Low-cost high-strength hot-rolled weather-resistant steel plate for container and preparation method thereof

Abstract

The invention discloses a low-cost and high-strength hot-rolled weather-resistant steel plate for a container and a preparation method of the hot-rolled weather-resistant steel plate, and belongs to the technical field of hot continuous rolling plate strip production. The hot-rolled weather-resistant steel plate comprises the following chemical components in percentage by weight: 0.06 to 0.08 percent of C, 0.20 to 0.30 percent of Si, 0.65 to 0.75 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.008 percent of S, 0.30 to 0.40 percent of Cr, 0.20 to 0.30 percent of Cu, 0.075 to 0.090 percent of Ti, 0.010 to 0.045 percent of Als, less than or equal to 0.0050 percent of N and the balance of Fe and impurities. Through reasonable composition and production process design, stable production and structure property control of thin products are guaranteed, and the problem that the alloy cost and the production cost of an existing high-strength hot-rolled weather-resistant steel plate are high can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-rolled plate and strip production, and specifically relates to a low-cost and high-strength hot-rolled weathering steel plate for containers and a preparation method thereof. Background Art

[0002] The damage of steel corrosion to various fields of national economy and national defense construction is a common and serious problem. According to statistics, in some industrially developed countries, the economic losses caused by corrosion account for 2% to 4% of the gross national economic output value, among which atmospheric corrosion is the main form of corrosion of steel structures, accounting for about half of all corrosion losses. Therefore, the research and development of weathering steel is of great significance. Weathering steel is a kind of low-alloy steel with good corrosion resistance in the atmosphere. Through a lot of research at home and abroad, it is generally believed that after long-term exposure to the atmosphere, a layer of dense and well-adhesive oxidation products will be generated on the surface of weathering steel to isolate the steel matrix from external corrosive substances, thereby significantly improving the corrosion resistance of weathering steel.

[0003] In recent years, the railway container transportation industry has developed rapidly. In order to achieve cost reduction, efficiency improvement and lightweight application, the container manufacturing industry has continuously upgraded its requirements for weathering steel for containers. It not only requires the material to have high strength to achieve high-strength thinning, but also requires the material to have a low production cost to reduce procurement costs, thereby further increasing profits.

[0004] CN113528956A discloses a high-strength weathering steel with excellent fatigue performance and corrosion resistance and a production method thereof. Precious metal elements Nb (0.075-0.095%) and Mo (0.15-0.30%) are added to the steel, and the Mn element content is relatively high (0.75-1.25%), resulting in a higher alloy cost of the product.

[0005] CN117305707A discloses a 700MPa grade CSP short process hot-rolled high weather-resistant container steel and a production method thereof. Sb element (0.02-0.25%) is added to the steel and the Mn element content is relatively high (1.1-1.8%), resulting in a high alloy cost of the product. In addition, the P element content is relatively high (0.035-0.15%), which easily reduces the plasticity and toughness of the material. The Ti element content is relatively high (0.10-0.18%), which easily forms large-sized Ti, resulting in reduced bending and forming properties of the material. Summary of the invention

[0006] The technical problem to be solved by the present invention is the high alloy cost and production cost of the existing high-strength hot-rolled weathering steel plate.

[0007] The technical solution adopted by the present invention to solve the technical problem is: the present invention provides a low-cost and high-strength hot-rolled weathering steel plate for containers, the chemical composition of the hot-rolled weathering steel plate is as follows by weight percentage: C 0.06-0.08%, Si 0.20-0.30%, Mn 0.65-0.75%, P≤0.020%, S≤0.008%, Cr 0.30-0.40%, Cu 0.20-0.30%, Ti 0.075-0.090%, Als 0.010-0.045%, N≤0.0050%, and the balance is Fe and unavoidable impurities.

[0008] The yield strength of the hot-rolled weathering steel plate is ≥650MPa, the tensile strength is ≥700MPa, the elongation after fracture is ≥18%, and the 180° bending test D=a.

