High-corrosion-resistance decorative stainless steel cold plate as well as preparation method and application thereof

Abstract

The high-corrosion-resistance stainless steel cold plate for decoration comprises the following chemical components: less than or equal to 0.015% of C, less than or equal to 0.015% of N, 0.15%-0.30% of Si, less than or equal to 0.15% of Mn, less than or equal to 0.002% of S, 16.0%-20.0% of Cr, 0.10%-0.20% of Ni, 0.030%-0.070% of Al, 0.40%-0.70% of Nb, 1.5%-2.0% of Mo, 0.20%-0.40% of Cu, less than or equal to 0.0015% of O and the balance of Fe and inevitable impurities, wCr + 4.7 * wMo + 3.6 * wNi + 11.5 * wCu-1. 42 * wMn is more than or equal to 28 and less than or equal to 34, and wAl * wO * 106 The preparation method of the high-corrosion-resistance decorative stainless steel comprises the working procedures of smelting, continuous casting, coping, hot rolling, multi-pass cold rolling, annealing and flattening. On the premise of ensuring high surface glossiness of the material, the stainless steel has extremely high purity and more excellent corrosion resistance, a wider and harsh application environment is met, and the application field and range of the stainless steel for decoration are effectively expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of stainless steel production, and in particular relates to a decorative stainless steel cold plate with high purity, high corrosion resistance and high gloss, and a preparation method and application thereof. Background Art

[0002] With the development of the national economy, the decoration industry has developed rapidly. The decoration materials currently used 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 bright surface. Stainless steel has good corrosion resistance, which makes it a decorative material with the characteristics of ensuring stable surface color and extending life, and it is increasingly favored in the decoration field.

[0003] At present, the main grades of decorative stainless steel are SUS304, SUS430, SUS430J1L, SUS430LX and SUS436L. Among them, SUS304 contains nickel, has high cost and large price fluctuations, and SUS430 has a high carbon content and poor 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, the consumption of automobiles, home appliances, construction and decoration has been upgraded, and the competition in various industries has become increasingly fierce. People have higher and higher requirements for the surface gloss, corrosion resistance and life of decorative stainless steel, and the existing materials are not competitive. In addition, decorative stainless steel is widely used in more and more scenes, including marine atmosphere, kitchen fumes, disinfectants, etc., requiring stainless steel to have more comprehensive corrosion resistance.

[0005] To this end, it is necessary to develop a higher grade ultra-pure ferritic stainless steel for use in high corrosion-resistant decorative fields, to improve its comprehensive corrosion resistance while ensuring high surface gloss, and to meet a wider and more demanding application environment. Summary of the invention

[0006] In view of the above technical problems in the prior art, the present invention provides a high corrosion-resistant decorative stainless steel cold plate and a preparation method thereof, which improves the purity and comprehensive corrosion resistance of decorative stainless steel while ensuring high surface gloss, meets a wider and more demanding application environment, and expands the application field of decorative stainless steel.

[0007] The chemical composition of the high corrosion-resistant decorative stainless steel provided by the present invention is as follows by mass percentage: 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 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 × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O They represent the mass percentage contents of elements Cr, Mo, Ni, Cu, Mn, Al and O respectively.

[0008] Preferably, the C and N contents in the highly corrosion-resistant decorative stainless steel are controlled to be C≤0.012% and N≤0.012%.

[0009] The method for preparing a high corrosion-resistant decorative stainless steel cold plate provided by the present invention comprises the following steps:

[0010] (1) Smelting: Dephosphorized molten iron, ferrochrome, ferromolybdenum and copper plates are used as raw materials, and smelted in an AOD or K-OBM-S furnace, and smelted 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%, and the balance is 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×wCu -1.42×w Mn ≤34, Al and O element content meets 50≤w Al × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O Respectively represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O;

[0011] (2) Protected continuous casting: After blowing argon in the tundish for 5 minutes, pouring begins. A carbon-free tundish covering agent is used. The tundish temperature is controlled at 1540-1560°C, and the continuous casting speed is controlled at 0.70-1.00 m / min.

