Raw material components of cold-rolled corrosion-resistant steel, cold-rolled corrosion-resistant steel and preparation method thereof

Abstract

The invention belongs to the technical field of corrosion-resistant steel manufacturing, and particularly relates to raw material components of cold-rolled corrosion-resistant steel, the cold-rolled corrosion-resistant steel and a preparation method of the cold-rolled corrosion-resistant steel. The cold-rolled corrosion-resistant steel is prepared from the following raw material components in percentage by mass: 0.04 to 0.12 percent of carbon element, 0.50 to 1.25 percent of silicon element, 0.20 to 0.60 percent of manganese element, 0.10 to 0.20 percent of phosphorus element, less than 0.015 percent of sulfur element, 0.20 to 0.60 percent of copper element, 0.020 to 0.055 percent of acid molten aluminum, 0.05 to 0.15 percent of antimony element, 0.0010 to 0.0020 percent of boron element, 0.01 to 0.02 percent of titanium element and the balance of iron element and impurity element, wherein the total mass of the raw material components is 100 percent. The cold-rolled corrosion-resisting steel prepared from the raw material components of the cold-rolled corrosion-resisting steel has excellent hydrochloric acid resistance and sulfuric acid resistance, and meanwhile the cold-rolled corrosion-resisting steel is good in toughness and not prone to breakage.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion-resistant steel manufacturing, and specifically relates to raw material components of cold-rolled corrosion-resistant steel, cold-rolled corrosion-resistant steel and a preparation method thereof, and especially relates to economical cold-rolled corrosion-resistant steel for consumable parts in a corrosive environment resistant to hydrochloric acid and sulfuric acid. Background Art

[0002] With the development of various industries at home and abroad, the use scope of some special products has gradually increased, and the corrosion-resistant environment they face has become more and more complex. Especially in some chemical and power industries, their flues will also face complex environmental corrosion. This is mainly because the combustion system will have S, N, Cl and other gases in the flue gas during the combustion process. If these gases encounter water vapor in the high-temperature area, boiling corrosion will occur. As the gas is discharged, dew point corrosion will occur in some low-temperature areas, thus forming a complex environment such as sulfuric acid and hydrochloric acid, which will cause serious corrosion to the pipe wall and equipment such as heat exchangers.

[0003] At present, cold-rolled corrosion-resistant steel is commonly used to prepare heat exchanger corrugated sheets and used for heat conduction. The heat exchanger corrugated sheets usually operate in the range of 80-200°C, but at this temperature, SO2 gas and chlorine gas easily form small fog beads on the surface of the steel plate and condense, thereby forming dew point corrosion. Therefore, the corrugated sheet faces a complex corrosion environment, and then corrodes and needs to be replaced in time. Therefore, the cold-rolled corrosion-resistant steel generally used in the preparation of heat exchanger corrugated sheets needs to be cheap and economical cold-rolled corrosion-resistant steel, so as to achieve the effect of effectively reducing costs. At the same time, since the corrosive droplets in dew point corrosion are mainly hydrochloric acid and sulfuric acid, the cold-rolled corrosion-resistant steel must be able to better cope with the corrosion environment of sulfuric acid and hydrochloric acid. At present, most of the corrosion-resistant steels in the industry are concentrated in the weather-resistant corrosion environment, and there are few reports on corrosion resistance in the sulfuric acid and hydrochloric acid corrosion environments.

[0004] Chinese patent "CN109487171A" discloses a corrosion-resistant steel resistant to hydrochloric acid corrosion and a preparation method thereof. The chemical composition system of the corrosion-resistant steel resistant to hydrochloric acid corrosion is: Cr: 12-15%, Mo: 2-4%, Sn: 0.25-0.65%, Cu: 0.3-0.5%, Sb: 0.1-0.4%, Nb: 0.15-0.25, Ti: 0.05-0.15%, C≤0.15, Fe is the balance. The corrosion-resistant steel has a certain corrosion resistance to hydrochloric acid, but the patent does not specify whether it can also resist sulfuric acid, and a large amount of alloy elements are added to the corrosion-resistant steel, which has a high cost. Summary of the invention

