Nickel-based low-temperature steel having high crack arrest performance in low-temperature environment of -165°c, and manufacturing method therefor

Abstract

Disclosed are a nickel-based low-temperature steel having high crack arrest performance in a low-temperature environment of -165°C, and a manufacturing method therefor. The method comprises: converter smelting; LF refining; an RH vacuum treatment; continuous casting; low-temperature rolling; and a heat treatment. The chemical components of the nickel-based low-temperature steel having high crack arrest performance in a low-temperature environment of -165°C are, in percentages by mass: C: 0.02-0.08%, Si≤0.35%, Mn≤0.80%, Al≤0.060%, P≤0.005%, S≤0.002%, Ni: 7.00-9.50%, O: 0.0005-0.0020%, N: 0.0010-0.0050%, Cr: 0.01-0.08%, and the balance of iron and inevitable impurities. In the present invention, the alloying elements are easy to control, the content of nickel is suitable, and the production process is simple, thereby effectively improving the cleanliness and microstructure uniformity of the steel. The thickness ratio of a continuously cast slab to a finished steel plate is controlled by means of rolling, thereby effectively improving the crack arrest performance. The microstructure obtained by the heat treatment is tempered sorbite, thereby effectively ensuring that the steel plate has good toughness and also exhibits good double-tension crack arrest performance.

Description

A nickel-based low-temperature steel with high crack arrest performance at -165℃ and its manufacturing method. Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a nickel-based low-temperature steel with high crack arrest performance at -165℃ and its manufacturing method. Background Technology

[0002] Liquefied natural gas (LNG) storage tanks are prestressed concrete cylindrical structures primarily used for storing LNG, with a minimum temperature of -163℃. The tank consists of two parts: an inner tank made of 9% Ni steel plates and an outer tank, which is a composite multi-layered concrete structure. 9% Ni steel, with its relatively low price, high strength, excellent low-temperature toughness, and safety reliability, has become a key material for LNG storage tanks and other cryogenic toughness structures.

[0003] Because 9% Ni steel comes into direct contact with frozen LNG and is used in a low-temperature environment of -163℃ for a long time, the technical conditions such as room temperature tensile mechanical properties and -196℃ low-temperature impact toughness of the steel plate are subject to relatively strict regulations. However, the requirements for crack arrest performance are generally not included in the standard.

[0004] In recent years, with the continuous updating of LNG storage tank design specifications and the continuous development of material and construction technologies, the construction of extra-large LNG storage tanks with a capacity of 270,000 cubic meters or more has increased, which can increase tank capacity, improve land utilization, and reduce tank evaporation rate to a greater extent. To ensure the safety of extra-large storage tanks, in addition to ensuring the excellent tensile properties and impact energy of nickel-based low-temperature steel plates at -196℃, further requirements have been added for double tensile crack arrest performance.

[0005] Therefore, in order to improve safety and ensure that the double tensile crack arrest performance meets the supplementary requirements, a nickel-based low-temperature steel with high crack arrest performance at -165℃ and its manufacturing method are provided. Summary of the Invention

[0006] To address some or all of the technical problems existing in the prior art, the present invention provides a nickel-based low-temperature steel with high crack arrest performance at -165℃ and its manufacturing method.

[0007] The manufacturing method of nickel-based low-temperature steel with high crack arrest performance at -165℃ according to the present invention includes: converter smelting - LF refining - RH vacuum treatment - continuous casting - low-temperature rolling - heat treatment. The chemical composition of the nickel-based low-temperature steel with high crack arrest performance at -165℃ is controlled by mass percentage as follows: C: 0.02%~0.08%, Si≤0.35%, Mn≤0.80%, Al≤0.060%, P≤0.005%, S≤0.002%, Ni: 7.00%~9.50%, O: 0.0005%~0.0020%, N: 0.0010%~0.0050%, Cr: 0.01%~0.08%, with the remainder being iron and unavoidable impurities.

