Corrosion-resistant stainless steel hot-rolled steel plate and method for manufacturing the same, tank container tank body, and welding method

Abstract

This application discloses a corrosion-resistant hot-rolled stainless steel plate, comprising 0.010~0.015% carbon (C), 0.30~0.60% manganese (Mn), 3.50~4.20% silicon (Si), ≤0.030% phosphorus (P), ≤0.005% sulfur (S), 13.50~14.50% nickel (Ni), and 13.50~14.50% chromium (Cr), with the remainder being unavoidable impurities. Another objective of this application discloses a preparation method: S1, smelting and refining; S2, continuous casting; S3, heating; S4, hot rolling; S5, laminar cooling and coiling; S6, annealing and solution treatment; S7, pickling and finishing. The corrosion-resistant hot-rolled stainless steel plate of this application exhibits good corrosion resistance, strong resistance to pitting corrosion, and effectively resists corrosion from strong acids such as nitric acid and hydrofluoric acid. Yet another objective of this application is to provide a tank container body made of corrosion-resistant hot-rolled stainless steel plate. The tank body of this application does not require a specially made inner lining, reducing assembly steps and improving assembly efficiency. Another objective of this application is to provide a welding method. The welding method of this application reduces welding deformation.

Description

Technical Field

[0001] This application relates to the field of tank container materials technology, and in particular to a corrosion-resistant stainless steel hot-rolled steel plate and its preparation method, a tank container body and welding method. Background Technology

[0002] In the transportation of liquid cargo in industries such as chemicals, energy, and food, tank containers are frequently used. Traditional tanks, constructed from a single material, are insufficient to meet corrosion resistance requirements. For example, special linings are necessary when transporting strong acids.

[0003] Currently, the corrosion-resistant materials commonly used on tank containers mainly include the following categories: Austenitic stainless steels, such as 304 and 316L, although possessing good overall performance, are prone to intergranular corrosion and pitting in nitric acid solutions with high concentrations (>65%) or high temperatures, and cannot meet the requirements for long-term service in concentrated nitric acid environments.

[0004] High-alloy austenitic stainless steels, such as 904L (00Cr20Ni25Mo4.5Cu) and Alloy 20, improve corrosion resistance by increasing the content of Ni, Mo and Cu. However, these materials are expensive, and the addition of Mo may actually accelerate corrosion in certain nitric acid environments (due to the change in the reduction potential of nitrate ions).

[0005] Duplex stainless steels, such as 2205, while possessing high strength, are prone to selective corrosion in strong oxidizing acids due to the potential difference between their two phases, and also exhibit relatively poor hot working properties. Therefore, a new technical solution is urgently needed to address at least one of these technical problems. Summary of the Invention

[0006] In view of the above shortcomings, one objective of this application is to provide a corrosion-resistant hot-rolled stainless steel plate and its preparation method, which has good corrosion resistance, strong resistance to pitting corrosion, and effectively resists corrosion from strong acids such as nitric acid and hydrofluoric acid. Another objective of this application is to provide a tank body for a tank container made of corrosion-resistant hot-rolled stainless steel plate, eliminating the need for a specially made inner lining, reducing assembly steps, and improving assembly efficiency. A further objective of this application is to provide a welding method that reduces welding deformation.

[0007] To achieve the above-mentioned technical objectives and meet the above-mentioned technical requirements, the technical solution adopted in this application is as follows: A corrosion-resistant stainless steel hot-rolled plate, characterized in that, by weight, it comprises 0.010~0.015% carbon (C), 0.30~0.60% manganese (Mn), 3.50~4.20% silicon (Si), ≤0.030% phosphorus (P), ≤0.005% sulfur (S), 13.50~14.50% nickel (Ni), 13.50~14.50% chromium (Cr), with the remainder being unavoidable impurities.

