Rare earth 12Cr1MoV heat-resistant alloy structural steel plate

Abstract

The invention discloses a rare earth 12Cr1MoV heat-resistant alloy structural steel plate which comprises the following chemical components in percentage by weight: 0.11 to 0.13 percent of C, 0.20 to 0.35 percent of Si, 0.40 to 0.65 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.90 to 1.10 percent of Cr, 0.25 to 0.35 percent of Mo, 0.15 to 0.16 percent of V, 0.020 to 0.035 percent of Als, 0.0008 to 0.0020 percent of Ce and the balance of Fe and impurities. The invention also discloses a manufacturing method thereof. The rare earth 12Cr1MoV heat-resisting alloy structural steel plate is produced by adopting reasonable components and combining a specific process, the yield strength is larger than or equal to 265 MPa, the tensile strength is larger than or equal to 450 MPa, the percentage elongation after fracture is larger than or equal to 23%, the impact energy at the temperature of 0 DEG C is larger than or equal to 100 J, and meanwhile the rare earth 12Cr1MoV heat-resisting alloy structural steel plate has the characteristics of being low in yield ratio, heat-resisting and the like.

Description

Technical Field

[0001] This invention belongs to the field of heat-resistant alloy steel technology, and particularly relates to a rare earth 12Cr1MoV heat-resistant alloy structural steel plate. Background Technology

[0002] 12Cr1MoV steel is a low-alloy heat-resistant steel, mainly used in high-temperature components such as steam boilers, steam turbines, and jet engines in the aerospace industry. The addition of Cr, Mo, and V elements ensures good high-temperature strength and chemical stability. Traditional 15CrMo steel plates are produced using controlled rolling and tempering or normalizing and tempering processes, resulting in high production costs. Directly using them to manufacture heat-resistant structural components would increase construction costs. Therefore, there is an urgent need to develop a 12Cr1MoV heat-resistant alloy steel plate that can meet the requirements of heat-resistant conditions while reducing manufacturing costs.

[0003] Chinese patent CN 109321728 A discloses a "rolling method for low-alloy 12Cr1MoV steel plate". It includes billet heating, billet rolling, and post-rolling cooling processes. In the billet rolling process, a high-reduction rolling process is used in the high-temperature stage, with the single-pass reduction controlled at 25-30%. In the post-rolling cooling process, ACC water cooling is used after rolling, controlling the reheat temperature to 740-760℃, producing 12Cr1MoV steel plates with a thickness of 30-60mm. The shortcomings are: firstly, it only provides the rolling method, without providing the chemical composition and other upstream process parameters; secondly, it requires very high-capacity rolling mill equipment, making it unsuitable for other steel mills; and thirdly, the use of ACC cooling after rolling increases the tendency for cracking.

[0004] Chinese patent CN 107099752A discloses "a low-alloy 12Cr1MoV steel plate and its production method," which employs a production process of converter smelting, refining, continuous casting billet heating, controlled rolling, and tempering heat treatment. The produced steel plate exhibits good strength and toughness matching, and all indicators fully meet the standard requirements. The drawback is the need for tempering heat treatment, which increases manufacturing costs.

[0005] Chinese patent CN 112442637 A discloses "a production method for a novel alloy container steel plate, 12Cr1Mo VR". The method includes processes such as hot metal pretreatment, converter smelting, LF refining, vacuum refining, casting, billet heating, normalizing rolling, ACC laminar flow cooling, slow cooling of the steel plate, finishing inspection, and warehousing to produce 12Cr1Mo VR steel plates. A drawback is the large number of process control points. Summary of the Invention

[0006] The purpose of this invention is to provide a rare earth 12Cr1MoV heat-resistant alloy structural steel plate with the following properties: yield strength ≥265MPa, tensile strength ≥450MPa, elongation after fracture ≥23%, impact energy at 0℃ ≥100J, and also has characteristics such as low yield strength ratio and heat resistance.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a rare earth 12Cr1MoV heat-resistant alloy structural steel plate. The chemical composition of the steel plate, by weight percentage, is: C: 0.11-0.13%, Si: 0.20-0.35%, Mn: 0.40-0.65%, P: ≤0.015%, S: ≤0.005%, Cr: 0.90-1.10%, Mo: 0.25-0.35%, V: 0.15-0.16%, Als: 0.020-0.035%, rare earth Ce: 0.0008-0.0020%, with the balance being Fe and unavoidable impurities.

