CN111763880A - Low-yield-ratio ultra-thick hydroelectric high-strength steel plate and manufacturing method thereof - Google Patents
Low-yield-ratio ultra-thick hydroelectric high-strength steel plate and manufacturing method thereof Download PDFInfo
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C21D2211/005—Ferrite
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Abstract
The low-yield-ratio ultra-thick hydroelectric high-strength steel comprises the following chemical components in percentage by mass: c: 0.03 to 0.08%, Si: 0.05 to 0.35%, Mn: 0.60-1.00%, P is less than or equal to 0.012%, S is less than or equal to 0.005%, Cr: 0.50 to 1.00%, Ni: 0.10-0.30%, V: 0.12-0.18%, B: 0.0010-0.0020%, and the balance of Fe and inevitable impurity elements. The low yield ratio ultra-thick hydroelectric high-strength steel produced by the method disclosed by the invention can meet the following requirements: the yield strength ReL is more than or equal to 560MPa, the tensile strength Rm is more than or equal to 700MPa, the elongation A is more than or equal to 18 percent, and the yield ratio is less than or equal to 0.83; the high-strength steel plate has the characteristics of high strength, low yield ratio, excellent low-temperature toughness, good weldability, low production cost and strong operability.
Description
Technical Field
The invention relates to low-yield-ratio ultra-thick hydroelectric high-strength steel and a manufacturing method thereof.
Background
The hydroelectric power generation of China occupies the second place of the domestic energy structure, in recent years, the hydroelectric power generation is rapidly developed with the advantages of small pollution, sustainable development and the like, various large-sized and oversize hydropower stations on large rivers of China are rapidly developed, and the capacity and the head pressure of the hydropower stations are increasingly large. The pressure steel pipe, the volute, the branch pipe and the like for the hydropower station increasingly expand the requirements on steel materials, and more strict requirements on the strength, the toughness and the like are provided. The steel for 600MPa quenched and tempered hydropower station pressure steel pipes, such as 07MnMoVR, WDL610D2, WDB620 and other domestic grades of steel, has low strength, so that the thickness of the steel plate is increased, the field welding construction is difficult, and the steel is not suitable for the requirements of an oversize high-head hydropower station, while the 800MPa steel has high strength and carbon equivalent, poor weldability, and severe construction welding environment due to preheating before welding. At present, the pressure steel pipe of the hydropower station urgently needs a steel grade with matched strength and weldability, and the problem of thick wall thickness is solved.
The patent (CN201310269680.2) applies for a high-strength steel for 800MPa hydropower station pressure pipelines and a production method thereof, the tensile strength of the steel exceeds 780MPa, the wall thickness of a pressure steel pipe can be greatly reduced, but the steel is produced by adopting a quenching and tempering process, noble alloy elements Mo, Nb and the like are added, the carbon equivalent is higher, the weldability is poorer, the requirement on welding is higher, the process flow is long, and the production cost is higher.
The patent (CN201510188306.9) applies for a yield 620 MPa-level hot rolled steel plate for hydroelectric engineering and a production method thereof, the hot rolled steel plate is produced by a two-stage controlled rolling, controlled cooling and tempering process, the tensile strength exceeds 700MPa, but the steel plate with the actual thickness of only 40mm is produced by adopting a blank with the thickness of 300mm, the steel plate does not belong to an ultra-thick steel plate, the content of noble elements Ni reaches 0.35%, the content of Nb exceeds 0.04%, and the production cost is high.
The patent (CN 103045965A) applies for a steel plate for 600MPa hydroelectric pressure steel pipe, a casting blank with the thickness of 250mm is rolled into a steel plate with the thickness of no more than 80mm by a TMCP process, and then the steel plate for the hydroelectric pressure steel pipe with excellent impact toughness at-20 ℃ is obtained by tempering treatment. But the strength is low, and the application in an oversize hydropower station necessarily causes the increase of the wall thickness, thereby causing great difficulty in welding.
In conclusion, the steel plate for the pressure steel pipe of the hydropower station and the super-thick steel plate of the same grade have the problems of high yield ratio, poor weldability, long process flow, high production cost and the like, bring great difficulties to the field manufacture, construction, welding and the like of the super-huge hydropower station, and cannot meet the requirements of newly-built large and super-huge hydropower stations.
Disclosure of Invention
The invention aims to provide the low-yield-ratio ultra-thick hydroelectric high-strength steel and the manufacturing method thereof, so as to solve the problems in the background technology, the low-yield-ratio ultra-thick hydroelectric high-strength steel is produced by adopting a low-carbon low-manganese high-Cr high-V component system supplemented with B, Ni microalloying and an on-line quenching and tempering process, and the finished product of the ultra-thick hydroelectric high-strength steel plate for the ultra-thick hydropower station with the thickness of 80-150 mm has the characteristics of low yield ratio, excellent low-temperature toughness, low carbon equivalent and excellent welding performance.
The technical scheme adopted for achieving the purpose is that the low-yield-ratio ultra-thick hydroelectric high-strength steel comprises the following chemical components in percentage by mass: c: 0.03 to 0.08%, Si: 0.05 to 0.35%, Mn: 0.60-1.00%, P is less than or equal to 0.012%, S is less than or equal to 0.005%, Cr: 0.50 to 1.00%, Ni: 0.10-0.30%, V: 0.12-0.18%, B: 0.0010-0.0020%, and the balance of Fe and inevitable impurity elements.
