Manufacturing method of sulfuric acid corrosion-resistant steel plate with yield strength of 450MPa

Abstract

The invention discloses a manufacturing method of a sulfuric acid corrosion resistant steel plate with yield strength of 450MPa. The manufacturing method is characterized by comprising the following steps: smelting; converter steelmaking; an LF refining furnace; an RH vacuum furnace; casting is conducted; heating the casting blank; rolling is conducted; the steel comprises the following chemical components in percentage by mass: 0.062%-0.085% of C, 0.22%-0.35% of Si, 0.52%-0.72% of Mn, less than or equal to 0.015% of P, less than or equal to 0.0050% of S, 1.02%-1.22% of Cr, 0.16%-0.26% of Ni, 0.21%-0.25% of Cu, 0.065%-0.105% of Sb, 0.015%-0.020% of Ti, 0.0012%-0.020% of Ce and the balance of iron and impurities. The sulfuric acid corrosion-resistant steel with excellent sulfuric acid resistance is obtained by designing the components and matching with a corresponding process.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion-resistant steel, and particularly relates to a manufacturing method of a steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance. Background Art

[0002] There are sulfuric acid corrosion problems in industrial fields such as metallurgy and petrochemical industry. In the steel pipes of coal burners and air heat exchangers, the hot surface is an acidic gas containing SO2 and SO3, and the cold surface is low-temperature air or water. Especially when the steel pipe has cracks or the weld joint is not penetrated, cold water sprays out and forms high-temperature and low-concentration sulfuric acid corrosion with SO2 and SO3 in the flue gas. Therefore, in order to reduce maintenance costs and extend the safe service life of steel structure parts, sulfuric acid corrosion-resistant steel with excellent sulfuric acid corrosion resistance needs to be used.

[0003] The technical content disclosed in the invention "Rare earth alloy steel resistant to sulfuric acid dew point corrosion" (publication number: CN1386886A) is that the composition strengthening elements of the alloy steel are Cu-W-Sn-Re-Sb-Mo, and the composition is: C: ≤0.15%, Si: 0.15% - 1.20%, Mn: 0.30% - 1.50%, Cu: 0.20% - 0.80%, W: 0.10% - 0.60%, Mo: 0.10% - 0.50%, Sn: 0.05% - 0.30%, Sb: 0.05% - 0.30%, RE ≤0.50%, S: ≤0.035%, P: ≤0.035%, and the balance is Fe and impurities; this invention needs to add metal W, and the increased alloy cost is relatively high.

[0004] In the technical solution disclosed in the invention "A kind of steel for resisting sulfuric acid dew point corrosion containing rare earth and its preparation method" (publication number: CN111206178A), the composition of the steel is: C: 0.07% - 0.11%, Si: 0.20% - 0.50%, Mn: 0.40% - 0.65%, P: ≤0.020%, S: ≤0.035%, Al: 0.010% - 0.060%, Cr: 0.85% - 1.10%, Cu: 0.30% - 0.45%, Sb: 0.04% - 0.10%, Ni: 0.15% - 0.35%, RE: 0.001% - 0.010%, and the balance is Fe and impurities. This method is a laboratory die-casting method and cannot be mass-produced in steel mills. The present invention can adapt to most production lines and can be mass-produced.

[0005] In the technical solution disclosed in the invention "Optimization Control Method for Rare Earth Addition Amount of Weathering Steel Containing Rare Earths" (authorization announcement number: CN1194108C), 0.010% - 0.030% rare earth is added to the weathering steel; in this invention, when Cu is added alone, the phenomenon of "copper embrittlement" is likely to occur, the hot rolling process is difficult, and cracking is likely to occur during production, increasing costs and risks. Moreover, the product performance of the steel in this invention is not described. Summary of the Invention

[0006] The purpose of the present invention is to provide a manufacturing method for a steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance, using a steel for sulfuric acid corrosion resistance designed with a rare earth addition component in terms of composition, and cooperating with corresponding smelting, continuous casting, slab heating, rolling, and cooling processes to obtain a steel for sulfuric acid corrosion resistance with excellent sulfuric acid resistance characteristics.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A manufacturing method for a steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance according to the present invention includes:

[0009] Smelting:

[0010] Hot metal desulfurization pretreatment: Spraying desulfurization powder into the torpedo ladle containing hot metal for desulfurization pretreatment, with S ≤ 0.003%.

[0011] Converter steelmaking: Adopting a combined top and bottom blowing process, the tapping temperature of the converter is 1685 ± 10 °C, the basicity R of the final slag ≥ 3.0, and the number of point blows shall not exceed one time.

[0012] LF refining furnace: Ensuring the composition of the molten steel and the temperature > 1610 °C.

[0013] RH vacuum furnace: The vacuum treatment time ≥ 15 min, adding rare earth cerium iron alloy after vacuum treatment, and the soft blowing time ≥ 10 min.