[0009] The process flow and main process parameters of the steel plate manufacturing method are as follows:

[0010] Hot metal pretreatment—converter top and bottom re-blowing smelting—LF ladle refining—RH vacuum degassing—slab continuous casting—insulating pit slow cooling—slab heating—descaling—rough rolling—finish rolling—air cooling—straightening—steel plate placed in a slow cooling hood for 24-36 hours after finishing line—shearing—flaw detection—sampling inspection—finished product warehousing.

[0011] Hot metal pretreatment: The molten iron arriving at the station must have both the front and rear slags removed to ensure that the slag layer thickness on the liquid surface is ≤20mm. After the molten iron is desulfurized by KR stirring, the S content of the molten iron must be ≤0.005%, the desulfurization cycle must be ≤21min, and the desulfurization temperature drop must be ≤20℃.

[0012] Converter smelting: Molten iron input S≤0.005%, P≤0.080%, molten iron temperature≥1270℃; high-quality scrap steel is strictly used; process is strictly controlled; slag basicity R is controlled at 2.5-4.0; tapped steel target P≤0.015%, C≥0.05%, S≤0.012%; deoxidizer and fluorite are added to the ladle during tapping; slag is blocked from the front slag before tapping with a slag plug, and slag is blocked with a slag cone before tapping ends, ensuring slag layer thickness ≤30mm; argon blowing is required throughout the converter tapping process; aluminum wire is added to the argon station, followed by argon blowing and stirring; the temperature away from the argon station must not be lower than 1570℃.

[0013] LF refining process: Argon is blown throughout the refining process; refining slag is added, and the basicity of the refining slag is controlled at 3.0-6.0; during the heating process, the appropriate current is selected for heating according to the rhythm and temperature conditions, and the heating time is controlled twice. During the heating process, deoxidizer is added according to the slag formation. Before leaving the station, a silicon-calcium wire is added. Argon gas must be turned off before adding the silicon-calcium wire. The temperature of molten steel leaving the station is 1610±15℃.

[0014] RH vacuum treatment: This treatment mode significantly reduces the content of hydrogen, oxygen and nitrogen gases in molten steel, and reduces the adverse effects of harmful gases on the steel quality; the vacuum degree is less than 80Pa, the vacuum time is maintained for more than 15 minutes, the pure degassing time is more than 15 minutes, the soft blowing time is more than 15 minutes, and the temperature of molten steel leaving the station is 1610±15℃.

[0015] Slab continuous casting: Dynamic light reduction is used during continuous casting, with light reduction positions at sections 8 and 9, and a total reduction of 7.5-8 mm; electromagnetic stirring is used during continuous casting, with electromagnetic stirring positions at the outlet of section 3 and the inlet of section 4, the electromagnetic stirring frequency at 5 Hz, and the current at 350 A; protective casting is used, and the steel surface must not turn red during the tundish casting process; the argon blowing volume of the stopper rod is reasonably controlled during the steel casting process to ensure that the liquid level in the crystallizer fluctuates slightly; the argon pressure at the long nozzle seal is greater than 0.4 MPa; the argon pressure at the tundish immersion nozzle seal is greater than 0.3 MPa; the superheat of continuous casting is 20-30℃; constant casting speed is used, and the casting speed is stabilized at 0.9 m / min; the billet straightening temperature is 950-1000℃, and the billet is placed in the heat preservation pit for more than 36 hours after leaving the casting line;

[0016] Heating: The heating temperature and heating time are as follows: preheating section temperature ≤900℃, heating section temperature 1220-1240℃, heat preservation section temperature 1200-1220℃, heating rate ≥9min / cm, heat soaking and heating time ≥30min, to ensure uniform steel plate temperature and thorough heating;

[0017] Controlled rolling: The rolling process adopts a two-stage controlled rolling process. The roughing rolling temperature is above 1170℃, and the relative reduction rate of a single pass is controlled at least 15% for at least two passes. During finishing rolling, the deformation of each pass is strictly controlled, with the finishing rolling temperature ≤940℃ and the finishing rolling temperature ≤840℃.