[0005] The purpose of the present invention is to address the defect that there is little research on economical cold-rolled steel with both hydrochloric acid resistance and sulfuric acid resistance in the prior art, and thus propose raw material components of cold-rolled corrosion-resistant steel, cold-rolled corrosion-resistant steel and a preparation method thereof. The raw material components of the cold-rolled corrosion-resistant steel described in the present invention contain a certain amount of elements such as Si, P, Cu, Sb and B. The Si element is easy to form SiO2 particles on the surface of the steel plate. The SiO2 particles on the surface of the steel plate can effectively fill the pores of the oxide film formed on the surface of the steel plate, and the P, Cu and Sb elements are easy to form a dense protective layer covering the surface of the steel plate under interaction. At the same time, due to the presence of SiO2 particles, the protective layer on the surface of the steel plate has a certain strength. The SiO2 particles and the protective layer can effectively prevent SO2 gas and chlorine from forming corrosive droplets on the surface of the steel plate under synergistic effect, thereby effectively improving the hydrochloric acid and sulfuric acid resistance of the cold-rolled corrosion-resistant steel. Since the elements such as Si, P, Cu and Sb in the raw material components are easy to enrich at the grain boundaries, this enrichment phenomenon may lead to adverse consequences such as grain boundary embrittlement and decreased corrosion resistance, and the B element in the raw material components can just improve the consequences of embrittlement at the grain boundaries and decreased corrosion resistance. The cold-rolled corrosion-resistant steel prepared by using the raw material components of the cold-rolled corrosion-resistant steel of the present invention has excellent hydrochloric acid resistance and sulfuric acid resistance. At the same time, the cold-rolled corrosion-resistant steel has good toughness and is not easy to break, thereby achieving the effect of effectively reducing costs.

[0006] The first aspect of the present invention provides a raw material component for cold-rolled corrosion-resistant steel, which, based on the total mass of the raw material component for cold-rolled corrosion-resistant steel as 100%, includes: 0.04-0.12% carbon element, 0.50-1.25% silicon element, 0.20-0.60% manganese element, 0.10-0.20% phosphorus element, less than 0.015% sulfur element, 0.20-0.60% copper element, 0.020-0.055% acid-fused aluminum, 0.05-0.15% antimony element, 0.0010-0.0020% boron element, 0.01-0.02% titanium element, and the remainder is iron element and impurity elements.

[0007] Preferably, based on the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, it includes: 0.05-0.06% carbon element, 0.65-1.25% silicon element, 0.30-0.55% manganese element, 0.10-0.18% phosphorus element, 0.008-0.010% sulfur element, 0.30-0.35% copper element, 0.033-0.040% acid-fused aluminum, 0.05-0.10% antimony element, 0.0010-0.0012% boron element, 0.018-0.02% titanium element, and the remainder is iron element and impurity elements.

[0008] More preferably, the relationship between the elements in the raw material composition of the cold-rolled corrosion-resistant steel is as shown in the following formula:

[0009] (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) /

[0010] (10.25*e+1.06*f)≥20;

[0011] Among them, a is the numerical value of the mass percentage of silicon element in the raw material components of cold-rolled corrosion-resistant steel, b is the numerical value of the mass percentage of copper element in the raw material components of cold-rolled corrosion-resistant steel, c is the numerical value of the mass percentage of antimony element in the raw material components of cold-rolled corrosion-resistant steel, d is the numerical value of the mass percentage of phosphorus element in the raw material components of cold-rolled corrosion-resistant steel, e is the numerical value of the mass percentage of boron element in the raw material components of cold-rolled corrosion-resistant steel, and f is the numerical value of the mass percentage of titanium element in the raw material components of cold-rolled corrosion-resistant steel.

[0012] Further preferably, the value range of (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f) is 20-38.

[0013] A second aspect of the present invention provides a method for preparing cold-rolled corrosion-resistant steel, the method comprising the following steps:

[0014] Step S1: smelting the pretreated molten iron to obtain molten steel;

[0015] Step S2: Tempering and refining the molten steel obtained in step S1 to adjust the composition and content of the raw material components of the cold-rolled corrosion-resistant steel described above;

[0016] Step S3: Continuously cast the molten steel obtained in step S2 to form a cast billet, and then sequentially subject the cast billet to hot rolling, cold rolling, continuous annealing and smoothing.

[0017] Preferably, based on the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, it includes: 0.05-0.06% carbon element, 0.65-1.25% silicon element, 0.30-0.55% manganese element, 0.10-0.18% phosphorus element, 0.008-0.010% sulfur element, 0.30-0.35% copper element, 0.033-0.040% acid-fused aluminum, 0.05-0.10% antimony element, 0.0010-0.0012% boron element, 0.018-0.02% titanium element, and the remainder is iron element and impurity elements.

