Lightweight high-strength cold-rolled ferritic steel sheet and method of manufacturing the same

Abstract

The present application relates to a kind of lightweight high-strength cold-rolled ferrite steel plate and its manufacturing method, the chemical composition of steel plate is C≤0.005%, Si≤0.05%, Cu:0.3%~0.8%, Al:5%~8%, S≤0.01%, P≤0.018%, the balance is Fe and impurities.The microstructure of finished steel plate is single ferrite.The alloy system and production process of the steel plate described in the present application are simple, and the production cost is low;By adding Cu, Al element improves the damping performance of steel, the strength of steel is improved by using the precipitation strengthening effect of Cu element, so that the steel plate has high damping performance while also has better mechanical properties;In addition, the composite addition of Al, Cu can also effectively improve the corrosion resistance of steel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cold rolling, in particular to a light high-strength cold-rolled ferrite steel plate applied to the automobile and home appliance industries and a manufacturing method thereof. BACKGROUND

[0002] With the improvement of people's environmental awareness, the demand of steel product users for steel has not been simply high strength and high toughness, but requires steel materials to have certain special properties (properties) in addition to basic mechanical properties, such as structural and functional integrated steel materials, which have certain other functions in addition to structural material properties, including vibration reduction, corrosion resistance, wave absorption performance, lightweight, etc. In order to meet the growing demand of users for special properties of steel materials, structural and functional integrated steel materials will become an important development direction of the next generation of steel materials.

[0003] A Chinese patent application with the application number CN 201811437499.7 discloses a "Fe-Mn-Si-Ni-C elastic-plastic damping steel and its manufacturing method and application", the mass percentage of chemical components in the steel is: 20.0%≤Mn≤34.0%, 3.5%≤Si≤6.0%, 0.1%≤Ni≤5.0%, 0.005%≤C<0.15%, P≤0.02%, S≤0.01%, N≤0.02%, and the rest is Fe and inevitable impurity elements, wherein the mass percentage of Mn, N and C elements also needs to satisfy the following relationships: Mn+1.6Ni+52C≥32% and Mn+2Ni≤37%. The elastic-plastic damping steel is prepared by a production process flow of melting, hot rolling, annealing after hot rolling, or a production process flow of melting, hot rolling, pickling, cold rolling, annealing after cold rolling. However, the alloy system of the steel is complex, the total amount of alloying elements is greater than 20%, and the production cost is high.

[0004] A Chinese patent application with the application number CN 201810419921.X discloses a "high-performance elastic-plastic damping steel and its manufacturing method and application", the mass percentage of chemical components in the steel is: 24%≤Mn≤32%, 3.5%≤Si≤6.0%, 1.0%<Al<2.5%, 0.005%≤C≤0.1%, P≤0.02%, S≤0.03%, N≤0.02%, and the rest is Fe and inevitable impurity elements, wherein the content of Si and Al also needs to satisfy the following relationship: 2.0。It adopts high alloy design, the total amount of alloying elements is more than 26%, the production cost is high, and it is difficult to realize continuous casting production.

[0005] The Chinese patent application with the application number CN 201710549325.9 discloses "a Nb-containing composite low-alloy damping steel and a preparation method thereof". The chemical composition of the steel is as follows: ≤0.15% of carbon, ≤0.2% of silicon, 0.5-2.0% of manganese, 0.2-0.6% of sulfur, 0.01-0.06% of niobium, the ratio of Mn / S is greater than 3.50 but not more than 4.50, and the rest is iron and inevitable trace amounts of chemical elements. The steel adopts an alloy design containing ultra-high sulfur, which improves the damping performance of the steel but seriously deteriorates the cold and hot working properties and the overall mechanical properties of the steel.

