High-toughness corrosion-resistant protective steel plate and method for manufacturing same

Abstract

This invention discloses a high-toughness, corrosion-resistant protective steel plate and its preparation method, belonging to the field of protective steel material preparation technology. It addresses the technical problem that the high-toughness, corrosion-resistant performance, and toughness of existing protective steel plates need further improvement. The invention first prepares a copper-nickel-chromium-aluminum-antimony alloy to establish a stable corrosion-resistant alloying foundation; then, it prepares a calcium-titanium-boron inoculant to improve the microstructure formation conditions during the solidification process of molten steel; simultaneously, it prepares a magnesium-aluminum-calcium regulating material to adjust the composition, morphology, and interface state of inclusions. The synergistic effect of these three materials makes the internal component distribution, microstructure evolution, and inclusion control of the steel plate more coordinated and continuous, thereby improving the microstructure uniformity, interface stability, and overall performance of the corrosion-resistant steel plate.

Description

Technical Field

[0001] This invention relates to the field of protective steel material preparation technology, specifically to a high-toughness and corrosion-resistant protective steel plate and its preparation method. Background Technology

[0002] In existing technologies, high-toughness and corrosion-resistant protective steel plates typically employ a low-alloying design approach. This involves adding corrosion-resistant alloying elements such as copper, nickel, chromium, aluminum, and antimony to the iron-based system to improve the surface stability and service life of the steel plate in atmospheric, humid, and saline environments. Simultaneously, processes such as converter or electric furnace smelting, ladle refining, continuous casting, controlled rolling and cooling, and heat treatment are combined to improve the strength-toughness balance of the steel plate. Some technologies also utilize inoculation treatment, deoxidation modification treatment, and inclusion control to adjust the cleanliness of the molten steel, solidification structure, and overall performance of the plate, thereby meeting the comprehensive requirements of protective components for strength, toughness, and corrosion resistance.

[0003] However, existing technologies often involve directly adding single-element or conventional intermediate alloys to the furnace when adding corrosion-resistant alloying elements. This makes it difficult to maintain consistency in the diffusion sequence, local distribution, and enrichment behavior of components such as copper, nickel, chromium, aluminum, and antimony in the molten steel. This can easily lead to uneven micro-area composition, local segregation, and increased differences in the microstructure transition zone. In particular, in multi-element composite corrosion-resistant systems, the synergistic effect between different components is difficult to fully exert, which in turn affects the continuity and stability of the corrosion-resistant matrix. As a result, it is difficult to simultaneously achieve the requirements of microstructure uniformity, interface integrity, and high toughness during subsequent hot working and service of the steel plate.

[0004] In addition, existing technologies for controlling inclusions and solidification structures in molten steel are mostly decentralized. There is a lack of effective connection between inclusion composition transformation, morphology adjustment and solidification nucleation improvement. This makes it easy for inclusions to remain in the steel matrix in a state of uneven size, sharp angular morphology or insufficient interfacial compatibility. These micro-discontinuous regions are more likely to become crack initiation sources, stress concentration sources and preferential sites for local corrosion when subjected to impact loads or corrosive media, thereby weakening the impact toughness and corrosion resistance of the steel plate and resulting in insufficient overall performance matching of the protective steel plate.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a high-toughness and corrosion-resistant protective steel plate and its preparation method, so as to solve the technical problem that the high-toughness and corrosion-resistant properties and toughness of the protective steel plate in the prior art need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing a high-toughness, corrosion-resistant protective steel plate includes the following steps:

[0009] S1. Weigh 780-860 parts of iron by weight and add it to a medium-frequency induction melting furnace to heat and melt it. Then add 80-100 parts of copper-nickel-chromium-aluminum-antimony alloy material. After stirring evenly, add 4-8 parts of manganese, 2-5 parts of industrial silicon and 0.3-0.8 parts of graphite powder. Then transfer the molten steel to a refining ladle. Under argon protection, add 4-6 parts of calcium-titanium-boron inoculant material, followed by 2-4 parts of magnesium-aluminum-calcium control material. After standing at 1500-1540℃ for 4-8 minutes, pour it into a billet. After post-treatment, obtain a corrosion-resistant slab.

[0010] S2. The corrosion-resistant slab is fed into a continuous heating furnace and heated to 1180-1230℃ under nitrogen or argon protection and held for 40-60 minutes. Then it is hot rolled to obtain a corrosion-resistant steel plate.

[0011] Furthermore, in step S1, the dimensions of the corrosion-resistant slab are 80-120mm in length, 50-70mm in width, and 18-25mm in thickness. The post-processing includes: naturally cooling to room temperature after casting, cleaning the surface oxide scale and gating gate after demolding, and obtaining the corrosion-resistant slab.

[0012] Furthermore, in step S2, the corrosion-resistant steel plate has dimensions of 300-500mm in length, 50-80mm in width, and 3-6mm in thickness. The hot rolling operation is as follows: the initial rolling temperature is controlled at 1080-1120℃, the final rolling temperature is 850-920℃, and after hot rolling, it is cooled to 620-680℃ at 8-15℃ / s and held for 20-40min. Then, leveling, edge trimming, and surface cleaning are performed to obtain the corrosion-resistant steel plate.

[0013] Furthermore, the calcium-titanium-boron inoculant is prepared by the following method:

[0014] A1. Add anhydrous ethanol and tetrabutyl titanate to the reaction vessel and stir. After mixing evenly, add glacial acetic acid and then the mixture. Heat the reaction vessel to 35-40℃ and stir for 2-3 hours. Then let it stand for 10-14 hours. After standing and aging, filter and collect the filter cake. Wash with anhydrous ethanol and dry to constant weight to obtain titanium boron precursor.