[0018] More preferably, the relationship between the elements in the raw material composition of the cold-rolled corrosion-resistant steel is as shown in the following formula:

[0019] (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) /

[0020] (10.25*e+1.06*f)≥20;

[0021] Among them, a is the numerical value of the mass percentage of silicon element in the raw material components of cold-rolled corrosion-resistant steel, b is the numerical value of the mass percentage of copper element in the raw material components of cold-rolled corrosion-resistant steel, c is the numerical value of the mass percentage of antimony element in the raw material components of cold-rolled corrosion-resistant steel, d is the numerical value of the mass percentage of phosphorus element in the raw material components of cold-rolled corrosion-resistant steel, e is the numerical value of the mass percentage of boron element in the raw material components of cold-rolled corrosion-resistant steel, and f is the numerical value of the mass percentage of titanium element in the raw material components of cold-rolled corrosion-resistant steel.

[0022] Further preferably, the value range of (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f) is 20-38.

[0023] Preferably, in step S1, the sulfur content in the pretreated molten iron is ≤0.005%; in step S3, the hot rolling conditions are: heating temperature of 1200-1240°C, heating time ≤150min, final rolling temperature of 850-900°C, and coiling temperature of 550-600°C; the cold rolling conditions are: total reduction rate of 55-75%; the continuous annealing conditions are: heating temperature of 790-810°C, soaking temperature of 770-800°C, and annealing speed of 80-200m / min; the flattening conditions are: flattening elongation of 0.8-1.4%.

[0024] A third aspect of the present invention provides a cold-rolled corrosion-resistant steel prepared according to the method for preparing the cold-rolled corrosion-resistant steel described above.

[0025] The raw material components of the cold-rolled corrosion-resistant steel, the cold-rolled corrosion-resistant steel and the preparation method thereof described in the present invention have at least the following beneficial effects:

[0026] (1) In the present invention, the cold-rolled corrosion-resistant steel is prepared by using the raw material components of the cold-rolled corrosion-resistant steel composed of a certain content of Si (silicon), P (phosphorus), Cu (copper), Sb (antimony) and B (boron). Since the Si element easily forms SiO2 particles on the surface of the steel plate, the P, Cu and Sb elements easily form a dense protective layer covering the surface of the steel plate under the interaction, and the presence of the SiO2 particles will further promote the protective layer to have a higher strength. Therefore, the SiO2 particles and the protective layer can effectively prevent SO2 gas and chlorine gas from forming corrosive droplets on the surface of the steel plate under the synergistic effect, thereby effectively improving the hydrochloric acid resistance of the cold-rolled corrosion-resistant steel. , resistance to sulfuric acid. At the same time, since elements such as Si, P, Cu and Sb in the raw material components are easily enriched at the grain boundaries, this enrichment phenomenon may lead to adverse consequences such as grain boundary embrittlement and decreased corrosion resistance. The B element in the raw material components can just improve the consequences of embrittlement at the grain boundaries and decreased corrosion resistance, so that the finally prepared cold-rolled corrosion-resistant steel has better hydrochloric acid and sulfuric acid resistance. At the same time, the cold-rolled corrosion-resistant steel has good toughness and is not easy to break. The yield strength of the prepared cold-rolled corrosion-resistant steel is ≥245MPa, the tensile strength is 360~510MPa, and its sulfuric acid dew point corrosion rate is <3.0mg / cm 2 *h, hydrochloric acid dew point corrosion rate <5.0mg / cm 2 *h, thereby achieving the effect of effectively reducing costs;

[0027] (2) In the process of preparing cold-rolled corrosion-resistant steel, the process parameters in each step are precisely controlled, and the raw material components of cold-rolled corrosion-resistant steel with specific composition and content are combined to finally prepare an economical cold-rolled sulfuric acid-resistant and hydrochloric acid-resistant steel plate with a yield strength of ≥280MPa, a tensile strength of 430-510MPa, and a sulfuric acid dew point corrosion rate of <2.08mg / cm 2 *h, hydrochloric acid dew point corrosion rate <3.8mg / cm 2 *h, can be used for structural stampings, heat exchange plates, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope image of the cold-rolled corrosion-resistant steel prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0030] The first aspect of the present invention proposes a raw material component for cold-rolled corrosion-resistant steel, which, based on the total mass of the raw material component of the cold-rolled corrosion-resistant steel as 100%, includes: 0.04-0.12% carbon, 0.50-1.25% silicon, 0.20-0.60% manganese, 0.10-0.20% phosphorus, less than 0.015% sulfur, 0.20-0.60% copper, 0.020-0.055% acid-fused aluminum, 0.05-0.15% antimony, 0.0010-0.0020% boron, 0.01-0.02% titanium, and the remainder is iron and impurity elements. The yield strength of the cold-rolled corrosion-resistant steel prepared by using the raw material component is ≥245MPa, the tensile strength is 360-510MPa, and the sulfuric acid dew point corrosion rate is <3.0mg / cm 2 *h, hydrochloric acid dew point corrosion rate <5.0mg / cm 2 *h.