[0006] The Chinese patent application with the application number CN 202210856214.3 discloses "a preparation method of high-carbon damping and vibration reduction steel and a melting and casting device thereof". The method adopts a combined casting mode of vacuum induction melting and centrifugal casting, utilizes the complex shear flow technology, combines with subsequent controlled rolling and controlled cooling and heat treatment technology, and shortens the heat treatment time of the high-carbon damping and vibration reduction steel. The method includes the following steps: (1) preparing raw materials needed for melting, the chemical composition of the high-carbon damping and vibration reduction steel is as follows: C≥1.2%, Si: 1.5%-1.7%, Mn: 0.20%-0.22%, Ni: 2.15%-2.25%, Al: 0.25%-0.27%, and the rest is Fe; (2) placing the raw materials into a crucible of a melting system, embedding a casting mold into a centrifugal bucket, filling refractory insulation materials between the casting mold and the centrifugal bucket, and preheating the casting mold; (3) heating and melting the raw materials in the crucible and keeping the temperature, pouring the alloy melt into the casting mold after the keeping temperature is completed; (4) starting the motor to drive the bottom centrifugal disc, driving the centrifugal bucket, and moving the centrifugal bucket and the bottom centrifugal disc at a set speed ratio until the alloy is completely solidified, and then taking out the cast ingot; (5) after homogenizing the cast ingot at high temperature, rolling the cast ingot by controlling the temperature in the rolling process; (6) after isothermal heat treatment of the rolled plate, carrying out furnace cooling treatment to make the rolled plate graphitized, and thus obtaining the high-carbon damping and vibration reduction steel. The technical core is to utilize the graphitization promotion effect of Ni and Al, to make the carbon of the high-carbon steel graphitized through a complex heat treatment process, and thus to improve the damping performance. However, the alloy cost and process cost are high.

[0007] The Chinese patent application with the application number CN 86102543 discloses an "iron-chromium-based mute damping steel and a manufacturing method thereof". In the smelting process, one, two, or three of Si-Ca alloy, Ti-Fe alloy, mixed rare earth metals or their alloys (rare earth-magnesium, rare earth-calcium, rare earth-magnesium-silicon alloy, etc.) are added to remove non-metallic impurities in the steel and realize non-vacuum smelting. In addition to Fe and Cr, the alloy composition also contains Mo, Si, Cu, Ti, Mn, C, and three or more components in the mixed rare earth, which can be used in various mechanical and electrical products that are greatly harmed by vibration and noise. The alloy system is complex and the production cost is high. SUMMARY

[0008] The present application provides a kind of lightweight high-strength cold-rolled ferrite steel plate and its manufacturing method, alloy system and production process are simple, and production cost is low;By adding Cu, Al element improves the damping performance of steel, utilizes the precipitation strengthening effect of Cu element to improve the strength of steel, so that the steel plate has high damping performance while also has better mechanical properties;In addition, the composite addition of Al, Cu can also effectively improve the corrosion resistance of steel.

[0009] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0010] A kind of lightweight high-strength cold-rolled ferrite steel plate, the chemical composition of steel plate is as follows in percentage by mass C≤0.005%, Si≤0.05%, Cu:0.3%~0.8%, Al:5%~8%, S≤0.01%, P≤0.018%, the balance is Fe and inevitable impurities.

[0011] Further, the microstructure of finished steel plate is single ferrite.

[0012] Further, the yield strength of finished steel plate is ≥500MPa, the tensile strength is ≥600MPa, the elongation A 50 After breaking is ≥20%, and the damping coefficient is ≥0.05.

[0013] A kind of manufacturing method of lightweight high-strength cold-rolled ferrite steel plate, comprising the following steps:

[0014] (1) heating: the billet is heated to 1100±50℃ in heating furnace, and is kept for 2±0.5h;

[0015] (2) hot rolling: the final rolling temperature of hot rolling is 880±20℃, and after rolling, water cooling is carried out to 350℃±50℃ and then coiling, and then air cooling to room temperature;

[0016] (3) cold rolling and annealing: the cold rolling reduction is ≥70%, the annealing temperature is 600±20℃, and after keeping for 1±0.2h, it is cooled to room temperature with furnace.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] 1) The produced cold-rolled steel plate has single ferrite structure, the yield strength is ≥500MPa, the tensile strength is ≥600MPa, the elongation A After breaking is ≥20%, which can meet the performance requirements of steel plate for automobile, household appliance and precision mechanical equipment.