[0018] Slow cooling process: On the one hand, it uses the residual heat after rolling the steel plate to eliminate the internal stress caused by rapid cooling, and at the same time, it can greatly reduce the hydrogen content in the steel plate and improve the internal quality of the steel plate; on the other hand, it uses the heat preservation and slow cooling of the steel plate to achieve the effect of tempering the steel plate; combined with the actual stacking cooling process, the slow cooling temperature is set as follows: for thickness ≤25mm, the slow cooling temperature is ≥400℃, and for thickness >25mm, the slow cooling temperature is ≥500℃, and an insulation cover is added to enhance the tempering effect.

[0019] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.25%, Mn: 0.46%, P: 0.013%, S: 0.002%, Cr: 0.93%, Mo: 0.27%, V: 0.15%, Als: 0.022%, rare earth Ce: 0.0014%, with the balance being Fe and unavoidable impurities.

[0020] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.24%, Mn: 0.52%, P: 0.011%, S: 0.002%, Cr: 0.95%, Mo: 0.26%, V: 0.15%, Als: 0.023%, rare earth Ce: 0.0013%, with the balance being Fe and unavoidable impurities.

[0021] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.23%, Mn: 0.55%, P: 0.010%, S: 0.002%, Cr: 0.98%, Mo: 0.28%, V: 0.16%, Als: 0.023%, rare earth Ce: 0.0015%, with the balance being Fe and unavoidable impurities.

[0022] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.22%, Mn: 0.53%, P: 0.011%, S: 0.001%, Cr: 0.99%, Mo: 0.30%, V: 0.16%, Als: 0.024%, rare earth Ce: 0.0016%, with the balance being Fe and unavoidable impurities.

[0023] Furthermore, the rare earth 12Cr1MoV heat-resistant alloy structural steel plate meets the following requirements: yield strength ≥ 265MPa, tensile strength ≥ 450MPa.

[0024] Furthermore, the rare earth 12Cr1MoV heat-resistant alloy structural steel plate meets the following requirements: elongation after fracture ≥23%, impact energy at 0℃ ≥100J.

[0025] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0026] This invention uses C, Mn, Cr, Mo, and V as the base and a rare earth micro-alloying design system to produce rare earth 12Cr1MoV heat-resistant alloy structural steel plates with a thickness of 10-40mm. The plates have a yield strength ≥265MPa, tensile strength ≥450MPa, elongation after fracture ≥23%, and impact energy at 0℃ ≥100J. They also have low yield strength ratio and heat resistance.

[0027] This invention employs air cooling and a thermal insulation cover for slow cooling, which reduces the strength of the steel plate, improves its plasticity and toughness, effectively improves the shape of the steel plate, and solves the problem of uneven internal stress in the product.

[0028] This invention uses hot rolling process instead of tempering or normalizing + tempering process, which reduces the manufacturing cost per ton of steel by more than 260 yuan. Attached Figure Description

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] Figure 1 The metallographic structure of the steel plate in Example 3 is shown.

[0031] Figure 2 This is the high-temperature tensile specimen from Example 3. Detailed Implementation

[0032] The present invention will now be described in more detail with reference to the accompanying drawings and specific embodiments. These embodiments are merely descriptions of the preferred embodiments of the invention and do not limit the scope of the invention in any way.

