Highly corrosion-resistant stainless steel cold plate for decoration and applications

Abstract

This invention discloses a high corrosion-resistant decorative stainless steel cold-rolled sheet and its application. The chemical composition of the high corrosion-resistant decorative stainless steel cold-rolled sheet is: C≤0.015%, N≤0.015%, Si: 0.15%~0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O≤0.0015%, with the balance being Fe and unavoidable impurities, and 28≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34 and 50≤ w Al × w O ×10 6 The high corrosion-resistant decorative stainless steel preparation method, with a surface gloss of ≤80, includes smelting, continuous casting, grinding, hot rolling, multi-pass cold rolling, annealing, and leveling processes. This invention ensures high surface gloss while maintaining extremely high purity and superior corrosion resistance, meeting the needs of a wider range of demanding applications and effectively expanding the application fields and scope of decorative stainless steel.

Description

Technical Field

[0001] This invention belongs to the field of stainless steel production technology, specifically relating to a decorative stainless steel cold-rolled sheet with high purity, high corrosion resistance, and high gloss, and its application. Background Technology

[0002] With the development of the national economy, the decoration industry has grown rapidly. Currently used decorative materials include wood, plastic, aluminum, ordinary steel, and stainless steel. Compared with other materials, stainless steel has the characteristics of high strength, good corrosion resistance, and a bright surface. Stainless steel's excellent corrosion resistance ensures stable surface color and extends its lifespan, making it increasingly popular in the decoration field.

[0003] Currently, the main grades of decorative stainless steel include SUS304, SUS430, SUS430J1L, SUS430LX and SUS436L. Among them, SUS304 contains nickel, which has a higher cost and greater price fluctuations. SUS430 has a higher carbon content and poorer corrosion resistance. Therefore, the most widely used decorative stainless steel is ultra-pure medium-chromium ferritic stainless steel.

[0004] In recent years, with the improvement of people's living standards in China, and the upgrading of consumption in automobiles, home appliances, construction, and decoration, competition in various industries has become increasingly fierce. People have higher and higher requirements for the surface gloss, corrosion resistance, and lifespan of decorative stainless steel, and existing materials are no longer competitive. In addition, decorative stainless steel has a wide range of applications and is used in more and more scenarios, including marine atmospheres, kitchen fumes, and disinfectants, requiring stainless steel to have more comprehensive corrosion resistance.

[0005] Therefore, it is necessary to develop a higher grade of ultra-pure ferritic stainless steel for high corrosion-resistant decorative applications, which can improve its overall corrosion resistance while ensuring high surface gloss, and meet a wider range of more demanding application environments. Summary of the Invention

[0006] In view of the above-mentioned technical problems in the prior art, the present invention provides a high corrosion-resistant decorative stainless steel cold-rolled sheet, which improves the purity and comprehensive corrosion resistance of decorative stainless steel while ensuring high surface gloss, so as to meet a wider range of more demanding application environments and expand the application fields of decorative stainless steel.

[0007] The chemical composition of the high corrosion-resistant decorative stainless steel provided by this invention, by mass percentage, is as follows: C≤0.015%, N≤0.015%, Si: 0.15%~0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O≤0.0015%, with the balance being Fe and unavoidable impurities. Furthermore, the content of Cr, Mo, Ni, Cu, and Mn elements satisfies 28≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34, Al and O element content meets 50≤ w Al × w O ×10 6 ≤80, of which w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O These represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O, respectively.

[0008] Preferably, the C and N content in the high corrosion-resistant decorative stainless steel is controlled to be C≤0.012% and N≤0.012%.

[0009] The method for preparing high corrosion-resistant decorative stainless steel cold-rolled sheet provided by the present invention includes the following steps:

[0010] (1) Smelting: Using dephosphorized molten iron, ferrochrome alloy, ferromolybdenum alloy and copper plate as raw materials, smelting is carried out in AOD or K-OBM-S furnace, and smelting is carried out through VOD and LF processes. The chemical composition of the molten steel obtained by smelting is controlled by mass percentage as follows: C≤0.015%, N≤0.015%, Si: 0.15%~0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O≤0.0015%, with the balance being Fe and unavoidable impurities, and the content of Cr, Mo, Ni, Cu and Mn elements meets the requirement of 28≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34, Al and O element content meets 50≤ w Al × w O ×10 6 ≤80, of which w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O These represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O, respectively.