[0012] (3) Grinding, hot rolling, multi-pass cold rolling, annealing and smoothing: The continuous casting ingot is produced into high corrosion-resistant decorative stainless steel cold plate after grinding, hot rolling, multi-pass cold rolling, annealing and smoothing.

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

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

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

[0016] (1.3) Slag reduction: add 15-20 kg of lime, 1.5-3.0 kg of fluorite and 5.0-7.0 kg of aluminum shot per ton of molten steel in VOD, and carry out reduction under the ultimate vacuum degree of ≤0.5 mbar. The reduction time is controlled to be ≥12 min. After slag reduction, the Al content is controlled to be 0.060%-0.100%;

[0017] (1.4) Slag adjustment and stirring: In the LF process, half of the slag is scraped off, and 7-10 kg of lime and 0.5-1.5 kg of fluorite are added per ton of molten steel to adjust the slag again. At the same time, 4-7 kg of ferroniobium is added per ton of molten steel, and then strong stirring, medium stirring, weak stirring and calming are carried out. Among them, the strong stirring time is controlled to be ≥15 min, the weak stirring time is controlled to be ≥20 min, and the calming time is controlled to be ≥25 min. After slag adjustment and stirring, the Al content is controlled to be 0.030% to 0.070%.

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

[0019] The high corrosion resistant decorative stainless steel cold plate provided by the present invention is prepared by the preparation method of the high corrosion resistant decorative stainless steel cold plate, and its chemical composition is as follows by mass percentage: 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 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 × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O They respectively represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O. The thickness of the highly corrosion-resistant decorative stainless steel cold plate is 0.3-1.2 mm, the width is 1000-2000 mm, and the surface type of the cold plate is BA surface.

[0020] Furthermore, the inclusion rating of the high corrosion resistant decorative stainless steel cold plate is better than that of A0.5, B0.5, C0.5 and D0.5, the surface glossiness of the high corrosion resistant decorative stainless steel cold plate is greater than 1000GU, and the high corrosion resistant decorative stainless steel cold plate is subjected to a copper accelerated acetic acid salt spray test at 50°C, 50g / L NaCl and 0.26g / L CuCl2·2H2O spray, and no rust spots are observed within 72 hours.

[0021] In addition, the present invention also provides the use of the above-mentioned high corrosion-resistant decorative stainless steel cold plate in decorative parts for household appliances, kitchen and bathroom, automobile exterior and building exterior.

[0022] The high corrosion-resistant decorative stainless steel cold plate and the preparation method thereof of the present invention have the following advantages and beneficial effects:

[0023] The present invention improves the corrosion resistance index of the material through reasonable component design, and further improves the purity of the steel through process optimization measures. The high-corrosion-resistant decorative stainless steel cold plate and its preparation method can ensure the high surface gloss of the material while having extremely high purity and more excellent corrosion resistance, meet a wider and more demanding application environment, and effectively expand the application field and scope of decorative stainless steel. Specifically, the present invention promotes the formation of a dense Cr2O3 passivation film through reasonable matching of the main elements of Cr, Mo and Nb, further improves the corrosion resistance through micro-alloying of Si, Cu and Ni elements, reduces the Al2O3 content on the surface of the cold plate passivation film by controlling the upper limit content of the Al element, and improves the surface gloss. The optimized process of "aluminum deoxidation, two slag adjustments, extended stirring time and protective continuous casting" is adopted to improve purity and corrosion resistance. The high-corrosion-resistant decorative stainless steel cold plate obtained thereby has a high Surface gloss, extremely high purity and excellent corrosion resistance, oxygen content ≤ 0.0015wt.%, inclusion rating better than A0.5, B0.5, C0.5 and D0.5, surface gloss> 1000GU, copper accelerated acetic acid salt spray test at 50℃, 50g / L NaCl and 0.26g / L CuCl2·2H2O spray, no rust spots were observed within 72h, and it can be widely used in home appliances, kitchen and bathroom, automobile exterior and architectural exterior decoration parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0025] Figure 1This is a graph showing the XPS composition analysis results of the surface of a high corrosion-resistant decorative stainless steel cold plate prepared by Example 3 of the present invention;

