Production method of 460MPa-grade high-strength steel plate with thickness of 50-80mm for wind power equipment

Abstract

The invention discloses a production method of a 460MPa-grade high-strength steel plate with the thickness of 50-80mm for wind power equipment. The production method comprises the following main process steps and parameters: step 1, smelting and continuous casting production process flow: KR desulfurization, converter treatment, LF refining, RH vacuum treatment, slab continuous casting and slow cooling; secondly, the plate blank is put into a furnace to be heated; the in-furnace time, the soaking time and the tapping temperature of the plate blank are strictly controlled, the in-furnace time is larger than or equal to 220 min, the soaking time is 30-60 min, and the tapping temperature is 1230 + / -20 DEG C; thirdly, rolling the plate blank, specifically including rough rolling and finish rolling; fourthly, the steel plate is straightened; and 5, quenching and tempering heat treatment of the steel plate. The method is simple to operate and suitable for industrial production. The quenched and tempered steel plate produced through the method is high in strength, good in impact toughness and excellent in forming performance and welding performance, and the mechanical performance and the technological performance meet the technical requirements of users.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical plate production, and in particular relates to a production method of a 50-80mm thick 460MPa grade high-strength steel plate for wind power equipment. Background Art

[0002] At present, the highest strength levels of steel used in wind power are 355MPa and 420MPa. As the capacity of onshore wind turbines increases from 3MW to 6-8MW, the tower needs to provide a higher bearing capacity, and the high strength of the steel plate can reduce the weight of the tower by 8-10%. Some parts of the tower are made of thick (50-80mm) high-strength steel plates, and thicker specifications and higher strength levels of 460MPa wind power steel have begun to be used in engineering. In order to ensure the safety of wind power service, wind power steel must have high strength while also having good low-temperature toughness, forming performance, welding performance and fatigue performance. The steel plates produced using this patent are stronger than 355MPa and 420MPa steel plates, and have excellent low-temperature toughness and fatigue performance, which can meet the needs of 50-80mm thick 460MPa high-strength steel plates for wind power equipment. This method is simple to operate and suitable for industrial production applications. Summary of the invention

[0003] The purpose of the present invention is to provide a method for producing a 50-80mm thick 460MPa high-strength steel plate for wind power equipment, which is simple to operate and suitable for industrial production. The quenched and tempered steel plate produced by the present invention has high strength, good impact toughness, excellent forming performance and welding performance, and the mechanical properties and process performance meet the technical requirements of users.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for producing a 50-80 mm thick 460 MPa high-strength steel plate for wind power equipment, the main process steps and parameters of which include:

[0006] Step 1: Smelting-continuous casting production process, KR desulfurization-converter-LF refining-RH vacuum treatment-slab continuous casting-slow cooling; Among them:

[0007] (1) The sulfur content of molten iron after pretreatment is ≤0.005%. Slag must be removed after desulfurization to ensure that the molten iron contains less slag;

[0008] (2) Use self-produced low-sulfur scrap steel, the converter end point is hit once or the number of re-blowing does not exceed one, and the steel tapping temperature is ≥1610℃;

[0009] (3) LF refining performs slag desulfurization, composition adjustment and temperature raising operations according to the composition and temperature of the molten steel in the converter, so that the composition and temperature of the molten steel meet the requirements of RH and continuous casting;

[0010] (4) RH vacuum treatment time is 20 minutes. After the RH vacuum treatment, the argon flow rate is adjusted to make the molten steel in a soft blowing state, and calcium wire is fed for calcium treatment. After wire feeding, the molten steel [Ca] is 0.0008-0.0025%. After wire feeding, the soft blowing time is ensured to be ≥10 minutes;

[0011] (5) The chemical composition of the molten steel supplied to the casting machine is C: 0.17-0.19%, Si: 0.20-0.30%, Mn: 1.55-1.65%, P: ≤0.010%, S≤0.005%, Al s: 0.020-0.030%, Nb: 0.040-0.050%, Ti: 0.010-0.020%, V: 0.040-0.050%, Ni: 0.35-0.45%; the rest is Fe and impurities; the target superheat of the continuous casting process is 20-35°C, the pouring is protected throughout the process, electromagnetic stirring and light pressure are used, the pulling speed is controlled at 0.9-1.2m / min to ensure the quality of the ingot, and the ingot is slowly cooled in the insulation pit, and the slow cooling time is ≥48 hours;

[0012] Step 2: The slab is put into the furnace for heating; the slab time in the furnace, soaking time and out-of-furnace temperature are strictly controlled, the time in the furnace is ≥220min, the soaking time is 30-60min, and the out-of-furnace temperature is 1230±20℃;

[0013] The third step: slab rolling, including rough rolling and finish rolling;