[0008] Converter smelting: Nickel plates are added to the converter along with scrap steel. The nickel recovery rate is calculated as 97%. Dephosphorization is carried out in the converter, and aluminum deoxidation is used for post-furnace alloying. Alloying elements are added during the steel flow process. The post-furnace temperature is controlled at 1590℃~1610℃ and the slag thickness is ≤100mm to obtain molten steel containing the alloying elements.

[0009] LF refining: molten steel containing the alloying elements is subjected to LF refining to obtain molten steel with the target element content;

[0010] RH vacuum treatment: molten steel with the target element content is subjected to RH vacuum treatment to obtain molten steel with impurities and harmful substances removed;

[0011] Continuous casting: The process of continuously casting molten steel, after removing impurities and harmful substances, into a continuous casting billet with a thickness of 200~230mm.

[0012] Low-temperature rolling: The billet is heated to an initial rolling temperature of 1000℃~1050℃. By adjusting the rolling speed and the pressure and flow rate of the cooling water during the rolling process, the finishing rolling temperature is controlled at 790℃~830℃. The billet is rolled into a steel plate with a thickness of 15mm~40mm and then air-cooled to room temperature.

[0013] Heat treatment: The rolled steel plate is heated in a normalizing furnace to 50~120℃ above Ar3, held for 2~3 min / mm, and then rapidly water-cooled to room temperature. The steel plate is then heated to 540~600℃, held for 3~5 min / mm, and then air-cooled to room temperature.

[0014] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃, the alloying elements added during the converter smelting process are aluminum, manganese, and silicon.

[0015] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃, during the LF refining process, LF temperature-controlled deep desulfurization is adopted, the composition is finely adjusted, and the molten steel is prevented from being exposed during argon blowing.

[0016] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃, during the RH vacuum treatment process, the vacuum degree is controlled at ≤10mbar and the cycle time is >10min.

[0017] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at a low temperature of -165℃, during the continuous casting process, the target temperature of the tundish is controlled at 1500℃~1555℃, and the corresponding casting speed is controlled at 0.65~1.20m / min.

[0018] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at a low temperature of -165℃, electromagnetic stirring is introduced during continuous casting.

[0019] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at a low temperature of -165℃, the compression ratio of the thickness of the continuously cast billet to the thickness of the finished steel plate is 5.5~21 during the rolling process.

[0020] Furthermore, in the above-mentioned method for manufacturing nickel-based low-temperature steel with high crack arrest performance at a low temperature of -165℃, during the rolling process, the billet heating temperature is controlled at 1160±20℃, and the heating time is >3h.

[0021] In a second aspect of the present invention, a nickel-based low-temperature steel with high crack arrest performance at -165°C is provided, wherein the nickel-based low-temperature steel with high crack arrest performance at -165°C is produced by the above-described method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165°C.

[0022] The nickel-based low-temperature steel with high crack arrest performance at -165℃ and its manufacturing method of the present invention have the following advantages and beneficial effects:

[0023] This invention features simple control of alloying elements, appropriate nickel content, and a simple production process, effectively improving the purity and uniformity of steel structure. By controlling the ratio of the thickness of the continuously cast billet to the thickness of the finished steel plate during rolling, the crack arrest performance is effectively improved. The heat treatment yields a tempered sorbite structure, effectively ensuring that the steel plate has good toughness, while also exhibiting good dual tensile crack arrest performance. 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 for further understanding of the embodiments of the present invention and constitute a part 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 shows the microstructure of the nickel-based low-temperature steel with high crack arrest performance at -165℃.

[0026] Figure 2 is a schematic diagram of the processing of the double tensile crack arresting specimen with high crack arresting performance at a low temperature of -165℃ according to the present invention.

[0027] Figure 3 shows a double tensile crack arrest specimen after testing its high crack arrest performance at a low temperature of -165℃ according to the present invention. Embodiments of the present invention

[0028] 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.