[0015] A2. Add ethylene glycol and deionized water to the reactor and stir. After mixing evenly, add calcium acetate and then titanium boron precursor. Heat the reactor to 85-95℃ and stir for 3-4 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Then heat treat the filter cake to obtain calcium titanium boron inoculant.

[0016] Furthermore, in step A1, the ratio of anhydrous ethanol, tetrabutyl titanate, glacial acetic acid, and the mixture is 100mL:16-20mL:3-4mL:8-12mL, wherein the mixture is obtained by mixing boric acid and deionized water in a ratio of 4-5g:12-16mL.

[0017] Further, in step A2, the ratio of ethylene glycol, deionized water, calcium acetate, and titanium boron precursor is 100mL:10-15mL:6-8g:12-16g. The heat treatment includes: placing the filter cake in a tube furnace under nitrogen protection at 680-760℃ for 2-3 hours, cooling it, crushing it, and passing it through a 100-150 mesh sieve to obtain calcium titanium boron inoculant.

[0018] Furthermore, the preparation method of the copper-nickel-chromium-aluminum-antimony alloy material is as follows: iron is added to a vacuum induction melting furnace, followed by copper, nickel, chromium, aluminum and antimony. The temperature is raised to 1520-1580℃ under vacuum and argon protection conditions, and the melting is held for 15-25 minutes. The copper-nickel-chromium-aluminum-antimony alloy material is obtained after post-treatment.

[0019] Furthermore, in the process of preparing copper-nickel-chromium-aluminum-antimony alloy, the ratio of iron, copper, nickel, chromium, aluminum and antimony is 820-860g:35-55g:25-40g:25-45g:3-8g:1.2-1.6g. The post-processing includes: after smelting, pouring the melt into a metal mold and allowing it to cool naturally, then crushing the ingot and passing it through a 40-60 mesh sieve to obtain the copper-nickel-chromium-aluminum-antimony alloy.

[0020] Furthermore, the magnesium-aluminum-calcium regulator is prepared by the following method:

[0021] B1. Add deionized water to the reactor and stir. Then add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate. After stirring evenly, add urea. Heat the reactor to 90-95℃ and keep it at that temperature for 6-8 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight to obtain magnesium-aluminum precursor.

[0022] B2. Add ethylene glycol and deionized water to the reactor and stir. After mixing evenly, add calcium nitrate tetrahydrate and then magnesium-aluminum precursor. Heat the reactor to 85-95℃ and stir for 3-5 hours. The resulting magnesium-aluminum-calcium conditioning material is obtained after post-processing.

[0023] Furthermore, in step B1, the ratio of deionized water, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea is 100mL:9-12g:6-8g:6-8g.

[0024] Further, in step B2, the ratio of ethylene glycol, deionized water, calcium nitrate tetrahydrate, and magnesium-aluminum precursor is 50mL:15-20mL:4-6g:5-6g. The post-treatment includes: after the reaction is completed, filtering and collecting the filter cake, washing with deionized water and drying to constant weight, placing the filter cake in a tube furnace under nitrogen protection at 700-780℃ for 2-3 hours, cooling, crushing and passing through a 100-150 mesh sieve to obtain magnesium-aluminum-calcium conditioning material.

[0025] The present invention also discloses a high-toughness and corrosion-resistant protective steel plate, which is prepared by a method for preparing a high-toughness and corrosion-resistant protective steel plate.

[0026] The present invention has the following beneficial effects:

[0027] 1. The copper-nickel-chromium-aluminum-antimony alloy material prepared by this invention, after entering the iron-based melt, first establishes a composite alloying foundation characterized by Cu, Ni, Cr, Al, and Sb at the composition level, so that the matrix and surface areas obtained after subsequent solidification have relatively stable chemical composition conditions. Subsequently, the calcium-titanium-boron inoculant intervenes in the solidification process, which plays a restraining role in the formation mode of the primary structure, making it difficult for local segregation zones and abrupt structural change zones to concentrate. Furthermore, the magnesium-aluminum-calcium regulating material further acts on the composition and interface state of the inclusions, weakening the condition that the corrosive medium preferentially cuts into the periphery of the inclusions. Thus, under intermittent spraying of salt solution and humid cyclic environment, a more coherent coordination relationship is formed between the surface reaction, structural uniformity, and interface stability of the material. The corrosion process is more controlled by the overall state of the matrix, rather than dominated by local weak parts.

[0028] 2. The calcium-titanium-boron inoculant prepared by this invention, when applied to molten steel, does not limit its inoculation effect to the initial solidification stage but extends its influence to the reheating and hot rolling stages of the slab, resulting in a clearer continuity in the microstructure evolution process. Based on this, the composite alloying background formed by the copper-nickel-chromium-aluminum-antimony alloy provides the necessary load-bearing framework for the matrix, enabling the material to establish a stable stress transfer path earlier during tensile testing. The magnesium-aluminum-calcium control material's adjustment of the inclusion morphology and distribution helps to weaken strain concentration induced by localized hard points. After the three types of materials are progressively connected from solidification structure and matrix composition to inclusion control, the yielding, uniform deformation, and subsequent elongation of the material under external load are no longer significantly separated, and a more natural coordination exists between the strength building process and the plasticity release process.