[0014] (1) Rough rolling: After the billet comes out of the furnace, it is quickly sent to the descaling machine to remove the iron oxide scale. The rough rolling is completed with as few passes as possible. The starting temperature of the rough rolling is ≥1050℃, and the final thickness of the rough rolling is 3-4 times that of the finished product;

[0015] (2) Finishing rolling and laminar cooling. After rough rolling, the slab is kept warm, rolling is carried out away from the recrystallization zone to avoid mixed crystals. The starting temperature of finishing rolling is 880±15℃-900±15℃, the final rolling temperature of finishing rolling is 820±10℃, and the final cooling temperature of laminar cooling is 650±20℃;

[0016] Step 4: Steel plate straightening, according to the steel plate thickness specifications and the actual plate shape after cooling;

[0017] Step 5: Steel plate tempering heat treatment (quenching + high temperature tempering), quenching process: temperature 880±10℃, holding time 20 minutes; tempering process: 650-680±10℃, holding time 40 minutes.

[0018] Furthermore, the mass percentage of the chemical composition of the steel plate is C: 0.17%, Si: 0.22%, Mn: 1.60%, P: 0.009%, S: 0.002%, Als: 0.024%, Nb: 0.040%, Ti: 0.016%, V: 0.040%, Ni: 0.40%, and the rest is Fe and unavoidable impurities.

[0019] Furthermore, the mass percentage of the chemical composition of the steel plate is C: 0.18%, Si: 0.25%, Mn: 1.55%, P: 0.008%, S: 0.001%, Als: 0.021%, Nb: 0.045%, Ti: 0.015%, V: 0.045%, Ni: 0.42%, and the rest is Fe and unavoidable impurities.

[0020] Furthermore, the mass percentage of the chemical composition of the steel plate is C: 0.16%, Si: 0.20%, Mn: 1.58%, P: 0.010%, S: 0.001%, Als: 0.025%, Nb: 0.048%, Ti: 0.016%, V: 0.043%, Ni: 0.38%, and the rest is Fe and unavoidable impurities.

[0021] Furthermore, the mass percentage of the chemical composition of the steel plate is C: 0.18%, Si: 0.28%, Mn: 1.60%, P: 0.009%, S: 0.002%, Als: 0.025%, Nb: 0.043%, Ti: 0.017%, V: 0.043%, Ni: 0.44%, and the rest is Fe and unavoidable impurities.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] The operation method of the invention is simple and suitable for industrial production.

[0024] At the same time, the steel plate produced by the present invention has high strength, good impact toughness, excellent forming performance and welding performance, and the mechanical properties and process performance meet the technical requirements of users. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 This is the microstructure diagram of the steel plate according to Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in more detail below through specific examples. The examples are merely descriptions of the best mode of implementation of the present invention and do not limit the scope of the present invention in any way.

[0028] Example 1

[0029] The molten iron is pre-treated for desulfurization, and the top and bottom combined blowing converter is used to decarbonize and dephosphorize the molten iron to obtain molten steel. Argon is blown throughout the converter smelting process, scrap steel is added to the converter, and the converter tapping temperature is 1630℃. Then the molten steel after converter smelting is subjected to LF refining outside the furnace, and the refining temperature is ≥1560℃. After LF refining outside the furnace, the molten steel is subjected to RH vacuum treatment, and the vacuum time is maintained for ≥10min. The slab is continuously cast according to the smelting chemical composition shown in Table 1, with an overheat of 24℃, followed by slab cleaning, slow cooling, and continuous casting billet quality inspection. The slab heating temperature is 1220℃, the heating time is 240min, and the soaking time is 50min. The heated slab is dephosphorized with high-pressure water. After descaling, rolling is carried out. Rough rolling and finishing rolling are both carried out using a 2-roll reversible rolling mill. The starting temperature of rough rolling is 1185℃, and the intermediate billet thickness is rolled to wait for temperature. The average starting temperature of finishing rolling is 910℃, and the average final rolling temperature of finishing rolling is 825℃. After final rolling, laminar cooling is carried out, and the average final cooling temperature is 665℃. The finished product thickness is 40.0mm, and then straightening is carried out. Finally, quenching and tempering heat treatment is carried out, quenching process: temperature 880℃, holding time 20 minutes; tempering process: 680℃, holding time 40 minutes.

