111360817.6A 2021-11-17 2021-11-17 Cold-rolled high-strength steel plate and preparation method thereof Pending CN114032467A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003113441A (en) * 2001-10-09 2003-04-18 Kobe Steel Ltd Steel sheet superior in phosphating property
CN103147015A (en) * 2011-12-07 2013-06-12 鞍钢股份有限公司 Hot-rolled pickled plate having good phosphorization performances
CN105420607A (en) * 2015-12-26 2016-03-23 首钢总公司 Control method for increasing painting performance and surface quality of cold rolling automobile sheet
CN106350731A (en) * 2016-08-30 2017-01-25 宝山钢铁股份有限公司 Cold-rolled high-strength steel plate with excellent phosphorization and formability and manufacturing method thereof
CN109136739A (en) * 2018-06-29 2019-01-04 唐山钢铁集团有限责任公司 The control method of dual phase steel cold rolling high strength car sheet paintable energy surface quality
CN111647733A (en) * 2020-05-11 2020-09-11 首钢集团有限公司 Method for improving phosphating performance of low-carbon aluminum killed steel automobile plate and automobile plate
CN112126855A (en) * 2020-09-11 2020-12-25 山东钢铁集团日照有限公司 Production method of cold-rolled weather-resistant steel with yield strength of more than 310MPa

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003113441A (en) * 2001-10-09 2003-04-18 Kobe Steel Ltd Steel sheet superior in phosphating property
CN103147015A (en) * 2011-12-07 2013-06-12 鞍钢股份有限公司 Hot-rolled pickled plate having good phosphorization performances
CN105420607A (en) * 2015-12-26 2016-03-23 首钢总公司 Control method for increasing painting performance and surface quality of cold rolling automobile sheet
CN106350731A (en) * 2016-08-30 2017-01-25 宝山钢铁股份有限公司 Cold-rolled high-strength steel plate with excellent phosphorization and formability and manufacturing method thereof
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Application publication date: 20220211