[0029] The manufacturing method of nickel-based low-temperature steel with high crack arrest performance at -165℃ according to the present invention includes: converter smelting - LF refining - RH vacuum treatment - continuous casting - low-temperature rolling - heat treatment. The chemical composition of the nickel-based low-temperature steel with high crack arrest performance at -165℃ is controlled by mass percentage as follows: C: 0.02%~0.08%, Si≤0.35%, Mn≤0.80%, Al≤0.060%, P≤0.005%, S≤0.002%, Ni: 7.00%~9.50%, O: 0.0005%~0.0020%, N: 0.0010%~0.0050%, Cr: 0.01%~0.08%, with the remainder being iron and unavoidable impurities.

[0030] Converter smelting: Nickel plates are added to the converter along with scrap steel. The nickel recovery rate is calculated as 97%. Dephosphorization is carried out in the converter, and aluminum deoxidation is used for post-furnace alloying. Alloying elements are added during the steel flow process. The post-furnace temperature is controlled at 1590℃~1610℃ and the slag thickness is ≤100mm to obtain molten steel containing the alloying elements.

[0031] LF refining: molten steel containing the alloying elements is subjected to LF refining to obtain molten steel with the target element content;

[0032] RH vacuum treatment: molten steel with the target element content is subjected to RH vacuum treatment to obtain molten steel with impurities and harmful substances removed, thereby obtaining high steel purity and uniformity of structure;

[0033] Continuous casting: The process of continuously casting molten steel, after removing impurities and harmful substances, into a continuous casting billet with a thickness of 200~230mm.

[0034] Low-temperature rolling: The billet is heated to an initial rolling temperature of 1000℃~1050℃. By adjusting the rolling speed and the cooling water pressure and flow rate during the rolling process, the finishing rolling temperature is controlled at 790℃~830℃. The billet is rolled into a steel plate with a thickness of 15mm~40mm and then air-cooled to room temperature. This process, through a high compression ratio and low-temperature reduction, results in a fine grain size.

[0035] Heat treatment: The rolled steel plate is heated in a normalizing furnace to 50-120℃ above Ar3, held for 2-3 min / mm, and then rapidly water-cooled to room temperature. The steel plate is then heated to 540-600℃, held for 3-5 min / mm, and then air-cooled to room temperature. This process produces a fine tempered sorbite structure and generates 5%-8% dispersed rotatable austenite. This austenite is evenly distributed on the tempered sorbite structure, ensuring that the steel plate has good strength and toughness, as well as good tensile crack arrest properties.

[0036] In this invention, the main reasons for controlling the chemical composition of the nickel-based low-temperature steel with high crack arrest performance at -165℃ as described above are as follows: C: 9% Ni steel requires high strength while possessing good low-temperature impact toughness. Carbon is an element that improves strength, but excessive carbon content will significantly reduce low-temperature toughness. Therefore, a carbon content of approximately 0.02-0.08%, combined with a low-cost heat treatment process, can achieve the best strength-toughness balance. Si: Silicon dissolves into the ferrite matrix, causing solid solution strengthening in the steel, but it also reduces the toughness of the steel. Too high a content is detrimental to weldability. Therefore, the silicon content in the steel is controlled at approximately ≤0.35%. Mn: Manganese is a solid solution strengthening element that can improve the strength of the steel. It is also an austenite stabilizing element, so it can be controlled within a relatively high range within the standard range, currently controlled at approximately ≤0.80%. P, S, N: P is a typical cold brittle element, and its content should be minimized. S easily leads to welding hot cracking and should be strictly controlled; the lower its content, the better. Therefore, P≤0.005%, S≤0.002%; Al: Aluminum is an element for deoxidation and grain refinement, and a certain content is necessary. However, if the aluminum content is too high, the billet is prone to cracking. Therefore, the aluminum content in the steel is controlled at a relatively low level of ≤0.060%; Ni: 9% Ni steel can obtain excellent low-temperature performance, and the effect of nickel is the most significant. Nickel can not only reduce the frictional resistance and pinning constant of dislocations in the matrix metal during low-temperature deformation of steel, but also increase stacking fault energy, promote cross-slip of screw dislocations at low temperatures, increase the energy consumed by crack propagation, and improve toughness. More importantly, a reasonable Ni content can promote the formation of dispersed rotatable austenite in ferrite during tempering. This dispersed austenite is beneficial to low-temperature toughness. Taking into account cost factors, Ni is controlled between 7.00% and 9.50%; Chromium and Copper: Chromium and copper in steel are both residual elements.