[0011] (2) Protective continuous casting: After blowing argon into the tundish for 5 minutes, start casting. Use carbon-free tundish covering agent. Control the tundish temperature at 1540~1560℃ and the continuous casting speed at 0.70~1.00m / min.

[0012] (3) Grinding, hot rolling, multi-pass cold rolling, annealing and leveling: After grinding, hot rolling, multi-pass cold rolling, annealing and leveling, the continuous casting billet is produced into high corrosion resistant decorative stainless steel cold plate.

[0013] Furthermore, in the above-mentioned method for preparing highly corrosion-resistant decorative stainless steel cold-rolled sheets, the smelting step includes the following sub-steps:

[0014] (1.1) Batching and smelting: Dephosphorized molten iron, ferrochrome alloy, ferromolybdenum alloy and copper plate are added to AOD or K-OBM-S furnace for smelting to achieve preliminary decarburization and alloying of main elements. The target content of chemical composition is controlled as follows: C: 0.20%~0.30%, Si≤0.015%, Ni: 0.10%~0.20%, and the tapping temperature is controlled as ≥1650℃;

[0015] (1.2) Deep decarburization treatment: Remove the slag, control the slag thickness to <50mm, control the free space to ≥1200mm, and further remove C and N in the VOD process, control the C and N content to C≤0.012% and N≤0.012%, and control the pure boiling time to ≥15min;

[0016] (1.3) Slag reduction: Add 15~20kg of lime, 1.5~3.0kg of fluorite, and 5.0~7.0kg of aluminum shot to VOD per ton of molten steel. Reduce the slag at an ultimate vacuum of ≤0.5mbar for ≥12min. After slag reduction, the Al content should be controlled at 0.060%~0.100%.

[0017] (1.4) Slag adjustment and stirring: Half of the slag is removed in the LF process. 7~10 kg of lime and 0.5~1.5 kg of fluorite are added per ton of molten steel to readjust the slag. At the same time, 4~7 kg of ferroniobium is added per ton of molten steel. Then strong stirring, medium stirring, weak stirring and killing are carried out. The strong stirring time is controlled at ≥15 min, the weak stirring time is controlled at ≥20 min, and the killing time is controlled at ≥25 min. After slag adjustment and stirring, the Al content is controlled at 0.030%~0.070%.

[0018] Furthermore, in the above-mentioned method for preparing high corrosion-resistant decorative stainless steel cold-rolled sheet, in sub-step (1.1), dephosphorized molten iron, ferrochrome alloy, ferromolybdenum alloy and copper plate are added to an AOD or K-OBM-S furnace for smelting using a ladle that has previously produced 300 series stainless steel.

[0019] The high corrosion-resistant decorative stainless steel cold-rolled sheet provided by this invention is prepared by the above-described preparation method for high corrosion-resistant decorative stainless steel cold-rolled sheet. Its chemical composition by mass percentage is: C≤0.015%, N≤0.015%, Si: 0.15%~0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O≤0.0015%, with the balance being Fe and unavoidable impurities. Furthermore, the content of Cr, Mo, Ni, Cu, and Mn elements satisfies 28≤ wCr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34, Al and O element content meets 50≤ w Al × w O ×10 6 ≤80, of which w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O The numbers represent the mass percentage content of elements Cr, Mo, Ni, Cu, Mn, Al, and O, respectively. The thickness of the high corrosion-resistant decorative stainless steel cold-rolled plate is 0.3~1.2mm, the width is 1000~2000mm, and the surface type of the cold-rolled plate is BA surface.

[0020] Furthermore, the inclusion rating of the high corrosion-resistant decorative stainless steel cold-rolled sheet is better than A0.5, B0.5, C0.5 and D0.5 grades. The surface gloss of the high corrosion-resistant decorative stainless steel cold-rolled sheet is >1000GU. The high corrosion-resistant decorative stainless steel cold-rolled sheet undergoes a copper-accelerated acetic acid salt spray test at 50℃ with 50g / L NaCl and 0.26g / L CuCl2‧2H2O sprays, and no rust spots are observed within 72 hours.

