Hot-dip aluminum-zinc steel plate with yield strength of 320MPa and manufacturing method thereof
阅读说明：本技术 一种屈服强度320MPa级热镀铝锌钢板及其制造方法 (Hot-dip aluminum-zinc steel plate with yield strength of 320MPa and manufacturing method thereof ) 是由 丁志龙 魏宝民 于 2020-05-25 设计创作，主要内容包括：本发明公开了一种屈服强度320MPa级热镀铝锌钢板及其制造方法,主要解决现有技术中屈服强度320MPa级热镀铝锌钢板在铆接胀形加工过程中发生开裂的技术问题。本发明提供的一种屈服强度320MPa级热镀铝锌钢板,其基板的化学成分重量百分比为：C：0.06～0.08％,Si：0～0.03％,Mn：0.15～0.25％,P：0～0.015％,S：0～0.015％,Nb：0.0045～0.0080％,Al：0.04～0.06％,N：0.0020～0.0040％,余量为Fe和不可避免的夹杂元素。本发明热镀铝锌钢板的n值为1.9～2.1；本发明热镀铝锌钢板主要用于车辆箱体用钢部件。(The invention discloses a hot-dip aluminum-zinc steel plate with a yield strength of 320MPa and a manufacturing method thereof, and mainly solves the technical problem that the hot-dip aluminum-zinc steel plate with the yield strength of 320MPa cracks in the riveting bulging processing process in the prior art. The invention provides a hot-dip aluminum-zinc plated steel plate with 320 MPa-level yield strength, which comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.25%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0045-0.0080%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent, and the balance of Fe and inevitable impurity elements. The n value of the hot-dip aluminum-zinc plated steel plate is 1.9-2.1; the hot-dip aluminum-zinc plated steel plate is mainly used for steel parts for vehicle boxes.)
1. A hot-dip aluminum-zinc plated steel plate with 320 MPa-grade yield strength comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.25%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0045-0.0080%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent of the balance of Fe and inevitable impurity elements; the metallographic structure of the hot-dip aluminum-zinc steel plate is recrystallized ferrite and fine cementite, and the grain size grade of the ferrite is I8.5-I9.5 grade.
2. The hot-dip Al-Zn-coated steel sheet having a yield strength of 320MPa according to claim 1, wherein the yield strength R of the hot-dip Al-Zn-coated steel sheet having a thickness of 1.0 to 1.2mmP0.2Is 320 to 360MPa, Rm389-404 MPa, elongation after break A50mm38 to 43% and n is 1.9 to 2.1.
3. The hot-dip aluminum-zinc plated steel sheet with the yield strength of 320MPa according to claim 1, wherein the substrate of the hot-dip aluminum-zinc plated steel sheet comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.20%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0055-0.0065%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent, and the balance of Fe and inevitable impurity elements.
4. A manufacturing method of a hot-dip aluminum-zinc steel plate with 320 MPa-level yield strength is characterized by comprising the following steps:
continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.25%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0045-0.0080%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent of the balance of Fe and inevitable impurity elements;
heating the continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 850-870 ℃; adopting front-section cooling for laminar cooling, and coiling at the coiling temperature of 530-550 ℃ to obtain a hot-rolled steel coil;
the hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot aluminum and zinc plating and leveling, and is coiled to obtain a finished hot aluminum and zinc plated steel plate with the thickness of 1.0-1.2 mm, the cold rolling reduction rate is 68-75%, the heating temperature of the cold rolled hard strip steel in the annealing in the horizontal continuous annealing furnace is 630-640 ℃, the temperature of a soaking section is 730-740 ℃, the annealing time of the strip steel in the soaking section is 50-60 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 20-25 ℃/s, and the strip steel is placed into a zinc pot for hot dip aluminum and zinc plating after being isothermal for 5-7 s; the leveling elongation is 1.0-1.5%.