[0037] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ in the present invention, the alloying elements added during the converter smelting process are aluminum, manganese and silicon.

[0038] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ in the present invention, during the LF refining process, LF temperature-controlled deep desulfurization is adopted, the composition is finely adjusted, and the molten steel is prevented from being exposed during argon blowing.

[0039] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ in the present invention, during the RH vacuum treatment process, the vacuum degree is controlled at ≤10mbar and the cycle time is >10min.

[0040] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at a low temperature of -165℃ according to the present invention, during the continuous casting process, the target temperature of the tundish is controlled at 1500℃~1555℃, and the corresponding casting speed is controlled at 0.65~1.20m / min.

[0041] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃, electromagnetic stirring is introduced during continuous casting.

[0042] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃, during the rolling process, the compression ratio of the thickness of the continuously cast billet to the thickness of the finished steel plate is 5.5~21.

[0043] Furthermore, in the method for manufacturing nickel-based low-temperature steel with high crack arrest performance at a low temperature of -165℃ according to the present invention, during the rolling process, the billet heating temperature is controlled at 1160±20℃ and the heating time is >3h.

[0044] In a second aspect of the present invention, a nickel-based low-temperature steel with high crack arrest performance at -165°C is provided, wherein the nickel-based low-temperature steel with high crack arrest performance at -165°C is produced by the above-described method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165°C.

[0045] Example 1

[0046] This embodiment utilizes a 180-ton converter in conjunction with ladle refining and a reversible rolling mill for heavy plates;

[0047] The chemical composition of nickel-based low-temperature steel with high crack arrest performance at -165℃ is controlled by mass percentage as follows: C: 0.035%, Si: 0.23%, Mn: 0.60%, Al: 0.040%, P: 0.003%, S: 0.001%, Ni: 9.09%, O: 0.0005%~0.0020%, N: 0.0010%~0.0050%, Cr: 0.01%~0.08%, with the remainder being iron and unavoidable impurities;

[0048] Converter smelting: Nickel plates are added to the converter along with the scrap steel. Dephosphorization is performed in the converter, and aluminum deoxidation is used for post-converter alloying. Aluminum shot, ferromanganese, and ferrosilicon are added during the steel flow process. The post-converter temperature is 1595℃, and the slag thickness is controlled at 80mm.

[0049] LF refining: LF temperature regulation deep desulfurization, fine-tuning composition, LF argon blowing should avoid exposing molten steel;

[0050] RH vacuum treatment: After controlling the vacuum level to ≤10mbar, the circulation time is 15 minutes;

[0051] Continuous casting: Continuous casting inlet temperature: 1575℃, continuous casting tundish temperature: 1525℃, corresponding casting speed: 0.95m / min, electromagnetic stirring is activated. Continuous casting produces billets with dimensions of 230×1800×9000 (mm), ready to be rolled into 20.2mm finished steel plates;

[0052] Low-temperature rolling: The continuously cast billet is heated to 1160℃ in the heating furnace, with an initial rolling temperature of 1020℃. It is water-cooled before finishing rolling, with an initial finishing rolling temperature of 880℃. The finishing rolling temperature is controlled to approximately 800℃ by appropriately lowering the rolling speed and adjusting the cooling water pressure and flow rate. After rolling, it is air-cooled to room temperature to obtain a bainitic + martensitic microstructure. The finished product has a thickness of 20.2mm, and the ratio of the continuously cast billet thickness to the finished product thickness (compression ratio) is 11.4.