[0030] Example 2

[0031] The molten iron is pre-treated for desulfurization, and the top and bottom combined blowing converter is used to decarbonize and dephosphorize the molten iron to obtain molten steel. Argon is blown throughout the converter smelting process, scrap steel is added to the converter, and the converter tapping temperature is 1640℃. Then the molten steel after converter smelting is subjected to LF refining outside the furnace, and the refining temperature is ≥1555℃. After LF refining outside the furnace, the molten steel is subjected to RH vacuum treatment, and the vacuum time is maintained for ≥10min. The slab is continuously cast according to the smelting chemical composition shown in Table 1, with an overheat of 27℃, followed by slab cleaning, slow cooling, and continuous casting billet quality inspection. The slab heating temperature is 1230℃, the heating time is 245min, and the soaking time is 55min. The heated slab is dephosphorized with high-pressure water. After descaling, rolling is carried out. Rough rolling and finishing rolling are both carried out using a 2-roll reversible rolling mill. The starting temperature of rough rolling is 1170℃, and the intermediate billet thickness is rolled to wait for temperature. The average starting temperature of finishing rolling is 900℃, and the average final rolling temperature of finishing rolling is 820℃. After final rolling, laminar cooling is carried out, and the average final cooling temperature is 660℃. The finished product thickness is 48.0mm, and then straightening is carried out. Finally, quenching and tempering heat treatment is carried out, quenching process: temperature 880℃, holding time 20 minutes; tempering process: 680℃, holding time 40 minutes.

[0032] Example 3

[0033] The molten iron is pre-treated for desulfurization, and the top and bottom combined blowing converter is used to decarbonize and dephosphorize the molten iron to obtain molten steel. Argon is blown throughout the converter smelting process, scrap steel is added to the converter, and the converter tapping temperature is 1632°C. Then the molten steel after converter smelting is subjected to LF refining outside the furnace, and the refining temperature is ≥1560°C. After LF refining outside the furnace, the molten steel is subjected to RH vacuum treatment, and the vacuum time is maintained for ≥10min. The slab is continuously cast according to the smelting chemical composition shown in Table 1, with an overheat of 28°C, followed by slab cleaning, slow cooling, and continuous casting slab quality inspection. The slab heating temperature is 1220°C, the heating time is 250min, and the soaking time is 50min. The heated slab is dephosphorized by high-pressure water. After descaling, rolling is carried out. Rough rolling and finishing rolling are both carried out using a 2-roll reversible rolling mill. The starting temperature of rough rolling is 1175℃, and the intermediate billet thickness is rolled to wait for temperature. The average starting temperature of finishing rolling is 890℃, and the average final temperature of finishing rolling is 820℃. After final rolling, laminar cooling is carried out, and the average final cooling temperature is 640℃. The finished product thickness is 62.0mm, and then straightening is carried out. Finally, quenching and tempering heat treatment is carried out, quenching process: temperature 880℃, holding time 20 minutes; tempering process: 650℃, holding time 40 minutes.

[0034] Example 4

[0035] The molten iron is pre-treated for desulfurization, and the top and bottom combined blowing converter is used to decarbonize and dephosphorize the molten iron to obtain molten steel. Argon is blown throughout the converter smelting process, scrap steel is added to the converter, and the converter tapping temperature is 1650℃. Then the molten steel after converter smelting is subjected to LF refining outside the furnace, and the refining temperature is ≥1554℃. After LF refining outside the furnace, the molten steel is subjected to RH vacuum treatment, and the vacuum time is maintained for ≥10min. The slab is continuously cast according to the smelting chemical composition shown in Table 1, with an overheat of 26℃, followed by slab cleaning, slow cooling, and continuous casting billet quality inspection. The slab heating temperature is 1225℃, the heating time is 240min, the soaking time is 60min, and the heated slab is dephosphorized by high-pressure water. After descaling, rolling is carried out. Rough rolling and finishing rolling are both carried out using a 2-roll reversible rolling mill. The starting temperature of rough rolling is 1170℃, and the intermediate billet thickness is rolled to wait for temperature. The average starting temperature of finishing rolling is 880℃, and the average final temperature of finishing rolling is 810℃. After final rolling, laminar cooling is carried out, and the average final cooling temperature is 635℃. The finished product thickness is 79.0mm, and then straightening is carried out. Finally, quenching and tempering heat treatment is carried out, quenching process: temperature 880℃, holding time 20 minutes; tempering process: 650℃, holding time 40 minutes.

[0036] It should be noted that all similar changes directly derived or associated from the contents disclosed in the present invention by those skilled in the art should fall within the protection scope of the present invention.

[0037] Table 1 Chemical composition of Examples 1 to 4 of the present invention (wt%)

[0038] Example C Si Mn P S Als Nb Ti V Ni 1 0.17 0.22 1.60 0.009 0.002 0.024 0.040 0.016 0.040 0.40 2 0.18 0.25 1.55 0.008 0.001 0.021 0.045 0.015 0.045 0.42 3 0.16 0.20 1.58 0.010 0.001 0.025 0.048 0.016 0.043 0.38 4 0.18 0.28 1.60 0.009 0.002 0.025 0.043 0.017 0.043 0.44

[0039] Table 2 Mechanical properties and process properties of Examples 1 to 4 of the present invention

[0040]