[0029] 3. The magnesium-aluminum-calcium modulator prepared by this invention plays a more concentrated role in the front-end control of crack-related behaviors. After being added to molten steel, it changes the distribution of potential crack sources inside the material by adjusting the size, morphology and interface bonding state of inclusions. Furthermore, the calcium-titanium-boron inoculant further affects the continuity of the solidification structure and subsequent hot working structure, reducing the traction of coarse grain regions and abrupt structural changes on the crack propagation path. Although the copper-nickel-chromium-aluminum-antimony alloy material undertakes the function of composite alloying, after the above-mentioned structural and inclusion conditions are integrated simultaneously, it does not introduce significant mismatch factors that are detrimental to impact bearing. Therefore, during the instantaneous load input process, the material is more likely to form a dispersed and gradual energy absorption mode, and a more complete hierarchical buffer relationship is presented between crack initiation, deflection and propagation. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The image is the SEM image prepared in Example 3 of this invention;

[0032] Figure 2 The SEM image prepared in Example 6 of this invention;

[0033] Figure 3 The image shown is the SEM image prepared in Example 9 of this invention. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In this application, the industrial silicon used was purchased from Shanghai McLean Biochemical Technology Co., Ltd., with item number S817858; the graphite powder used was purchased from Shanghai McLean Biochemical Technology Co., Ltd., with item number G864778.

[0036] Example 1

[0037] This embodiment provides a method for preparing a calcium-titanium-boron inoculant, comprising the following steps:

[0038] Step ①: Preparation of titanium-boron precursor material

[0039] Weigh out 4.0 g of boric acid and mix it with 12.0 mL of deionized water to obtain a mixed solution;

[0040] Weigh out 100.0 mL of anhydrous ethanol and 16.0 mL of tetrabutyl titanate and add them to the reaction vessel. Stir and mix well. Then add 3.0 mL of glacial acetic acid and 8.0 mL of the mixture. Heat the reaction vessel to 35°C and stir for 2 hours. Then let it stand for 10 hours. After standing and aging, filter and collect the filter cake. Wash with anhydrous ethanol and dry to constant weight to obtain titanium boron precursor.

[0041] Step 2: Preparation of calcium-titanium-boron inoculant

[0042] Weigh out 100.0 mL of ethylene glycol and 10.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 6.0 g of calcium acetate and 12.0 g of titanium boron precursor. Heat the reaction vessel to 85 °C and stir for 3 h. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection and keep it at 680 °C for 2 h. After cooling, crush and pass through a 100-mesh sieve to obtain calcium titanium boron inoculant.

[0043] The reaction principle for preparing calcium-titanium-boron inoculants is as follows:

[0044] In an anhydrous ethanol system, tetrabutyl titanate undergoes controlled hydrolysis and condensation with a mixture of boric acid and deionized water under the regulation of glacial acetic acid. A precursor structure with a Ti-O bond backbone and uniformly dispersed boron-containing components gradually forms in the system. After the introduction of calcium acetate, Ca... 2+ In an ethylene glycol-water medium, the calcium source combines with hydroxyl oxygen, bridging oxygen, and boron-containing oxygen groups on the surface of the precursor, allowing the calcium source to be distributed in the titanium boron precursor at the molecular or near-molecular scale. After subsequent heat treatment, the system undergoes dehydration, dehydroxylation, acetate decomposition, and inorganic network rearrangement, ultimately completing the solid-phase coupling and structural solidification between the Ca, Ti, and B components, forming a calcium-titanium-boron inorganic product with a relatively uniform composition distribution.

[0045] The mechanism of action of calcium titanium boron inoculants in corrosion-resistant steel plates is as follows:

[0046] In this process, the substances obtained in steps ① and ② can be understood as a calcium-titanium-boron composite functional additive system with an inherent structural relationship. The titanium-boron precursor material first provides the basis for the coupling distribution of Ti and B components at the microscale, while the calcium-titanium-boron inoculant further forms a composite structural unit with Ca, Ti, and B interrelated on this basis. Therefore, after entering the molten steel, it does not exhibit a simple release from a single element source, but rather tends to play a role simultaneously around the solidification interface and the inclusion interface.

[0047] On the one hand, this composite additive system is beneficial to improving the conditions for the formation of primary structure during the solidification of molten steel, reducing the differences in grain size, local segregation and discontinuous transition of structure in the as-cast structure, and improving the stability of structure inheritance during subsequent hot working. On the other hand, it can also regulate the composition, morphological characteristics and interface relationship with the matrix of non-metallic inclusions, reducing the tendency of inclusions to evolve into stress concentration sources, crack initiation sources and preferential sites for local corrosion.

[0048] This makes the microstructure of the final corrosion-resistant steel plate, consisting of component distribution, microstructure and interface state, more coordinated, and thus makes it easier to obtain a more balanced comprehensive performance between corrosion resistance, strength, plasticity and impact toughness.

[0049] Example 2

[0050] This embodiment provides a method for preparing a calcium-titanium-boron inoculant, comprising the following steps:

[0051] Step ①: Preparation of titanium-boron precursor material

[0052] Weigh out 5.0 g of boric acid and mix it with 16.0 mL of deionized water to obtain a mixed solution;

[0053] Weigh out 100.0 mL of anhydrous ethanol and 20.0 mL of tetrabutyl titanate and add them to the reaction vessel. Stir and mix well. Then add 4.0 mL of glacial acetic acid and 12.0 mL of the mixture. Heat the reaction vessel to 40°C and stir for 3 hours. Then let it stand for 14 hours. After standing and aging, filter and collect the filter cake. Wash with anhydrous ethanol and dry to constant weight to obtain titanium boron precursor.