[0053] Heat treatment: The steel plate is heated to 810℃ in a normalizing furnace, held for a certain time, and then rapidly water-cooled to room temperature. The steel plate is then heated to 560℃, held for a certain time, and then air-cooled to room temperature to obtain a uniform tempered sorbite + dispersed rotatable austenite microstructure, as shown in Figure 1.

[0054] The double tensile crack arrest specimen with high crack arrest performance at a low temperature of -165℃ was prepared as shown in Figure 2. The steel plate was subjected to room temperature tensile test according to GB / T228.1, and the steel plate was subjected to low temperature impact test at -196℃ according to GB / T229. The crack arrest test was carried out according to Appendix B of "Application Guide for High Strength Steel Thick Plates for Marine Use: Double Tensile Crack Arrest Test". The double tensile crack arrest specimen after the test is shown in Figure 3.

[0055] Table 1 shows the room temperature tensile properties and -196℃ impact energy of the steel plate, and Table 2 shows the double tensile crack arrest performance.

[0056] Table 1

[0057]

[0058] Table 2

[0059]

[0060] Example 2:

[0061] This embodiment utilizes a 180-ton converter in conjunction with ladle refining and a reversible rolling mill for heavy plates;

[0062] The chemical composition of the nickel-based low-temperature steel with high crack arrest performance at -165℃ in this embodiment is controlled by mass percentage as follows: C: 0.041%, Si: 0.06%, Mn: 0.68%, Al: 0.030%, P: 0.002%, S: 0.001%, Ni: 7.5%, O: 0.0005%~0.0020%, N: 0.0010%~0.0050%, Cr: 0.01%~0.08%, with the remainder being iron and unavoidable impurities;

[0063] Converter smelting: Nickel plates are added to the converter along with the scrap steel. Dephosphorization is performed in the converter, and aluminum deoxidation is used for post-converter alloying. Aluminum shot, ferromanganese, and ferrosilicon are added during the steel flow process. The post-converter temperature is 1595℃, and the slag thickness is controlled at 80mm.

[0064] LF refining: LF temperature regulation deep desulfurization, fine-tuning composition, LF argon blowing should avoid exposing molten steel;

[0065] RH vacuum treatment: After controlling the vacuum level to ≤10mbar, the circulation time is 15 minutes;

[0066] Continuous casting: Continuous casting inlet temperature: 1572℃, continuous casting tundish temperature: 1520℃, corresponding casting speed: 0.95m / min, electromagnetic stirring is activated. Continuous casting produces billets with dimensions of 230×1800×9000 (mm), ready to be rolled into 15mm finished steel plates;

[0067] Low-temperature rolling: The continuously cast billet is heated to 1165℃ in the heating furnace, with an initial rolling temperature of 1030℃. It is then water-cooled before finishing rolling, with an initial finishing rolling temperature of 925℃. By appropriately lowering the rolling speed and adjusting the cooling water pressure and flow rate during the rolling process, the final finishing rolling temperature is controlled to approximately 825℃. After rolling, it is air-cooled to room temperature to obtain a bainitic + martensitic microstructure. The finished product has a thickness of 15mm, and the ratio of the continuously cast billet thickness to the finished product thickness (compression ratio) is 15.

[0068] Heat treatment: The steel plate is heated to 810℃ in a normalizing furnace, held at that temperature for a certain time, and then rapidly water-cooled to room temperature. The steel plate is then heated to 570℃, held at that temperature for a certain time, and then air-cooled to room temperature to obtain a uniform tempered sorbite + dispersed rotatable austenite finished product structure.

[0069] Sampling was carried out according to GB / T228.1 for room temperature tensile testing of steel plates, according to GB / T229 for -196℃ low temperature impact testing of steel plates, and according to Appendix B of "GD24-2020 Application Guide for Marine High Strength Steel Thick Plates: Double Tensile Crack Arrest Test" for crack arrest testing.

[0070] Table 3 shows the room temperature tensile properties and -196℃ impact energy of the steel plate, and Table 4 shows the double tensile crack arrest performance.