[0041] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing a 50-80 mm thick 460 MPa high-strength steel plate for wind power equipment, characterized in that: The main process steps and parameters include: Step 1: Smelting-continuous casting production process, KR desulfurization-converter-LF refining-RH vacuum treatment-slab continuous casting-slow cooling; Among them: (1) The sulfur content of molten iron after pretreatment is ≤0.005%. Slag must be removed after desulfurization to ensure that the molten iron contains less slag; (2) Use self-produced low-sulfur scrap steel, the converter end point is hit once or the number of re-blowing does not exceed one, and the steel tapping temperature is ≥1610℃; (3) LF refining performs slag desulfurization, composition adjustment and temperature raising operations according to the composition and temperature of the molten steel in the converter, so that the composition and temperature of the molten steel meet the requirements of RH and continuous casting; (4) RH vacuum treatment time is 20 minutes. After the RH vacuum treatment, the argon flow rate is adjusted to make the molten steel in a soft blowing state, and calcium wire is fed for calcium treatment. After wire feeding, the molten steel [Ca] is 0.0008-0.0025%. After wire feeding, the soft blowing time is ensured to be ≥10 minutes; (5) The chemical composition of the molten steel supplied to the casting machine is C: 0.17-0.19%, Si: 0.20-0.30%, Mn: 1.55-1.65%, P: ≤0.010%, S≤0.005%, Als: 0.020-0.030%, Nb: 0.040-0.050%, Ti: 0.010-0.020%, V: 0.040-0.050%, Ni: 0.35-0.45%; the rest is Fe and impurities; the target superheat of the continuous casting process is 20-35°C, the pouring is protected throughout the process, electromagnetic stirring and light pressure are used, the pulling speed is controlled at 0.9-1.2m / min to ensure the quality of the ingot, and the ingot is slowly cooled in the insulation pit, and the slow cooling time is ≥48 hours; Step 2: The slab is put into the furnace for heating; the slab time in the furnace, soaking time and out-of-furnace temperature are strictly controlled, the time in the furnace is ≥220min, the soaking time is 30-60min, and the out-of-furnace temperature is 1230±20℃; The third step: slab rolling, including rough rolling and finish rolling; (1) Rough rolling: After the billet comes out of the furnace, it is quickly sent to the descaling machine to remove the iron oxide scale. The rough rolling is completed with as few passes as possible. The starting temperature of the rough rolling is ≥1050℃, and the final thickness of the rough rolling is 3-4 times that of the finished product; (2) Finishing rolling and laminar cooling. After rough rolling, the slab is kept warm, rolling is carried out away from the recrystallization zone to avoid mixed crystals. The starting temperature of finishing rolling is 880±15℃-900±15℃, the final rolling temperature of finishing rolling is 820±10℃, and the final cooling temperature of laminar cooling is 650±20℃; Step 4: Steel plate straightening, according to the steel plate thickness specifications and the actual plate shape after cooling; Step 5: Tempering heat treatment of steel plate, quenching process: temperature 880±10℃, holding time 20 minutes; tempering process: 650-680±10℃, holding time 40 minutes.

2. The method for producing a 50-80 mm thick 460 MPa high-strength steel plate for wind power equipment according to claim 1, characterized in that: The mass percentage of the chemical composition of the steel plate is C: 0.17%, Si: 0.22%, Mn: 1.60%, P: 0.009%, S: 0.002%, Als: 0.024%, Nb: 0.040%, Ti: 0.016%, V: 0.040%, Ni: 0.40%, and the rest is Fe and unavoidable impurities.

3. The method for producing a 50-80 mm thick 460 MPa high-strength steel plate for wind power equipment according to claim 1, characterized in that: The chemical composition of the steel plate is in the following mass percentages: C: 0.18%, Si: 0.25%, Mn: 1.55%, P: 0.008%, S: 0.001%, Als: 0.021%, Nb: 0.045%, Ti: 0.015%, V: 0.045%, Ni: 0.42%, and the rest is Fe and unavoidable impurities.

4. The method for producing a 50-80 mm thick 460 MPa high-strength steel plate for wind power equipment according to claim 1, characterized in that: The mass percentage of the chemical composition of the steel plate is C: 0.16%, Si: 0.20%, Mn: 1.58%, P: 0.010%, S: 0.001%, Als: 0.025%, Nb: 0.048%, Ti: 0.016%, V: 0.043%, Ni: 0.38%, and the rest is Fe and unavoidable impurities.

5. The method for producing a 50-80 mm thick 460 MPa high-strength steel plate for wind power equipment according to claim 1, characterized in that: The mass percentage of the chemical composition of the steel plate is C: 0.18%, Si: 0.28%, Mn: 1.60%, P: 0.009%, S: 0.002%, Als: 0.025%, Nb: 0.043%, Ti: 0.017%, V: 0.043%, Ni: 0.44%, and the rest is Fe and unavoidable impurities.

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