[0008] This application also provides a preparation method, characterized by comprising the following steps: S1. Smelting and refining: Smelting is carried out according to the weight percentage of chemical composition. The primary smelting is carried out in an electric arc furnace or converter, followed by LF furnace refining and VD / VOD vacuum refining. The vacuum degree is controlled below 100Pa. During the refining process, the composition of ferrosilicon, ferrochrome, nickel plate and low carbon ferromanganese is finely adjusted to ensure uniform composition. S2. Continuous casting: Molten steel is cast into slabs using full-process protective casting. The superheat of the tundish is controlled at 20~35℃, the casting speed is controlled at 0.8~1.2m / min, and the slab thickness is 200~250mm. S3. Heating: The slab is sent into the heating furnace and the heating temperature is controlled at 1150~1250℃. The holding time is calculated according to the slab thickness of 1.5~2.5min / mm to ensure that the temperature of the core of the slab is uniform and the temperature of the heat soaking zone is not lower than 1180℃. S4. Hot rolling: The roughing and finishing rolling process is adopted. The initial rolling temperature is ≥1050℃. The roughing stage is carried out in 3~5 passes with a cumulative deformation of ≥70%. The finishing stage is carried out in the non-recrystallized austenite region, and the final rolling temperature is controlled at 850~950℃. S5. Laminar flow cooling and coiling: Laminar flow cooling is performed immediately after rolling, with the cooling rate controlled at 30~60℃ / s. Coiling is carried out after cooling to the coiling temperature of 550~650℃. S6. Annealing and solution treatment: The hot-rolled coil is annealed at a temperature of 1050~1150℃ for 1~3 hours. Then it is cooled by water quenching or rapid air cooling at a rate of ≥30℃ / s to allow carbides to fully precipitate and fix the austenitic structure. S7. Pickling and Finishing: Pickling is performed using a mixture of nitric acid and hydrofluoric acid at a temperature of 40~60℃ to remove iron oxide scale. Subsequently, edge trimming, straightening, and surface polishing are carried out to obtain the finished corrosion-resistant stainless steel hot-rolled steel plate.

[0009] As a preferred technical solution, in S1, during the VD / VOD vacuum refining stage, a strong stirring mode is adopted, with an argon stirring intensity of 0.5~1.0 Nm³ / min·t, a refining time of not less than 30 minutes, and calcium treatment is carried out in the later stage of refining, by feeding in a silicon-calcium wire, controlling the oxygen content in the molten steel to ≤15ppm, and the calcium content to be controlled at 10~20ppm.

[0010] As a preferred technical solution, in step S3, the slab adopts a segmented heating system in the heating furnace, with a preheating section temperature of 800~900℃, a heating section temperature of 1200~1250℃, and a soaking section temperature of 1180~1220℃; during the heating process, the atmosphere inside the furnace is controlled to be a weakly oxidizing or neutral atmosphere, and the H2O content in the furnace gas is controlled to be ≤3%.

[0011] As a preferred technical solution, in S5, laminar flow cooling adopts a cooling strategy of denser cooling at the front and sparser cooling at the back. The opening rate of the head cooling manifold is 100%, and the opening rate of the tail cooling manifold is dynamically adjusted according to the strip temperature feedback to ensure that the transverse temperature difference of the strip is ≤20℃. The winding adopts fully automatic winding with auxiliary winding rollers, and the tension of the winding drum is gradually increased to prevent scratches caused by interlayer slippage.

[0012] As a preferred technical solution, in step S6, the annealing process is carried out in a continuous annealing furnace or a bell-type furnace. If continuous annealing is used, the protective gas in the furnace is a mixture of high-purity nitrogen and hydrogen, with hydrogen accounting for 5~10% of the volume and a dew point ≤-40℃.

[0013] As a preferred technical solution, in step S7, the mixed acid pickling solution is composed of: nitric acid concentration of 15-25%, hydrofluoric acid concentration of 5-10%, and the remainder being water; a corrosion inhibitor is added to the acid solution, which is rutin or hexamethylenetetramine, and the amount added is 0.1-0.3% of the total acid solution; after pickling, it is immediately rinsed with high-pressure water at a pressure ≥5MPa and neutralized with sodium carbonate solution, and finally rinsed with pure water and dried with hot air.

[0014] This application provides a tank body for a tank container, characterized in that the material of the tank body is a corrosion-resistant stainless steel hot-rolled plate prepared by the aforementioned preparation method.

[0015] This application provides another welding method, characterized in that the method is used to weld the tank body of the tank container as described in claim 8. The tank body welding adopts tungsten inert gas welding process, first performing tack welding, then performing root pass welding, and finally performing fill and cover pass welding. The welding parameters of the tack welding are as follows: welding current 100-120A, arc voltage 10-12V, welding speed 70-100mm / min, and maximum heat input not exceeding 1.27KJ / mm. The welding parameters for the root pass are as follows: welding current 90-100A, arc voltage 12-15V, welding speed 70-100mm / min, and maximum heat input not exceeding 1.41KJ / mm. The welding parameters for the filler and cover welds are as follows: welding current 100-120A, arc voltage 12-15V, welding speed 60-90mm / min, and maximum heat input not exceeding 1.8KJ / mm.

