Steel for aerosol can top cover and preparation method thereof

Abstract

A steel for aerosol can top covers and its preparation method, which relates to the technical field of iron and steel production, can enable the steel for aerosol can top covers to meet the service conditions without tin plating. Its chemical composition in mass percentage includes: C: 0.0061% - 0.0085%, Si: 0.020% - 0.035%, Mn: 0.36% - 0.45%, P: ≤0.015%, S: ≤0.0030%, Cu: 0.15% - 0.25%, Ni: 0.01% - 0.15%, Mo: 0.014% - 0.025%, Ln: 0.003% - 0.008%, Al: 0.010% - 0.040%, Nb: 0.012% - 0.025%, Ti: 0.026% - 0.035%, O: ≤0.0030%, N: ≤0.0040%; M Ln is 0.10 - 0.50; I M ≥7.0.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to steel for an aerosol can top cover and a preparation method thereof. Background Art

[0002] Air fresheners, insecticides, gas, and other products that need to be sprayed in the form of aerosols during use are mostly contained in aerosol cans. However, the corrosiveness of the contents and the high-pressure environment inside the aerosol cans place high demands on the corrosion resistance and pressure-bearing performance of the aerosol can materials.

[0003] The existing steel used for aerosol can tops is mainly tin-plated steel, which has complex processes and high costs. The aerosol can top is made by deep drawing of the steel used for aerosol can tops, so the control requirements for inclusions in the steel used for aerosol can tops are high. Minimizing the number of inclusions or refining the inclusions as much as possible can reduce the occurrence of various defects caused by inclusions after deep drawing. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problem in the prior art that steel for aerosol can top covers needs to be tin-plated to improve corrosion resistance and has high cost, thereby providing steel for aerosol can top covers and a preparation method thereof.

[0005] To this end, the present invention provides the following technical solutions:

[0006] The invention provides a steel for an aerosol can top cover, wherein the chemical composition comprises, by mass percentage, C: 0.0061%-0.0085%, Si: 0.020%-0.035%, Mn: 0.36%-0.45%, P: ≤0.015%, S: ≤0.0030%, Cu: 0.15%-0.25%, Ni: 0.01%-0.15%, Mo: 0.014%-0.025%, Ln: 0.003%-0.008%, Al: 0.010%-0.040%, Nb: 0.012%-0.025%, Ti: 0.026%-0.035%, O: ≤0.0030%, N: ≤0.0040%, and the rest are iron elements and inevitable impurity elements; the deterioration index M Ln 0.10~0.50; M Ln =Ln / (7.8×O+3.46×S+0.89×Al); Comprehensive weather resistance index I M ≥7.0; I M =26.01×Cu+3.88×Ni+1.49×Si+17.28×P-7.29×Cu×Ni-9.10×Ni×P-33.39×Cu 2 +1.62×Mo 0.5 +38.73×Ln 0.404 .

[0007] Calculate M Ln and I M When calculating, use the value before the percentage sign. For example, if the content of O is a%, substitute a into the formula for calculation.

[0008] Optionally, Ln includes Ce, Pr, and Nd in a mass ratio of 2~3:1~2:1.

[0009] The preferred mass percentages and functions of the various element components in the steel of the present invention and the functions of rolling and heat treatment are as follows:

[0010] C is an important element for improving the strength of steel, but too high a C content will reduce the plasticity of the steel and affect the formability of the steel. In order to make the product have good performance matching, the C content in the present invention is controlled within 0.0061% to 0.0085%.

[0011] Si is a ferrite-forming element, which is beneficial to the hot rolling and low temperature rolling production of steel, can improve the strength of the solid solution in steel, and is more significant in improving the tensile strength of steel. Moreover, when Si is combined with elements such as Cu, Ni, Mo, and Ln, the corrosion resistance of steel can be improved. When the silicon content is relatively high, it is beneficial to refine the corrosion product α-FeOOH, promote the formation of a dense silicon-rich protective rust layer on the surface of the steel, thereby improving the corrosion resistance. However, if the silicon content is too high, it will form strip-shaped aluminum-silicon inclusions with aluminum, and will also aggravate the surface oxide scale of the steel. Therefore, the Si content in the present invention is controlled to be 0.020%~0.035%.