[0033] Example 1

[0034] The chemical composition of Example 1 is shown in Table 1. The basicity of the LF refining slag was 4.3, the slag holding time was 30 min, the LF departure temperature was 1620℃, the vacuum degree during the RH refining process was 67 Pa, the vacuum holding time was 20 min, and the tapping temperature after refining was 1570℃. The rolling process and slow cooling process parameters are shown in Table 2.

[0035] Example 2

[0036] The chemical composition of Example 2 is shown in Table 1; the basicity of the white slag in LF refining is 3.8, the white slag holding time is 25 min, the LF departure temperature is 1615℃, the vacuum degree in the RH refining process is 67 Pa, the vacuum holding time is 25 min, and the tapping temperature after refining is 1574℃; the rolling process and slow cooling process parameters are shown in Table 2.

[0037] Example 3

[0038] The chemical composition of Example 2 is shown in Table 1; the basicity of the white slag in LF refining is 4.0, the white slag holding time is 26 min, the LF departure temperature is 1618℃, the vacuum degree in the RH refining process is 67 Pa, the vacuum holding time is 25 min, and the tapping temperature after refining is 1573℃; the rolling process and slow cooling process parameters are shown in Table 2.

[0039] Example 4

[0040] The chemical composition of Example 2 is shown in Table 1; the basicity of the white slag in LF refining is 4.1, the white slag holding time is 28 min, the LF departure temperature is 1615℃, the vacuum degree in the RH refining process is 67 Pa, the vacuum holding time is 25 min, and the tapping temperature after refining is 1575℃; the rolling process and slow cooling process parameters are shown in Table 2.

[0041] Table 1 lists the chemical composition of the examples, and Table 2 lists the rolling process parameters of the examples.

[0042] Table 1 Chemical composition (wt%) of the embodiments of the present invention

[0043] Example C Si Mn P S Cr Mo V Als Ce 1 0.12 0.25 0.46 0.013 0.002 0.93 0.27 0.15 0.022 0.0014 2 0.12 0.24 0.52 0.011 0.002 0.95 0.26 0.15 0.023 0.0013 3 0.12 0.23 0.55 0.010 0.002 0.98 0.28 0.16 0.023 0.0015 4 0.12 0.22 0.53 0.011 0.001 0.99 0.30 0.16 0.024 0.0016

[0044] Table 2 Rolling process parameters of the embodiments of the present invention

[0045] Example steel plate thickness (mm) Roughing rolling temperature / ℃ Finishing rolling start temperature / ℃ Finishing rolling temperature / ℃ Cooling temperature / ℃ Final cooling temperature / ℃ Thermal insulation cover slows down cooling 1 10 1200 929 806 / air cooling 25 hours 2 25 1205 899 803 / air cooling 26 hours 3 35 1203 907 800 / air cooling 30 hours 4 40 1197 909 798 / air cooling 32 hours

[0046] The test results of mechanical properties, low-temperature impact properties, cold bending properties, and heat resistance properties of the steel plate in the embodiments of the present invention are shown in Tables 3 and 4.

[0047] Table 3 Mechanical properties of the steel plates in the embodiments of the present invention

[0048] Example Thickness (mm) Yield strength (MPa) Tensile strength (MPa) The ratio of yield strength Elongation (%) Transverse impact energy at 0℃ (J) cold bending performance 1 10 365 538 0.69 24.5 127、108、176 qualified 2 25 374 538 0.70 25.0 188、172、184 qualified 3 35 388 545 0.71 24.0 156、140、145 qualified 4 40 375 539 0.70 23.0 156、148、167 qualified Technical Requirements ≥265 ≥450 / ≥19 ≥60 180° D=3a

[0049] Table 4. High-temperature heat resistance of steel plates in the embodiments of the present invention at 350℃

[0050] Example Thickness (mm) Yield strength (MPa) Tensile strength (MPa) Elongation (%) 1 10 236 455 25.5 2 25 237 462 25.5 3 35 235 464 24.0 4 40 223 457 25.5 Technical Requirements ≥167

[0051] This invention utilizes a rational chemical composition and a specific process to produce rare-earth 12Cr1MoV heat-resistant alloy structural steel plates with a yield strength ≥265MPa, tensile strength ≥450MPa, elongation after fracture ≥23%, and impact energy at 0℃ ≥100J. It also exhibits low yield-to-tensile ratio and heat resistance. Compared to traditional processes, this invention shortens the overall process flow, reduces production costs, minimizes the online occupation of steel plates, and significantly improves overall logistics, making it highly valuable for widespread application.