5. The method for producing a hot-dip aluminized zinc sheet having a yield strength of 320MPa according to claim 4, wherein the thickness of the hot-rolled sheet is controlled to 3.8 to 4.0mm after the finish rolling.
Technical Field
The invention relates to a cold-rolled hot-dipped aluminum-zinc steel plate, in particular to a hot-dipped aluminum-zinc steel plate with the yield strength of 320MPa and a manufacturing method thereof, belonging to the technical field of iron-based alloy.
Background
The hot-dip aluminum-zinc steel plate has excellent atmospheric corrosion resistance and heat resistance of a pure aluminum coating, has good cathode protection and certain notch protection functions of the pure zinc coating, has excellent heat radiation resistance and heat reflectivity, and is widely applied to the fields of buildings, automobiles, household appliances and the like.
In recent years, in the field of new containers, aluminized zinc sheets have been used as panels because of their beautiful steel sheet surfaces, and because they require a certain load-bearing capacity, products are required to have not only high strength but also certain formability.
In the actual box body processing process, on one hand, the material strength requirement is continuously improved, but the steel plate is cracked in the riveting bulging processing process while the strength is improved.
The application publication number CN101348880A discloses a production method of a high-strength galvanized sheet for a structure, which is characterized in that the galvanized sheet comprises the following chemical components in percentage by mass: c, 0.16-0.20%; 0.9 to 1.1 percent of Mn; si is less than or equal to 0.05 percent; p is less than or equal to 0.020%; s is less than or equal to 0.020%; 0.02-0.06% of Als, and the balance of Fe; hot rolling technological parameters are as follows: the heating temperature is 1250 +/-20 ℃; the rough rolling outlet temperature is 1070 +/-20 ℃; the finishing temperature is 850 +/-20 ℃; coiling temperature is 560 +/-20 ℃; cold rolling reduction: according to different specifications, the content is controlled to be 60-75%; galvanizing annealing temperature: 680-720 ℃; soaking time: 30-45 s. The requirement that the yield strength is greater than 320MPa is met, and the elongation can not meet the riveting forming requirement as can be seen from the tensile strength parameters provided by the embodiment.
Chinese patent application publication No. CN102199723A discloses a high-strength cold-rolled hot-dipped aluminum-zinc precipitation strengthened steel and a manufacturing method thereof, wherein the chemical components of a substrate are as follows: c: 0.09-0.12 wt%, Si not more than 0.05 wt%, Mn: 0.8-1.8 wt%, P is less than or equal to 0.02 wt%, S is less than or equal to 0.01 wt%, N is less than or equal to 0.008 wt%, Al: 0.02-0.06 wt%, Nb + Ti: 0.05 to 0.08 wt%, and the balance of Fe and inevitable impurities. The microstructure is ferrite and second phase particles, the diameter of the particles in the second phase is less than 6 microns, the yield strength is 500-600 MPa, the tensile strength is 570-710 MPa, the total elongation is greater than 14% (80 gauge length and transverse stretching), more alloy elements Nb and Ti are added into the components, and meanwhile, the material has overhigh yield strength and low elongation and cannot meet the requirements of riveting forming.
Chinese patent application publication No. CN102094149A discloses a niobium-containing high-strength hot-dip galvanized steel sheet and a production method thereof, and provides a niobium-containing high-strength hot-dip galvanized steel sheet for a structure with a high value and a low Δ γ value and a manufacturing method thereof. The niobium-containing high-strength hot-dip galvanized steel sheet comprises the following components: contains C in mass%: 0.03-0.1%, Si: less than or equal to 0.05 percent, Mn: 0.5-0.9%, P: less than or equal to 0.025 percent, S: less than or equal to 0.015 percent, N: less than or equal to 0.005 percent, Ti: less than or equal to 0.005 percent, Nb: 0.03-0.06%, Al: 0.01 to 0.08 percent, and the balance of Fe and inevitable impurities. The preparation method comprises the following steps: the steel billet is subjected to the working procedures of hot rolling, coiling, pickling, cold rolling and hot galvanizing. The Nb-containing high-strength hot-dip galvanized steel sheet delta gamma is less than or equal to 0, the yield strength is greater than or equal to 460MPa, the tensile strength is greater than or equal to 570MPa, and the elongation at break is greater than or equal to 28 percent, namely, the forming performance is excellent while the high strength is ensured. The patent provides a material high delta gamma method which meets the requirement of material tensile deformation, but the elongation can not meet the requirement of riveting forming.