[0012] Mn is one of the important solid solution strengthening elements in steel, but too high a Mn content will not only reduce the elongation and damage the toughness of the steel, but also reduce the corrosion resistance of the steel and increase the manufacturing cost. Therefore, the Mn content in the present invention is controlled at 0.36% to 0.45%.

[0013] P can improve the corrosion resistance of steel and has a strong solid solution strengthening effect, but P is easy to segregate at the grain boundary to reduce the toughness of the steel. Therefore, the P content of the present invention is controlled to be ≤0.015%.

[0014] S is a harmful element in steel. It is easy to form long strips of sulfide inclusions, which deteriorate the plasticity, toughness and corrosion resistance of steel. It is easy to combine with Ti to form Ti 4 C 2 S 2 , reducing the content of Ti which has a strengthening effect, thereby affecting the strengthening effect of the microalloying element Ti. Therefore, the present invention controls the S content to ≤0.0030%.

[0015] Cu is the most common alloying element for improving the corrosion resistance of steel. During the corrosion process, it is mainly distributed in the outer corrosion product film in the form of CuS, preventing the corrosion medium from penetrating into the inner layer and passivating the matrix. However, Cu has a low melting point, and a high content can easily lead to the "copper brittleness" phenomenon. Therefore, the Cu content of the present invention is controlled at 0.15% to 0.25%.

[0016] Ni can significantly improve the corrosion resistance of steel. During the corrosion process, Ni is distributed in the rust layer in the form of oxides, which increases the compactness of the rust layer and prevents ion exchange between the corrosive medium and the reaction surface. At the same time, Ni can also significantly improve the strength and plasticity of steel, making the steel have good forming properties. Moreover, for Cu-containing steel, the addition of Ni element can effectively prevent the occurrence of "copper brittleness". Therefore, the Ni content of the present invention is controlled at 0.05% to 0.15%.

[0017] Mo can greatly reduce the corrosion rate of steel and improve the corrosion resistance of steel. At the same time, Mo is a ferrite solid solution strengthening element, which can improve the strength of steel, and can also reduce the problem of uneven structure during hot working, and improve the thermal stability of microalloy carbonitride. Therefore, the Mo content of the present invention is controlled at 0.014% to 0.025%.

[0018] Ln represents three rare earth elements, Ce, Pr and Nd, and can improve the comprehensive performance of steel by purifying steel, modifying inclusions, refining grains, etc., and can also significantly improve the corrosion resistance of steel. However, if the Ln content of steel is too high during heat treatment, solid solution Ln desolvation is likely to occur, making the grain boundaries brittle and deteriorating the performance of the steel. Therefore, the Ln content of the present invention is controlled at 0.003%~0.008%.

[0019] Al is an important deoxidizing element in steel and can form AlN particles with N in steel to refine the grain size. At the same time, Als (acid-soluble aluminum) fixes the free N in the steel and increases the effective Ti content in the steel. However, excessive Al will form a large number of dispersed needle-shaped Al in the steel. 2 O 3 Inclusions reduce the toughness and formability of steel, so the Al content is controlled within 0.010% to 0.040% in the present invention.

[0020] Nb has a strong inhibitory effect on recrystallization. It inhibits austenite recrystallization through the solute drag effect of undissolved Nb (C, N) and dissolved Nb, maintains the deformation effect to refine ferrite grains, and makes the steel have good formability under high strength. This effect is higher than Ti, Vi, and Mo. Another important role of niobium is to achieve precipitation strengthening effect. In the present invention, the Nb content is controlled at 0.012% to 0.022%.

[0021] Ti is a strong carbonitride-forming element, which can play the role of precipitation strengthening and fine grain strengthening, reduce the anisotropy of steel, and increase the deep drawing performance of steel for aerosol can top cover. However, if the Ti content is too high, the size and quantity of the second phase precipitate TiN will increase, which will affect the forming performance of the steel. Therefore, the present invention controls the Ti content to 0.026%~0.035%.

[0022] O and N have extremely strong affinity with niobium and titanium. O in the molten steel combines with niobium and titanium to form niobium-titanium oxides, and N combines with niobium and titanium to form coarse nitride particles, thereby reducing the content of niobium and titanium in the molten steel that have a strengthening effect, and reducing the strengthening effect of niobium and titanium. At the same time, a high O content is prone to form string-like oxide inclusions, which reduces the formability of the steel. Therefore, the O content in the present invention is controlled to be ≤0.0030%, and the N content is controlled to be ≤0.0040%.