[0009] The thickness of the hot-rolled weathering steel plate is 1.5 to 6.0 mm.

[0010] The metallographic structure of the hot-rolled weathering steel plate is polygonal ferrite + a small amount of pearlite; the volume fractions thereof are 92-97% polygonal ferrite and 3-8% pearlite.

[0011] The present invention also provides a method for preparing the above-mentioned low-cost and high-strength hot-rolled weathering steel plate for containers: smelting the slab according to the chemical composition of the hot-rolled weathering steel plate, and then heating, rough rolling, finish rolling, laminar cooling and coiling the slab in sequence to obtain the low-cost and high-strength hot-rolled weathering steel plate for containers.

[0012] Furthermore, the slab is heated by hot delivery and hot loading, the heating temperature is 1240-1280° C., and the heating time is 130-230 min.

[0013] Furthermore, the rough rolling process is performed through 6 rough rolling passes, and the deformation amount of each pass is ≥ 18%;

[0014] When the finished product thickness δ is 1.5≤δ<2.5mm, the intermediate billet thickness is controlled to be 38~42mm;

[0015] When the finished product thickness δ is 2.5≤δ≤6.0mm, the intermediate billet thickness is controlled to be 42-46mm.

[0016] Furthermore, the finishing rolling process is performed through 7 finishing rolling passes;

[0017] When the finished product thickness δ is 1.5≤δ<2.5mm, the final rolling temperature is controlled to be 860~900℃;

[0018] When the finished product thickness δ is 2.5≤δ≤6.0mm, the final rolling temperature is controlled to be 840~880℃.

[0019] Furthermore, the laminar flow process adopts a front-stage cooling mode, and the cooling rate is ≥40°C / s.

[0020] Furthermore, when the finished product thickness δ is 1.5≤δ<2.5mm, the coiling temperature is controlled to be 600-640°C.

[0021] Furthermore, when the finished product thickness δ is 2.5≤δ≤6.0 mm, the coiling temperature is controlled to be 580-620°C.

[0022] The beneficial effects of the present invention are as follows: the present invention effectively reduces the alloy cost by not adding the Ni element, and at the same time ensures the performance and avoids the generation of "copper brittleness" defects through a reasonable heating system design; the fine grain strengthening and precipitation strengthening effects are exerted by Ti microalloying, and the microstructure performance is regulated by combining the controlled rolling and controlled cooling process, so that the product achieves high strength and excellent plasticity without adding precious metal elements such as Nb and Mo and reducing the Mn element content; through a reasonable production process design, the stable production and microstructure performance control of thin-gauge products are guaranteed. The method of the present invention has a simple process and low production cost, and the obtained product is suitable for the field of container manufacturing, and can achieve good lightweight application and cost reduction effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the metallographic structure diagram of the low-cost and high-strength hot-rolled weathering steel plate for containers prepared in Example 1. DETAILED DESCRIPTION

[0024] The technical solution of the present invention can be specifically implemented in the following manner.

[0025] The low-cost and high-strength hot-rolled weathering steel plate for containers has the following chemical compositions by weight: C 0.06-0.08%, Si 0.20-0.30%, Mn 0.65-0.75%, P≤0.020%, S≤0.008%, Cr 0.30-0.40%, Cu 0.20-0.30%, Ti 0.075-0.090%, Als 0.010-0.045%, N≤0.0050%, and the balance is Fe and unavoidable impurities.

[0026] The composition design principle of the low-cost and high-strength hot-rolled weathering steel plate for containers according to the present invention is as follows.

[0027] Carbon: Carbon is an effective strengthening element in steel. It can be dissolved into the matrix to play a role in solid solution strengthening, and can combine with titanium to form carbide precipitation particles, which play a role in fine grain strengthening and precipitation strengthening. Therefore, increasing the carbon content is beneficial to improving strength. However, too high a carbon content will increase the carbon equivalent of the steel and reduce weldability; at the same time, it is easy to form a segregation band in the center of the steel plate, and when the cooling rate is high, it is easy to form a martensitic structure at the segregation band, resulting in reduced bending performance, impact performance, and forming performance. Therefore, the value range of C in the present invention is set to 0.06-0.08%.