[0021] In addition, the present invention also provides the application of the above-mentioned high corrosion-resistant decorative stainless steel cold-rolled sheet in home appliances, kitchen and bathroom appliances, automotive exteriors and architectural exterior decorative parts.

[0022] The high corrosion-resistant decorative stainless steel cold-rolled sheet of the present invention has the following advantages and beneficial effects:

[0023] This invention improves the corrosion resistance index of materials through rational component design and further enhances the purity of steel through process optimization. The resulting high corrosion-resistant decorative stainless steel cold-rolled sheet can guarantee high surface gloss while possessing extremely high purity and superior corrosion resistance, meeting a wider range of more demanding application environments and effectively expanding the application fields and scope of decorative stainless steel. Specifically, this invention promotes the formation of a dense Cr2O3 passivation film through the rational matching of Cr, Mo, and Nb as the main elements. It further enhances corrosion resistance through micro-alloying with Si, Cu, and Ni elements. By controlling the upper limit of Al content, the Al2O3 content on the surface of the passivation film of the cold-rolled plate is reduced, improving surface gloss. An optimized process of "aluminum deoxidation, double slag adjustment, extended stirring time, and protective continuous casting" is employed to improve purity and corrosion resistance. The resulting high-corrosion-resistant decorative stainless steel cold-rolled plate exhibits high surface gloss, extremely high purity, and excellent corrosion resistance, with an oxygen content ≤0.0015wt.%, an inclusion rating better than A0.5, B0.5, C0.5, and D0.5 grades, and a surface gloss >1000. GU, when subjected to accelerated acetic acid salt spray tests at 50℃ with 50 g / L NaCl and 0.26 g / L CuCl2‧2H2O, showed no rust spots within 72 hours, making it suitable for widespread application in kitchen and bathroom appliances, automotive exteriors, and architectural exterior decoration parts. Attached Figure Description

[0024] 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. In the drawings:

[0025] Figure 1 The image shows the XPS composition analysis results of the surface of the high corrosion-resistant decorative stainless steel cold plate prepared using Example 3 of the present invention.

[0026] Figure 2 The figure shows the XPS composition analysis results of the stainless steel cold plate surface prepared using existing technology in Comparative Example 2. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] In a first aspect of the invention, a highly corrosion-resistant decorative stainless steel is provided, the chemical composition of which, by mass percentage, is: C ≤ 0.015%, N ≤ 0.015%, Si: 0.15%~0.30%, Mn ≤ 0.15%, S ≤ 0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O ≤ 0.0015%, with the balance being Fe and unavoidable impurities, and the content of Cr, Mo, Ni, Cu, and Mn elements satisfies 28 ≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34, Al and O element content meets 50≤ w Al × w O ×10 6 ≤80, of which w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O These represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O, respectively.

[0029] In this invention, the composition system design for decorative stainless steel mainly includes: promoting the formation of a dense Cr2O3 passivation film by adding Cr, Mo, and Nb as main elements; further improving corrosion resistance by adding trace amounts of Si, Cu, and Ni elements; and reducing the Al2O3 content on the surface of the cold-rolled plate passivation film by controlling the upper limit of Al content, thereby reducing surface whitening and improving surface gloss. The resulting high corrosion-resistant decorative stainless steel exhibits high surface gloss, extremely high purity, and excellent corrosion resistance. The roles and content requirements of each element in the high corrosion-resistant decorative stainless steel of this invention are described below:

[0030] C and N: Carbon and nitrogen adversely affect the corrosion resistance, uniform corrosion resistance, pitting corrosion resistance, crevice corrosion resistance, and intergranular corrosion resistance of ferritic stainless steel. Ferritic stainless steel is extremely sensitive to intergranular corrosion. To avoid sensitized or post-weld intergranular corrosion, the upper limit of the allowable value of C+N should be strictly controlled, usually not exceeding 0.030%. In this invention, the C and N contents are both controlled to ≤0.015%, preferably ≤0.012%.

[0031] Si: Adding an appropriate amount of silicon to stainless steel can give it excellent resistance to high-temperature, high-concentration nitric acid, and sulfuric acid corrosion. This is related to the formation of a silicon-rich oxide protective film on the surface of the stainless steel. However, as the silicon content increases, the plasticity and toughness of the steel decrease, and its weldability deteriorates. Therefore, in this invention, the Si content is controlled at 0.15%~0.30%.