[0016] As a preferred technical solution, the tank body of the tank container is welded using tungsten inert gas welding (TIG) with an argon content of 99.99% and a gas flow rate of 10-14 L / min.

[0017] As a preferred technical solution, the welding material selected is WZ1913SiNL welding wire with a diameter of 2.4mm.

[0018] As a preferred technical solution, the welding groove adopts a 60° V-shaped groove.

[0019] Compared with traditional technical solutions, the beneficial effects of this application are: This application utilizes a composition design of "ultra-low carbon + high silicon + high chromium-nickel," maintaining a single austenitic structure with a high Cr / Ni ratio to ensure passivation film stability and extremely strong resistance to pitting corrosion. VD / VOD vacuum refining and calcium treatment significantly reduce inclusion content and improve thermoplasticity. Combined with high-temperature homogenization and a "rough rolling with large reduction + finish rolling with low temperature" process, the as-cast structure is broken down, and the grains are refined, giving the steel plate both high strength and good formability. A nitric acid-hydrofluoric acid mixed pickling process effectively removes the dense, silicon-rich oxide scale unique to high-silicon steel. Passivation treatment after pickling forms a chromium-rich oxide film, further enhancing corrosion resistance and preventing surface scratches. It is also well-suited for use in tank containers, effectively resisting the strong oxidative corrosion of nitric acid and avoiding leakage risks caused by pitting or intergranular corrosion. Simultaneously, its excellent weldability and mechanical strength ensure the structural safety and long service life of the tank, significantly reducing maintenance costs and guaranteeing the safety and reliability of dangerous goods transportation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the preparation process of the corrosion-resistant stainless steel hot-rolled sheet in this application; Figure 2 Tensile curve of the corrosion-resistant stainless steel hot-rolled sheet prepared for this application at room temperature; Figure 3 Tensile curve of the corrosion-resistant stainless steel hot-rolled sheet prepared for this application at high temperature; Figure 4 This is a structural diagram of the welding bevel. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings.

[0022] In the accompanying drawings of the embodiments of this application, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "top", "bottom", "left", "right", "front", "rear", "inner", "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this application, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0023] Please refer to Figures 1-3 One embodiment of this application provides a corrosion-resistant stainless steel hot-rolled sheet, comprising, by weight percentage: carbon C 0.010~0.015%, manganese Mn 0.30~0.60%, silicon Si 3.50~4.20%, phosphorus P≤0.030%, sulfur S≤0.005%, nickel Ni 13.50~14.50%, and chromium Cr 13.50~14.50%.

[0024] The core of this application lies in the ratio of "ultra-low carbon + high silicon + high chromium nickel + trace impurities": C (Carbon): 0.010~0.015%: The extremely low carbon content is fundamental to preventing intergranular corrosion (chromium depletion theory). Traditional high-silicon steel has C ≥ 0.05%, but this application reduces it by an order of magnitude to ensure that no Cr is precipitated during welding or at high temperatures. 23 C6.

[0025] Si (Silicon): 3.50~4.20%: Silicon is a key element for improving resistance to nitric acid corrosion. Silicon promotes the formation of a dense SiO2 protective film on the steel surface, hindering the reduction reaction of nitrate ions. However, Si > 2% will significantly reduce thermoplasticity, therefore specific heating and rolling processes are required.

[0026] Cr (chromium): 13.50~14.50% & Ni (nickel): 13.50~14.50%: High Cr ensures the stability of the passivation film, while high Ni maintains a single austenitic structure (preventing the precipitation of the ferrite phase and avoiding phase boundary corrosion). The Cr / Ni ratio is close to 1:1, exhibiting optimal thermodynamic stability.

[0027] Mn (manganese): 0.30~0.60%: assists in deoxidation and solid solution enhancement, but should not be too high to avoid increasing sensitization tendency.

[0028] P and S: Strictly control P ≤ 0.030% and S ≤ 0.005%, especially S ≤ 0.001%, which can significantly reduce sulfide inclusions and avoid the generation of pitting corrosion sources.