[0019] 2) By the composite addition of Al and Cu, the corrosion resistance of steel plate is improved, and the service life of equipment is effectively improved.

[0020] 3) The damping value δ of the cold-rolled steel plate is ≥0.05, which is more than 10 times of that of common steel materials, and the mechanical vibration resistance of the automobile and household appliance is improved; the noise generated by the automobile and mechanical equipment can be effectively reduced;

[0021] 4) The produced cold-rolled steel plate has good mechanical properties, and is beneficial to realize the lightweight of the equipment;

[0022] 5) The alloy system and production process are simple, and the production cost is low; PREFERRED EMBODIMENT

[0023] The yield strength of the finished steel plate is ≥500 MPa, the tensile strength is ≥600 MPa, the elongation A after fracture is ≥20%, and the damping coefficient is ≥0.05, so that the steel plate has high mechanical properties, meets the requirements of structural materials, and has excellent damping performance and corrosion resistance. 50

[0024] The chemical composition of the light high-strength cold-rolled ferrite steel plate according to the application is C≤0.005%, Si≤0.05%, Cu: 0.3%-0.8%, Al: 5%-8%, S≤0.01%, P≤0.018%, and the balance is Fe and inevitable impurities.

[0025] Based on the production cost and the comprehensive performance of the steel plate, the chemical composition and the main role of the steel plate according to the application are as follows:

[0026] C: Carbon is the most important solid solution strengthening element in steel, but the solid solution carbon will significantly reduce the damping performance of the steel plate, and the increase of carbon will lead to the generation of non-ferrite structure in the steel. Considering the cost factor, the upper limit of the carbon content in the steel is controlled to be 0.005%.

[0027] Si: Silicon is a common element in steel, which can improve the strength of the steel, but will reduce the plasticity of the steel, and further reducing the Si content will increase the metallurgical cost, so the Si content in the steel is controlled to be less than 0.05%.

[0028] Cu: Copper has the effects of solid solution strengthening and precipitation strengthening, and the copper precipitates can also improve the damping performance of the steel. Cu is precipitated in the form of elemental Cu in the steel, and its strength is less than the matrix strength, and its strengthening effect is between vacancies and rigid points, which can form abnormal pinning of dislocations, absorb energy when the dislocations are pinned and unpinned, thereby improving the damping performance of the steel. In addition, copper is also a common corrosion-resistant element, which can improve the corrosion resistance of the steel by forming a dense oxide film. However, too high copper content will increase the surface defects of the casting blank and the hot-rolled steel plate. At the same time, the maximum solid solubility of Cu in ferrite is about 0.8%, so the Cu content in the steel is controlled to be 0.3%-0.8%.​

[0029] Al: Aluminum can form inhibition of cementite precipitation, reduce the density of steel, play a solid solution strengthening effect, fixed nitrogen in steel, play a certain role in grain refinement, and solid solution aluminum can promote ferrite formation, while aluminum can also increase the mobility of magnetic domain wall, improve the damping performance of steel. Considering the lightweight requirements of the steel and the difficulty of steel casting, the aluminum content in the steel is controlled at 5% to 8%.

[0030] P: Although phosphorus can improve the strength of the steel plate, it can seriously deteriorate the cold forming performance of the steel, therefore the upper limit of the present application is controlled at 0.018%.

[0031] S: Sulfur is a harmful element in steel, which can form manganese sulfide to reduce the performance of the steel plate, therefore the less the better, considering the cost problem, the upper limit of the present application is controlled at 0.01%.

[0032] The present application improves the strength and damping performance of the steel by adding Al and Cu elements, while improving the corrosion resistance and high temperature oxidation resistance of the steel. The microstructure of the finished steel plate is single ferrite. The specific manufacturing method comprises the following steps:

[0033] (1) Heating process: the steel billet with qualified composition is heated to 1100±50℃ in a heating furnace and is kept for 2±0.5 hours. The alloying elements are fully solid-solved and the composition is uniform.

[0034] (2) Rolling process: normal rolling + water cooling, finish rolling temperature 880±20℃, water cooling to 350℃±50℃ to simulate coiling, air cooling to room temperature.