[0032] Mn: Manganese is a relatively weak austenite-forming element and acts as a deoxidizer in stainless steel. The manganese content in ferritic stainless steel is generally ≤1%. As the manganese content increases, the steel's resistance to pitting corrosion and crevice corrosion decreases. Therefore, in this invention, the Mn content is controlled to ≤0.15%.

[0033] S: Sulfur is a harmful element, and when it combines with manganese to form MnS, it often becomes a source of pitting and crevice corrosion. Therefore, in this invention, the S content is controlled to ≤0.002%.

[0034] Cr: Chromium not only increases corrosion resistance in oxidizing acid media, but also plays an important role in improving the resistance of stainless steel to stress corrosion, pitting corrosion, and crevice corrosion in chloride solutions. However, when the chromium content increases to above 20%, the ductility and toughness decrease, and the cold formability and weldability deteriorate. Therefore, in this invention, the Cr content is controlled at 16.0%~20.0%.

[0035] Ni: Nickel is the second most important alloying element in stainless steel after chromium. To resist corrosion from reducing acid and alkaline media, chromium alone is insufficient; nickel must be added. Nickel promotes the stability of the passivation film in stainless steel and improves its thermodynamic stability, but Ni alloys are relatively expensive. Therefore, in this invention, the Ni content is controlled at 0.10%~0.20%.

[0036] Al: Aluminum has been widely and successfully used as a deoxidizer in the production of ferritic stainless steel. An appropriate amount of aluminum can achieve deoxidation and lower the brittle transition temperature. Al can reduce the oxygen content in steel and decrease the number of non-metallic inclusions, thus improving the steel's corrosion resistance. However, Al is an easily oxidized element; excessive Al will form Al₂O₃ inclusions, which, when incorporated into the passivation film, will cause the surface to whiten. Therefore, in this invention, the Al content is controlled at 0.030%~0.070%.

[0037] Niobium (Nb) can stabilize C and N elements, improving the corrosion resistance of stainless steel in various forms. Nb increases the pitting potential in ultrapure ferritic stainless steel. Both dissolved Nb and Nb precipitates can refine the grain structure, thereby improving the wrinkle resistance of ferritic stainless steel. Therefore, in this invention, the Nb content is controlled at 0.40%~0.70%.

[0038] Mo: Molybdenum significantly promotes the enrichment of chromium in the passivation film, thereby enhancing the stability of the stainless steel passivation film and significantly strengthening the corrosion resistance of chromium in the steel, thus greatly improving the stainlessness and corrosion resistance of various stainless steels to various reducing acid media. Molybdenum is also beneficial in preventing stress corrosion originating from pitting corrosion. Therefore, in this invention, the Mo content is controlled at 1.5%~2.0%.

[0039] Cu: Copper can improve the rust resistance and corrosion resistance of stainless steel, especially in reducing media such as sulfuric acid. The effect is even better when copper is added to steel in combination with molybdenum. Copper can significantly reduce the strength and cold work hardening tendency of stainless steel, and improve its plasticity. Therefore, in this invention, the Cu content is controlled at 0.20%~0.40%.

[0040] O: Oxygen is an unavoidable impurity element in steel. Inclusions in steel are generally oxides. The oxygen content corresponds to the purity of the steel; reducing the oxygen content in steel is equivalent to increasing the purity of the steel. At the same time, considering that Al and Si are easily oxidized elements in steel and can easily form oxide inclusions, the O content is controlled to ≤0.0015% in this invention.

[0041] In a second aspect of the invention, a method for preparing a high corrosion-resistant decorative stainless steel cold-rolled sheet is provided, comprising smelting, continuous casting, grinding, hot rolling, multi-pass cold rolling, annealing, and leveling processes. An optimized process of "aluminum deoxidation, two slag adjustments, extended stirring time, and protection of continuous casting" is used to prepare the high corrosion-resistant decorative stainless steel cold-rolled sheet. The prepared high corrosion-resistant decorative stainless steel cold-rolled sheet has high purity and excellent corrosion resistance. Specifically, the method includes the following steps:

[0042] (1) Smelting: Using dephosphorized molten iron, ferrochrome alloy, ferromolybdenum alloy and copper plate as raw materials, smelting is carried out in AOD or K-OBM-S furnace, and smelting is carried out through VOD and LF processes. The chemical composition of the molten steel obtained by smelting is controlled by mass percentage as follows: C≤0.015%, N≤0.015%, Si: 0.15%~0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O≤0.0015%, with the balance being Fe and unavoidable impurities, and the content of Cr, Mo, Ni, Cu and Mn elements meets the requirement of 28≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34, Al and O element content meets 50≤ w Al × w O ×10 6 ≤80, of which w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O These represent the mass percentage content of elements Cr, Mo, Ni, Cu, Mn, Al, and O, respectively. The smelting process includes the following sub-steps:

[0043] (1.1) Batching and smelting: Dephosphorized molten iron, ferrochrome alloy, ferromolybdenum alloy and copper plate are added to AOD or K-OBM-S furnace for smelting to achieve preliminary decarburization and alloying of main elements. The target content of chemical composition is controlled as follows: C: 0.20%~0.30%, Si≤0.015%, Ni: 0.10%~0.20%, and the tapping temperature is controlled as ≥1650℃;

[0044] (1.2) Deep decarburization treatment: Remove the slag, control the slag thickness to <50mm, control the free space to ≥1200mm, and further remove C and N in the VOD process, control the C and N content to C≤0.012% and N≤0.012%, and control the pure boiling time to ≥15min;

[0045] (1.3) Slag reduction: Add 15~20kg of lime, 1.5~3.0kg of fluorite, and 5.0~7.0kg of aluminum shot to VOD per ton of molten steel. Reduce the slag at an ultimate vacuum of ≤0.5mbar for ≥12min. After slag reduction, the Al content should be controlled at 0.060%~0.100%.

[0046] (1.4) Slag adjustment and stirring: Half of the slag is removed in the LF process. 7~10 kg of lime and 0.5~1.5 kg of fluorite are added per ton of molten steel to readjust the slag. At the same time, 4~7 kg of ferroniobium is added per ton of molten steel. Then strong stirring, medium stirring, weak stirring and killing are carried out. The strong stirring time is controlled at ≥15 min, the weak stirring time is controlled at ≥20 min, and the killing time is controlled at ≥25 min. After slag adjustment and stirring, the Al content is controlled at 0.030%~0.070%.

[0047] (2) Protect the continuous casting: blow argon into the tundish for 5 minutes before casting. Use carbon-free tundish covering agent. Control the tundish temperature at 1540~1560℃ and the continuous casting speed at 0.70~1.00m / min.

[0048] (3) Grinding, hot rolling, multi-pass cold rolling, annealing and leveling: After grinding, hot rolling, multi-pass cold rolling, annealing and leveling, the continuous casting billet is produced into high corrosion resistant decorative stainless steel cold plate with a thickness of 0.3~1.2mm and a width of 1000~2000mm.

[0049] In the above-mentioned method for preparing high corrosion-resistant decorative stainless steel cold-rolled sheet, preferably, in sub-step (1.1), dephosphorized molten iron, ferrochrome alloy, ferromolybdenum alloy and copper plate are added to an AOD or K-OBM-S furnace for smelting using a ladle that has previously produced 300 series stainless steel.

[0050] In a third aspect of the present invention, a high corrosion-resistant decorative stainless steel cold-rolled sheet is provided. This high corrosion-resistant decorative stainless steel cold-rolled sheet is produced by the aforementioned method for preparing high corrosion-resistant decorative stainless steel cold-rolled sheets. Its chemical composition, by mass percentage, is: C ≤ 0.015%, N ≤ 0.015%, Si: 0.15%~0.30%, Mn ≤ 0.15%, S ≤ 0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O ≤ 0.0015%, with the balance being Fe and unavoidable impurities. Furthermore, the content of Cr, Mo, Ni, Cu, and Mn elements satisfies 28 ≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34, Al and O element content meets 50≤ w Al × w O ×10 6 ≤80, of which w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O The numbers represent the mass percentage content of elements Cr, Mo, Ni, Cu, Mn, Al, and O, respectively. The thickness of the high corrosion-resistant decorative stainless steel cold-rolled plate is 0.3~1.2mm, the width is 1000~2000mm, and the surface type of the cold-rolled plate is BA surface.