[0031] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of carbon element can be 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11% or 0.12%. Carbon element is the most economical strengthening element for steel, and mainly improves the strength of steel through solid solution strengthening and precipitation strengthening. However, at the same time, too high carbon content in alloy steel will deteriorate the welding performance of steel, and too high C content will reduce the plastic toughness of the material.

[0032] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of silicon element can be 0.50%, 0.55%, 0.60%, 0.62%, 0.65%, 0.86%, 0.92%, 1.02% or 1.25%. Silicon element can play a role of solid solution strengthening in steel, and can be added to steel as a reducing agent and deoxidizer during the smelting process. At the same time, silicon element can improve the hardenability and tempering resistance of steel. The increase of Si element will form SiO crystals on the surface during the corrosion process, which can effectively increase the wear resistance and strength of the steel plate surface. At the same time, Si can be combined with Cu and Sb in the steel to effectively improve the weather resistance of the steel and improve the corrosion resistance performance. However, too high Si content will reduce the toughness and welding performance of the steel.

[0033] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of manganese element can be 0.20%, 0.28%, 0.30%, 0.35%, 0.45%, 0.50%, 0.55% or 0.60%. Manganese element, as a commonly used desulfurization and deoxidation element, can prevent hot brittleness and welding hot cracks caused by FeS, and can be infinitely dissolved in ferrite and austenite to improve the strength of the steel plate. It can be combined with hardenability elements to control the diffusion of C element to form local pearlite and bainite structures; however, too much Mn element will coarsen the grains, form a banded structure in the steel plate, and C segregation is likely to occur in local positions, which will accelerate the corrosion of the steel plate. Therefore, the Mn content should not be too high.

[0034] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of phosphorus can be 0.10%, 0.12%, 0.13%, 0.16%, 0.18% or 0.20%. Phosphorus can improve the corrosion resistance of the steel plate. During the corrosion process, P will gather on the inner side of the oxide layer, increasing the adhesion and corrosion resistance of the steel plate. However, P is easy to segregate at the grain boundaries in the steel, thereby reducing the plasticity, low-temperature toughness and welding performance of the steel. Therefore, this patent adds a small amount of B element to the steel. The increase of B can effectively improve the segregation problem of elements at the grain boundaries.

[0035] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of sulfur element can be 0.012%, 0.010%, 0.008% or 0.005%. When the content of sulfur element is higher than 0.015%, segregation will occur in the steel, and MnS particles will be formed with the Mn element in the steel. The MnS particles have a negative effect on the corrosion performance of the substrate, and are also not conducive to the enrichment of elements. The MnS particles will also cause the local original electrolytic cell to aggravate the local corrosion reaction, which is not conducive to improving the corrosion resistance of the substrate.

[0036] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of copper element can be 0.20%, 0.30%, 0.35%, 0.40%, 0.44%, 0.50% or 0.60%. The copper element can form a barrier layer mainly composed of Cu and P between the substrate and the rust layer, which is firmly combined with the substrate and has good protection for the steel plate. In addition, Cu can also offset the harmful effects of the impurity element S in the steel plate, and plays an important role in the weather resistance of the steel plate. However, excessive addition of Cu will cause the "Cu brittleness" problem, and the Cu content is controlled to be 0.20-0.60%.

[0037] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of acid-fused aluminum can be 0.020%, 0.030%, 0.033%, 0.035%, 0.040%, 0.050% or 0.055%. If the content of acid-fused aluminum is lower than 0.020%, it is impossible to economically remove oxygen from molten steel, and the oxygen content is retained in the steel. In the subsequent steel plate manufacturing process, oxide inclusions such as voids are prone to occur, which is not conducive to the corrosion resistance of the substrate. If the content of acid-fused aluminum is higher than 0.055%, it is easy to form Al2O3 inclusion particles with the O element of the steel plate, which will also affect the strength, plasticity and corrosion resistance of the material.

[0038] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of antimony element can be 0.05%, 0.08%, 0.10%, 0.12% or 0.15%. Antimony element is a very effective alloy element for improving the corrosion resistance of sulfuric acid and hydrochloric acid. Combining with Cu to form Cu2Sb can significantly reduce the corrosion rate of hydrochloric acid and sulfuric acid. At the same time, in the mixed solution of sulfuric acid and hydrochloric acid, Sb and Cl will act as a catalyst to promote the formation of a composite compound, thereby improving the corrosion resistance of the substrate.