[0026] Figure 2 This is a graph showing the XPS composition analysis results of the surface of a stainless steel cold plate prepared using comparative example 2 of the prior art. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] In a first aspect of the present invention, a highly corrosion-resistant decorative stainless steel is provided, wherein the chemical composition of the highly corrosion-resistant decorative stainless steel is, 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%, the remainder 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 × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O They represent the mass percentage contents of elements Cr, Mo, Ni, Cu, Mn, Al and O respectively.

[0029] In the present invention, the composition system design for decorative stainless steel mainly includes: promoting the formation of dense Cr2O3 passivation film by composite addition of Cr, Mo and Nb main elements, further improving corrosion resistance by adding trace Si, Cu and Ni elements, and reducing the Al2O3 content on the surface of the cold plate passivation film by controlling the upper limit content of the Al element, reducing the surface whitening phenomenon, and improving the surface gloss. The highly corrosion-resistant decorative stainless steel thus obtained has high surface gloss, extremely high purity and excellent corrosion resistance. Among them, the role of each element in the highly corrosion-resistant decorative stainless steel of the present invention and its content requirements are introduced as follows:

[0030] C, N: Carbon and nitrogen have adverse effects on the corrosion resistance, uniform corrosion resistance, pitting resistance, crevice corrosion resistance and intergranular corrosion resistance of ferritic stainless steel. Ferritic stainless steel is extremely sensitive to intergranular corrosion. To avoid intergranular corrosion in the sensitized state or after welding, the upper limit of the allowable value of C+N should be strictly controlled, usually not exceeding 0.030%. In the present invention, the contents of C and N are both controlled to ≤0.015%, preferably ≤0.012%.

[0031] Si: Adding an appropriate amount of silicon to stainless steel can make it have excellent resistance to high temperature, high concentration nitric acid and sulfuric acid corrosion. This is related to the silicon-rich oxide protective film formed on the surface of the stainless steel. As the silicon content increases, the plasticity and toughness of the steel decrease, and the weldability is poor. Therefore, in the present invention, the Si content is controlled to 0.15% to 0.30%.

[0032] Mn: Manganese is a weak austenite-forming element. It is a deoxidizer in stainless steel. The manganese content in ferritic stainless steel is generally ≤1%. As the manganese content increases, the pitting corrosion resistance and crevice corrosion resistance of the steel decrease. Therefore, in the present invention, the Mn content is controlled to ≤0.15%.

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

[0034] Cr: Chromium not only increases the corrosion resistance in oxidizing acid media, but also plays an important role in improving the ability of stainless steel to resist local corrosion such as stress corrosion, pitting corrosion, crevice corrosion, etc. in chloride solutions. However, when the chromium content increases to more than 20%, the plastic toughness decreases, and the cold formability and weldability deteriorate. Therefore, in the present invention, the Cr content is controlled to 16.0% to 20.0%.

[0035] Ni: Nickel is an important alloying element in stainless steel after chromium. In order to resist corrosion in reducing acid and alkaline media, it is not enough for steel to contain only chromium, and nickel must be added to the steel. Nickel can promote the stability of the stainless steel passivation film and improve the thermodynamic stability of stainless steel, but the cost of Ni alloy is relatively high. Therefore, in the present invention, the Ni content is controlled to 0.10% to 0.20%.

[0036] Al: Aluminum is widely and successfully used as a deoxidizer in the production of ferritic stainless steel. An appropriate amount of aluminum can achieve the deoxidation effect and reduce the brittle transition temperature. Al can reduce the oxygen content in steel and the number of non-metallic inclusions in steel, so the corrosion resistance of steel is improved. However, Al is an easily oxidized element. Excessive Al will form Al2O3 inclusions, and entering the passivation film will make the surface white. Therefore, in the present invention, the Al content is controlled to 0.030% to 0.070%.