[0028] Silicon: Silicon can be dissolved in ferrite and austenite to increase the hardness and strength of steel, which is beneficial to refine the rust layer structure and reduce the overall corrosion rate of steel. However, too high a content will reduce the plasticity and toughness of the steel and make it difficult to remove scale during rolling. Therefore, the value range of Si in the present invention is set to 0.20-0.30%.

[0029] Manganese: Manganese has a strong solid solution strengthening effect, can significantly reduce the phase transition temperature of steel, refine the microstructure of steel, and is an important strengthening element. However, when the manganese content is too high, the continuous casting process is prone to cracks in the ingot, and may cause component segregation in the core of the steel plate, resulting in reduced bending performance, impact performance, and forming performance, while increasing production costs. Therefore, the value range of Mn in the present invention is set to 0.65-0.75%.

[0030] Phosphorus: Although phosphorus has a strong solid solution strengthening effect and can effectively improve the atmospheric corrosion resistance of steel with low cost, excessive phosphorus content will significantly reduce the plasticity and low-temperature toughness of steel. Therefore, the value range of P in the present invention is set to P≤0.020%.

[0031] Sulfur: Sulfur will have an adverse effect on the structure and properties of steel plates. Too high a sulfur content will increase the hot brittleness tendency of steel. At the same time, sulfur will form sulfide inclusions that deteriorate the properties of steel. Therefore, the value range of S in the present invention is set to S≤0.008%.

[0032] Chromium: Chromium has a significant effect on improving the passivation ability of steel, and can promote the formation of a dense passivation film or protective rust layer on the steel surface. Its enrichment in the rust layer can effectively improve the selective permeability of the rust layer to corrosive media; however, too high a chromium content will increase production costs, and at a high cooling rate, it is easy to cause martensite structure to be produced, which reduces the plasticity and toughness of the steel. Therefore, the value range of Cr in the present invention is set to 0.30-0.40%.

[0033] Copper: Copper added to steel is conducive to forming a dense, well-adhesive amorphous oxide (hydrocarbon oxide) protective layer on the surface of the steel, which has a significant corrosion resistance effect; in addition, copper and sulfur form insoluble sulfides, thereby offsetting the harmful effects of S on the corrosion resistance of steel; however, when the copper content is too high, due to the low melting point of copper, which is lower than the heating temperature of the steel billet, the precipitated copper is in liquid and aggregates at the austenite grain boundary. When the precipitated copper content reaches a certain level, it is easy to produce cracks during heating or hot rolling, that is, "copper brittleness" defects; in addition, according to the calculation formula of the atmospheric corrosion resistance index I, too little or too much copper content will reduce the calculated value of I. Therefore, the value range of Cu in the present invention is set to 0.20-0.30%.

[0034] Titanium and nitrogen: Titanium combined with carbon and nitrogen can form tiny carbonitrides to pin grain boundaries, delay recrystallization, inhibit the growth of austenite grains, and produce fine grain strengthening and precipitation strengthening effects; increasing the titanium content can increase the volume fraction of its carbonitrides, enhance the fine grain strengthening and precipitation strengthening effects; increasing the nitrogen content in the steel is conducive to promoting the precipitation of the second phase of titanium; but too high a titanium or nitrogen content is likely to form large-sized TiN, resulting in reduced bending performance, impact performance, and forming performance, and too high a nitrogen content will increase the aging tendency and cold brittleness and hot brittleness of the steel, and damage the welding performance and cold bending performance of the steel; therefore, the value range of Ti in the present invention is set to 0.075-0.90%, and the value range of N is set to ≤0.0050%.