[0029] Please refer to Figures 1-3 An embodiment of this application provides a method for preparing corrosion-resistant stainless steel hot-rolled sheet, comprising the following steps: S1. Smelting and Refining: Smelting is carried out according to the following chemical composition by weight percentage: Carbon C 0.010~0.015%, Manganese Mn 0.30~0.60%, Silicon Si 3.50~4.20%, Phosphorus P≤0.030%, Sulfur S≤0.005%, Nickel Ni 13.50~14.50%, Chromium Cr 13.50~14.50%. Primary smelting is carried out in an electric arc furnace or converter, followed by LF furnace refining and VD / VOD vacuum refining. The vacuum degree is controlled below 100Pa. During the refining process, the composition of ferrosilicon, ferrochrome, nickel plate and low carbon ferromanganese is finely adjusted to ensure uniform composition. S2. Continuous casting: Molten steel is cast into slabs using full-process protective casting. The superheat of the tundish is controlled at 20~35℃, the casting speed is controlled at 0.8~1.2m / min, and the slab thickness is 200~250mm. S3. Heating: The slab is sent into the heating furnace and the heating temperature is controlled at 1150~1250℃. The holding time is calculated based on the slab thickness of 1.5~2.5min / mm to ensure that the core temperature of the slab is uniform and the temperature of the heat soaking zone is not lower than 1180℃. S4. Hot rolling: The roughing and finishing process is adopted. The initial rolling temperature is ≥1050℃. The roughing stage is carried out in 3~5 passes with a cumulative deformation of ≥70%. The finishing stage is carried out in the non-recrystallized austenite region, and the final rolling temperature is controlled at 850~950℃. S5. Laminar flow cooling and coiling: Laminar flow cooling is performed immediately after rolling, with the cooling rate controlled at 30~60℃ / s. Coiling is carried out after cooling to the coiling temperature of 550~650℃. S6. Annealing and solution treatment: The hot-rolled coil is annealed at a temperature of 1050~1150℃ for 1~3 hours, followed by water quenching or rapid air cooling at a rate of ≥30℃ / s to allow carbides to fully precipitate and fix the austenitic structure. S7. Pickling and Finishing: Pickling is performed using a mixture of nitric acid and hydrofluoric acid at a temperature of 40~60℃ to remove iron oxide scale. Subsequently, edge trimming, straightening, and surface polishing are carried out to obtain the finished corrosion-resistant stainless steel hot-rolled steel plate, which is respectively designated as 00Cr14Ni14Si4 series stainless steel, 00Cr14Ni14Si4+C4 steel, SA240 304 stainless steel, and 00Cr14Ni14Si4+304 composite steel plate.

[0030] Preparation process principle Refining: VD / VOD vacuum refining is adopted, with a vacuum degree of <100Pa, deep degassing (O≤15ppm), and calcium treatment is carried out to transform solid Al2O3 inclusions into liquid calcium aluminate, thereby improving thermoplasticity.

[0031] Heating: High silicon steel has poor thermal conductivity and requires high temperature (1150~1250℃) for homogenization to eliminate as-cast segregation. Rolling is carried out by utilizing the plastic recovery zone of ferrosilicon at high temperature.

[0032] Rolling: The strategy of "large reduction in rough rolling + low temperature rolling in finish rolling" is adopted. Rough rolling breaks up the as-cast microstructure; finish rolling is carried out in the non-recrystallized austenite region (850~950℃) to accumulate deformation energy, provide driving force for recrystallization, and refine the grains.

[0033] Cooling and solution treatment: After rolling, rapid cooling (30~60℃ / s) is used to suppress carbide precipitation. Then, solution treatment at 1050~1150℃ is performed online or offline to homogenize the microstructure. The solution is then fixed by rapid cooling (water quenching or air cooling).

[0034] Pickling: A mixed acid of nitric acid and hydrofluoric acid is used to remove the dense oxide scale (silicon-rich layer) unique to high silicon steel by utilizing the oxidizing properties of nitric acid and the reducing properties of hydrofluoric acid.

[0035] In S1, during the VD / VOD vacuum refining stage, a strong stirring mode is adopted, with an argon stirring intensity of 0.5~1.0 Nm³ / min·t, and a refining time of no less than 30 minutes. Calcium treatment is carried out in the later stage of refining, and a silicon-calcium wire is fed in to control the oxygen content in the molten steel to ≤15ppm and the calcium content to 10~20ppm.

[0036] In S3, the slab adopts a segmented heating system in the heating furnace. The preheating section temperature is 800~900℃, the heating section temperature is 1200~1250℃, and the soaking section temperature is 1180~1220℃. During the heating process, the furnace atmosphere is controlled to be a weakly oxidizing or neutral atmosphere, and the H2O content in the furnace gas is controlled to be ≤3%.