[0071] Table 3

[0072]

[0073] Table 4

[0074]

[0075] Example 3:

[0076] This embodiment utilizes a 180-ton converter in conjunction with ladle refining and a reversible rolling mill for heavy plates;

[0077] The chemical composition of the nickel-based low-temperature steel with high crack arrest performance at -165℃ in this embodiment is controlled by mass percentage as follows: C: 0.040%, Si: 0.19%, Mn: 0.68%, Al: 0.030%, P: 0.002%, S: 0.001%, Ni: 9.0%, O: 0.0005%~0.0020%, N: 0.0010%~0.0050%, Cr: 0.01%~0.08%, with the remainder being iron and unavoidable impurities;

[0078] Converter smelting: Nickel plates are added to the converter along with the scrap steel. Dephosphorization is performed in the converter, and aluminum deoxidation is used for post-converter alloying. Aluminum shot, ferromanganese, and ferrosilicon are added during the steel flow process. The post-converter temperature is 1592℃, and the slag thickness is controlled at 80mm.

[0079] LF refining: LF temperature regulation deep desulfurization, fine-tuning composition, LF argon blowing should avoid exposing molten steel;

[0080] RH vacuum treatment: After controlling the vacuum level to ≤10mbar, the circulation time is 15 minutes;

[0081] Continuous casting: The continuous casting inlet temperature is 1576℃, the continuous casting tundish temperature is 1522℃, the corresponding casting speed is 0.93m / min, and electromagnetic stirring is activated. The continuous casting produces a billet with dimensions of 230×1800×9000 (mm), ready to be rolled into a 35.2mm finished steel plate.

[0082] Low-temperature rolling: The continuously cast billet is heated to 1151℃ in the heating furnace, with an initial rolling temperature of 1010℃. Water cooling is applied before finishing rolling, with the finishing rolling temperature at 919℃. By appropriately lowering the rolling speed and adjusting the cooling water pressure and flow rate during the rolling process, the final finishing rolling temperature is controlled at approximately 828℃. After rolling, the billet is air-cooled to room temperature to obtain a bainitic + martensitic microstructure. The finished product has a thickness of 35.2mm, and the ratio of the continuously cast billet thickness to the finished product thickness (compression ratio) is 6.5.

[0083] Heat treatment: The steel plate is heated to 810℃ in a normalizing furnace, held at that temperature for a certain time, and then rapidly water-cooled to room temperature. The steel plate is then heated to 570℃, held at that temperature for a certain time, and then air-cooled to room temperature to obtain a uniform tempered sorbite + dispersed rotatable austenite finished product structure.

[0084] Sampling was carried out according to GB / T228.1 for room temperature tensile testing of steel plates, according to GB / T229 for -196℃ low temperature impact testing of steel plates, and according to Appendix B of "GD24-2020 Application Guide for Marine High Strength Steel Thick Plates: Double Tensile Crack Arrest Test" for crack arrest testing.

[0085] Table 5 shows the room temperature tensile properties and -196℃ impact energy of the steel plate, and Table 6 shows the double tensile crack arrest properties.

[0086] Table 5

[0087]

[0088] Table 6

[0089]

[0090] In summary, compared with the prior art, the nickel-based low-temperature steel with high crack arrest performance at -165℃ and its manufacturing method of the present invention have the following advantages and beneficial effects:

[0091] This invention features simple control of alloying elements, appropriate nickel content, and a simple production process, effectively improving the purity and uniformity of steel structure. By controlling the ratio of the thickness of the continuously cast billet to the thickness of the finished steel plate during rolling, the crack arrest performance is effectively improved. The heat treatment yields a tempered sorbite structure, effectively ensuring that the steel plate has good toughness, while also exhibiting good dual tensile crack arrest performance.

[0092] It should be noted that, unless otherwise expressly specified and limited, the term "connection" or its synonyms should be interpreted broadly in this document. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, expressions such as "first" and "second" are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Meanwhile, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In addition, the terms "front," "rear," "left," "right," "upper," and "lower" in this document refer to the placement states shown in the accompanying drawings.

