Rolling method of rare-earth high-strength low-temperature-resistant wind power flange steel

Abstract

The invention discloses a rolling method of rare-earth high-strength low-temperature-resistant wind power flange steel, which comprises the following steps: (1) the specification of low-temperature-resistant wind power flange hot-rolled round steel is phi 100mm-phi 200mm, and adopted continuous casting blanks are 280 * 380mm and 320 * 415mm; (2) different heating systems are determined according to different specifications of the continuous casting billets, the preheating section is smaller than or equal to 850 DEG C, the first heating section is 1080-1180 DEG C, the second heating section is 1120-1220 DEG C, the soaking section is 1130-1220 DEG C, slow heating is adopted in the heating sections, overburning or overheating is forbidden, and it is guaranteed that the internal temperature and the external temperature of the continuous casting billets are uniform; and (3) the initial rolling temperature of the continuous casting billet is controlled to be 1050-1180 DEG C, and the final rolling temperature is controlled to be more than or equal to 850 DEG C. No surface crack defect is found on the surface of the hot-rolled round steel, and the mechanical properties of the hot-rolled round steel meet the requirements that the yield strength is larger than or equal to 390, the tensile strength is 580-650 MPa, and the ductility is larger than or equal to 20%.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling, and in particular relates to a method for rolling rare earth high-strength and low-temperature resistant steel for wind power flanges. Background Art

[0002] With the rapid growth of wind power generation, the market demand for wind turbine towers is increasing, and the importance of the key connecting parts of wind turbine towers - tower flanges - is also receiving more and more attention.

[0003] Wind turbine tower flange is the key connection, support and stress-bearing part of wind turbine tower, and is an important part of wind power generation equipment, which has very strict requirements for production and manufacturing. The main reason is that the flange must be used reliably in the field for more than 20 years, and withstand various extremely severe weather and complex wind alternating loads, and bear the forces of tension, bending and shearing for a long time. If the product does not have superior low-temperature impact resistance and the company does not have stable quality assurance capabilities, it is hard to imagine that it will bring unpredictable disasters to the long-term stable operation of wind turbines.

[0004] Wind power flange steel working under complex low temperature conditions requires high strength, high low temperature impact toughness, good surface quality, internal quality and excellent forming performance. The performance of flange products, especially low temperature impact performance, has been further improved, and rare earth high strength and low temperature resistant wind power flange steel suitable for the market has been developed.

[0005] Rare earth elements have strong chemical activity, variable valence and large atomic size due to their unique outer electron structure, making them deep purifiers of steel, modifiers of inclusions and important microalloying elements of high value-added steel materials. A large number of studies have shown that rare earths can effectively improve the thermal strength, wear / corrosion resistance, fatigue resistance, hot processing performance, low temperature performance, yield rate, oxidation resistance, etc. of steel. Adding 30ppm of rare earth alloys to steel can effectively improve the processing performance, low temperature performance and corrosion resistance of flange steel, thereby improving the comprehensive performance of flange steel. Summary of the invention

[0006] The purpose of the present invention is to provide a rolling method for rare earth high-strength and low-temperature resistant wind power flange steel, and to develop rare earth high-strength and low-temperature resistant wind power flange steel that is suitable for the market.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention discloses a rolling method for rare earth high-strength and low-temperature resistant wind power flange steel, comprising:

[0009] 1) Selection of continuous casting billet

[0010] To ensure that the composition of the finished continuous casting billet meets the user's requirements, determine the reasonable specifications of the continuous casting billet;

[0011] The specifications of hot-rolled round steel for low-temperature resistant wind turbine flanges are Φ100mm-Φ200mm, and the continuous casting billet types used are 280*380mm and 320*415mm;

[0012] 2) Heating process

[0013] Different heating systems are determined according to different specifications of continuous casting billets. The preheating stage is ≤850℃, the first heating stage is 1080~1180℃, the second heating stage is 1120~1220℃, and the soaking stage is 1130~1220℃. The heating stage adopts slow heating, and overburning or overheating is prohibited to ensure uniform temperature inside and outside the continuous casting billet.

[0014] 3) Rolling process

[0015] The continuous casting billet adopts the rolling process of Ф850 billet opening machine and Ф700mm×3+Ф550mm×4 continuous rolling mill group. The starting rolling temperature of the continuous casting billet is controlled at 1050~1180℃, and the final rolling temperature is controlled at ≥850℃.

[0016] Furthermore, the chemical components of the rare earth high-strength and low-temperature resistant wind power flange steel are as follows by mass percentage: C0.13-0.18%, Si 0.15-0.35%, Mn 1.40-1.60%, P≤0.020%, S≤0.015%, Al≤0.020-0.050%, V 0.05-0.08%, Nb 0.02-0.04%, Cr≤0.30%, Cu≤0.30%, Ni≤0.30%, rare earth alloy is added at 30PPm / ton of steel during smelting, [H]≤2.0ppm, [O]≤20ppm, [N]≤120ppm, Al / N≥2, CE≤0.44, and the rest are Fe and unavoidable impurities.

[0017] Furthermore, the continuous casting billet production process is: blast furnace molten iron - molten iron pretreatment - converter top and bottom blowing smelting - LF refining - VD vacuum treatment - continuous casting.