[0039] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of boron element can be 0.0010%, 0.0012%, 0.0015%, 0.0018% or 0.0020%. Boron element preferentially gathers at the grain boundary and fills in the "vacancies" and "defects", avoiding the aggregation of elements such as P and Cu at this position, resulting in reduced plastic toughness and corrosion performance of the steel. Therefore, B can effectively improve the performance at the grain boundary.

[0040] In the raw material components of the cold-rolled corrosion-resistant steel described in the present invention, specifically, the content of titanium can be 0.010%, 0.012%, 0.015%, 0.016%, 0.018% or 0.020%. Titanium has a strong affinity with C and N. It is easy to form TiN and Ti (C, N) during the preparation process, which can effectively prevent the growth of austenite grains and play a pinning role on the grain boundaries. It can reduce the segregation of P and Cu at the grain boundaries to form a brittle network, resulting in reduced plasticity of the material and reduced corrosion resistance.

[0041] In a preferred embodiment of the raw material components of the cold-rolled corrosion-resistant steel of the present invention, based on the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, the raw material components include: 0.05-0.06% carbon, 0.65-1.25% silicon, 0.30-0.55% manganese, 0.10-0.18% phosphorus, 0.008-0.010% sulfur, 0.30-0.35% copper, 0.033-0.040% acid-fused aluminum, 0.05-0.10% antimony, 0.0010-0.0012% boron, 0.018-0.02% titanium, and the balance is iron and impurity elements. The yield strength of the cold-rolled corrosion-resistant steel prepared by using the raw material components is ≥280MPa, the tensile strength is 430-510MPa, and the sulfuric acid dew point corrosion rate is <2.08mg / cm 2 *h, hydrochloric acid dew point corrosion rate <3.8mg / cm 2 *h.

[0042] In a more preferred case, the relationship between the elements in the raw material composition of the cold-rolled corrosion-resistant steel is shown in the following formula:

[0043] (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) /

[0044] (10.25*e+1.06*f)≥20;

[0045] Among them, a is the numerical value of the mass percentage of silicon element in the raw material components of cold-rolled corrosion-resistant steel, b is the numerical value of the mass percentage of copper element in the raw material components of cold-rolled corrosion-resistant steel, c is the numerical value of the mass percentage of antimony element in the raw material components of cold-rolled corrosion-resistant steel, d is the numerical value of the mass percentage of phosphorus element in the raw material components of cold-rolled corrosion-resistant steel, e is the numerical value of the mass percentage of boron element in the raw material components of cold-rolled corrosion-resistant steel, and f is the numerical value of the mass percentage of titanium element in the raw material components of cold-rolled corrosion-resistant steel.

[0046] In a further preferred case, the value range of (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f) is 20-38.

[0047] A second aspect of the present invention provides a method for preparing cold-rolled corrosion-resistant steel, the method comprising the following steps:

[0048] Step S1: smelting the pretreated molten iron to obtain molten steel;

[0049] Step S2: Tempering and refining the molten steel obtained in step S1 to adjust the composition and content of the raw material components of the cold-rolled corrosion-resistant steel described above;

[0050] Step S3: Continuously cast the molten steel obtained in step S2 to form a cast billet, and then sequentially subject the cast billet to hot rolling, cold rolling, continuous annealing and smoothing.

[0051] In a preferred embodiment of the preparation method of the cold-rolled corrosion-resistant steel of the present invention, based on the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, it includes: 0.05-0.06% carbon element, 0.65-1.25% silicon element, 0.30-0.55% manganese element, 0.10-0.18% phosphorus element, 0.008-0.010% sulfur element, 0.30-0.35% copper element, 0.033-0.040% acid-fused aluminum, 0.05-0.10% antimony element, 0.0010-0.0012% boron element, 0.018-0.02% titanium element, and the remainder is iron element and impurity elements.

[0052] In a more preferred case, the relationship between the elements in the raw material composition of the cold-rolled corrosion-resistant steel is shown in the following formula:

[0053] (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) /

[0054] (10.25*e+1.06*f)≥20;

[0055] Among them, a is the mass percentage of silicon element in the raw material components of cold-rolled corrosion-resistant steel, b is the mass percentage of copper element in the raw material components of cold-rolled corrosion-resistant steel, c is the mass percentage of antimony element in the raw material components of cold-rolled corrosion-resistant steel, d is the mass percentage of phosphorus element in the raw material components of cold-rolled corrosion-resistant steel, e is the mass percentage of boron element in the raw material components of cold-rolled corrosion-resistant steel, f is the mass percentage of titanium element in the raw material components of cold-rolled corrosion-resistant steel, and the value of (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f) is 20.4, 24.2, 25.2, 37.2, 45.2 or 62.3.