[0052] The external inspection rate of steel plates was 100%; the first-level pass rate of flaw detection according to energy standards was 100%, achieving the expected results.

[0053] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A rare earth 12Cr1MoV heat-resistant alloy structural steel plate, characterized in that, The chemical composition of the steel plate, by weight percentage, is: C: 0.11–0.13%, Si: 0.20–0.35%, Mn: 0.40–0.65%, P: ≤0.015%, S: ≤0.005%, Cr: 0.90–1.10%, Mo: 0.25–0.35%, V: 0.15–0.16%, Als: 0.020–0.035%, rare earth Ce: 0.0008–0.0020%, with the balance being Fe and unavoidable impurities; The process flow and main process parameters of the steel plate manufacturing method are as follows: Hot metal pretreatment—converter top and bottom re-blowing smelting—LF ladle refining—RH vacuum degassing—slab continuous casting—insulating pit slow cooling—slab heating—descaling—rough rolling—finish rolling—air cooling—straightening—steel plate placed in a slow cooling hood for 24-36 hours after finishing line—shearing—flaw detection—sampling inspection—finished product warehousing. Hot metal pretreatment: The molten iron arriving at the station must have both the front and rear slags removed to ensure that the slag layer thickness on the liquid surface is ≤20mm. After the molten iron is desulfurized by KR stirring, the S content of the molten iron must be ≤0.005%, the desulfurization cycle must be ≤21min, and the desulfurization temperature drop must be ≤20℃. Converter smelting: Molten iron input S≤0.005%, P≤0.080%, molten iron temperature≥1270℃; high-quality scrap steel is strictly used; process is strictly controlled; slag basicity R is controlled at 2.5-4.0; tapped steel target P≤0.015%, C≥0.05%, S≤0.012%; deoxidizer and fluorite are added to the ladle during tapping; slag is blocked from the front slag before tapping with a slag plug, and slag is blocked with a slag cone before tapping ends, ensuring slag layer thickness ≤30mm; argon blowing is required throughout the converter tapping process; aluminum wire is added to the argon station, followed by argon blowing and stirring; the temperature away from the argon station must not be lower than 1570℃. LF refining process: Argon is blown throughout the refining process; refining slag is added, and the basicity of the refining slag is controlled at 3.0-6.0; during the heating process, the appropriate current is selected for heating according to the rhythm and temperature conditions, and the heating time is controlled twice. During the heating process, deoxidizer is added according to the slag formation. Before leaving the station, a silicon-calcium wire is added. Argon gas must be turned off before adding the silicon-calcium wire. The temperature of molten steel leaving the station is 1610±15℃. RH vacuum treatment: This treatment mode significantly reduces the content of hydrogen, oxygen and nitrogen gases in molten steel, and reduces the adverse effects of harmful gases on the steel quality; the vacuum degree is less than 80Pa, the vacuum time is maintained for more than 15 minutes, the pure degassing time is more than 15 minutes, the soft blowing time is more than 15 minutes, and the temperature of molten steel leaving the station is 1610±15℃. Slab continuous casting: Dynamic light reduction is used during continuous casting, with light reduction positions at sections 8 and 9, and a total reduction of 7.5-8 mm; electromagnetic stirring is used during continuous casting, with electromagnetic stirring positions at the outlet of section 3 and the inlet of section 4, the electromagnetic stirring frequency at 5 Hz, and the current at 350 A; protective casting is used, and the steel surface must not turn red during the tundish casting process; the argon blowing volume of the stopper rod is reasonably controlled during the steel casting process to ensure that the liquid level in the crystallizer fluctuates slightly; the argon pressure at the long nozzle seal is greater than 0.4 MPa; the argon pressure at the tundish immersion nozzle seal is greater than 0.3 MPa; the superheat of continuous casting is 20-30℃; constant casting speed is used, and the casting speed is stabilized at 0.9 m / min; the billet straightening temperature is 950-1000℃, and the billet is placed in the heat preservation pit for more than 36 hours after leaving the casting line; Heating: The heating temperature and heating time are as follows: preheating section temperature ≤900℃, heating section temperature 1220-1240℃, heat preservation section temperature 1200-1220℃, heating rate ≥9min / cm, heat soaking and heating time ≥30min, to ensure uniform steel plate temperature and thorough heating; Controlled rolling: The rolling process adopts a two-stage controlled rolling process. The roughing rolling temperature is above 1170℃, and the relative reduction rate of a single pass is controlled at least 15% for at least two passes. During finishing rolling, the deformation of each pass is strictly controlled, with the finishing rolling temperature ≤940℃ and the finishing rolling temperature ≤840℃. Slow cooling process: On the one hand, it uses the residual heat after rolling the steel plate to eliminate the internal stress caused by rapid cooling, and at the same time, it can greatly reduce the hydrogen content in the steel plate and improve the internal quality of the steel plate; on the other hand, it uses the heat preservation and slow cooling of the steel plate to achieve the effect of tempering the steel plate; combined with the actual stacking cooling process, the slow cooling temperature is set as follows: for thickness ≤25mm, the slow cooling temperature is ≥400℃, and for thickness >25mm, the slow cooling temperature is ≥500℃, and an insulation cover is added to enhance the tempering effect.