[0093] Finally, 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 spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a nickel-based cryogenic steel having high crack arrest performance in a -165°C cryogenic environment, characterized by, include: The process involves converter smelting, LF refining, RH vacuum treatment, continuous casting, low-temperature rolling, and heat treatment. The chemical composition of the nickel-based low-temperature steel with high crack-arresting performance at -165℃ is controlled by mass percentage as follows: C: 0.02%~0.08%, Si≤0.35%, Mn≤0.80%, Al≤0.060%, P≤0.005%, S≤0.002%, Ni: 7.00%~9.50%, O: 0.0005%~0.0020%, N: 0.0010%~0.0050%, Cr: 0.01%~0.08%, with the remainder being iron and unavoidable impurities. Converter smelting: Nickel plates are added to the converter along with scrap steel. The nickel recovery rate is calculated as 97%. Dephosphorization is performed in the converter, and aluminum deoxidation is used for post-furnace alloying. Alloying elements are added during the steel flow process. The post-furnace temperature is controlled at 1590℃~1610℃, and the slag thickness is ≤100mm to obtain molten steel containing the alloying elements. LF refining: molten steel containing the alloying elements is subjected to LF refining to obtain molten steel with the target element content; RH vacuum treatment: molten steel with the target element content is subjected to RH vacuum treatment to obtain molten steel with impurities and harmful substances removed; Continuous casting: The process of continuously casting molten steel, after removing impurities and harmful substances, into a continuous casting billet with a thickness of 200~230mm; Low-temperature rolling: The billet is heated to an initial rolling temperature of 1000℃~1050℃. By adjusting the rolling speed and the pressure and flow rate of the cooling water during the rolling process, the finishing rolling temperature is controlled at 790℃~830℃. The billet is rolled into a steel plate with a thickness of 15mm~40mm and then air-cooled to room temperature. Heat treatment: The rolled steel plate is heated in a normalizing furnace to 50~120℃ above Ar3, held for 2~3 min / mm, and then rapidly water-cooled to room temperature. The steel plate is then heated to 540~600℃, held for 3~5 min / mm, and then air-cooled to room temperature.

2. The method of claim 1, wherein the nickel-based cryogenic steel has a high crack arrest property in a low temperature environment of -165°C, and the method comprises: During the converter smelting process, the alloying elements added are aluminum, manganese, and silicon. ​ 3. The method of claim 1, wherein the nickel-based cryogenic steel has a high crack arrest property in a low temperature environment of -165°C, and the method comprises: In the LF refining process, LF temperature-controlled deep desulfurization is used to fine-tune the composition, and the molten steel is kept out of the open during argon blowing. ​ 4. The method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ as described in claim 1, characterized in that, During the RH vacuum treatment process, the vacuum level is controlled at ≤10mbar and the cycle time is >10min.

5. The method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ as described in claim 1, characterized in that, During continuous casting, the target temperature of the tundish is controlled at 1500℃~1555℃, and the corresponding casting speed is controlled at 0.65~1.20m / min.

6. The method of claim 1, wherein the nickel-based cryogenic steel having high crack arrest performance in a low temperature environment of -165°C is manufactured by the steps of: Electromagnetic stirring is introduced during continuous casting. ​ 7. The method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ as described in claim 1, characterized in that, During the rolling process, the compression ratio between the thickness of the continuously cast billet and the thickness of the finished steel plate is 5.5~21.

8. The method for manufacturing nickel-based low-temperature steel with high crack arrest performance at -165℃ as described in claim 1, characterized in that, During the rolling process, the billet heating temperature is controlled at 1160±20℃, and the heating time is >3h.

9. A nickel-based cryogenic steel having high crack arrest performance in a -165°C cryogenic environment, characterized in that, The nickel-based low-temperature steel with high crack arrest performance at -165℃ is produced by the manufacturing method of nickel-based low-temperature steel with high crack arrest performance at -165℃ as described in any one of claims 1 to 8.

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