[0037] Nb: Niobium can stabilize C and N elements and improve the corrosion resistance of various forms of stainless steel. Nb increases the pitting potential in ultrapure ferritic stainless steel. Both solid solution Nb and Nb precipitate can refine the grain structure, thereby improving the wrinkle resistance of ferritic stainless steel. Therefore, in the present invention, the Nb content is controlled to 0.40% to 0.70%.

[0038] Mo: Mo can significantly promote 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, thereby greatly improving the stainlessness and corrosion resistance of various stainless steels to various reducing acid media. Molybdenum is also beneficial for preventing stress corrosion originating from pitting corrosion. Therefore, in the present invention, the Mo content is controlled to 1.5% to 2.0%.

[0039] Cu: Copper can improve the stainlessness and corrosion resistance of stainless steel, especially in reducing media such as sulfuric acid. When copper and molybdenum are added to steel, the effect is better. Copper can significantly reduce the strength and cold work hardening tendency of stainless steel and improve the plasticity of steel. Therefore, in the present invention, the Cu content is controlled to 0.20% to 0.40%.

[0040] O: Oxygen is an inevitable 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 the steel is equivalent to improving the purity of the steel. At the same time, considering the presence of easily oxidizable elements such as Al and Si in the steel, oxide inclusions are easily formed. Therefore, in the present invention, the O content is controlled to ≤0.0015%.

[0041] In the second aspect of the present invention, a method for preparing a high corrosion resistant decorative stainless steel cold plate is provided, comprising smelting, continuous casting, grinding, hot rolling, multi-pass cold rolling, annealing and leveling processes, and adopting an optimized process of "aluminum deoxidation, two slag adjustment, extended stirring time and protective continuous casting" to prepare a high corrosion resistant decorative stainless steel cold plate. The prepared high corrosion resistant decorative stainless steel cold plate has high purity and excellent corrosion resistance, and specifically comprises the following steps:

[0042] (1) Smelting: Dephosphorized molten iron, ferrochrome, ferromolybdenum and copper plates are used as raw materials, and smelted in an AOD or K-OBM-S furnace, and smelted 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%, and the balance is 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, Al and O element content meets 50≤w Al × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O Respectively represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O, wherein the smelting step includes the following sub-steps:

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

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

[0045] (1.3) Slag reduction: add 15-20 kg of lime, 1.5-3.0 kg of fluorite and 5.0-7.0 kg of aluminum shot per ton of molten steel in VOD, and carry out reduction under the ultimate vacuum degree of ≤0.5 mbar. The reduction time is controlled to be ≥12 min. After slag reduction, the Al content is controlled to be 0.060%-0.100%;

[0046] (1.4) Slag adjustment and stirring: In the LF process, half of the slag is scraped off, and 7-10 kg of lime and 0.5-1.5 kg of fluorite are added per ton of molten steel to adjust the slag again. At the same time, 4-7 kg of ferroniobium is added per ton of molten steel, and then strong stirring, medium stirring, weak stirring and calming are carried out. Among them, the strong stirring time is controlled to be ≥15 min, the weak stirring time is controlled to be ≥20 min, and the calming time is controlled to be ≥25 min. After slag adjustment and stirring, the Al content is controlled to be 0.030% to 0.070%.

[0047] (2) Protective continuous casting: After blowing argon in the tundish for 5 minutes, pouring begins. A carbon-free tundish covering agent is used. The tundish temperature is controlled at 1540-1560°C and the continuous casting speed is controlled at 0.70-1.00 m / min.

[0048] (3) Grinding, hot rolling, multi-pass cold rolling, annealing and smoothing: The continuous casting ingot is produced into a high corrosion-resistant decorative stainless steel cold plate after grinding, hot rolling, multi-pass cold rolling, annealing and smoothing. The cold plate has a thickness of 0.3-1.2 mm and a width of 1000-2000 mm.