[0037] In S4, a large reduction process is adopted in the rough rolling stage, with a single-pass reduction rate of not less than 15%, in order to break the as-cast structure.

[0038] In S4, the finishing rolling stage adopts continuous variable thickness rolling technology, and the plate shape is controlled by the work roll shifting and bending technology, and the total deformation of finishing rolling is controlled between 70% and 85%.

[0039] In S4, the final rolling temperature is controlled with an accuracy of ±10℃. Secondary iron oxide scale is removed by a high-pressure water descaling device before the finishing mill, with a descaling water pressure ≥20MPa.

[0040] In S5, laminar flow cooling adopts a cooling strategy of denser cooling at the front and sparser cooling at the back. The opening rate of the head cooling manifold is 100%, and the opening rate of the tail cooling manifold is dynamically adjusted according to the strip temperature feedback to ensure that the transverse temperature difference of the strip is ≤20℃. The winding adopts fully automatic winding with auxiliary winding rollers, and the tension of the winding drum is gradually increased to prevent interlayer slippage and scratches.

[0041] In S6, the annealing process is carried out in a continuous annealing furnace or a bell-type furnace. If continuous annealing is used, the protective gas in the furnace is a mixture of high-purity nitrogen and hydrogen, with hydrogen accounting for 5~10% of the volume and a dew point ≤-40℃.

[0042] In S7, the mixed acid pickling solution consists of: 15-25% nitric acid, 5-10% hydrofluoric acid, and the remainder is water; a corrosion inhibitor is added to the acid solution, which is either rutin or hexamethylenetetramine, and the amount added is 0.1-0.3% of the total acid solution; after pickling, it is immediately rinsed with high-pressure water at a pressure ≥5MPa and neutralized with sodium carbonate solution, and finally rinsed with pure water and dried with hot air.

[0043] After pickling and drying, a passivation solution is sprayed onto the surface of the steel plate. The passivation solution consists of 100-150 g / L potassium dichromate, 50-80 g / L sulfuric acid, and 30-50 g / L nitric acid. The plate is then immersed at 50-60°C for 5-10 minutes to form a dense chromium-rich oxide film, which further improves the resistance to nitric acid corrosion.

[0044] Please see Figure 4 This application also provides a welding method for welding the tank body of the tank container. The tank body welding adopts tungsten inert gas (TIG) welding, which involves first performing tack welding, then root pass welding, and finally fill and cover pass welding. The welding parameters for the tack welding are as follows: welding current 100-120A, arc voltage 10-12V, welding speed 70-100mm / min, and maximum heat input not exceeding 1.27KJ / mm. The welding parameters for the root pass welding are as follows: welding current 90-100A, arc voltage 12... The welding parameters for the filler and cover welds are as follows: welding current 100-120A, arc voltage 12-15V, welding speed 60-90mm / min, and maximum heat input not exceeding 1.8KJ / mm. To match the corrosion-resistant stainless steel hot-rolled steel plate, the welding parameters must be strictly within the above range. If the welding parameters are not within the above range, the welding process will cause excessive deformation of the corrosion-resistant stainless steel hot-rolled steel plate, affecting the welding accuracy.

[0045] like Figure 4 As shown, the tank body of the tank container is welded using tungsten inert gas (TIG) welding, with an argon content of 99.99% in the protective gas and a gas flow rate of 10-14 L / min.

[0046] like Figure 4 As shown, the welding material used is WZ1913SiNL welding wire with a diameter of 2.4mm.

[0047] like Figure 4 As shown, the welding groove adopts a 60° V-shaped groove with a groove depth of 8mm and an inter-root gap of 1-2mm, resulting in good welding strength.

[0048] The present application will be further described in detail below with reference to specific embodiments, but the scope of protection of the present application is not limited thereto. All embodiments use electric arc furnace + LF + VOD process for smelting, and the chemical composition is controlled within the range of Table 1 (weight %): Table 1 Chemical Composition of Examples Example 1:

[0049] Smelting: A 100t electric arc furnace is used for primary smelting. Ferrosilicon, ferrochrome, nickel plates, and low-carbon ferromanganese are added during tapping for alloying. The steel is then refined in an LF furnace to produce white slag for desulfurization. Finally, it undergoes vacuum refining in a VOD furnace, with the vacuum level controlled at 50Pa and the refining time at 40 minutes. During the later stages of refining, 300m of CaSi wire is fed into the molten steel, controlling the oxygen content to 12ppm and the calcium content to 15ppm. Argon soft blowing is performed for 15 minutes before continuous casting.