[0054] Step 2: Preparation of calcium-titanium-boron inoculant

[0055] Weigh out 100.0 mL of ethylene glycol and 15.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 8.0 g of calcium acetate and 16.0 g of titanium boron precursor. Heat the reaction vessel to 95 °C and stir for 4 h. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection and keep it at 760 °C for 3 h. After cooling, crush and pass through a 150 mesh sieve to obtain calcium titanium boron inoculant.

[0056] Example 3

[0057] This embodiment provides a method for preparing a calcium-titanium-boron inoculant, comprising the following steps:

[0058] Step ①: Preparation of titanium-boron precursor material

[0059] Weigh out 4.5g of boric acid and mix it with 14.0mL of deionized water to obtain a mixed solution;

[0060] Weigh out 100.0 mL of anhydrous ethanol and 18.0 mL of tetrabutyl titanate and add them to the reaction vessel. Stir and mix well. Then add 3.5 mL of glacial acetic acid and 10.0 mL of the mixture. Heat the reaction vessel to 38°C and stir for 3 hours. Then let it stand for 12 hours. After standing and aging, filter and collect the filter cake. Wash with anhydrous ethanol and dry to constant weight to obtain titanium boron precursor.

[0061] Step 2: Preparation of calcium-titanium-boron inoculant

[0062] Weigh out 100.0 mL of ethylene glycol and 12.5 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 7.0 g of calcium acetate and 14.0 g of titanium boron precursor. Heat the reaction vessel to 90 °C and stir for 4 h. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection and keep it at 720 °C for 3 h. After cooling, crush and pass through a 125 mesh sieve to obtain calcium titanium boron inoculant.

[0063] Example 4

[0064] This embodiment provides a method for preparing a magnesium-aluminum-calcium modifier, including the following steps:

[0065] Step I: Preparation of magnesium-aluminum precursor

[0066] Weigh 100.0 mL of deionized water and add it to the reaction vessel and stir. Then add 9.0 g of magnesium nitrate hexahydrate and 6.0 g of aluminum nitrate nonahydrate, stir evenly, and then add 6.0 g of urea. Heat the reaction vessel to 90°C and keep it at that temperature for 6 hours. After the reaction is complete, filter and collect the filter cake. Wash it with deionized water and dry it to constant weight to obtain magnesium-aluminum precursor.

[0067] Step II: Preparation of magnesium-aluminum-calcium regulator

[0068] Weigh out 50.0 mL of ethylene glycol and 15.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 4.0 g of calcium nitrate tetrahydrate and 5.0 g of magnesium-aluminum precursor. Heat the reaction vessel to 85°C and stir for 3 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection and keep it at 700°C for 2 hours. After cooling, crush and pass through a 100-mesh sieve to obtain magnesium-aluminum-calcium regulator.

[0069] The reaction principle for preparing magnesium-aluminum-calcium regulators is as follows:

[0070] In the aqueous phase, magnesium nitrate hexahydrate and aluminum nitrate nonahydrate dissolve to form Mg. 2+ Al 3+In the coexisting system, urea slowly decomposes under heating conditions, releasing alkaline components, causing metal ions to precipitate uniformly and constructing a magnesium-aluminum composite hydroxide precursor structure; after introducing calcium nitrate tetrahydrate, Ca... 2+ In an ethylene glycol-water medium, the calcium component binds to the hydroxyl and oxygen coordination sites on the surface of the magnesium-aluminum precursor, dispersing the calcium component between the magnesium-aluminum skeleton. After heat treatment, the system completes dehydration, dehydroxylation, nitrate decomposition, and metal-oxygen bond rearrangement, forming an inorganic composite control material containing Mg, Al, and Ca components.

[0071] The mechanism of action of magnesium-aluminum-calcium modifiers in corrosion-resistant steel plates is as follows:

[0072] In this process, the magnesium-aluminum-calcium control material obtained in steps I and II can be understood as a composite control additive system for the inclusion state and interface stability of molten steel. The magnesium-aluminum precursor material provides the structural basis for the uniform correlation of Mg and Al components. After Ca is introduced, it further forms an inorganic composite unit with Mg, Al and Ca synergistic distribution. Therefore, after entering the molten steel, it does not exist as a single deoxidizing or modifying component, but tends to participate in the transformation of inclusion composition, morphology adjustment and interface state optimization.

[0073] Among them, Mg and Al components are beneficial to influencing the formation and stability of oxide inclusions, while Ca components can further adjust the melting point, morphology and bonding relationship between inclusions and the steel matrix, transforming sharp-angled, brittle or unevenly distributed inclusions into a finer, more dispersed state with better interfacial compatibility. As a result, the micro-discontinuous regions inside the steel plate are reduced, and the tendency of inclusions to act as crack initiation sources, stress concentration sources and preferential corrosion initiation points is reduced. This is conducive to the final corrosion-resistant steel plate obtaining more stable plasticity, impact toughness and corrosion resistance while maintaining strength.

[0074] Example 5

[0075] This embodiment provides a method for preparing a magnesium-aluminum-calcium modifier, including the following steps:

[0076] Step I: Preparation of magnesium-aluminum precursor

[0077] Weigh 100.0 mL of deionized water and add it to the reaction vessel and stir. Then add 12.0 g of magnesium nitrate hexahydrate and 8.0 g of aluminum nitrate nonahydrate, stir evenly, and then add 8.0 g of urea. Heat the reaction vessel to 95°C and keep it at that temperature for 8 hours. After the reaction is complete, filter and collect the filter cake. Wash it with deionized water and dry it to constant weight to obtain magnesium-aluminum precursor.