[0056] In a further preferred case, the value range of (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f) is 20 to 38.

[0057] In a specific embodiment of the preparation method of cold-rolled corrosion-resistant steel of the present invention, the method also includes pretreatment of molten iron. During the pretreatment of molten iron, front slag removal and back slag removal are required to avoid the protective slag of molten steel being drawn into the molten steel during the pouring process, resulting in reduced purity of the molten steel, residual large amounts of inclusions, and affecting product performance.

[0058] In a specific implementation of the method for preparing cold-rolled corrosion-resistant steel of the present invention, in step S1, the sulfur content in the pretreated molten iron is ≤0.005%, which is beneficial to improving the corrosion resistance of the substrate.

[0059] In a specific implementation of the method for preparing cold-rolled corrosion-resistant steel of the present invention, in step S1, the pretreated molten iron is transported to a converter for smelting to obtain molten steel. During the specific operation, due to the high alloy content, the slag blocking operation is strengthened.

[0060] In a specific embodiment of the method for preparing cold-rolled corrosion-resistant steel of the present invention, in step S2, the molten steel obtained in step S1 is transported to a ladle refining furnace (LF) for tempering and refining.

[0061] In a specific implementation of the method for preparing cold-rolled corrosion-resistant steel of the present invention, in step S3, during the continuous casting process, the target temperature of the middle package is controlled at 10 to 35°C above the liquidus temperature, the fluidity of the molten steel is better, which is beneficial to the pouring of molten steel; at the same time, the ingot is cooled by stacking slow cooling in a protective pit.

[0062] In a specific embodiment of the preparation method of cold-rolled corrosion-resistant steel of the present invention, in step S3, the hot rolling conditions are: the heating temperature is 1200-1240°C, and the heating time is ≤150min, so as to avoid the enrichment of Cu element at the grain boundary during the heating process, thereby reducing the toughness and corrosion resistance of the cold-rolled corrosion-resistant steel; the final rolling temperature is 850-900°C. If the final rolling temperature is too high, the Cu element is easy to aggregate at the grain interface, resulting in lower plasticity of the material, and the uniformity of elements in the steel deteriorates, and the corrosion resistance will be reduced; if the final rolling temperature is too low, the production rate is required to be slow, which affects the production rhythm. At the same time, the temperature is low and the cooling rate is fast, which will affect the strength of the material and increase the production risk; the coiling temperature is 550-600°C. If the coiling temperature is too high or too low, it will affect the hot-rolled plate and the surface oxygen pressure.

[0063] In a specific embodiment of the method for preparing cold-rolled corrosion-resistant steel of the present invention, in step S3, the cold rolling condition is: the total reduction rate is 55-75%. Under the condition of the total cold rolling reduction rate of the present invention, it is beneficial to the deformation energy storage in the steel, promote the recrystallization during the annealing process, refine the grains, and improve the plastic toughness of the material. In the specific operation process, the hot-rolled coil first enters the pickling tank to remove the surface iron oxide scale, and is sent to the five-stand continuous rolling unit to be rolled to the target thickness of 0.5-2.5 mm.

[0064] In a specific embodiment of the preparation method of cold-rolled corrosion-resistant steel of the present invention, in step S3, the conditions of continuous annealing are: heating temperature is 790-810°C, soaking temperature is 770-800°C; annealing speed is 80-200m / min. If the annealing speed is too fast and the annealing time is short, the structure does not fully recrystallize, the grain uniformity deteriorates, and the strength and plasticity of the material decrease. If the annealing speed is too slow, the steel strip stays in the furnace for a long time, the steel strip is easily overburned, the grains grow, the surface quality of the steel plate decreases, the plasticity increases, and the strength decreases.

[0065] In a specific embodiment of the method for preparing cold-rolled corrosion-resistant steel of the present invention, in step S3, the flattening condition is: the flattening elongation is 0.8-1.4%; in a preferred case, the target value of the flattening elongation is controlled to be 1.2% to eliminate the yield platform.