The existing hot-dip aluminum-zinc steel plate with the yield strength of 320MPa cannot meet the requirement of riveting bulging processing, and cracks occur in the riveting bulging processing process.
Disclosure of Invention
The invention aims to provide a hot-dip aluminum-zinc steel plate with the yield strength of 320MPa and a manufacturing method thereof, mainly solves the technical problem that the hot-dip aluminum-zinc steel plate with the yield strength of 320MPa cracks in the riveting bulging processing process in the prior art, and meets the requirement of the box body industry on complex forming plasticity processing of the hot-dip aluminum-zinc steel plate.
The invention adopts the technical idea that the high yield strength, high elongation and high n value of the material are achieved by utilizing the component design of low-carbon and low-manganese elements, adding trace niobium alloy elements, regulating and controlling the steel plate structure through a hot rolling process, a cold rolling annealing and cooling technology, and obtaining recrystallized ferrite and fine cementite precipitate structures. The cold-rolled hot-dip aluminum-zinc plated steel plate is mainly used for a box body panel structural member.
Based on the following research of the applicant, the applicant carries out years of research on the cracking problem of a hot-dip aluminum-zinc steel plate with the yield strength of 320MPa in the riveting bulging processing process, carries out riveting bulging test on the hot-dip aluminum-zinc steel plate with the yield strengths of 302MPa, 354MPa, 405MPa and 454MPa and the thicknesses of 1.0 mm and 1.2mm through a large number of materials and forming test works, finds that the cracking phenomenon of the hot-dip aluminum-zinc steel plate in the riveting bulging processing process is closely related to the strength, the elongation after fracture and the strain index n value of the hot-dip aluminum-zinc steel plate through a large number of tests, and can realize that the hot-dip aluminum-zinc steel plate does not crack in the riveting bulging processing process through scientific design and control of the strength, the elongation after fracture and the strain index n value of the hot-dip aluminum-zinc steel plate.
The invention adopts the technical scheme that a hot-dip aluminum-zinc plated steel plate with the yield strength of 320MPa comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.25%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0045-0.0080%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent, and the balance of Fe and inevitable impurity elements.
Further, the hot-dip aluminum-zinc plated steel plate of the invention has the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.20%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0055-0.0065%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent, and the balance of Fe and inevitable impurity elements.
The metallographic structure of the hot-dip aluminum-zinc coated steel plate is recrystallized ferrite and fine cementite, and the grain size grade of the ferrite is I8.5-I9.5 grade; yield strength R of hot-dip aluminum-zinc steel plate with thickness of 1.0-1.2 mmP0.2Is 320 to 360MPa, Rm389-404 MPa, elongation after break A50mm38 to 43% and n is 1.9 to 2.1.
The reason why the chemical composition of the substrate of the hot-dip aluminum-zinc plated steel sheet having a yield strength of 320MPa is limited to the above range is as follows:
carbon: carbon is a relatively inexpensive and economical solid solution strengthening element and also forms niobium carbide with the steel matrix niobium alloying elements for strengthening purposes. The influence of carbon content on strength, elongation and structure is mainly considered in the design process of the steel base, the steel base strength is increased along with the increase of the carbon content, excessive pearlite appears in the base structure, the elongation of the material can be rapidly reduced, and the content range of C is comprehensively set to be 0.06% -0.08%.