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

[0050] In a third aspect of the present invention, a high corrosion resistant decorative stainless steel cold plate is provided. The high corrosion resistant decorative stainless steel cold plate is produced by the above-mentioned preparation method of the high corrosion resistant decorative stainless steel cold plate, and its chemical composition is as follows by mass percentage: 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 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 × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O They respectively represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O. The thickness of the highly corrosion-resistant decorative stainless steel cold plate is 0.3-1.2 mm, the width is 1000-2000 mm, and the surface type of the cold plate is BA surface.

[0051] After actual testing, the inclusion rating of the high corrosion resistant decorative stainless steel cold plate is better than that of A0.5, B0.5, C0.5 and D0.5. Moreover, the Al2O3 content in the surface passivation film of the high corrosion resistant decorative stainless steel cold plate is low, the surface glossiness is greater than 1000GU, and a copper accelerated acetic acid salt spray test is carried out at 50°C, 50g / L NaCl and 0.26g / L CuCl2·2H2O spray. No rust spots can be observed within 72 hours.

[0052] In a fourth aspect of the present invention, there is also provided the use of the above-mentioned high corrosion resistant decorative stainless steel cold plate in decorative parts for household appliances, kitchen and bathroom appliances, automobile exteriors, and building exteriors.

[0053] The following is a detailed description of the high corrosion resistant decorative stainless steel cold plate and its preparation method of the present invention in combination with the embodiments of the present invention and the comparative examples of the prior art. The implementation methods of the following embodiments and comparative examples without specifying specific conditions are carried out according to conventional methods and conditions, and the present invention does not make specific limitations on this. The chemical composition of the high corrosion resistant decorative stainless steel cold plate produced by the high corrosion resistant decorative stainless steel cold plate preparation method of Examples 1-3 of the present invention and the stainless steel cold plate prepared by the prior art comparative examples 1-3 are shown in Table 1 below (the balance is Fe and unavoidable impurity elements):

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

[0055]

[0056] In Examples 1-3 of the present invention, the element contents of Cr, Mo, Ni, Cu, Mn, Al, and O satisfy the following conditions: 28≤w Cr +4.7×w Mo +3.6×w Ni +11.5×w Cu -1.42×w Mn ≤34 and 50≤w Al × 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 × O ×10 6 >110, in comparative example 3, w Al × O ×10 6 <40.

[0057] The main process parameters of the preparation method of the high corrosion resistant decorative stainless steel cold plate of Examples 1-3 of the present invention are shown in Table 2 below:

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

[0059]

[0060] Analysis, detection and performance testing were performed on the high corrosion-resistant decorative stainless steel cold plates prepared by using Examples 1-3 of the present invention and the stainless steel cold plates prepared by using Comparative Examples 1-3 of the prior art, wherein the analysis, detection 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 plate, and the oxygen content T[O] was measured according to GB / T11261-2006 "Determination of oxygen content of steel - pulse heating inert gas-melting infrared absorption method", and the four types of inclusions A, B, C, and D were rated according to GB / T 10561-2023 "Standard rating chart microscopic inspection method for determination of non-metallic inclusion content in steel", and the copper accelerated acetic acid salt spray test was performed according to ISO 9227:2022 "Corrosion test salt spray test in artificial environment".

[0061] The XPS composition analysis results of the surface of the high corrosion resistant decorative stainless steel cold plate prepared by Example 3 of the present invention are shown in Figure 1 The XPS composition analysis results of the stainless steel cold plate surface prepared by the prior art comparative example 2 are shown in Figure 2 ,The performance test results are summarized in Table 3 below.