[0078] Step II: Preparation of magnesium-aluminum-calcium regulator

[0079] Weigh out 50.0 mL of ethylene glycol and 20.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 6.0 g of calcium nitrate tetrahydrate and 6.0 g of magnesium-aluminum precursor. Heat the reaction vessel to 95°C and stir for 5 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection and keep it at 780°C for 3 hours. After cooling, crush and pass through a 150-mesh sieve to obtain magnesium-aluminum-calcium regulator.

[0080] Example 6

[0081] This embodiment provides a method for preparing a magnesium-aluminum-calcium modifier, including the following steps:

[0082] Step I: Preparation of magnesium-aluminum precursor

[0083] Weigh 100.0 mL of deionized water and add it to the reaction vessel and stir. Then add 10.5 g of magnesium nitrate hexahydrate and 7.0 g of aluminum nitrate nonahydrate, stir evenly, and then add 7.0 g of urea. Heat the reaction vessel to 93°C and keep it at that temperature for 7 hours. After the reaction is complete, filter and collect the filter cake. Wash it with deionized water and dry it to constant weight to obtain magnesium-aluminum precursor.

[0084] Step II: Preparation of magnesium-aluminum-calcium regulator

[0085] Weigh out 50.0 mL of ethylene glycol and 18.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 5.0 g of calcium nitrate tetrahydrate and 5.5 g of magnesium-aluminum precursor. Heat the reaction vessel to 90 °C and stir for 4 h. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection and keep it at 740 °C for 3 h. After cooling, crush and pass through a 125 mesh sieve to obtain magnesium-aluminum-calcium regulator.

[0086] Example 7

[0087] This embodiment provides a method for preparing a high-toughness, corrosion-resistant protective steel plate, including the following steps:

[0088] Step 1: Preparation of copper-nickel-chromium-aluminum-antimony alloy material

[0089] Weigh out 820.0g of iron and add it to a vacuum induction melting furnace. Then add 35.0g of copper, 25.0g of nickel, 25.0g of chromium, 3.0g of aluminum and 1.2g of antimony. Under vacuum and argon protection, heat to 1520℃ and hold for 15 minutes. After melting, pour the melt into a metal mold and let it cool naturally. Then crush the ingot and pass it through a 40-mesh sieve to obtain copper-nickel-chromium-aluminum-antimony alloy material.

[0090] The reaction principle for preparing copper-nickel-chromium-aluminum-antimony alloys is as follows:

[0091] At 1520℃, the iron matrix is ​​in a molten state. The added copper, nickel, chromium, aluminum and antimony melt sequentially and enter the molten iron. The components are mixed through dissolution, diffusion and convection in the liquid phase. The system changes from a multi-metallic element to an iron-based alloy melt with continuous component distribution. Vacuum and argon protection together restrict the entry of active gases such as oxygen and nitrogen into the molten pool and inhibit the oxidation of active elements such as aluminum and chromium. This allows each component to participate in the melt equilibrium mainly in the metallic state. Subsequently, solidification is completed according to the phase equilibrium relationship of the Fe-Cu-Ni-Cr-Al-Sb multi-component system, resulting in a copper-nickel-chromium-aluminum-antimony alloy material composed of iron-based solid solution and locally enriched components.

[0092] The mechanism of action of copper-nickel-chromium-aluminum-antimony alloys in corrosion-resistant steel plates is as follows:

[0093] In this process, the copper-nickel-chromium-aluminum-antimony alloy material obtained in step one can be understood as a pre-alloying addition system for establishing the matrix composition of corrosion-resistant steel plates and supporting the subsequent microstructure evolution. Its structure does not come from the mechanical mixing of various elements, but rather from the relatively stable and interconnected alloying state of Cu, Ni, Cr, Al, and Sb components in the iron-based carrier. Therefore, in the subsequent steel addition process, the above components no longer disperse into the melt in an independent manner, but are more conducive to participating in the matrix construction as a whole unit with a high degree of compositional correlation, thereby reducing the tendency of local enrichment, inconsistent diffusion timing, and micro-area segregation that are easy to occur when directly adding elements.

[0094] Among them, Cu, Ni, and Cr mainly participate in the formation of the corrosion-resistant matrix and affect the formation stability of the corrosion product film. Al is beneficial to improve the local interface state in the system and cooperate with subsequent microstructure adjustment. Sb helps to enhance the inhibition effect in the surface corrosion process and the synergistic performance between corrosion-resistant components. Thus, this pre-alloying system provides a more uniform compositional basis and a more stable interface for the subsequent calcium-titanium-boron inoculant and magnesium-aluminum-calcium control material to play their roles. On the other hand, it also makes the microstructure chain composed of alloy element distribution, solidification structure formation and inclusion interface state in the final steel plate more continuous, which is conducive to the formation of a more coordinated comprehensive match between corrosion resistance, strength, plasticity and impact toughness.

[0095] Step 2: Preparation of corrosion-resistant slab blanks

[0096] Weigh out 780 parts by weight of iron and add it to a medium-frequency induction melting furnace to heat and melt it. Then add 80 parts of copper-nickel-chromium-aluminum-antimony alloy material. After stirring evenly, add 4 parts of manganese, 2 parts of industrial silicon and 0.3 parts of graphite powder. Then transfer the molten steel to a refining ladle. Under argon protection, add 4 parts of the calcium-titanium-boron inoculant prepared in Example 1, followed by 2 parts of the magnesium-aluminum-calcium control material prepared in Example 4. After standing at 1500℃ for 4 minutes, pour it into a billet. After pouring, let it cool naturally to room temperature. After demolding, clean the surface oxide scale and the riser to obtain a corrosion-resistant slab with a length of 80mm, a width of 50mm and a thickness of 18mm.