Silicon: the silicon has a large contribution degree to the strength, but the heating process of the horizontal annealing furnace is an oxidizing atmosphere, silicon elements in the steel plate are easily oxidized and are unfavorable for the binding force of an aluminum-zinc-plated coating, according to the test result, silicon alloy is not added in the production and manufacturing process and is a residual element, and the content of Si is designed to be 0-0.03%.
Manganese: important solid solution strengthening elements are added to ensure the comprehensive mechanical strength of steel, proper Mn is added to improve the strength of a steel plate, excessive Mn is added to cause overhigh strength and cost and lower elongation, and the Mn content control range is Mn: 0.15 to 0.25 percent. The preferable Mn content is 0.15-0.20%, and better elongation is obtained.
Niobium: nb is an important trace element in the substrate of the hot-dip aluminum-zinc plated steel sheet. The purpose of the invention is to add Nb element into steel to perform grain refinement and strengthening, except for a certain strengthening effect, the Nb element is mainly added into the steel to form niobium carbide with carbon in the steel, thereby preventing or avoiding precipitation of pearlite in the steel, and a large number of tests prove that the Nb-containing niobium carbide steel combines low cost requirements, and the Nb-containing niobium carbide steel is added into the steel in an amount of Nb: 0.0045 to 0.0080%, preferably 0.0055 to 0.0065% of Nb, and more stable yield strength can be obtained.
Aluminum: the main purpose of adding Al in the steel is the deoxidation purpose, the aluminum content is set in the patent, aluminum and nitrogen elements in the steel are mainly considered to form AlN, residual element nitrogen in the steel is fixed, the precipitation in the annealing process is ensured to control the grain growth, and Al: 0.04-0.06%.
Nitrogen: n in the steel is an impurity element. The technical scheme of the invention sets the N content to be 0.0020-0.0040 percent, which is a normal smelting level.
Sulfur: s in the steel is an impurity element, and the cost of steel-making and desulphurization can be increased by excessively low S content. The technical scheme of the invention sets the S content to be 0-0.015%.
Phosphorus: p in the steel is an impurity element, and the cost is increased due to the excessively low P content. The technical scheme of the invention sets the P content to be 0-0.015%.
The manufacturing method of the hot-dip aluminum-zinc plated steel plate with the yield strength of 320MPa comprises the following steps:
the method comprises the following steps of continuously casting molten steel to obtain a continuous casting slab, wherein the molten steel comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.25%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0045-0.0080%, Al: 0.04-0.06%, N: 0.0020 to 0.0040 percent of the balance of Fe and inevitable impurity elements;
heating the continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 850-870 ℃; the thickness of the steel plate after finish rolling is 3.8-4.0 mm, the laminar cooling adopts front-section cooling, and the coiling temperature is 530-550 ℃ to obtain a hot-rolled steel coil;
the hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot aluminum and zinc plating and leveling, and is coiled to obtain a finished hot aluminum and zinc plated steel plate with the thickness of 1.0-1.2 mm, the cold rolling reduction rate is 68-75%, the heating temperature of the cold rolled hard strip steel in the annealing in the horizontal continuous annealing furnace is 630-640 ℃, the temperature of a soaking section is 730-740 ℃, the annealing time of the strip steel in the soaking section is 50-60 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 20-25 ℃/s, and the strip steel is placed into a zinc pot for hot dip aluminum and zinc plating after being isothermal for 5-7 s; the leveling elongation is 1.0-1.5%.
The production process adopted by the invention has the following reasons:
1. setting of heating temperature of continuous casting slab
The heating process of the economical continuous casting slab needs a lower heating temperature, and in order to prevent austenite crystal grain size from growing after the slab is heated and reduce the yield strength of a finished steel plate, the heating temperature is set to 1150-1200 ℃.