2. The rare earth 12Cr1MoV heat-resistant alloy structural steel plate according to claim 1, characterized in that, The chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.25%, Mn: 0.46%, P: 0.013%, S: 0.002%, Cr: 0.93%, Mo: 0.27%, V: 0.15%, Als: 0.022%, rare earth Ce: 0.0014%, with the balance being Fe and unavoidable impurities.

3. The rare earth 12Cr1MoV heat-resistant alloy structural steel plate according to claim 1, characterized in that, The chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.24%, Mn: 0.52%, P: 0.011%, S: 0.002%, Cr: 0.95%, Mo: 0.26%, V: 0.15%, Als: 0.023%, rare earth Ce: 0.0013%, with the balance being Fe and unavoidable impurities.

4. The rare earth 12Cr1MoV heat-resistant alloy structural steel plate according to claim 1, characterized in that, The chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.23%, Mn: 0.55%, P: 0.010%, S: 0.002%, Cr: 0.98%, Mo: 0.28%, V: 0.16%, Als: 0.023%, rare earth Ce: 0.0015%, with the balance being Fe and unavoidable impurities.

5. The rare earth 12Cr1MoV heat-resistant alloy structural steel plate according to claim 1, characterized in that, The chemical composition of the steel plate by weight percentage is C: 0.12%, Si: 0.22%, Mn: 0.53%, P: 0.011%, S: 0.001%, Cr: 0.99%, Mo: 0.30%, V: 0.16%, Als: 0.024%, rare earth Ce: 0.0016%, with the balance being Fe and unavoidable impurities.

6. The rare earth 12Cr1MoV heat-resistant alloy structural steel plate according to claim 1, characterized in that, The rare earth 12Cr1MoV heat-resistant alloy structural steel plate meets the following requirements: yield strength ≥ 265MPa, tensile strength ≥ 450MPa.

7. The rare earth 12Cr1MoV heat-resistant alloy structural steel plate according to claim 1, characterized in that, The rare earth 12Cr1MoV heat-resistant alloy structural steel plate meets the following requirements: elongation after fracture ≥23%, impact energy at 0℃ ≥100J.

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