[0097] Step 3: Preparation of corrosion-resistant steel plates

[0098] The corrosion-resistant slab is fed into a continuous heating furnace and heated to 1180℃ under nitrogen or argon protection and held for 40 minutes. Then it is hot rolled, with the initial rolling temperature controlled at 1080℃ and the final rolling temperature at 850℃. After hot rolling, it is cooled to 620℃ at 8℃ / s and held for 20 minutes. Then it is leveled, trimmed, and cleaned to obtain a corrosion-resistant steel plate with a length of 300mm, a width of 50mm, and a thickness of 3mm.

[0099] The reaction principle for preparing corrosion-resistant steel plates is as follows:

[0100] After the iron melts, copper-nickel-chromium-aluminum-antimony alloy, manganese, industrial silicon, and graphite powder are sequentially added to the molten steel. Each component is dissolved, diffused, and convectioned in the high-temperature liquid phase to achieve composition homogenization, forming a multi-element iron-based melt system. After the addition of calcium-titanium-boron inoculant and magnesium-aluminum-calcium regulator, the Ca, Ti, B, Mg, Al, and other components contained therein participate in the metallurgical equilibrium in the molten steel and, together with the original metal elements, affect the phase composition and microstructure formation during solidification. After reheating, the billet enters the hot rolling temperature zone, where the as-cast microstructure is compacted, extended, and reconstructed under hot deformation conditions. Subsequently, corresponding microstructure adjustments occur during controlled cooling and heat preservation, ultimately resulting in a corrosion-resistant steel plate whose composition and morphology have undergone plate-like transformation.

[0101] Example 8

[0102] This embodiment provides a method for preparing a high-toughness, corrosion-resistant protective steel plate, including the following steps:

[0103] Step 1: Preparation of copper-nickel-chromium-aluminum-antimony alloy material

[0104] Weigh out 860.0g of iron and add it to a vacuum induction melting furnace. Then add 55.0g of copper, 40.0g of nickel, 45.0g of chromium, 8.0g of aluminum and 1.6g of antimony. Under vacuum and argon protection, heat to 1580℃ and hold for 25 minutes. After melting, pour the melt into a metal mold and let it cool naturally. Then crush the ingot and pass it through a 60-mesh sieve to obtain copper-nickel-chromium-aluminum-antimony alloy material.

[0105] Step 2: Preparation of corrosion-resistant slab blanks

[0106] Weigh out 860 parts by weight of iron and add it to a medium-frequency induction melting furnace to heat and melt it. Then add 100 parts of copper-nickel-chromium-aluminum-antimony alloy material. After stirring evenly, add 8 parts of manganese, 5 parts of industrial silicon and 0.8 parts of graphite powder. Then transfer the molten steel to a refining ladle. Under argon protection, add 6 parts of the calcium-titanium-boron inoculant prepared in Example 2, and then add 4 parts of the magnesium-aluminum-calcium control material prepared in Example 5. After standing at 1540℃ for 8 minutes, pour it into a billet. After pouring, let it cool naturally to room temperature. After demolding, clean the surface oxide scale and the riser to obtain a corrosion-resistant slab with a length of 120mm, a width of 70mm and a thickness of 25mm.

[0107] Step 3: Preparation of corrosion-resistant steel plates

[0108] The corrosion-resistant slab is fed into a continuous heating furnace and heated to 1230℃ under nitrogen or argon protection and held for 60 minutes. Then it is hot rolled, with the initial rolling temperature controlled at 1120℃ and the final rolling temperature at 920℃. After hot rolling, it is cooled to 680℃ at 15℃ / s and held for 40 minutes. Then it is leveled, trimmed, and cleaned to obtain a corrosion-resistant steel plate with a length of 500mm, a width of 80mm, and a thickness of 6mm.

[0109] Example 9

[0110] This embodiment provides a method for preparing a high-toughness, corrosion-resistant protective steel plate, including the following steps:

[0111] Step 1: Preparation of copper-nickel-chromium-aluminum-antimony alloy material

[0112] Weigh out 840.0g of iron and add it to a vacuum induction melting furnace. Then add 45.0g of copper, 33.0g of nickel, 35.0g of chromium, 5.5g of aluminum and 1.4g of antimony. Under vacuum and argon protection, heat to 1550℃ and hold for 20 minutes. After melting, pour the melt into a metal mold and let it cool naturally. Then crush the ingot and pass it through a 50-mesh sieve to obtain copper-nickel-chromium-aluminum-antimony alloy material.

[0113] Step 2: Preparation of corrosion-resistant slab blanks

[0114] Weigh out 820 parts by weight of iron and add it to a medium-frequency induction melting furnace to heat and melt it. Then add 90 parts of copper-nickel-chromium-aluminum-antimony alloy material. After stirring evenly, add 6 parts of manganese, 4 parts of industrial silicon and 0.6 parts of graphite powder. Then transfer the molten steel to a refining ladle. Under argon protection, add 5 parts of the calcium-titanium-boron inoculant prepared in Example 3, and then add 3 parts of the magnesium-aluminum-calcium control material prepared in Example 6. After standing at 1520℃ for 6 minutes, pour it into a billet. After pouring, let it cool naturally to room temperature. After demolding, clean the surface oxide scale and the riser to obtain a corrosion-resistant slab with a length of 100mm, a width of 60mm and a thickness of 22mm.