[0035] Aluminum: Aluminum is added to steel to deoxidize and improve the quality of steel. However, if the aluminum content is too high, its nitrogen oxides are easily precipitated at the austenite grain boundaries, causing cracks in the casting. Therefore, the value range of Als in the present invention is set to 0.010-0.045%.

[0036] The method for preparing the above-mentioned low-cost and high-strength hot-rolled weathering steel plate for containers is to smelt the slab according to the chemical composition in the above content, and then heat, rough roll, finish roll, laminar cool and coil the slab in sequence to obtain the low-cost and high-strength hot-rolled weathering steel plate for containers.

[0037] The functions and mechanisms of the main processes in the method for preparing the low-cost and high-strength hot-rolled weathering steel plate for containers described in the present invention are as follows.

[0038] Further specifically, in the heating step, the slab is heated in a regenerative heating furnace. The purpose of heating the slab is to homogenize the as-cast structure and component segregation, and to dissolve the alloy elements. The low-cost and high-strength hot-rolled weathering steel plate for containers according to the present invention has many types of alloy elements and a high content, and the precipitate solution temperature of Ti is relatively high, so the heating process requires sufficient temperature and time; in addition, since the temperature of thin-gauge steel plates drops rapidly during hot rolling, and the low-cost and high-strength hot-rolled weathering steel plates for containers according to the present invention have a high strength, it is easy to cause a large rolling load during the finishing rolling process, so it is necessary to increase the heating temperature; but too high a heating temperature and too long a heating time will lead to coarse austenite grains, as well as problems such as burning, overheating, and overburning; at the same time, compared with traditional weathering steel, in order to reduce the alloy cost, a certain amount of Cu is added to the low-cost and high-strength hot-rolled weathering steel plate for containers according to the present invention without adding Ni, and a Ni-containing copper-rich phase cannot be formed to reduce the chance of formation of a liquid copper-rich phase, so too long a heating time will lead to "copper brittleness" defects. Therefore, in the present invention, in the heating step, the casting is required to be hot transported and hot loaded, the heating temperature is set to 1240-1280° C., and the heating time is 130-230 min.

[0039] Further specific to the rough rolling step, the rough rolling needs to achieve sufficient deformation to ensure austenite recrystallization, refine austenite grains, and prevent the appearance of mixed crystal structure. If the thickness of the intermediate billet is too small, the deformation of the finishing rolling may be insufficient; if the thickness of the intermediate billet is too large, the deformation of the rough rolling may be insufficient, and at the same time, it will promote the strain-induced phase transformation precipitation during the finishing rolling process and after the finishing rolling, resulting in the consumption of Ti elements, etc., thereby weakening the supersaturated precipitation in the coiling stage, resulting in a reduction in the final precipitation strengthening effect; in addition, when the thickness of the finished product is small, the temperature drop of the strip during the finishing rolling process is faster, and the thickness of the intermediate billet can be appropriately reduced to avoid excessive finishing load while ensuring sufficient finishing deformation. Therefore, the present invention sets the rough rolling step to undergo 6 rough rolling passes, and the deformation of each pass is ≥18%; when the thickness of the finished product is 1.5~<2.5mm, the thickness of the intermediate billet is 38~42mm; when the thickness of the finished product is 2.5~6.0mm, the thickness of the intermediate billet is 42~46mm.

[0040] To be more specific, in the finishing step, if the final rolling temperature is too low, there is a risk of rolling in the two-phase region in the last few stands of finishing rolling, especially because the temperature of the strip in the width direction is different, and its edge temperature is often lower. As the thickness of the strip decreases, the temperature of the strip edge is faster during the finishing rolling process. When the strip is rolled in the last few stands of finishing rolling, the temperature is easily reduced to the austenite-ferrite two-phase region, resulting in mixed crystal structure and poor product comprehensive performance; if the final rolling temperature is too high, the deformation of the non-recrystallized zone rolled in the last few stands of finishing rolling is insufficient, which is not conducive to the final organization refinement. Therefore, in the present invention, it is set that after 7 passes of finishing rolling in the finishing step, when the finished product thickness is 1.5~<2.5mm, the final rolling temperature is 860~900℃; when the finished product thickness is 2.5~6.0mm, the final rolling temperature is 840~880℃.