2. Setting of finish Rolling finishing temperature
According to the Fe-C phase diagram, the composition range of the design steel belongs to hypoeutectoid steel, after the material is completely austenitized under the equilibrium condition, the material generates proeutectoid ferrite transformation at the A3 transformation position in the cooling process, the ferrite composition changes along a GP line along the temperature reduction, the austenite composition changes along a GS line, and when the temperature is reduced to the A1 point, the eutectoid transformation occurs under the constant temperature condition, and the austenite is transformed into a pearlite structure. Thus, under equilibrium conditions, we should obtain a ferrite + pearlite structure. According to the weight percentage of each element in the steel, C: 0.06-0.08%, Si: 0-0.03%, Mn: 0.15-0.25%, P: 0-0.015%, S: 0-0.015%, Nb: 0.0045-0.0080%, and calculating the equilibrium phase-change point temperature A of the material by the material3The temperature was 876.177 ℃. After adding trace niobium element, the phase transformation point A is determined by material test3840-850 ℃, the actual dynamic phase change point can be reduced by 20 ℃, in order to achieve the purpose of austenite rolling, fine hot rolling matrix tissues are obtained, and the finish rolling temperature of the hot rolling process is set to be 850-870 ℃.
3. Cooling method and setting of hot-rolling coiling temperature
The fine grain structure can be obtained by rapid cooling in the phase change process, and the strength is improved. The design of the patent mainly considers that the reduction of the coiling temperature can control the growth of ferrite grains, enhance the strengthening effect and reduce the precipitation of pearlite, thereby better playing the role of adding trace niobium, simultaneously the low-temperature coiling is also favorable for reducing the precipitation of AlN and is favorable for controlling the formation of a cake-shaped structure of a finished product. Comprehensively considering, the laminar cooling adopts front-section cooling, and the coiling temperature is 530-550 ℃ to obtain the hot-rolled steel coil.
4. Setting of Cold Rolling reduction
The invention provides a cold rolling process of the aluminum-zinc-plated high-strength steel plate with the yield strength of 320 MPa. The high-strength steel hot rolled coil which is hot rolled by the components is uncoiled again, surface iron scales are removed by acid washing, and the high-strength steel hot rolled coil is limited by rolling capacity after being subjected to cold rolling for multiple times on a cold continuous rolling mill or a reciprocating single-stand rolling mill, wherein the rolling reduction rate of the cold rolling is 68-75%.
5. Setting of annealing temperature and post-annealing cooling process
According to the research of a material annealing process, the starting temperature of the annealing recrystallization temperature under the conditions of the components and the hot rolling process is 680-710 ℃, and in order to obtain a steel plate with a recrystallized ferrite structure and a fine cementite structure, the steel plate is subjected to rapid cooling and isothermal treatment after being annealed. The heating temperature of the strip steel in a horizontal continuous annealing furnace is 630-640 ℃, the temperature of a soaking section is 730-740 ℃, the annealing time of the strip steel in the soaking section is 50-60 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 20-25 ℃/s, and the strip steel is subjected to isothermal treatment for 5-7 s and then is put into a zinc pot for hot-dip aluminum and zinc plating.
6. Setting of the Flat elongation
In order to eliminate the upper yield point and ensure the stability of the material in the riveting bulging process, the stable processing performance can be obtained by determining the set flat elongation to be 1.0-1.5% through repeated tests.
The metallographic structure of the hot-dip aluminum-zinc steel plate produced by the method is recrystallized ferrite and fine cementite, the grain size grade of the ferrite is I8.5-I9.5, and the yield strength R of the hot-dip aluminum-zinc steel plateP0.2Is 320 to 360MPa, Rm389-404 MPa, elongation after break A50mm38 to 43% and n is 1.9 to 2.1.
Compared with the prior art, the invention has the following positive effects: 1. the metallographic structure of the hot-dip aluminum-zinc plated steel plate is recrystallized ferrite and fine cementite structure, so that the purposes of high strength, high elongation and high n value of the material are achieved, and the processing requirement of the aluminum-zinc plated high-strength steel plate on riveting bulging is met. 2. The design of the invention has better economy, only a small amount of manganese element and trace niobium are added, thereby achieving the purpose of high strength and simultaneously having the characteristic of low component, and the invention has better economy compared with the similar section steel. 3. The tissue regulation and control method in the method has strong operability and easy implementation, and can be realized by controlling the temperature in the hot rolling process and the process parameters of the annealing furnace. 4. In the smelting production process of the components in the method, on one hand, the alloy amount is less, and meanwhile, the method has operability in the continuous casting production process, and the smelting and casting difficulty caused by design can be avoided.