[0115] Step 3: Preparation of corrosion-resistant steel plates

[0116] The corrosion-resistant slab is fed into a continuous heating furnace and heated to 1205℃ under nitrogen or argon protection and held for 50 minutes. Then it is hot rolled, with the initial rolling temperature controlled at 1100℃ and the final rolling temperature at 885℃. After hot rolling, it is cooled to 650℃ at 12℃ / s and held for 30 minutes. Then it is leveled, trimmed, and cleaned to obtain a corrosion-resistant steel plate with a length of 400mm, a width of 65mm, and a thickness of 5mm.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 9 is that the addition of calcium-titanium-boron inoculant is omitted in step two.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 9 is that the addition of magnesium-aluminum-calcium modifier is omitted in step two.

[0121] Comparative Example 3

[0122] The difference between this comparative example and Example 9 is that in step one, iron, copper, nickel, chromium, aluminum and antimony are weighed out and set aside for later use without reaction, and are used to replace the copper-nickel-chromium-aluminum-antimony alloy material used in step two in equal amounts.

[0123] Performance testing:

[0124] The average corrosion rates of the corrosion-resistant steel plates prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 20853-2007 "Corrosion of metals and alloys - Corrosion in artificial atmospheres - Accelerated corrosion test under controlled conditions of intermittent spraying of salt solution and humid cycling".

[0125] The yield strength, tensile strength and elongation after fracture of the corrosion-resistant steel plates prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature".

[0126] The impact absorption energy of the corrosion-resistant steel plates prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 229-2020 "Metallic Materials Charpy Pendulum Impact Test Method".

[0127] See Table 1 for specific data;

[0128] Table 1 - Performance Test Data for Each Sample

[0129] Project Group Example 7 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Average corrosion rate / mm·year -1 > 0.068 0.067 0.067 0.086 0.094 0.091 Yield strength / MPa 412 413 413 398 404 392 Tensile strength / MPa 556 558 559 535 542 529 Elongation after fracture / % 27.8 27.9 27.9 24.9 25.3 23.8 Impact absorption energy / J 24 25 25 20 16 18

[0130] Data Analysis:

[0131] A comparative analysis of the data in Table 1 reveals that the average corrosion rate of the corrosion-resistant steel plate prepared by this invention is 0.067 mm·year. -1 The yield strength is 413 MPa, the tensile strength is 559 MPa, the elongation after fracture is 27.9%, and the Charpy V-notch impact absorption energy is 25 J. All these data are superior to the comparative example. This indicates that:

[0132] In Comparative Example 1, after the calcium-titanium-boron inoculant was removed in step two, the solidification stage of the molten steel lost its basis for regulating the nucleation process and the evolution of the primary structure. The grain size, segregation degree and structural continuity inside the billet were more likely to differ. These differences were difficult to completely eliminate in the subsequent heating and hot rolling process, which weakened the structural bond between the plate and the material. As a result, there was no stable structural carrier between the alloy matrix formed by the copper-nickel-chromium-aluminum-antimony alloy and the inclusion state improved by the magnesium-aluminum-calcium control material. The material was more susceptible to the influence of local non-uniform regions during corrosion, tensile and impact processes, and the composite performance decreased accordingly.

[0133] In Comparative Example 2, after the magnesium-aluminum-calcium control material was removed in step two, the inclusions after steel refining lost the conditions for further composition adjustment, morphology optimization and interface stabilization. The inclusions were more likely to remain in the matrix in the form of larger size, irregular shape or weak interface bonding. Such discontinuous areas are prone to become stress concentration sites in subsequent hot rolling deformation and form local reaction initiation points under the action of corrosive media. Due to the lack of inclusion control, the homogenization effect of the microstructure formed by the calcium-titanium-boron inoculated material is difficult to fully connect with the alloying basis provided by the copper-nickel-chromium-aluminum-antimony alloy, resulting in simultaneous limitation of comprehensive mechanical and corrosion resistance performance.

[0134] In Comparative Example 3, step one was omitted and copper, nickel, chromium, aluminum, and antimony were directly added to the molten steel in step two. This caused the alloying elements to lose their pre-alloying overall entry method. Since the melting, diffusion, and distribution behaviors of different elements are different, direct addition is more likely to cause asynchronous local composition establishment, weakening the uniformity of the composite alloying base in the iron-based melt. This state further affects the matching role of calcium-titanium-boron inoculant and magnesium-aluminum-calcium control material in the subsequent solidification and refining stages, reducing the continuity between composition configuration, microstructure adjustment, and inclusion control. As a result, the composite performance of the obtained steel plate is difficult to maintain the level of the example.

[0135] In conclusion, this application does not simply add copper-nickel-chromium-aluminum-antimony alloys, calcium-titanium-boron inoculants, and magnesium-aluminum-calcium control materials in parallel. Instead, it configures corresponding materials and forms a sequential action path around different stages of the iron-based melt in the process of composition establishment, solidification nucleation, inclusion evolution, and subsequent hot working. In step one, the pre-alloying state provides a relatively stable starting point for the subsequent element dispersion and matrix construction in the molten steel. In step two, the calcium-titanium-boron inoculant further intervenes in the solidification structure formation process. The magnesium-aluminum-calcium control material continues to act on the inclusion composition and interface conditions. After the three comparative examples cut off the above different levels, the hierarchical relationship from composition and structure to interface within the system is no longer complete. It can be seen that the technical structure corresponding to this solution is closer to the overall operation relationship under orderly configuration, rather than a single raw material replacement or conventional process superposition.