[0050] Continuous casting: A 230mm thick slab continuous casting machine is used, with a tundish superheat of 28℃ and a casting speed of 1.0m / min. A long nozzle and protective slag are used throughout the process to prevent secondary oxidation.

[0051] Heating: The slab is fed into a walking beam furnace. The preheating section is 900℃ (60 min), the heating section is 1230℃ (90 min), and the soaking section is 1200℃ (40 min). The furnace atmosphere is controlled as a weakly oxidizing atmosphere with an excess air coefficient of 1.05 to prevent carburization. The temperature uniformity of the slab upon exiting the furnace is ≤15℃.

[0052] Hot rolling: (Rough rolling) The initial rolling temperature is 1100℃, and after 5 passes, the cumulative deformation is 75%, breaking down the coarse cast structure. (Finish rolling) is carried out on a 7-stand continuous rolling mill, and the final rolling temperature is controlled at 920℃ (in the austenite non-recrystallization region). The work roll bending technology is used to control the plate crown, and the total deformation of finish rolling is 80%.

[0053] Descaling: Before finishing rolling, use 25MPa high-pressure water to descaling and remove secondary iron oxide scale.

[0054] Cooling and winding: Laminar flow cooling is initiated immediately after rolling, with a cooling rate of 50℃ / s in the front section and 20℃ / s in the rear section. Winding is performed when the temperature reaches 600℃. The winding tension is set to 50kN, and a fully automatic winding roller is used.

[0055] Heat treatment: After uncoiling, the hot-rolled coil is fed into a continuous annealing furnace at 1100℃ for 2 hours (based on a plate thickness of 20mm). A protective gas mixture of 5% H2 and 95% N2 is introduced into the furnace, with a dew point of -50℃. After annealing, water quenching is used for cooling at a rate >40℃ / s.

[0056] Pickling and passivation: Pickling: A mixed acid tank was used. The acid solution formula was: 20% HNO3 + 8% HF + 72% H2O, with 0.2% rutin corrosion inhibitor added. The pickling temperature was 55℃, and the time was 10 minutes. After pickling, the mixture was rinsed with 5MPa high-pressure water and neutralized with Na2CO3 solution.

[0057] Passivation: After pickling, immerse in passivation solution (potassium dichromate 120g / L + sulfuric acid 60g / L + nitric acid 40g / L) at 55℃ for 8 minutes to form a chromium-rich passivation film.

[0058] Finishing: trimming, straightening, and surface polishing to obtain the finished steel plate.

[0059] Examples 2 and 3 were carried out using a process similar to that of Example 1, with only minor adjustments to the heating temperature based on the composition (in Example 3, the heating temperature was increased to 1250°C due to the higher Si content).

[0060] Performance testing: The above embodiments and comparative examples were subjected to the following tests, and the results are shown in Table 2: Intergranular corrosion test: according to GB / T 4334-2020, boiling method with 65% nitric acid (120 hours).

[0061] Corrosion rate: The weight loss method was used, and the test conditions were 65% HNO3 boiling solution and 98% HNO3 50℃ solution.

[0062] Metallographic structure: observed under an optical microscope.

[0063] Hot-rolled edge crack rate: The number of edge cracks per 1000-meter rolling length.

[0064] Table 2: Performance Test Results

[0065] Results analysis: Example 1 (corresponding to the customer-supplied composition) exhibited the best corrosion resistance, with a corrosion rate far lower than the industry standard (typically required to be <1.0 mm / a), indicating that this corrosion-resistant stainless steel hot-rolled sheet is suitable for tank containers. This is due to the extremely low S content (0.001%) which reduces pitting corrosion sources, and the precise Cr / Ni / Si ratio.

[0066] Comparative Example 1 used the composition of traditional high-silicon steel (high C, low Si). Although Si has a certain effect, the high C content leads to unqualified intergranular corrosion and high hot-rolled edge cracking rate.

[0067] Although Comparative Example 2 had a low C content, its S content was as high as 0.015%, which led to an increase in pitting corrosion and a significant increase in corrosion rate, demonstrating the importance of ultra-low sulfur.

[0068] Although the Si content in Example 3 was as high as 4.10%, hot rolling cracks were successfully avoided by increasing the heating temperature to 1250°C, demonstrating the inclusiveness of the process in this application for high silicon content.