[0051] Actual testing showed that the inclusion rating of the above-mentioned high corrosion-resistant decorative stainless steel cold-rolled sheet was better than A0.5, B0.5, C0.5 and D0.5 grades. Moreover, the Al2O3 content in the passivation film on the surface of the high corrosion-resistant decorative stainless steel cold-rolled sheet was low, the surface gloss was >1000GU, and no rust spots were observed within 72 hours in a copper-accelerated acetic acid salt spray test at 50℃ with 50g / L NaCl and 0.26g / L CuCl2‧2H2O.

[0052] In a fourth aspect of the invention, the application of the above-mentioned high corrosion-resistant decorative stainless steel cold-rolled sheet in kitchen and bathroom appliances, automotive exteriors, and architectural exterior decorative parts is also provided.

[0053] The following describes in detail the high corrosion-resistant decorative stainless steel cold-rolled sheet of the present invention with reference to embodiments of the present invention and comparative examples of the prior art. Unless otherwise specified, the implementation methods in the following embodiments and comparative examples are carried out according to conventional methods and conditions, and the present invention does not impose specific limitations on them. The chemical compositions of the high corrosion-resistant decorative stainless steel cold-rolled sheets prepared using the preparation method of the high corrosion-resistant decorative stainless steel cold-rolled sheet of the present invention in Examples 1-3 and the stainless steel cold-rolled sheets prepared using the prior art in Comparative Examples 1-3 are shown in Table 1 below (balance is Fe and unavoidable impurity elements):

[0054] Table 1. Composition (wt.%) of stainless steel cold-rolled sheets from Examples 1-3 and Comparative Examples 1-3

[0055]

[0056] In embodiments 1-3 of this invention, the elemental contents of Cr, Mo, Ni, Cu, Mn, Al, and O satisfy the following condition: 28 ≤ w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn ≤34 and 50≤ w Al × w O ×10 6 ≤80; in comparative examples 1-3, w Cr +4.7× w Mo +3.6× w Ni +11.5× w Cu -1.42× w Mn <28, in Comparative Examples 1 and 2, w Al × w O ×10 6 >110, in Comparative Example 3 w Al × w O ×10 6 <40.

[0057] The main process parameters for the preparation methods of high corrosion-resistant decorative stainless steel cold-rolled sheets in Examples 1-3 of this invention are shown in Table 2 below:

[0058] Table 2 Main process parameters of Examples 1-3

[0059]

[0060] Analysis and performance testing were conducted on the high corrosion-resistant decorative stainless steel cold-rolled sheets prepared using Examples 1-3 of this invention and the stainless steel cold-rolled sheets prepared using existing technologies in Comparative Examples 1-3. The analysis and performance testing standards and methods are as follows: X-ray photoelectron spectroscopy (XPS) was used to compare and analyze the chemical composition of the passivation film on the surface of the cold-rolled sheets. The oxygen content T[O] was measured according to GB / T 11261-2006 "Determination of Oxygen Content in Steel - Pulse Heating Inert Gas-Melting Infrared Absorption Method". The inclusions were rated into four categories (A, B, C, and D) according to GB / T 10561-2023 "Determination of Non-metallic Inclusion Content in Steel - Standard Rating Chart Microscopic Examination Method". The copper-accelerated acetic acid salt spray test was performed according to ISO 9227:2022 "Corrosion Tests in Man-Made Environments - Salt Spray Test".

[0061] XPS composition analysis results of the surface of the high corrosion-resistant decorative stainless steel cold-rolled sheet prepared using Example 3 of the present invention are shown below. Figure 1 The XPS composition analysis results of the stainless steel cold-rolled plate surface prepared using existing technology are shown in [reference]. Figure 2 The performance test results are summarized in Table 3 below.