[0136] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0137] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0138] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-toughness, corrosion-resistant protective steel plate, characterized in that, Includes the following steps: S1. Weigh 780-860 parts of iron by weight and add it to a medium-frequency induction melting furnace to heat and melt it. Then add 80-100 parts of copper-nickel-chromium-aluminum-antimony alloy material. After stirring evenly, add 4-8 parts of manganese, 2-5 parts of industrial silicon and 0.3-0.8 parts of graphite powder. Then transfer the molten steel to a refining ladle. Under argon protection, add 4-6 parts of calcium-titanium-boron inoculant material, followed by 2-4 parts of magnesium-aluminum-calcium control material. After standing at 1500-1540℃ for 4-8 minutes, pour it into a billet. After post-treatment, obtain a corrosion-resistant slab. S2. The corrosion-resistant slab is fed into a continuous heating furnace and heated to 1180-1230℃ under nitrogen or argon protection and held for 40-60 minutes. Then it is hot rolled to obtain a corrosion-resistant steel plate.

2. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 1, characterized in that, In step S1, the dimensions of the corrosion-resistant slab are 80-120mm in length, 50-70mm in width, and 18-25mm in thickness; in step S2, the dimensions of the corrosion-resistant steel plate are 300-500mm in length, 50-80mm in width, and 3-6mm in thickness. The hot rolling operation is as follows: the initial rolling temperature is controlled at 1080-1120℃, the final rolling temperature is 850-920℃, and after hot rolling, the temperature is cooled to 620-680℃ at 8-15℃ / s and held for 20-40min. Then, leveling, edge trimming, and surface cleaning are performed to obtain the corrosion-resistant steel plate.

3. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 1, characterized in that, The calcium-titanium-boron inoculant is prepared by the following method: A1. Add anhydrous ethanol and tetrabutyl titanate to the reaction vessel and stir. After mixing evenly, add glacial acetic acid and then the mixture. Heat the reaction vessel to 35-40℃ and stir for 2-3 hours. Then let it stand for 10-14 hours. After standing and aging, filter and collect the filter cake. Wash with anhydrous ethanol and dry to constant weight to obtain titanium boron precursor. A2. Add ethylene glycol and deionized water to the reactor and stir. After mixing evenly, add calcium acetate and then titanium boron precursor. Heat the reactor to 85-95℃ and stir for 3-4 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Then heat treat the filter cake to obtain calcium titanium boron inoculant.

4. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 3, characterized in that, In step A1, the ratio of anhydrous ethanol, tetrabutyl titanate, glacial acetic acid, and the mixture is 100mL:16-20mL:3-4mL:8-12mL, wherein the mixture is obtained by mixing boric acid and deionized water in a ratio of 4-5g:12-16mL.

5. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 3, characterized in that, In step A2, the ratio of ethylene glycol, deionized water, calcium acetate, and titanium boron precursor is 100mL:10-15mL:6-8g:12-16g. The heat treatment includes: placing the filter cake in a tube furnace under nitrogen protection at 680-760℃ for 2-3 hours, cooling it, crushing it, and passing it through a 100-150 mesh sieve to obtain calcium titanium boron inoculant.

6. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 1, characterized in that, The preparation method of the copper-nickel-chromium-aluminum-antimony alloy is as follows: iron is added to a vacuum induction melting furnace, followed by copper, nickel, chromium, aluminum and antimony. The temperature is raised to 1520-1580℃ under vacuum and argon protection conditions, and the melting is held for 15-25 minutes. The copper-nickel-chromium-aluminum-antimony alloy is then obtained after post-treatment.

7. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 5, characterized in that, In the preparation of copper-nickel-chromium-aluminum-antimony alloy, the ratio of iron, copper, nickel, chromium, aluminum and antimony is 820-860g:35-55g:25-40g:25-45g:3-8g:1.2-1.6g.

8. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 1, characterized in that, The magnesium-aluminum-calcium regulator is prepared by the following method: B1. Add deionized water to the reactor and stir. Then add magnesium nitrate hexahydrate and aluminum nitrate nonahydrate. After stirring evenly, add urea. Heat the reactor to 90-95℃ and keep it at that temperature for 6-8 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight to obtain magnesium-aluminum precursor. B2. Add ethylene glycol and deionized water to the reactor and stir. After mixing evenly, add calcium nitrate tetrahydrate and then magnesium-aluminum precursor. Heat the reactor to 85-95℃ and stir for 3-5 hours. After the reaction is complete, filter and collect the filter cake. Wash with deionized water and dry to constant weight. Place the filter cake in a tube furnace under nitrogen protection at 700-780℃ for 2-3 hours. After cooling, crush and pass through a 100-150 mesh sieve to obtain magnesium-aluminum-calcium regulator.

9. The method for preparing a high-toughness, corrosion-resistant protective steel plate according to claim 8, characterized in that, In step B1, the ratio of deionized water, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and urea is 100mL:9-12g:6-8g:6-8g; in step B2, the ratio of ethylene glycol, deionized water, calcium nitrate tetrahydrate, and magnesium-aluminum precursor is 50mL:15-20mL:4-6g:5-6g.

10. A high-toughness, corrosion-resistant protective steel plate, characterized in that, The high-toughness and corrosion-resistant protective steel plate is prepared by the preparation method of the high-toughness and corrosion-resistant protective steel plate as described in any one of claims 1-9.

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