[0023] In order to ensure the modification effect of reducing, refining and spheroidizing inclusions, the chemical composition of the steel of the present invention must meet the modification index M Ln In the range of 0.10~0.50, and with the metamorphic index M Ln The enlargement and metamorphism effect is getting better and better.

[0024] Optionally, the thickness of the steel used for the aerosol can top cover is 0.15~0.4mm.

[0025] The present invention provides a method for preparing the steel for the aerosol can top cover, comprising the following steps: continuous casting→heating of the ingot→rough rolling→finishing rolling→laminar cooling→acid continuous rolling→continuous annealing.

[0026] Optionally, the continuous casting speed is 1.6-2.1 m / min, the ingot thickness is 170-190 mm, the ingot width is ≤950 mm, and the ingot length is 10000-12000 mm.

[0027] Optionally, the furnace entry temperature of the ingot is ≥700°C, the heating time is ≥165min, and the furnace exit temperature is 1090~1130°C.

[0028] Optionally, the pickling continuous rolling includes pickling, rinsing, and cold rolling in sequence.

[0029] Optionally, the outlet temperature of the rough rolling is 940-980° C., and the thickness of the intermediate billet is 32-34 mm.

[0030] In the method for preparing steel for aerosol can top cover provided by the present invention, typically but not limitedly, the rough rolling adopts a two-stand R1+R2=1+5 mode, that is, R1 adopts 1 rolling pass and R2 adopts 5 rolling passes.

[0031] Optionally, the inlet temperature of the finishing rolling is 850-890° C., the outlet temperature is 785-825° C., and the total reduction rate of the finishing rolling is 88.6%-94.1%.

[0032] Optionally, the outlet temperature of the laminar cooling is 610-650°C.

[0033] Optionally, the temperature of the steel before pickling is less than 45°C, the pickling medium includes an acid solution with a concentration of 30~200g / L, and the acid solution temperature is 80~90°C; rinsing is performed using a rinsing liquid, the rinsing liquid temperature is 70~80°C, the pH of the rinsing liquid at the outlet is greater than 6, and the conductivity of the rinsing liquid at the outlet is ≤30μS / cm; the total cold rolling reduction is 80.0%~94.5%.

[0034] Optionally, the continuous annealing includes: subjecting the steel strip obtained by acid continuous rolling to an annealing section, a controlled cooling section and a flattening section in sequence for treatment.

[0035] Optionally, at least one of the following conditions must be met:

[0036] (1) The steel belt speed is 460~500m / min;

[0037] (2) The annealing section includes a heating section and a soaking section in sequence;

[0038] The heating rate of the heating section is 11.01-12.67°C / s, and the temperature of the soaking section is 680-720°C;

[0039] (3) The controlled cooling section includes a quick cooling section, a radiation tube cooling section, and a jet cooling section in sequence;

[0040] Rapid cooling rate is 109.52~142.86℃ / s, radiation cooling rate is 0.60~0.66℃ / s, and jet cooling rate is 1.41~1.53℃ / s;

[0041] (4) The leveling elongation of the leveling section is 1.5%~1.9%, and the leveling tension is 75~80kN.

[0042] In the method for preparing steel for aerosol can top cover provided by the present invention, typically but not limitedly, in the leveling section of the continuous retardation, the surface roughness Ra of the working roll of the leveling machine used is 1.5-2.3 μm, and the peak count Rpc of the surface roughness is 110-150 cm -1 , two racks can be used for leveling.

[0043] The beneficial effects of the present invention are:

[0044] 1. The steel for aerosol can top provided by the present invention comprises, by mass percentage, the following chemical compositions: C: 0.0061% to 0.0085%, Si: 0.020% to 0.035%, Mn: 0.36% to 0.45%, P: ≤0.015%, S: ≤0.0030%, Cu: 0.15% to 0.25%, Ni: 0.01% to 0.15%, Mo: 0.014% to 0.025%, Ln: 0.003% to 0.008%, Al: 0.010% to 0.040%, Nb: 0.012% to 0.025%, Ti: 0.026% to 0.035%, O: ≤0.0030%, N: ≤0.0040%, and the remainder is iron and unavoidable impurity elements; the deterioration index M Ln 0.10~0.50; M Ln =Ln / (7.8×O+3.46×S+0.89×Al); Comprehensive weather resistance index I M ≥7.0; I M =26.01×Cu+3.88×Ni+1.49×Si+17.28×P-7.29×Cu×Ni-9.10×Ni×P-33.39×Cu 2 +1.62×Mo 0.5 +38.73×Ln 0.404 .