[0018] Furthermore, the rolling process is: heating of ingot - high-pressure water dephosphorization - Ф850 ingot opening machine - Ф700mm×3+Ф550mm×4 continuous rolling mill - sawing (sampling) - stacking (cooling, heat collection) - inspection - grinding - bundling - warehousing - delivery.

[0019] Furthermore, no surface crack defects were found on the surface of the hot-rolled round steel.

[0020] Furthermore, the elongation of the hot-rolled round steel meets ≥20%.

[0021] Furthermore, the mechanical properties of hot-rolled round steel meet the following requirements: yield strength ≥ 390, tensile strength 580-650MPa.

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

[0023] No surface cracks or other defects were found on the surface of the hot-rolled round steel, which fully meets the requirements of the technical agreement; at the same time, it has excellent mechanical properties. DETAILED DESCRIPTION

[0024] The industrial production process is briefly described as follows:

[0025] Ingot heating - high-pressure water dephosphorization - Ф850 ingot opening machine - Ф700mm×3+Ф550mm×4 continuous rolling mill - sawing (sampling) - stacking (cooling, heat collection) - inspection - grinding - bundling - storage - delivery

[0026] More than 20 furnaces have been produced industrially, and the specific process parameters are controlled as follows:

[0027] 1) Heating furnace heating process

[0028] The continuous casting billet is determined according to different specifications based on thermodynamic formulas to determine the reasonable heating time and heating speed.

[0029] Table 1 Heating temperature and soaking time

[0030]

[0031] 2) Rolling process

[0032] In order to ensure product quality and smooth rolling, uniform rolling is adopted and temperature increase rolling is strictly prohibited. Specific parameters are shown in Table 2.

[0033] Table 2 Starting rolling temperature, final rolling temperature and slow cooling pit temperature

[0034]

[0035] 3) Surface quality

[0036] No surface cracks or other defects were found on the surface of the hot-rolled round steel, which fully met the requirements of the technical agreement.

[0037] 4) Performance test

[0038] According to the technical agreement, the hot rolled round steel is subjected to mechanical properties and low temperature impact tests, as follows:

[0039] Table 3 Mechanical properties

[0040]

[0041] Table 4 Impact test results (hot rolled) Unit: J

[0042]

[0043]

[0044] 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 rolling method for rare earth high-strength and low-temperature resistant wind power flange steel, characterized in that: include: 1) Selection of continuous casting billet To ensure that the composition of the finished continuous casting billet meets the user's requirements, determine the reasonable specifications of the continuous casting billet; The specifications of hot-rolled round steel for low-temperature resistant wind turbine flanges are Φ100mm-Φ200mm, and the continuous casting billet types used are 280*380mm and 320*415mm; 2) Heating process Different heating systems are determined according to different specifications of continuous casting billets. The preheating stage is ≤850℃, the first heating stage is 1080~1180℃, the second heating stage is 1120~1220℃, and the soaking stage is 1130~1220℃. The heating stage adopts slow heating, and overburning or overheating is prohibited to ensure uniform temperature inside and outside the continuous casting billet. 3) Rolling process The continuous casting billet adopts the rolling process of Ф850 billet opening machine and Ф700mm×3+Ф550mm×4 continuous rolling mill group. The starting rolling temperature of the continuous casting billet is controlled at 1050~1180℃, and the final rolling temperature is controlled at ≥850℃.

2. The rolling method of rare earth high-strength and low-temperature resistant wind power flange steel according to claim 1 is characterized in that: The chemical components of the rare earth high-strength and low-temperature resistant wind power flange steel are as follows by mass percentage: C 0.13-0.18%, Si 0.15-0.35%, Mn 1.40-1.60%, P≤0.020%, S≤0.015%, Al≤0.020-0.050%, V 0.05-0.08%, Nb 0.02-0.04%, Cr≤0.30%, Cu≤0.30%, Ni≤0.30%, rare earth alloy is added at 30PPm / ton of steel during smelting, [H]≤2.0ppm, [O]≤20ppm, [N]≤120ppm, Al / N≥2, CE≤0.44, and the rest are Fe and unavoidable impurities.

3. The rolling method of rare earth high-strength and low-temperature resistant wind power flange steel according to claim 1 is characterized in that: The production process of continuous casting billets is: blast furnace molten iron - molten iron pretreatment - converter top and bottom blowing smelting - LF refining - VD vacuum treatment - continuous casting.

4. The rolling method of rare earth high-strength and low-temperature resistant wind power flange steel according to claim 1 is characterized in that: The rolling process is: heating of ingot - high-pressure water dephosphorization - Ф850 ingot opening machine - Ф700mm×3+Ф550mm×4 continuous rolling mill - sawing (sampling) - stacking (cooling, heat collection) - inspection - grinding - bundling - warehousing - delivery.

5. The rolling method of rare earth high-strength and low-temperature resistant wind power flange steel according to claim 1 is characterized in that: No surface crack defects were found on the surface of the hot-rolled round steel.

6. The rolling method of rare earth high-strength and low-temperature resistant wind power flange steel according to claim 1 is characterized in that: The elongation of hot-rolled round steel shall be ≥20%.

7. The rolling method of rare earth high-strength and low-temperature resistant wind power flange steel according to claim 1 is characterized in that: The mechanical properties of hot-rolled round steel meet the following requirements: yield strength ≥390, tensile strength 580-650MPa.

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