[0014] Casting:

[0015] The whole process of the slab is protected by casting, the casting speed is 1.1 - 1.2 m / min, and dynamic soft reduction and electromagnetic stirring are applied.

[0016] Slab heating:

[0017] The slab heating temperature is 1210 - 1250 °C, and the time in the furnace is 240 - 300 min.

[0018] Rolling:

[0019] Hot rolling adopts two-stage controlled rolling. The starting rolling temperature in the austenite recrystallization zone rolling ≥ 1090 °C, the starting rolling temperature in the austenite non-recrystallization zone rolling is 990 - 1050 °C, the finishing rolling temperature is 855 - 870 °C, and it is rapidly cooled to 640 - 650 °C after rolling.

[0020] The chemical composition of the steel plate in mass percentage is as follows: C: 0.062% - 0.085%, Si: 0.22% - 0.35%, Mn: 0.52% - 0.72%, P: ≤0.015%, S: ≤0.0050%, Cr: 1.02% - 1.22%, Ni: 0.16% - 0.26%, Cu: 0.21% - 0.25%, Sb: 0.065% - 0.105%, Ti: 0.015% - 0.020%, Ce: 0.0012% - 0.020%, Ce / S < 7, and the balance is Fe and unavoidable impurities.

[0021] Furthermore, the thickness of the steel plate is 10 mm - 19 mm.

[0022] Furthermore, the final structure of the product is ferrite + bainite + pearlite.

[0023] Furthermore, the chemical composition of the steel plate in mass percentage is as follows: C: 0.062%, Si: 0.22%, Mn: 0.72%, P: 0.013%, S: 0.0040%, Cr: 1.18%, Ni: 0.16%, Cu: 0.22%, Sb: 0.105%, Ti: 0.015%, Ce: 0.0020%, and the balance is Fe and unavoidable impurities.

[0024] Furthermore, the chemical composition of the steel plate in mass percentage is as follows: C: 0.072%, Si: 0.29%, Mn: 0.68%, P: 0.012%, S: 0.0040%, Cr: 1.12%, Ni: 0.17%, Cu: 0.21%, Sb: 0.095%, Ti: 0.020%, Ce: 0.0019%, and the balance is Fe and unavoidable impurities.

[0025] Furthermore, the chemical composition of the steel plate in mass percentage is as follows: C: 0.085%, Si: 0.34%, Mn: 0.52%, P: 0.012%, S: 0.0050%, Cr: 1.02%, Ni: 0.26%, Cu: 0.25%, Sb: 0.065%, Ti: 0.018%, Ce: 0.0012%, and the balance is Fe and unavoidable impurities.

[0026] Furthermore, the impact performance of the prepared steel plate at -40°C meets the requirement of being greater than 120 J.

[0027] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0028] The manufacturing process of the rare earth sulfate-resistant steel plate of the present invention is simple, with excellent comprehensive performance and good sulfuric acid corrosion resistance, and can be widely used in the manufacture of equipment for service in sulfuric acid environments. Brief Description of the Drawings

[0029] The present invention will be further described below in conjunction with the drawings.

[0030] Figure 1 Microstructure of Example 1;

[0031] Figure 2 Microstructure of Example 2;

[0032] Figure 3 Microstructure of Example 3. Detailed Description of the Invention

[0033] A steel with a yield strength of 450 MPa grade, which has a simple manufacturing process, excellent comprehensive performance, good sulfuric acid corrosion resistance, and can be widely used in the manufacture of equipment for service in sulfuric acid environments. The invention adopts a rare earth addition component design and is combined with corresponding smelting, continuous casting, slab heating, rolling, and cooling processes to obtain a sulfuric acid corrosion-resistant steel with excellent sulfuric acid resistance characteristics.

[0034] The production method specifically includes the following steps:

[0035] 1. Smelting

[0036] Hot metal desulfurization pretreatment: Inject desulfurization powder into the torpedo ladle containing hot metal for desulfurization pretreatment, with S≤0.003%.

[0037] Converter steelmaking: Adopt the combined blowing process of top and bottom blowing. The tapping temperature of the converter is 1685±10°C, the basicity of the final slag R≥3.0, and the number of point blows shall not exceed one.

[0038] LF refining furnace: Ensure the composition and temperature of the molten steel >1610°C.

[0039] RH vacuum furnace: The vacuum treatment time ≥15 min. After vacuum treatment, add rare earth cerium-iron alloy, and the soft blowing time ≥10 min.

[0040] 2. Casting

[0041] The whole process of the slab casting adopts protective casting, with a casting speed of 1.1 - 1.2 m / min, and dynamic soft reduction and electromagnetic stirring are applied.

[0042] 3. Slab heating

[0043] The slab heating temperature is 1210 - 1250°C, and the time in the furnace is 240 - 300 min.