[0041] To be more specific, in the laminar cooling step, the front-stage cooling mode is adopted and the cooling rate is controlled to be ≥40°C / s, which can achieve a larger degree of supercooling and thus refine the final structure. The use of a larger cooling rate can improve the core banded structure to a certain extent, while increasing the precipitation driving force of the Ti element, thereby precipitating fine and dispersed second phase particles to enhance the precipitation strengthening effect.

[0042] To be more specific, in the coiling step, if the coiling temperature is too low, the cooling rate during the cooling process will be too high, resulting in the formation of martensite structure, resulting in reduced plasticity and toughness, and at the same time, the diffusion rate of Ti and C elements will be slowed down, resulting in their precipitation being blocked, resulting in reduced precipitation strengthening effect; if the coiling temperature is too high, the grains and second phase particles will be coarse, resulting in reduced strength, plasticity and toughness. Therefore, in the present invention, when the thickness of the finished product is 1.5 to <2.5 mm, the coiling temperature is set to 600 to 640°C; when the thickness of the finished product is 2.5 to 6.0 mm, the coiling temperature is set to 580 to 620°C.

[0043] The technical solution and effects of the present invention are further illustrated below through practical examples.

[0044] Example

[0045] The yield strength, tensile strength and elongation after fracture of the hot-rolled weathering steel plate described in this embodiment are tested according to "Tensile Test of Metallic Materials Part 1: Room Temperature Test Method" (GB / T 228.1); the bending performance is tested according to "Bending Test Method for Metallic Materials" (GB / T 232).

[0046] The present invention provides three groups of embodiments 1 to 3 for preparing low-cost and high-strength hot-rolled weathering steel plates for containers by the method of the present invention, and the weathering steel and its preparation method described in the prior art are used as comparative examples 1 to 2; wherein, comparative example 1 specifically refers to embodiment 2 in "A high-strength weathering steel with excellent fatigue performance and corrosion resistance and its production method" (CN113528956A), and comparative example 2 specifically refers to embodiment 1 in "A 700MPa-grade CSP short-process hot-rolled high-weathering container steel and its production method (CN117305707A).

[0047] The chemical compositions of the hot-rolled weathering steels of Examples 1 to 3 and Comparative Examples 1 to 2 are shown in Table 1, with the remainder being Fe and unavoidable impurities.

[0048] Table 1 Chemical composition (by mass percentage, %)

[0049]

[0050]

[0051] Example 1

[0052] A low-cost and high-strength hot-rolled weathering steel plate for containers is smelted into a slab by a conventional method according to the composition shown in Table 1, and the slab obtained by the smelting is further processed, and heating, rough rolling, finish rolling, laminar cooling and coiling are performed in sequence. The specific processing technology is as follows: the heating temperature is 1280°C, and the heating time is 195min; after 6 rough rolling passes, the deformation of each pass is 18%, 22%, 22%, 25%, 26%, and 27%, respectively, and the intermediate billet thickness is 40mm; after 7 finish rolling passes, the final rolling temperature is 870-890°C; the front-stage cooling mode is adopted, the cooling rate is 60°C / s, and the coiling temperature is 600-620°C.

[0053] A low-cost, high-strength hot-rolled weathering steel plate for containers, the specific properties of which are shown in Table 2; the metallographic structure is composed of polygonal ferrite (95%) + pearlite (5%), such as Figure 1 shown.