[0045] The steel for the top cover of the aerosol can of the present invention is micro-alloyed with Cu, Ni, Mo, Nb, Ti and Ln on the basis of the C-Mn component system, and the mass ratio of Ce, Pr and Nd in Ln is also specified, and the modification index M to be satisfied is specified. Ln And comprehensive weather resistance index I M This makes the steel for the aerosol can top cover in the present invention have good comprehensive mechanical properties, performance, corrosion resistance and pressure bearing performance, and can also reduce the generation of hole defects in the acid rolling production process and reduce various defects caused by inclusions in the punching process. The addition of an appropriate amount of Ln rare earth element reduces the content of harmful elements in the steel and the segregation at the grain boundaries, which can improve inclusions and purify the steel. The combined addition of Cu and Ni significantly improves the corrosion resistance of the steel, so that the steel for the aerosol can top cover of the present application can meet the use conditions without tin plating. Moreover, the comprehensive weathering index I M The larger it is, the better the corrosion performance of the steel used for aerosol can top covers.

[0046] 2. The present invention provides a method for preparing the above-mentioned steel for aerosol can top cover, comprising the steps of continuous casting → heating of ingot → rough rolling → finishing rolling → laminar cooling → acid continuous rolling → continuous annealing, wherein the furnace discharge temperature of the heated ingot is 1090-1130°C, the outlet temperature of rough rolling is 940-980°C, the inlet temperature of finishing rolling is 850-890°C, and the outlet temperature is 785-825°C. No tinning operation is required, and steel for aerosol can top cover that meets the use requirements can be obtained, and the finishing rolling temperature used is low, the preparation cost is reduced, and energy conservation and environmental protection are achieved. In addition, low-temperature heating and low-temperature rolling are used in the preparation process, which reduces the consumption of heating energy and the oxidation and burning of steel, and improves the yield rate and production efficiency. Low-temperature rolling can reduce fatigue cracking and fracture caused by thermal stress of roll temperature rise, and reduce roll consumption; low-temperature temperature system can reduce the formation of secondary iron oxide scale, improve the surface quality of hot-rolled products, acid continuous rolling pickling effect and efficiency; the cold-rolled base material produced by low-temperature process has low strength, which can effectively reduce the cold rolling load, save energy and reduce consumption, and can appropriately increase the cold rolling deformation to improve production efficiency; the cold-rolled annealed products produced by low-temperature process have good anisotropy and excellent forming performance.

[0047] At present, the hot rolling process of steel for aerosol can top cover mainly adopts high temperature hot rolling process, that is, the slab is heated to Ar 3 Above (generally about 1200℃), rough rolling is first performed and then finishing rolling is performed in the austenite zone (generally about 880℃). However, this process consumes a lot of energy and will aggravate the aging of the rolls, resulting in high costs; at the same time, the steel is severely oxidized and burned, especially the secondary iron scale on the surface of the steel strip is relatively serious, which will lead to low pickling effect and efficiency of pickling; the strength of the cold-rolled base material produced is relatively high, the rolling load of the cold rolling mill is high, and the energy consumption is further increased. However, too low hot rolling temperature will lead to an increase in the rolling load of the hot rolling mill, and the energy and roll consumption will also increase simultaneously, and production accidents such as rolling load overload are very likely to occur. The existing composition system of steel for aerosol can top covers is mostly C-Mn, and deoxidation is carried out by adding aluminum, but it is difficult to control inclusions in this composition system. If the deoxidation time is not well controlled, the number and size of inclusions in the steel will increase significantly, affecting subsequent acid continuous rolling and stamping. In addition, the corrosion resistance of the steel in this composition system is also poor, and tin plating is required to improve the corrosion resistance of the material, which makes the preparation steps more cumbersome and the cost more expensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1This is a metallographic diagram of the product obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0051] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0052] Example 1

[0053] The present embodiment provides a steel for an aerosol can top cover, whose chemical composition and mass percentage are C: 0.0073%, Si: 0.033%, Mn: 0.40%, P: 0.013%, S: 0.0019%, Cu: 0.23%, Ni: 0.010%, Mo: 0.023%, Ln: 0.007% (Ce, Pr, Nd in a mass ratio of 3:2:1), Al: 0.023%, Nb: 0.019%, Ti: 0.027%, O: 0.0013%, N: 0.0011%, and the balance is Fe and unavoidable impurities, as shown in Table 1.