[0069] In addition, this application has also undergone tensile testing, such as Figure 2 and Figure 3 As shown, Figure 2 This is a tensile curve of the corrosion-resistant stainless steel hot-rolled sheet prepared in this application at room temperature. Figure 3 Tensile curve of the corrosion-resistant stainless steel hot-rolled sheet prepared for this application at high temperature; Explain the following conclusions: 1. Excellent room temperature mechanical properties, meeting the requirements of conventional structures. High strength: Figure 2 The peak value (tensile strength) of the curve corresponds to a large load (longitudinal force value close to 70 kN), and there is a clear yield plateau and strengthening stage, indicating that the material can withstand high loads and undergo significant plastic deformation at room temperature.

[0070] Good plasticity: large transverse displacement / deformation before fracture ( Figure 2 The transverse axis extends to more than 60 mm, indicating high elongation after fracture. The material has excellent ductility at room temperature and is not prone to brittle fracture.

[0071] The elastic behavior is well-defined: the slope (elastic modulus) of the initial straight segment of the curve is stable, reflecting that the material has high stiffness and controllable elastic deformation at room temperature.

[0072] 2. Excellent high-temperature mechanical properties retention, suitable for high-temperature operating conditions. Although the intensity has decreased, reserves are still available: Figure 3 The peak tensile strength decreased significantly at medium and high temperatures (the longitudinal force was only about 8kN), but the curve still showed a complete elastic-plastic-strengthening-fracture process without the phenomenon of "instantaneous brittle fracture", indicating that the material still retains a certain strength reserve at high temperatures.

[0073] Incomplete loss of plasticity: transverse deformation before high-temperature fracture ( Figure 3 Although the horizontal axis extends to 27 mm, which is less than room temperature, it does not drop sharply to zero, indicating that the material still has the ability to undergo plastic deformation at high temperatures, thus avoiding the risk of high-temperature brittle failure.

[0074] High-temperature stability verification: Combined with the "resistance to nitric acid corrosion" characteristic, it shows that the material can still maintain structural integrity in a high-temperature and corrosive environment (synergistic effect of mechanical properties and corrosion resistance), making it suitable for tank containers.

[0075] This application also provides a tank container body made of corrosion-resistant stainless steel hot-rolled steel plate as described above, which eliminates the need for a special inner lining, reduces assembly steps, and improves assembly efficiency.

[0076] Any numerical values ​​cited herein include all values ​​ranging from a lower limit to an upper limit, increasing by one unit, with at least two units between any lower and any higher value. For example, if the quantity of a component or the value of a process variable (e.g., temperature, pressure, time, etc.) is described as being from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in this specification. For values ​​less than 1, a unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1, etc. These are merely examples intended for explicit expression, and it can be assumed that all possible combinations of values ​​listed between the minimum and maximum values ​​are explicitly described in this specification in a similar manner.

[0077] Unless otherwise stated, all ranges include the endpoints and all numbers between them. The terms "approximately" or "about" used with ranges apply to both endpoints of the range. Thus, "approximately 20 to 30" is intended to cover "approximately 20 to approximately 30," including at least the specified endpoints.

[0078] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute included by “may” is optional.

[0079] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0080] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the appended claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the inventors have not considered that subject matter as part of the disclosed subject matter.

Claims

1. A corrosion-resistant stainless steel hot-rolled sheet, characterized in that, By weight, it includes 0.010~0.015% carbon (C), 0.30~0.60% manganese (Mn), 3.50~4.20% silicon (Si), ≤0.030% phosphorus (P), ≤0.005% sulfur (S), 13.50~14.50% nickel (Ni), 13.50~14.50% chromium (Cr), with the remainder being unavoidable impurities.