[0062] Table 3. Performance test results of stainless steel cold-rolled plates prepared in Examples 1-3 and Comparative Examples 1-3

[0063]

[0064] As can be seen from Table 3, in terms of oxygen content, Examples 1-3 of the present invention and Comparative Examples 1-2 of the prior art are comparable, while Comparative Example 3 of the prior art has an extremely high oxygen content; in terms of inclusion rating, Examples 1-3 of the present invention and Comparative Examples 1-2 of the prior art are comparable, with good purity, but Comparative Example 3 of the prior art has a higher inclusion rating and poorer purity; in terms of surface gloss, Examples 1-3 of the present invention and Comparative Example 3 of the prior art have good surface gloss, both exceeding 1000 GU, while Comparative Examples 1-2 of the prior art are poor, with a maximum of 970 GU; in terms of corrosion resistance, Examples 1-3 of the present invention have excellent corrosion resistance, with no rust spots within 72 hours of copper accelerated acetic acid salt spray test, while Comparative Examples 1-3 of the prior art have poor corrosion resistance, even showing a large number of rust spots within 24 hours.

[0065] In addition, such as Figure 1 and 2As shown, for the sample with an Al content of 0.056% in Example 3 of the present invention, the surface Al atomic percentage is 18.2%, while for the sample with an Al content of 0.113% in Comparative Example 2 of the prior art, the surface Al atomic percentage is 37.5%. The surface with high Al content is white, which seriously affects the surface gloss. Therefore, the gloss of Comparative Example 2 is only 910 GU.

[0066] In summary, compared with the prior art, the technical solution of the present invention has the following advantages and beneficial effects:

[0067] This invention improves the corrosion resistance index of materials through rational component design and further enhances the purity of steel through process optimization. The resulting high corrosion-resistant decorative stainless steel cold-rolled sheet can guarantee high surface gloss while possessing extremely high purity and superior corrosion resistance, meeting a wider range of more demanding application environments and effectively expanding the application fields and scope of decorative stainless steel. Specifically, this invention promotes the formation of a dense Cr2O3 passivation film through the rational matching of Cr, Mo, and Nb as the main elements. It further enhances corrosion resistance through micro-alloying with Si, Cu, and Ni elements. By controlling the upper limit of Al content, the Al2O3 content on the surface of the passivation film of the cold-rolled plate is reduced, improving surface gloss. An optimized process of "aluminum deoxidation, double slag adjustment, extended stirring time, and protective continuous casting" is employed to improve purity and corrosion resistance. The resulting high-corrosion-resistant decorative stainless steel cold-rolled plate exhibits high surface gloss, extremely high purity, and excellent corrosion resistance, with an oxygen content ≤0.0015wt.%, an inclusion rating better than A0.5, B0.5, C0.5, and D0.5 grades, and a surface gloss >1000. GU, when subjected to accelerated acetic acid salt spray tests at 50℃ with 50 g / L NaCl and 0.26 g / L CuCl2‧2H2O, showed no rust spots within 72 hours, making it suitable for widespread application in kitchen and bathroom appliances, automotive exteriors, and architectural exterior decoration parts.