[0054] The production process is: continuous casting → heating of ingot → rough rolling → finishing rolling → laminar cooling → acid continuous rolling → continuous annealing, which specifically includes the following steps:

[0055] 1. Smelting: Smelt the raw materials into molten steel with the above mentioned components.

[0056] 2. Continuous casting: continuous casting speed 2.0m / min, ingot thickness 170mm, ingot width 950mm, ingot length 12000mm.

[0057] 3. Billet heating, rough rolling, finishing rolling and laminar cooling: the billet is hot loaded into the furnace, the furnace entry temperature is 737℃, the heating time is 170min, the furnace exit temperature is 1125℃, the hot rolling and rough rolling adopts two-stand R1+R2=1+5 mode, that is, R1 adopts 1 pass rolling and R2 adopts 5 passes rolling, the rough rolling R2 outlet temperature is 964℃, the intermediate billet thickness is 32mm, the finishing rolling inlet temperature is 877℃, the finishing rolling outlet temperature is 799℃, the finishing rolling total reduction rate is 93.8%, and the laminar cooling outlet temperature is 635℃.

[0058] 4. Acid continuous rolling: The temperature of hot-rolled raw materials before pickling is less than 45°C, the pickling medium is industrial hydrochloric acid with a concentration of 30~200g / L at 85°C, the rinsing liquid temperature is 79°C, the pH value of the outlet tank rinsing water is greater than 6.0, the conductivity of the outlet tank rinsing water is ≤30μS / cm, and the total cold rolling reduction is 90.0%.

[0059] 5. Continuous annealing: Continuous annealing annealing soaking temperature is 694℃, steel strip speed is 464m / min, heating rate is 11.33℃ / s, rapid cooling rate is 118.21℃ / s, radiation tube cooling rate is 0.61℃ / s, and spray cooling rate is 1.42℃ / s.

[0060] The continuous annealing furnace has a heating section length of 470m, a soaking section length of 300m, a rapid cooling section length of 14m, a radiation tube cooling section length of 635m, and a jet cooling section length of 164m.

[0061] The continuous annealing and leveling process adopts two-frame leveling. The surface roughness Ra of the working roll of the leveling machine is 1.5~2.3μm, and the peak count Rpc of the surface roughness is 110~150cm -1 , flattening elongation 1.7%, flattening tension 79kN.

[0062] The thickness of the steel product for the aerosol can top cover is 0.20 mm, and the mechanical properties, surface and inclusions are shown in Tables 2 and 3. Figure 1 shown.

[0063] Example 2

[0064] The present embodiment provides a steel for an aerosol can top cover, whose chemical composition and mass percentage are C: 0.0069%, Si: 0.034%, Mn: 0.44%, P: 0.014%, S: 0.0013%, Cu: 0.20%, Ni: 0.013%, Mo: 0.020%, Ln: 0.007% (Ce, Pr, Nd in a mass ratio of 3:2:1), Al: 0.019%, Nb: 0.025%, Ti: 0.033%, O: 0.0017%, N: 0.0009%, and the balance is Fe and unavoidable impurities, as shown in Table 1.

[0065] The production process is: continuous casting → heating of ingot → rough rolling → finishing rolling → laminar cooling → acid continuous rolling → continuous annealing, which specifically includes the following steps:

[0066] 1. Smelting: Smelt the raw materials into molten steel with the above mentioned components.

[0067] 2. Continuous casting: continuous casting speed 2.0m / min, ingot thickness 170mm, ingot width 950mm, ingot length 12000mm.