[0054] Example 2

[0055] A low-cost and high-strength hot-rolled weathering steel plate for containers is smelted into a slab by a conventional method according to the composition shown in Table 1, and the slab obtained by the smelting is further processed, and heating, rough rolling, finish rolling, laminar cooling and coiling are performed in sequence. The specific processing technology is as follows: the heating temperature is 1270°C, and the heating time is 205min; after 6 rough rolling passes, the deformation of each pass is 18%, 22%, 22%, 23%, 24%, and 25%, respectively, and the intermediate billet thickness is 44mm; after 7 finish rolling passes, the final rolling temperature is 870-880°C; the front-stage cooling mode is adopted, the cooling rate is 55°C / s, and the coiling temperature is 580-610°C.

[0056] A low-cost and high-strength hot-rolled weathering steel plate for containers, the specific properties of which are shown in Table 2; the metallographic structure consists of polygonal ferrite (96%) + pearlite (4%).

[0057] Example 3

[0058] A low-cost and high-strength hot-rolled weathering steel plate for containers is smelted into a slab by a conventional method according to the composition shown in Table 1, and the slab obtained by the smelting is further processed, and heating, rough rolling, finish rolling, laminar cooling and coiling are performed in sequence. The specific processing technology is as follows: the heating temperature is 1250°C, and the heating time is 170min; after 6 rough rolling passes, the deformation of each pass is 18%, 21%, 23%, 25%, 23%, and 24% respectively, and the intermediate billet thickness is 44mm; after 7 finish rolling passes, the final rolling temperature is 850-870°C; the front-stage cooling mode is adopted, the cooling rate is 50°C / s, and the coiling temperature is 590-610°C.

[0059] A low-cost and high-strength hot-rolled weathering steel plate for containers, the specific properties of which are shown in Table 2; the metallographic structure consists of polygonal ferrite (93%) + pearlite (7%).

[0060] Comparative Example 1

[0061] A high-strength weathering steel with excellent fatigue performance and corrosion resistance, the chemical composition is shown in Table 1, and the production method is hot metal desulfurization, converter top and bottom composite blowing, vacuum treatment, casting into slabs, hot rolling mill controlled rolling and controlled cooling, and coiling. The hot rolling controlled rolling and controlled cooling process includes: heating the cast slab to 1130°C; then rolling, the final rolling temperature is 770°C; then laminar cooling, the coiling temperature is 585°C, and hot rolled coils are obtained. The specific properties are shown in Table 2.

[0062] Comparative Example 2

[0063] A 700MPa grade CSP short process hot-rolled high weather-resistant container steel, the chemical composition of which is shown in Table 1, is produced by the following steps: molten steel is smelted in a converter and then enters an LF furnace for refining treatment; the molten steel is subjected to thin slab continuous casting and rolling production: the thickness of the cast steel billet is 84mm; the cast billet is heated in a soaking furnace at a heating temperature of 1210°C; it is rolled in a 7-stand finishing mill, the finishing rolling start temperature is 1110°C, the first three passes have a reduction rate of 57%, the F4 pass has a reduction rate of 47%, and the F5 pass has a reduction rate of 37%, constant speed rolling is adopted according to the thickness specification, the rolling speed is controlled at 2.9m / s, the final rolling temperature is 880°C, and the rolling thickness is 4.5mm; the laminar cooling water cooling rate is 85°C / s, cooled to 660°C, and then cooled to 580°C at a water cooling rate of 10°C / s for coiling.

[0064] A 700MPa grade CSP short process hot-rolled high weather-resistant container steel, the specific properties of which are shown in Table 2, and the metallographic structure is ferrite.