Drawings
FIG. 1 is a photograph of a metallographic structure of a hot-dip aluminum-zinc plated steel sheet according to example 4 of the present invention.
Detailed Description
The present invention is further described below with reference to examples 1 to 6, which are shown in tables 1 to 4.
Table 1 shows the chemical composition (in weight%) of the substrate of the hot-dip aluminum-zinc coated steel sheet according to the example of the present invention, and the balance Fe and inevitable impurities.
Table 1 chemical composition of substrate of hot-dip aluminum-zinc coated steel sheet of example of the present invention, unit: and (4) weight percentage.
Smelting in a converter to obtain a continuous casting billet meeting the requirement on chemical components, wherein the thickness of the continuous casting billet is 210-240 mm, the width of the continuous casting billet is 800-1300 mm, and the length of the continuous casting billet is 5000-10000 mm.
Heating the continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then carrying out hot rolling, wherein the hot rolling is a two-section rolling process, the rough rolling is 5-pass continuous rolling, the finish rolling is 7-pass continuous rolling, and the finish rolling temperature is 850-870 ℃; the laminar cooling adopts front-section cooling, and the coiling temperature is 530-550 ℃ to obtain a hot-rolled steel coil; the hot rolling process control is shown in Table 2.
TABLE 2 Hot Rolling Process control parameters of the inventive examples
The hot rolled steel coil is uncoiled again, then is subjected to acid pickling, cold rolling, annealing in a horizontal continuous annealing furnace, hot aluminum and zinc plating and leveling, and is coiled to obtain a finished hot aluminum and zinc plated steel plate with the thickness of 1.0-1.2 mm, the cold rolling reduction rate is 68-75%, the heating temperature of the cold rolled hard strip steel in the annealing in the horizontal continuous annealing furnace is 630-640 ℃, the temperature of a soaking section is 730-740 ℃, the annealing time of the strip steel in the soaking section is 50-60 s, the annealed strip steel is cooled to 590-600 ℃, the cooling speed is 20-25 ℃/s, and the strip steel is placed into a zinc pot for hot dip aluminum and zinc plating after being isothermal for 5-7 s; the leveling elongation is 1.0-1.5%. The control parameters of the cold rolling, annealing and flattening processes are shown in Table 3.
TABLE 3 control parameters for the cold rolling, annealing and temper rolling process of the examples of the invention
Referring to fig. 1, the metallographic structure of the hot-dip aluminum-zinc steel plate produced by the method is recrystallized ferrite and fine cementite, the grain size of the ferrite is I8.5-I9.5 grade, and the yield strength R of the hot-dip aluminum-zinc steel plateP0.2Is 320 to 360MPa, Rm389-404 MPa, elongation after break A50mm38 to 43% and n is 1.9 to 2.1.
According to the part 1 of a GB/T228.1-2010 metal material tensile test, the hot-dip aluminum-zinc plated steel plate obtained by the invention: the mechanical properties of the steel sheets are shown in Table 4, in which tensile tests were conducted according to the Room temperature test method and the measurement of the tensile strain hardening index (n value) of thin sheet or thin strip of GBT 5028-2008.
TABLE 4 mechanical properties and grain size of hot-dip aluminum-zinc coated steel sheets according to the examples of the present invention
Example 4 yield Strength R of Steel sheetP0.2330MPa, 395MPa of tensile strength and A elongation after fracture50mm42.5 percent and n is 1.94, and the manufacturing of the hot-dip aluminum-zinc plated steel plate with the yield strength of 320MPa is realized by the hot rolling control and annealing process technology through the component design of the microalloy.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.