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

[0063]

[0064] It can be seen from Table 3 that, in terms of oxygen content, Examples 1-3 of the present invention and Comparative Examples 1-2 of the prior art are equivalent, while the oxygen content of Comparative Example 3 of the prior art is extremely high; in terms of inclusion rating, Examples 1-3 of the present invention and Comparative Examples 1-2 of the prior art are equivalent, and the purity is good, but the inclusion rating of Comparative Example 3 of the prior art is high, and the purity is poor; 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 higher than 1000GU, while Comparative Example 1-2 of the prior art is poor, with a maximum of 970GU; in terms of corrosion resistance, Examples 1-3 of the present invention have excellent corrosion resistance, and there is no rust spot within 72 hours after the copper accelerated acetic acid salt spray test, while Comparative Examples 1-3 of the prior art have poor corrosion resistance, and even a large number of rust spots appear within 24 hours.

[0065] In addition, if Figure 1 and 2 As 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 the sample with an Al content of 0.113% in the prior art comparative example 2 has a surface Al atomic percentage of 37.5%. The surface with a high Al content is white, which seriously affects the surface gloss. Therefore, the glossiness of comparative example 2 is only 910GU.

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

[0067] The present invention improves the corrosion resistance index of the material through reasonable component design, and further improves the purity of the steel through process optimization measures. The high-corrosion-resistant decorative stainless steel cold plate and its preparation method can ensure the high surface gloss of the material while having extremely high purity and more excellent corrosion resistance, meet a wider and more demanding application environment, and effectively expand the application field and scope of decorative stainless steel. Specifically, the present invention promotes the formation of a dense Cr2O3 passivation film through reasonable matching of the main elements of Cr, Mo and Nb, further improves the corrosion resistance through micro-alloying of Si, Cu and Ni elements, reduces the Al2O3 content on the surface of the cold plate passivation film by controlling the upper limit content of the Al element, and improves the surface gloss. The optimized process of "aluminum deoxidation, two slag adjustments, extended stirring time and protective continuous casting" is adopted to improve purity and corrosion resistance. The high-corrosion-resistant decorative stainless steel cold plate obtained thereby has a high Surface gloss, extremely high purity and excellent corrosion resistance, oxygen content ≤ 0.0015wt.%, inclusion rating better than A0.5, B0.5, C0.5 and D0.5, surface gloss> 1000GU, copper accelerated acetic acid salt spray test at 50℃, 50g / L NaCl and 0.26g / L CuCl2·2H2O spray, no rust spots were observed within 72h, and it can be widely used in home appliances, kitchen and bathroom, automobile exterior and architectural exterior decoration parts.

[0068] It should be noted that, in addition to the explicit description herein, the process method of the present invention can be implemented by conventional methods or devices in the art, and the noun terms in this article, unless otherwise specified, have the meanings generally understood by those skilled in the art. Moreover, when a numerical range is disclosed herein, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, and each value between such minimum and maximum values. Further, when the range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple range description features are provided, the range can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges included therein.

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

[0070] In addition, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the present invention.

Claims

1. A highly corrosion-resistant decorative stainless steel, characterized in that: The chemical composition of the highly corrosion-resistant decorative stainless steel is as follows by mass percentage: 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 remainder is 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 × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O They represent the mass percentage contents of elements Cr, Mo, Ni, Cu, Mn, Al and O respectively.

2. The highly corrosion-resistant decorative stainless steel according to claim 1, characterized in that: The contents of C and N in the highly corrosion-resistant decorative stainless steel are controlled to be C≤0.012% and N≤0.012%.

3. A method for preparing a highly corrosion-resistant decorative stainless steel cold plate, characterized in that: The steps include: (1) Smelting: Dephosphorized molten iron, ferrochrome, ferromolybdenum and copper plates are used as raw materials, and smelted in an AOD or K-OBM-S furnace, and smelted 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%, and the balance is 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, Al and O element content meets 50≤w Al × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O Respectively represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O; (2) Protected continuous casting: After blowing argon in the tundish for 5 minutes, pouring begins. A carbon-free tundish covering agent is used. The tundish temperature is controlled at 1540-1560°C, and the continuous casting speed is controlled at 0.70-1.00 m / min. (3) Grinding, hot rolling, multi-pass cold rolling, annealing and smoothing: The continuous casting ingot is produced into high corrosion-resistant decorative stainless steel cold plate after grinding, hot rolling, multi-pass cold rolling, annealing and smoothing.