[0066] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0067] (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f)=A;

[0068] The raw material components of the cold-rolled corrosion-resistant steels of Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1, and the rest are inevitable iron elements and impurity elements;

[0069] Table 1 Raw material composition of cold-rolled corrosion-resistant steel of Examples 1 to 6 and Comparative Examples 1 to 5

[0070]

[0071]

[0072] The preparation method of the cold-rolled corrosion-resistant steel of Examples 1 to 6 and Comparative Examples 1 to 5 comprises the following steps:

[0073] Step S1: transporting the pretreated molten iron with a sulfur content of 0.005% to a converter to smelt molten steel;

[0074] Step S2: tempering and refining the molten steel obtained in step S1 in a ladle refining furnace, so that the components and contents in the molten steel are adjusted to the components and contents of the raw material components of the cold-rolled corrosion-resistant steel of Examples 1 to 6 and Comparative Examples 1 to 5;

[0075] Step S3: continuously casting the molten steel obtained in step S2 to form a cast billet, and then sequentially subjecting the cast billet to hot rolling, cold rolling, continuous annealing and smoothing, with main process parameters as shown in Table 2;

[0076] Table 2 Main process parameters for preparing cold-rolled corrosion-resistant steels of Examples 1 to 6 and Comparative Examples 1 to 5

[0077]

[0078]

[0079] Test Case

[0080] The cold-rolled corrosion-resistant steel prepared in Example 4 was observed under a scanning electron microscope, and it can be found that the structure is mainly ferrite plus a small amount of carbide. The structure is relatively simple, and corrosion occurs preferentially at the carbide position, achieving uniform corrosion of the structure, avoiding abnormal corrosion at local positions, and forming accelerated corrosion of the original electrolytic cell.

[0081] The yield strength, tensile strength, elongation, sulfuric acid dew point corrosion rate and hydrochloric acid dew point corrosion rate of the cold-rolled corrosion-resistant steels prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were tested respectively; the sulfuric acid dew point corrosion rate was tested according to GB / T28907-2012 "Sulfuric Acid Dew Point Corrosion Resistant Steel Plates and Steel Strips": 20°C, 20% sulfuric acid full immersion for 24h; the hydrochloric acid dew point corrosion rate was tested according to 60°C, 10.5% hydrochloric acid full immersion for 6h, and the results are shown in Table 3;

[0082] Table 3 Test results of cold-rolled corrosion-resistant steel of Examples 1 to 6 and Comparative Examples 1 to 5

[0083]

[0084] It can be seen from the results of Examples 1 to 6 and Comparative Examples 1 to 5 that the present invention uses a raw material component of cold-rolled corrosion-resistant steel composed of elements such as Si (silicon), P (phosphorus), Cu (copper), Sb (antimony) and B (boron) to prepare cold-rolled corrosion-resistant steel. Since the Si element easily forms SiO2 particles on the surface of the steel plate, the P, Cu and Sb elements easily form a dense protective layer covering the surface of the steel plate under the interaction, and the presence of SiO2 particles will further promote the protective layer to have a higher strength. Therefore, the SiO2 particles and the protective layer can effectively prevent SO2 gas under the synergistic effect. The chlorine gas forms corrosive droplets on the surface of the steel plate, thereby effectively improving the hydrochloric acid and sulfuric acid resistance of the cold-rolled corrosion-resistant steel. At the same time, since the elements Si, P, Cu and Sb in the raw material components are easily enriched at the grain boundaries, this enrichment phenomenon may lead to adverse consequences such as grain boundary embrittlement and decreased corrosion resistance. The B element in the raw material components can just improve the consequences of embrittlement at the grain boundaries and decreased corrosion resistance, so that the yield strength of the finally prepared cold-rolled corrosion-resistant steel is ≥245MPa, the tensile strength is 360-510MPa, and its sulfuric acid dew point corrosion rate is <3.0mg / cm 2 *h, hydrochloric acid dew point corrosion rate <5.0mg / cm 2 *h.

[0085] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A raw material component for cold-rolled corrosion-resistant steel, characterized in that: Taking the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, the raw material components include: 0.04-0.12% of carbon element, 0.50-1.25% of silicon element, 0.20-0.60% of manganese element, 0.10-0.20% of phosphorus element, less than 0.015% of sulfur element, 0.20-0.60% of copper element, 0.020-0.055% of acid-fused aluminum, 0.05-0.15% of antimony element, 0.0010-0.0020% of boron element, 0.01-0.02% of titanium element, and the balance is iron element and impurity elements.