[0044] 4. Rolling

[0045] Hot rolling adopts two-stage controlled rolling. The starting rolling temperature in the austenite recrystallization zone rolling is ≥1090°C, the starting rolling temperature in the austenite non-recrystallization zone rolling is 990 - 1050°C, the finishing rolling temperature is 855 - 870°C, and it is rapidly cooled to 640 - 650°C after rolling. The final structure of the product is ferrite + bainite + pearlite.

[0046] The chemical composition table of the steel in the embodiments of the present invention is shown in Table 1, the main heating and rolling process parameters of the steel in the embodiments of the present invention are shown in Table 2, the properties of the steel in the embodiments of the present invention are shown in Table 3, the full immersion corrosion test results of the steel in the embodiments of the present invention are shown in Table 4, and the microstructure of the steel in the embodiments of the present invention is shown in Figure 1 .

[0047] Table 1: Chemical composition of the steel plate (wt%)

[0048]

[0049] Table 2 Heating and rolling process of the steel plate

[0050]

[0051]

[0052] Table 3: Properties of the steel plate

[0053]

[0054] Table 4 Corrosion test results of the steel strip of the present invention

[0055]

[0056] The embodiments described above are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A manufacturing method of a steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance, characterized in that: Including: Smelting: Hot metal desulfurization pretreatment: Inject desulfurization powder into the torpedo ladle filled with hot metal for desulfurization pretreatment, with S ≤ 0.003%; Converter steelmaking: Adopt the combined blowing process of top and bottom blowing. The tapping temperature of the converter is 1685 ± 10 °C, the basicity of the final slag R ≥ 3.0, and the number of spot blows shall not exceed once; LF refining furnace: Ensure the composition of molten steel and the temperature > 1610 °C; RH vacuum furnace: The vacuum treatment time ≥ 15 min. After vacuum treatment, add rare earth ferrosilicon alloy, and the soft blowing time ≥ 10 min; Casting: The whole process of the casting billet adopts protective casting, the casting speed is 1.1 - 1.2 m / min, and dynamic soft reduction and electromagnetic stirring are applied; Casting billet heating: The heating temperature of the casting billet is 1210 - 1250 °C, and the residence time in the furnace is 240 - 300 min; Rolling: Hot rolling adopts two-stage controlled rolling. The starting rolling temperature in the austenite recrystallization zone rolling ≥ 1090 °C, the starting rolling temperature in the austenite non-recrystallization zone rolling is 990 - 1050 °C, the finishing rolling temperature is 855 - 870 °C, and it is rapidly cooled to 640 - 650 °C after rolling; The chemical composition mass percentage of the said steel plate is: C: 0.062% - 0.085%, Si: 0.22% - 0.35%, Mn: 0.52% - 0.72%, P: ≤ 0.015%, S: ≤ 0.0050%, Cr: 1.02% - 1.22%, Ni: 0.16% - 0.26%, Cu: 0.21% - 0.25%, Sb: 0.065% - 0.105%, Ti: 0.015% - 0.020%, Ce: 0.0012% - 0.020%, Ce / S < 7, and the balance is Fe and inevitable impurities.

2. The manufacturing method of the steel plate for resisting sulfuric acid corrosion with a yield strength of 450 MPa according to claim 1, characterized in that: The thickness of the steel plate is 10 mm - 19 mm.

3. The manufacturing method of the steel plate for resisting sulfuric acid corrosion with a yield strength of 450 MPa according to claim 1, characterized in that: The final structure of the product is ferrite + bainite + pearlite.

4. The manufacturing method of the steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance according to claim 1, characterized in that: The chemical composition mass percentage of the said steel plate is: C: 0.062%, Si: 0.22%, Mn: 0.72%, P: 0.013%, S: 0.0040%, Cr: 1.18%, Ni: 0.16%, Cu: 0.22%, Sb: 0.105%, Ti: 0.015%, Ce: 0.0020%, and the balance is Fe and inevitable impurities.

5. The manufacturing method of the steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance according to claim 1, characterized in that: The chemical composition mass percentage of the said steel plate is: C: 0.072%, Si: 0.29%, Mn: 0.68%, P: 0.012%, S: 0.0040%, Cr: 1.12%, Ni: 0.17%, Cu: 0.21%, Sb: 0.095%, Ti: 0.020%, Ce: 0.0019%, and the balance is Fe and inevitable impurities.

6. The manufacturing method of the steel plate for resisting sulfuric acid corrosion with a yield strength of 450 MPa according to claim 1, characterized in that: The chemical composition mass percentage of the said steel plate is: C: 0.085%, Si: 0.34%, Mn: 0.52%, P: 0.012%, S: 0.0050%, Cr: 1.02%, Ni: 0.26%, Cu: 0.25%, Sb: 0.065%, Ti: 0.018%, Ce: 0.0012%, and the balance is Fe and inevitable impurities.

7. The manufacturing method of the steel plate with a yield strength of 450 MPa for sulfuric acid corrosion resistance according to claim 1, characterized in that: The impact performance of the prepared steel plate at - 40 °C meets the requirement of being greater than 120 J.

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