2. A method for preparing corrosion-resistant stainless steel hot-rolled sheet as described in claim 1, characterized in that, Includes the following steps: S1. Smelting and refining: Smelting is carried out according to the weight percentage of chemical composition. The primary smelting is carried out in an electric arc furnace or converter, followed by LF furnace refining and VD / VOD vacuum refining. The vacuum degree is controlled below 100Pa. During the refining process, the composition of ferrosilicon, ferrochrome, nickel plate and low carbon ferromanganese is finely adjusted to ensure uniform composition. S2. Continuous casting: Molten steel is cast into slabs using full-process protective casting. The superheat of the tundish is controlled at 20~35℃, the casting speed is controlled at 0.8~1.2m / min, and the slab thickness is 200~250mm. S3. Heating: The slab is sent into the heating furnace and the heating temperature is controlled at 1150~1250℃. The holding time is calculated according to the slab thickness of 1.5~2.5min / mm to ensure that the temperature of the core of the slab is uniform and the temperature of the heat soaking zone is not lower than 1180℃. S4. Hot rolling: The roughing and finishing rolling process is adopted. The initial rolling temperature is ≥1050℃. The roughing stage is carried out in 3~5 passes with a cumulative deformation of ≥70%. The finishing stage is carried out in the non-recrystallized austenite region, and the final rolling temperature is controlled at 850~950℃. S5. Laminar flow cooling and coiling: Laminar flow cooling is performed immediately after rolling, with the cooling rate controlled at 30~60℃ / s. Coiling is carried out after cooling to the coiling temperature of 550~650℃. S6. Annealing and solution treatment: The hot-rolled coil is annealed at a temperature of 1050~1150℃ for 1~3 hours. Then it is cooled by water quenching or rapid air cooling at a rate of ≥30℃ / s to allow carbides to fully precipitate and fix the austenitic structure. S7. Pickling and Finishing: Pickling is performed using a mixture of nitric acid and hydrofluoric acid at a temperature of 40~60℃ to remove iron oxide scale. Subsequently, edge trimming, straightening, and surface polishing are carried out to obtain the finished corrosion-resistant stainless steel hot-rolled steel plate.

3. The preparation method according to claim 2, characterized in that, In S1, during the VD / VOD vacuum refining stage, a strong stirring mode is adopted, with a stirring intensity of 0.5~1.0 Nm³ / min·t, and the refining time is not less than 30 minutes. Calcium treatment is carried out in the later stage of refining, and a silicon-calcium wire is fed in to control the oxygen content in the molten steel to ≤15ppm and the calcium content to 10~20ppm.

4. The preparation method according to claim 2, characterized in that, In S3, the slab is heated in a segmented heating system in the heating furnace. The temperature of the preheating section is 800~900℃, the temperature of the heating section is 1200~1250℃, and the temperature of the soaking section is 1180~1220℃. During the heating process, the atmosphere in the furnace is controlled to be a weakly oxidizing or neutral atmosphere, and the H2O content in the furnace gas is controlled to be ≤3%.

5. The preparation method according to claim 2, characterized in that, In step S6, the annealing process is carried out in a continuous annealing furnace or a bell-type furnace. If continuous annealing is used, the protective gas in the furnace is a mixture of high-purity nitrogen and hydrogen, with hydrogen accounting for 5~10% of the volume and a dew point ≤-40℃.

6. The preparation method according to claim 2, characterized in that, In step S7, the mixed acid pickling solution consists of: 15-25% nitric acid, 5-10% hydrofluoric acid, and the remainder is water; a corrosion inhibitor is added to the acid solution, which is either rutin or hexamethylenetetramine, and the amount added is 0.1-0.3% of the total acid solution; after pickling, it is immediately rinsed with high-pressure water at a pressure ≥5MPa and neutralized with sodium carbonate solution, and finally rinsed with pure water and dried with hot air.

7. A tank-type container body, characterized in that, The tank body is made of corrosion-resistant stainless steel hot-rolled steel plate prepared by any one of the preparation methods described in claims 2-6.

8. A welding method, characterized in that, The method involves welding the tank body of the tank container as described in claim 7. The tank body welding adopts tungsten inert gas welding process, first performing tack welding, then performing root pass welding, and finally performing filler welding. The welding parameters for the tack welding are as follows: welding current 100-120A, arc voltage 10-12V, welding speed 70-100mm / min, and maximum heat input not exceeding 1.27KJ / mm. The welding parameters for the root pass are as follows: welding current 90-100A, arc voltage 12-15V, welding speed 70-100mm / min, and maximum heat input not exceeding 1.41KJ / mm. The welding parameters for the filler and cover welds are as follows: welding current 100-120A, arc voltage 12-15V, welding speed 60-90mm / min, and maximum heat input not exceeding 1.8KJ / mm.

9. The welding method according to claim 8, characterized in that, The tank body of the tank container is welded using tungsten inert gas (TIG) welding, with an argon content of 99.99% in the protective gas and a gas flow rate of 10-14 L / min.

10. The welding method according to claim 8, characterized in that, The welding material used is WZ1913SiNL welding wire with a diameter of 2.4mm.

11. The welding method according to claim 8, characterized in that, The welding groove adopts a 60° V-shaped groove.

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