[0068] 3. Billet heating, rough rolling, finishing rolling and laminar cooling: the billet is hot loaded into the furnace, the furnace entry temperature is 713℃, the heating time is 169min, the furnace exit temperature is 1130℃, the hot rolling and rough rolling adopt the two-stand R1+R2=1+5 mode, that is, R1 adopts 1 pass rolling and R2 adopts 5 passes rolling, the rough rolling R2 outlet temperature is 955℃, the intermediate billet thickness is 33mm, the finishing rolling inlet temperature is 864℃, the finishing rolling outlet temperature is 813℃, the finishing rolling total reduction rate is 91.8%, and the laminar cooling outlet temperature is 645℃.

[0069] 4. Acid continuous rolling: The temperature of hot-rolled raw materials before pickling is less than 45°C, the pickling medium is industrial hydrochloric acid with a concentration of 30~200g / L at 85°C, the rinsing liquid temperature is 73°C, the pH value of the outlet tank rinsing water is greater than 6.0, the conductivity of the outlet tank rinsing water is ≤30μS / cm, and the total cold rolling reduction is 88.9%.

[0070] 5. Continuous annealing: Continuous annealing annealing soaking temperature is 699℃, steel strip speed is 466m / min, heating rate is 11.47℃ / s, rapid cooling rate is 121.49℃ / s, radiation tube cooling rate is 0.61℃ / s, and spray cooling rate is 1.42℃ / s.

[0071] The continuous annealing furnace has a heating section length of 470m, a soaking section length of 300m, a rapid cooling section length of 14m, a radiation tube cooling section length of 635m, and a jet cooling section length of 164m.

[0072] The continuous annealing and leveling process adopts two-frame leveling. The surface roughness Ra of the working roll of the leveling machine is 1.5~2.3μm, and the peak count Rpc of the surface roughness is 110~150cm -1 , flattening elongation 1.7%, flattening tension 77kN.

[0073] The thickness of the obtained steel product for aerosol can top cover is 0.30 mm, and the mechanical properties, surface and inclusion conditions are shown in Tables 2 and 3.

[0074] Example 3

[0075] The present embodiment provides a steel for an aerosol can top cover, whose chemical composition and mass percentage are C: 0.0075%, Si: 0.032%, Mn: 0.43%, P: 0.011%, S: 0.0015%, Cu: 0.23%, Ni: 0.012%, Mo: 0.022%, Ln: 0.006% (Ce, Pr, Nd in a mass ratio of 3:2:1), Al: 0.033%, Nb: 0.023%, Ti: 0.030%, O: 0.0012%, N: 0.0009%, and the balance is Fe and unavoidable impurities, as shown in Table 1.

[0076] The production process is: continuous casting → heating of ingot → rough rolling → finishing rolling → laminar cooling → acid continuous rolling → continuous annealing, which specifically includes the following steps:

[0077] 1. Smelting: Smelt the raw materials into molten steel with the above mentioned components.

[0078] 2. Continuous casting: continuous casting speed 2.0m / min, ingot thickness 180mm, ingot width 950mm, ingot length 10000mm.

[0079] 3. Billet heating, rough rolling, finishing rolling and laminar cooling: the billet is hot loaded into the furnace, the furnace entry temperature is 725℃, the heating time is 175min, the furnace exit temperature is 1118℃, the hot rolling and rough rolling adopts two-stand R1+R2=1+5 mode, that is, R1 adopts 1 pass rolling and R2 adopts 5 passes rolling, the rough rolling R2 outlet temperature is 969℃, the intermediate billet thickness is 34mm, the finishing rolling inlet temperature is 863℃, the finishing rolling outlet temperature is 805℃, the finishing rolling total reduction rate is 91.9%, and the laminar cooling outlet temperature is 640℃.

[0080] 4. Acid continuous rolling: The temperature of hot-rolled raw materials before pickling is less than 45°C, the pickling medium is industrial hydrochloric acid with a concentration of 30~200g / L at 83°C, the rinsing liquid temperature is 75°C, the pH value of the outlet trough rinsing water is greater than 6.0, the conductivity of the outlet trough rinsing water is ≤30μS / cm, and the total cold rolling reduction is 85.5%.

[0081] 5. Continuous annealing: Continuous annealing annealing soaking temperature is 713℃, steel strip speed is 469m / min, heating rate is 11.77℃ / s, rapid cooling rate is 130.09℃ / s, radiation tube cooling rate is 0.61℃ / s, and spray cooling rate is 1.43℃ / s.