4. The method for preparing a highly corrosion-resistant decorative stainless steel cold plate according to claim 3, characterized in that: The smelting step includes the following sub-steps: (1.1) Batching and smelting: Add dephosphorized molten iron, ferrochrome, ferromolybdenum and copper plate into AOD or K-OBM-S furnace for smelting to achieve preliminary decarburization and main element alloying. The target chemical composition content is controlled as follows: C: 0.20% to 0.30%, Si ≤ 0.015%, Ni: 0.10% to 0.20%, and the tapping temperature is controlled to be ≥ 1650°C; (1.2) Deep decarburization treatment: remove the slag, control the slag thickness to <50mm, control the free space to ≥1200mm, and further remove carbon and nitrogen in the VOD process, control the C and N content to C≤0.012%, N≤0.012%, and control the pure boiling time to ≥15min; (1.3) Slag reduction: add 15-20 kg of lime, 1.5-3.0 kg of fluorite and 5.0-7.0 kg of aluminum shot per ton of molten steel in VOD, and carry out reduction under the ultimate vacuum degree of ≤0.5 mbar. The reduction time is controlled to be ≥12 min. After slag reduction, the Al content is controlled to be 0.060%-0.100%; (1.4) Slag adjustment and stirring: In the LF process, half of the slag is scraped off, and 7-10 kg of lime and 0.5-1.5 kg of fluorite are added per ton of molten steel to adjust the slag again. At the same time, 4-7 kg of ferroniobium is added per ton of molten steel, and then strong stirring, medium stirring, weak stirring and calming are carried out. Among them, the strong stirring time is controlled to be ≥15 min, the weak stirring time is controlled to be ≥20 min, and the calming time is controlled to be ≥25 min. After slag adjustment and stirring, the Al content is controlled to be 0.030% to 0.070%.

5. The method for preparing a highly corrosion-resistant decorative stainless steel cold plate according to claim 4, characterized in that: In sub-step (1.1), the dephosphorized molten iron, ferrochrome, ferromolybdenum and copper plate are added to the AOD or K-OBM-S furnace for smelting using a ladle that has produced 300 series stainless steel in the previous furnace.

6. A high corrosion resistant decorative stainless steel cold plate, characterized in that: The high corrosion resistant decorative stainless steel cold plate is prepared by the preparation method of the high corrosion resistant decorative stainless steel cold plate according to any one of claims 3 to 5, and the chemical composition of the high corrosion resistant decorative stainless steel cold plate is calculated by mass percentage: 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 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 × O ×10 6 ≤80, where w Cr 、w Mo 、w Ni 、w Cu 、w Mn 、w Al 、w O They respectively represent the mass percentage content of the elements Cr, Mo, Ni, Cu, Mn, Al, and O. The thickness of the highly corrosion-resistant decorative stainless steel cold plate is 0.3-1.2 mm, the width is 1000-2000 mm, and the surface type of the cold plate is BA surface.

7. The highly corrosion-resistant decorative stainless steel cold plate according to claim 6, characterized in that: The inclusion rating of the high corrosion resistant decorative stainless steel cold plate is better than that of A0.5, B0.5, C0.5 and D0.5, the surface glossiness of the high corrosion resistant decorative stainless steel cold plate is greater than 1000GU, and the high corrosion resistant decorative stainless steel cold plate is subjected to a copper accelerated acetic acid salt spray test at 50°C, 50g / L NaCl and 0.26g / L CuCl2·2H2O spray, and no rust spots are observed within 72 hours.

8. Application of the highly corrosion-resistant decorative stainless steel cold plate according to claim 6 or 7 in decorative parts for household appliances, kitchen and bathroom appliances, automobile exteriors, and architectural exteriors.

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