[0035] (3) Cold rolling and annealing process: cold rolling reduction rate is not less than 70%, 600±20℃ for 1±0.2, and cooling to room temperature with the furnace.

[0036] In the manufacturing method of the light weight high strength cold rolled ferrite steel plate, the selection reasons of each process and process parameters are as follows:

[0037] (1) The steel described in the present application does not contain difficult-to-dissolve metals, so a lower soaking temperature can be selected to achieve alloy element homogenization, while preventing thermal embrittlement caused by copper elements, and saving energy and reducing production cost.

[0038] (2) Finish rolling temperature 880±20℃ can ensure that copper element is fully solid-solved, and water cooling to 350℃±50℃ can avoid copper precipitation during cooling, which can reduce the deformation resistance of the steel plate, facilitate cold rolling, and at the same time can reduce the annealing temperature and reduce the production cost.

[0039] (3) The cold rolling reduction of not less than 70% helps to improve the mechanical properties of the steel, and the 600±20℃ holding for 1±0.2h can ensure the cold-rolled steel plate to have suitable grain size, and the copper can also be analyzed out to improve the strength and damping performance. The furnace cooling can reduce the internal stress of the steel plate and improve the damping performance.

[0040] In order to more directly reflect the present application, the embodiments of the present application are further described in combination with examples. The following examples are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can obtain the technical solutions which are obvious within the technical range disclosed by the present application, including simple changes or equivalent replacements, and all of them are within the protection scope of the present application.

[0041]

Example

[0042] The production process of the present example is as follows: after the 80kg cast blank with qualified components is cut off the head and tail and heated to 1050±50℃, it is held for 2±0.5h and then rolled. The hot rolling final rolling temperature is 880±20℃, water cooling to 350±50℃ coiling, air cooling to room temperature; the cold rolling reduction is not less than 70%, and after holding at 600±20℃ for 1±0.2h, it is cooled to room temperature in the furnace.

[0043] The chemical components of the steel in the 6 examples are shown in Table 1, the main process parameters are shown in Table 2, and the mechanical property parameters of the finished steel plate are shown in Table 3.

[0044] Table 1 Chemical components of the steel (wt, %)

[0045] Embodiments C Si P S Al Cu 1 0.001 0.04 0.016 0.007 5.5 0.4 2 0.003 0.05 0.014 0.006 6.1 0.5 3 0.005 0.03 0.015 0.009 7.5 0.3 4 0.002 0.05 0.008 0.005 6.6 0.62 5 0.002 0.04 0.012 0.007 5.0 0.72 6 0.003 0.04 0.011 0.005 8.0 0.8

[0046] Table 2 Main process parameters

[0047]

[0048] Table 3 Mechanical property parameters of the finished steel plate

[0049]

[0050] The above description is only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can obtain the technical solutions which are obvious within the technical range disclosed by the present application, including simple changes or equivalent replacements, and all of them are within the protection scope of the present application.

Claims

1. A method for manufacturing a lightweight, high-strength cold-rolled ferritic steel sheet, characterized in that, The chemical composition of the steel plate, by mass percentage, is C≤0.005%, Si≤0.05%, Cu: 0.3%~0.8%, Al: 5%~8%, S≤0.01%, P≤0.018%, with the balance being Fe and unavoidable impurities; The microstructure of the finished steel plate is a single ferrite; the yield strength of the finished steel plate is ≥500MPa, the tensile strength is ≥600MPa, and the elongation after fracture is A 50 ≥20%, damping coefficient ≥0.05; The manufacturing method of the lightweight, high-strength cold-rolled ferritic steel plate includes the following steps: (1) Heating: The steel billet is heated to 1100±50℃ in a heating furnace and held at that temperature for 2±0.5h; (2) Hot rolling: The final rolling temperature of hot rolling is 880±20℃. After rolling, the water is cooled to 350℃±50℃ and then coiled, and then air-cooled to room temperature. (3) Cold rolling and annealing: The cold rolling reduction rate is ≥70%, the annealing temperature is 600±20℃, and the temperature is held for 1±0.2h before being cooled to room temperature in the furnace.

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