[0082] The continuous annealing furnace has a heating section length of 470m, a soaking section length of 300m, a rapid cooling section length of 14m, a radiation tube cooling section length of 635m, and a jet cooling section length of 164m.

[0083] The continuous annealing and leveling process adopts two-frame leveling. The surface roughness Ra of the working roll of the leveling machine is 1.5~2.3μm, and the peak count Rpc of the surface roughness is 110~150cm -1 , flattening elongation 1.8%, flattening tension 80kN.

[0084] The thickness of the obtained steel product for aerosol can top cover is 0.40 mm, and the mechanical properties, surface and inclusion conditions are shown in Tables 2 and 3.

[0085] Comparative Example 1

[0086] This comparative example provides a steel for an aerosol can top cover, which is different from Example 1 only in that its chemical composition and mass percentage are C: 0.0077%, Si: 0.028%, Mn: 0.39%, P: 0.012%, S: 0.0023%, Cu: 0.16%, Ni: 0.011%, Mo: 0.019%, Al: 0.018%, Nb: 0.018%, Ti: 0.028%, O: 0.0027%, N: 0.0035%, and the balance is Fe and unavoidable impurities, as shown in Table 1. Its mechanical properties, surface and inclusions are shown in Tables 2 and 3.

[0087] Table 1 Composition of steel for aerosol can top cover in each embodiment and comparative example (wt%)

[0088]

[0089] Table 1 Continuation of the table Composition of steel for aerosol can top cover in each embodiment and comparative example (wt%)

[0090]

[0091] Test Example 1

[0092] The mechanical properties of the steel for aerosol can top cover obtained in the embodiments and comparative examples were tested: the yield strength, tensile strength and elongation A50 were tested according to GB / T 228.1, the tensile strain hardening index (n value) was tested according to GB / T 5028, the plastic strain ratio (r value) was tested according to GB / T 5027, the anisotropy |Δr| was tested according to GB / T 5027, and the hardness HR30T was tested according to GB / T 230.1. The results are shown in Table 2.

[0093] Table 2 Mechanical properties of steel for aerosol can top cover in various embodiments and comparative examples

[0094]

[0095] As shown in Table 2, the elongation A50 of the steel for the aerosol can top cover prepared in Comparative Example 1 is 39%, which is no longer within the range of ≥40%; the n value is 0.18, which is not within the range of ≥0.195; the r value is 1.77, which is not within the range of ≥1.95; the anisotropy |Δr| is 0.23, which is not within the range of ≤0.15; and the HR30T is 55, which is not within the range of 60 to 65. Although the yield strength and tensile strength are within the specified range, they are significantly worse than those in the embodiment, so the mechanical properties are poor and the performance in later use will also be poor.

[0096] Test Example 2

[0097] The surface Ra value and surface Rpc value of the steel for aerosol can top cover obtained in the embodiment and comparative example were tested according to GB / T 2523; the results are shown in Table 3.

[0098] Table 3 Surface and inclusions of steels in various embodiments and comparative examples

[0099]

[0100] As shown in Table 3, although the surface Ra value and surface Rpc value of the steel for aerosol can top cover prepared in Comparative Example 1 are similar to those of the product prepared in the embodiment of the present invention, the average size of its inclusions is 2.15 μm, which is not within the range of ≤1 μm; the number of inclusions with a size of ≥5.0 μm is 0.23 pieces / mm 2 , not less than 0.01 pieces / mm 2 Inclusions with a size of ≥1.0μm are 25 / mm 2 , not less than 10 pieces / mm 2 range; high inclusion content will affect further processing performance and final use performance.

[0101] The component system and production process of the present invention can stably produce steel for aerosol can top covers with a thickness of 0.15-0.40 mm, and the product performance meets the yield strength of 240-310 MPa, tensile strength of 370-450 MPa, and elongation A 50 : ≥40%, tensile strain hardening index (work hardening index, n value): ≥0.195, plastic strain ratio (r value): ≥1.95, anisotropy |Δr|: ≤0.15, hardness HR30T: 60~65, board surface roughness Ra: 0.5~1.0μm, board surface roughness peak count Rpc: 80~120cm -1 , average inclusion size: ≤1.0μm, size ≥5.0μm inclusion density: ≤0.01 / mm 2 , size ≥ 1.0μm inclusion density: ≤ 10 / mm 2 , the metallographic structure is ferrite and cementite (such as Figure 1 As shown), the product has good forming and corrosion resistance, and the surface quality can meet the requirements of corresponding working conditions, realizing the low-temperature and low-load rolling production and alternative application of steel for aerosol can top covers.