2. The raw material composition of cold-rolled corrosion-resistant steel according to claim 1, characterized in that: Taking the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, the raw material components include: 0.05-0.06% of carbon element, 0.65-1.25% of silicon element, 0.30-0.55% of manganese element, 0.10-0.18% of phosphorus element, 0.008-0.010% of sulfur element, 0.30-0.35% of copper element, 0.033-0.040% of acid-fused aluminum, 0.05-0.10% of antimony element, 0.0010-0.0012% of boron element, 0.018-0.02% of titanium element, and the remainder is iron element and impurity elements.

3. The raw material composition of cold-rolled corrosion-resistant steel according to claim 1, characterized in that: The relationship between the elements in the raw material composition of the cold-rolled corrosion-resistant steel is shown in the following formula: (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f)≥20; Among them, a is the numerical value of the mass percentage of silicon element in the raw material components of cold-rolled corrosion-resistant steel, b is the numerical value of the mass percentage of copper element in the raw material components of cold-rolled corrosion-resistant steel, c is the numerical value of the mass percentage of antimony element in the raw material components of cold-rolled corrosion-resistant steel, d is the numerical value of the mass percentage of phosphorus element in the raw material components of cold-rolled corrosion-resistant steel, e is the numerical value of the mass percentage of boron element in the raw material components of cold-rolled corrosion-resistant steel, and f is the numerical value of the mass percentage of titanium element in the raw material components of cold-rolled corrosion-resistant steel.

4. The raw material composition of cold-rolled corrosion-resistant steel according to claim 3, characterized in that: (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / The value range of (10.25*e+1.06*f) is 20 to 38.

5. A method for preparing cold-rolled corrosion-resistant steel, characterized in that: The method comprises the following steps: Step S1: smelting the pretreated molten iron to obtain molten steel; Step S2: tempering and refining the molten steel obtained in step S1 to adjust the composition and content of the raw material components of the cold-rolled corrosion-resistant steel as claimed in any one of claims 1 to 4; Step S3: Continuously cast the molten steel obtained in step S2 to form a cast billet, and then sequentially subject the cast billet to hot rolling, cold rolling, continuous annealing and smoothing.

6. The method for preparing cold-rolled corrosion-resistant steel according to claim 5, characterized in that: Taking the total mass of the raw material components of the cold-rolled corrosion-resistant steel as 100%, the raw material components include: 0.05-0.06% of carbon element, 0.65-1.25% of silicon element, 0.30-0.55% of manganese element, 0.10-0.18% of phosphorus element, 0.008-0.010% of sulfur element, 0.30-0.35% of copper element, 0.033-0.040% of acid-fused aluminum, 0.05-0.10% of antimony element, 0.0010-0.0012% of boron element, 0.018-0.02% of titanium element, and the remainder is iron element and impurity elements.

7. The method for preparing cold-rolled corrosion-resistant steel according to claim 5, characterized in that: The relationship between the elements in the raw material composition of the cold-rolled corrosion-resistant steel is shown in the following formula: (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / (10.25*e+1.06*f)≥20; Among them, a is the numerical value of the mass percentage of silicon element in the raw material components of cold-rolled corrosion-resistant steel, b is the numerical value of the mass percentage of copper element in the raw material components of cold-rolled corrosion-resistant steel, c is the numerical value of the mass percentage of antimony element in the raw material components of cold-rolled corrosion-resistant steel, d is the numerical value of the mass percentage of phosphorus element in the raw material components of cold-rolled corrosion-resistant steel, e is the numerical value of the mass percentage of boron element in the raw material components of cold-rolled corrosion-resistant steel, and f is the numerical value of the mass percentage of titanium element in the raw material components of cold-rolled corrosion-resistant steel.

8. The method for preparing cold-rolled corrosion-resistant steel according to claim 7, characterized in that: (48.5*a*b*c+56.8*d*b*c)*10+((1.26*a+3.62*d)*0.28) / The value range of (10.25*e+1.06*f) is 20 to 38.

9. The method for preparing cold-rolled corrosion-resistant steel according to claim 5, characterized in that: In step S1, the sulfur content in the pretreated molten iron is ≤0.005%; In step S3, the hot rolling conditions are: heating temperature is 1200-1240°C, heating time is ≤150min, final rolling temperature is 850-900°C, and coiling temperature is 550-600°C; The cold rolling conditions are: the total reduction rate is 55-75%; The continuous annealing conditions are: heating temperature of 790-810°C, soaking temperature of 770-800°C, and annealing speed of 80-200 m / min; The flattening condition is: the flattening elongation is 0.8-1.4%.

10. A cold-rolled corrosion-resistant steel prepared according to the method for preparing cold-rolled corrosion-resistant steel according to any one of claims 5 to 9.

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