[0068] It should be noted that, except for those explicitly described herein, the process methods of the present invention can be implemented using conventional methods or apparatus in the art. Unless otherwise specified, the terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, when a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple range descriptive features are provided, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0069] It should also be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0070] Furthermore, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A high corrosion-resistant decorative stainless steel cold-rolled sheet, characterized in that, The high-corrosion-resistant decorative stainless steel cold plate is prepared by a preparation method of the high-corrosion-resistant decorative stainless steel cold plate, and the preparation method comprises the following steps: (1) smelting: taking dephosphorized molten iron, chromium iron alloy, molybdenum iron alloy and copper plate as raw materials, smelting is carried out in AOD or K-OBM-S furnace, and smelting is carried out through VOD, LF process, the chemical composition of the molten steel prepared by smelting is controlled as follows in percentage by mass: C≤0.015%, N≤0.015%, Si: 0.15%~0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%~20.0%, Ni: 0.10%~0.20%, Al: 0.030%~0.070%, Nb: 0.40%~0.70%, Mo: 1.5%~2.0%, Cu: 0.20%~0.40%, O≤0.0015%, the balance is Fe and inevitable impurities, and the element content of Cr, Mo, Ni, Cu and Mn satisfies 28≤w Cr +4.7×w Mo +3.6×w Ni +11.5×w Cu -1.42×w Mn ≤34, the element content of Al and O satisfies 50≤w Al ×w O ×10 6 ≤80, wherein w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O respectively represent the mass percentage content of elements Cr, Mo, Ni, Cu, Mn, Al and O. The smelting step comprises the following sub-steps: (1.1) ingredient smelting: the dephosphorized molten iron, chromium-iron alloy, molybdenum-iron alloy and copper plate are added into an AOD or K-OBM-S furnace for smelting to realize preliminary decarburization and main element alloying, the chemical component target content is controlled to be C: 0.20%-0.30%, Si≤0.015%, Ni: 0.10%-0.20%, and the tapping temperature is controlled to be ≥1650℃; (1.2) deep decarburization treatment: the slag is removed, the slag thickness is controlled to be <50mm, the free space is controlled to be ≥1200mm, and the C and N contents are controlled to be C≤0.012%, N≤0.012% by further removing C and N in the VOD process, and the pure boiling time is controlled to be ≥15min; (1.3) slag preparation reduction: 15-20kg of lime, 1.5-3.0kg of fluorite and 5.0-7.0kg of aluminum pellets are added into the VOD per ton of molten steel, the reduction is carried out under the limit vacuum degree of ≤0.5mbar, the reduction time is controlled to be ≥12min, and the Al content is controlled to be 0.060%-0.100% after the slag preparation reduction; (1.4) slag adjustment stirring: half of the slag is removed in the LF process, 7-10kg of lime and 0.5-1.5kg of fluorite are added into the slag per ton of molten steel, the slag is adjusted again, 4-7kg of niobium-iron is added into the slag per ton of molten steel, then strong stirring, medium stirring, weak stirring and setting are carried out, the strong stirring time is controlled to be ≥15min, the weak stirring time is controlled to be ≥20min, the setting time is controlled to be ≥25min, and the Al content is controlled to be 0.030%-0.070% after the slag adjustment stirring (2) protective continuous casting: the pouring is started after argon blowing in the tundish for 5min, the carbon-free tundish covering agent is used, the tundish temperature is controlled to be 1540-1560℃, and the continuous casting speed is controlled to be 0.70-1.00m / min; (3) grinding, hot rolling, multi-pass cold rolling, annealing and flattening: the continuous casting billet is ground, hot rolled, multi-pass cold rolled, annealed and flattened to produce the high-corrosion-resistant decorative stainless steel cold plate; The oxygen content of the high-corrosion-resistant decorative stainless steel cold plate is ≤0.0015wt.%, and the inclusion rating is better than A0.5, B0.5, C0.5 and D0.5; The chemical composition of the high corrosion-resistant stainless steel cold plate for decoration, by mass percent, is: C≤0.015%, N≤0.015%, Si: 0.15%-0.30%, Mn≤0.15%, S≤0.002%, Cr: 16.0%-20.0%, Ni: 0.10%-0.20%, Al: 0.030%-0.070%, Nb: 0.40%-0.70%, Mo: 1.5%-2.0%, Cu: 0.20%-0.40%, O≤0.0015%, the balance being Fe and unavoidable impurities, and the content of Cr, Mo, Ni, Cu and Mn satisfies 28≤w Cr +4.7×w Mo +3.6×w Ni +11.5×w Cu -1.42×w Mn ≤34, the content of Al and O satisfies 50≤w Al ×w O ×10 6 ≤80, wherein w Cr , w Mo , w Ni , w Cu , w Mn , w Al , w O respectively represent the mass percent content of elements Cr, Mo, Ni, Cu, Mn, Al and O, the thickness of the high corrosion-resistant stainless steel cold plate for decoration is 0.3-1.2 mm, the width is 1000-2000 mm, and the surface type of the cold plate is BA surface.

2. The high corrosion-resistant stainless steel cold plate for decoration according to claim 1, characterized by The C and N contents of the high-corrosion-resistant decorative stainless steel cold plate are controlled to be C≤0.012%, N≤0.012%.

3. The high corrosion-resistant stainless steel cold plate for decoration according to claim 1, characterized by In the sub-step (1.1), the dephosphorized molten iron, chromium-iron alloy, molybdenum-iron alloy and copper plate are added into the AOD or K-OBM-S furnace for smelting by using the ladle used for producing the 300 series stainless steel in the last furnace 4. Application of the high-corrosion-resistant decorative stainless steel cold plate in claim 1 in parts for decoration of household appliances, kitchens and bathrooms, automobile appearance and building appearance.

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