[0102] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A steel for an aerosol can top cover, characterized in that: The chemical composition includes by mass percentage: C: 0.0061%~0.0085%, Si: 0.020%~0.035%, Mn: 0.36%~0.45%, P: ≤0.015%, S: ≤0.0030%, Cu: 0.15%~0.25%, Ni: 0.01%~0.15%, Mo: 0.014%~0.025%, Ln: 0.003%~0.008%, Al: 0.010%~0.040%, Nb: 0.012%~0.025%, Ti: 0.026%~0.035%, O: ≤0.0030%, N: ≤0.0040%, and the rest are iron elements and unavoidable impurity elements; Deterioration index M Ln 0.10~0.50; M Ln =Ln / (7.8×O+3.46×S+0.89×Al); Comprehensive weather resistance index I M ≥7.0; I M =26.01×Cu+3.88×Ni+1.49×Si+17.28×P-7.29×Cu×Ni-9.10×Ni×P-33.39×Cu 2 +1.62×Mo 0.5 +38.73×Ln 0.404 ; Ln includes Ce, Pr, and Nd in a mass ratio of 2~3:1~2:

1.

2. The steel for aerosol can top cover according to claim 1, characterized in that: The thickness of the steel used for the aerosol can top cover is 0.15-0.4 mm.

3. A method for preparing steel for aerosol can top cover according to claim 1 or 2, characterized in that: The process comprises the following steps: continuous casting→slab heating→rough rolling→finishing rolling→laminar cooling→acid continuous rolling→continuous annealing.

4. The preparation method according to claim 3, characterized in that: The continuous casting speed is 1.6-2.1 m / min, the thickness of the ingot is 170-190 mm, the width of the ingot is ≤950 mm, and the length of the ingot is 10000-12000 mm.

5. The preparation method according to claim 3, characterized in that: The furnace temperature of the ingot heating is ≥700°C, the heating time is ≥165min, and the furnace outlet temperature is 1090-1130°C; And / or, the acid continuous rolling includes pickling, rinsing, and cold rolling in sequence.

6. The preparation method according to claim 3, characterized in that: The outlet temperature of the rough rolling is 940-980°C, and the thickness of the intermediate billet is 32-34 mm; And / or, the inlet temperature of the finishing rolling is 850-890°C, the outlet temperature is 785-825°C, and the total reduction rate of the finishing rolling is 88.6%-94.1%; And / or, the outlet temperature of the laminar cooling is 610-650°C.

7. The preparation method according to claim 5, characterized in that: The temperature of the steel before pickling is less than 45°C, the pickling medium includes an acid solution with a concentration of 30-200 g / L and a temperature of 80-90°C; Use rinsing liquid for rinsing, the rinsing liquid temperature is 70~80℃, the rinsing liquid pH at the outlet is greater than 6, and the conductivity of the rinsing liquid at the outlet is ≤30μS / cm; The total cold rolling reduction rate is 80.0%~94.5%.

8. The preparation method according to claim 3, characterized in that: The continuous annealing comprises: processing the steel strip obtained by acid continuous rolling in sequence through an annealing section, a controlled cooling section and a flattening section.

9. The preparation method according to claim 8, characterized in that: At least one of the following conditions is met: (1) The steel belt speed is 460~500m / min; (2) The annealing section includes a heating section and a soaking section in sequence; The heating rate of the heating section is 11.01-12.67°C / s, and the temperature of the soaking section is 680-720°C; (3) The controlled cooling section includes a quick cooling section, a radiation tube cooling section, and a jet cooling section in sequence; Rapid cooling rate is 109.52~142.86℃ / s, radiation cooling rate is 0.60~0.66℃ / s, and jet cooling rate is 1.41~1.53℃ / s; (4) The leveling elongation of the leveling section is 1.5%~1.9%, and the leveling tension is 75~80kN.

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