[0065] Table 2 Performance test results

[0066] category Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Thickness / mm 1.5 4.0 6.0 - 4.5 Yield strength / MPa 678 666 654 715 715 Tensile strength / MPa 740 718 717 800 772 Elongation after break / % 28.5 22.0 28.5 21.0 22.0 180° bending test D=aQualified D=aQualified D=aQualified - D=aQualified

[0067] In combination with the preparation methods of the embodiments and comparative examples, according to the chemical composition in Table 1 and the performance test results of the embodiments and comparative examples obtained in Table 2, it can be seen that: although the strength of the comparative example is slightly higher, the addition of precious metal elements Nb, Mo, Sb and the high content of Mn element result in a high alloy cost. In addition, the P and Ti element contents in comparative example 2 are relatively high, which reduces the plasticity of the material and easily leads to reduced bending and forming properties. According to the embodiments produced according to the alloy composition and key process parameters provided by the present invention, the alloy cost is low and the production method is simple. At the same time, the product has high strength and high plasticity, and has good comprehensive performance and application prospects.

Claims

1. Low-cost and high-strength hot-rolled weathering steel plate for containers, characterized by: The chemical composition of the hot-rolled weathering steel plate is C 0.06-0.08%, Si 0.20-0.30%, Mn 0.65-0.75%, P≤0.020%, S≤0.008%, Cr0.30-0.40%, Cu 0.20-0.30%, Ti 0.075-0.090%, Als 0.010-0.045%, N≤0.0050% by weight, and the balance is Fe and unavoidable impurities.

2. The low-cost and high-strength hot-rolled weathering steel plate for containers according to claim 1, characterized in that: The yield strength of the hot-rolled weathering steel plate is ≥650MPa, the tensile strength is ≥700MPa, the elongation after fracture is ≥18%, and the 180° bending test D=a.

3. The low-cost and high-strength hot-rolled weathering steel plate for containers according to claim 1, characterized in that: The thickness of the hot-rolled weathering steel plate is 1.5 to 6.0 mm.

4. The low-cost and high-strength hot-rolled weathering steel plate for containers according to claim 1, characterized in that: The metallographic structure of the hot-rolled weathering steel plate is polygonal ferrite + a small amount of pearlite; the volume fractions thereof are 92-97% of polygonal ferrite and 3-8% of pearlite.

5. The method for preparing a low-cost, high-strength hot-rolled weathering steel plate for a container according to any one of claims 1 to 4, characterized in that: The slab is smelted according to the chemical composition of the hot-rolled weathering steel plate, and then the slab is heated, roughly rolled, finely rolled, laminar cooled and coiled in sequence to obtain the low-cost and high-strength hot-rolled weathering steel plate for containers.

6. The method for preparing a low-cost and high-strength hot-rolled weathering steel plate for a container according to claim 5, characterized in that: The slab is heated by hot delivery and hot loading, the heating temperature is 1240-1280° C., and the heating time is 130-230 min.

7. The method for preparing a low-cost and high-strength hot-rolled weathering steel plate for a container according to claim 5, characterized in that: The rough rolling process is carried out through 6 rough rolling passes, and the deformation of each pass is ≥18%; When the finished product thickness δ is 1.5≤δ<2.5mm, the intermediate billet thickness is controlled to be 38~42mm; When the finished product thickness δ is 2.5≤δ≤6.0mm, the intermediate billet thickness is controlled to be 42-46mm.

8. The method for preparing a low-cost and high-strength hot-rolled weathering steel plate for a container according to claim 5, characterized in that: The finishing rolling process is carried out through 7 passes; When the finished product thickness δ is 1.5≤δ<2.5mm, the final rolling temperature is controlled to be 860~900℃; When the finished product thickness δ is 2.5≤δ≤6.0mm, the final rolling temperature is controlled to be 840~880℃.

9. The method for preparing a low-cost and high-strength hot-rolled weathering steel plate for a container according to claim 5, characterized in that: The laminar flow process adopts the front cooling mode, and the cooling rate is ≥40℃ / s.

10. The method for preparing a low-cost and high-strength hot-rolled weathering steel plate for a container according to claim 5, characterized in that: When the finished product thickness δ is 1.5≤δ<2.5mm, the coiling temperature is controlled to be 600~640℃; When the finished product thickness δ is 2.5≤δ≤6.0mm, the coiling temperature is controlled to be 580~620℃.

Images