The low yield ratio ultra-thick hydroelectric high-strength steel simultaneously satisfies the following requirements:
Ceq=C+Si/24+Mn/6+Cr/5+Mo/4+V/14≤0.42%，
Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B≤0.20%。
the thickness of the low-yield-ratio ultra-thick hydroelectric high-strength steel is 80-150 mm.
The mechanical properties of the low yield ratio ultra-thick hydroelectric high-strength steel meet the following requirements: the yield strength ReL is more than or equal to 560MPa, the tensile strength Rm is more than or equal to 700MPa, the elongation A is more than or equal to 18 percent, the yield ratio is less than or equal to 0.83, and the transverse impact energy KV2 at the temperature of-20 ℃ is more than or equal to 60J; 5% strain aging impact energy-20 ℃ KV2 is more than or equal to 47J.
The invention also discloses a manufacturing method of the low-yield-ratio ultra-thick hydroelectric high-strength steel, which comprises the following steps:
(1) smelting: the blast furnace molten iron is desulfurized by KR and then smelted by an oxygen converter, and the content of [ P ] is controlled to be less than or equal to 0.010 percent and the content of [ C ] is controlled to be less than or equal to 0.04 percent; refining in a ladle furnace, simultaneously adding ferrochromium, ferrovanadium, ferronickel and ferromanganese alloy, adjusting the components to target values, and simultaneously ensuring that [ S ] is less than or equal to 0.004%; refining in an RH vacuum furnace, and adding ferroboron after 1 cycle of vacuum treatment;
(2) continuous casting: casting the casting blank with the thickness of 450mm or above by adopting the matched drawing speed and temperature and the whole-process protective casting and electromagnetic stirring technology, stacking the casting blank and slowly cooling for 48 hours, and transferring to the next procedure when the temperature of the casting blank is lower than 300 ℃;
(3) rolling: heating the casting blank to 1170-1250 ℃, wherein the furnace time is 0.6-1.2 min/mm multiplied by the thickness of the plate, and removing iron scales on the surface of the casting blank by using high-pressure water after the casting blank is discharged from the furnace; then, controlled rolling is carried out in two stages, the final rolling temperature in the stage I is controlled to be 970-1010 ℃, and the rolling reduction of the first 3 passes is more than or equal to 35 mm; the initial rolling temperature in the stage II is not more than 930 ℃, the final rolling temperature is 900-920 ℃, the final reduction of 1 pass is not more than 5mm, the straightness of the steel plate is strictly controlled, and the steel plate is rolled into a steel plate with the thickness of 80-150 mm;
(4) online quenching: after finishing rolling in the stage II, performing temperature correction, controlling the temperature of the steel plate to be 890-910 ℃ after temperature correction, directly performing online quenching on the steel plate with the thickness of 80-150 mm to a lower temperature by using an online accelerated cooling device, wherein the temperature of the steel plate does not exceed 60 ℃, and performing flaw detection to ensure that the steel plate has no inherent quality problem and then transferring to the next process;
(5) tempering: the high-strength steel plate for the ultra-thick hydropower station with the thickness of 80-150 mm is tempered at 500-580 ℃, the in-furnace time is 240-450 minutes, and the steel plate is taken out of the furnace and cooled to room temperature in an air cooling mode to form a finished steel plate.
In order to ensure the purposes of the invention and meet the characteristics of low yield ratio, excellent low-temperature toughness, low carbon equivalent, excellent welding performance and the like of the high-strength steel plate for the ultra-thick hydropower station, the limiting reasons of the elements such as C, Si, Mn, P, S, Cr, Ni, V, B and the like in the invention are explained as follows:
carbon: excessive C will reduce the low temperature toughness of the steel sheet, deteriorating its weldability, but it can significantly improve the strength of the steel sheet. The lower the carbon content, the better the low temperature toughness of the steel. The lower carbon content can promote more carbon-free areas to be formed near austenite in the rolling process, promote the transformation of the austenite to bainite containing high-density dislocation, and further improve the low-temperature toughness of the steel. The content of C is 0.03-0.08%.
Manganese: the Mn and C increase is an important means for improving the strength of the steel plate and improving the low-temperature toughness of the steel plate, but the excessive Mn content obviously aggravates the center segregation of a casting blank, influences the low-temperature toughness of the steel plate, and simultaneously obviously improves the carbon equivalent of the steel and deteriorates the weldability of the steel. The content of Mn is 0.60-1.00%.
Phosphorus and sulfur: p, S is an inevitable impurity element, and has effects on formability, corrosion and low-temperature toughness of steel sheet, and the lower the content, the better the content is, the content of P is less than or equal to 0.012%, and the content of S is less than or equal to 0.005%.
Chromium: cr can obviously improve the hardenability of steel and has the function of secondary hardening, so that the quenched steel has excellent comprehensive performance and stable tempering stability after tempering. Excessive Cr will reduce the plasticity of the steel, and reduce the elongation and reduction of area of the steel. The content of Cr is 0.50-1.00%.
Nickel: ni can reduce the low-temperature ductile-brittle transition temperature of steel and improve the low-temperature toughness of the steel, but the cost is increased by adding too much Ni, and the content of Ni is 0.10-0.30%.
Vanadium: v and C, N are combined to form a V (C, N) compound, so that the content of free nitrogen in the steel is reduced, and the strain aging performance of the steel is improved. And V (C, N) austenite grain boundary ferrite precipitates, and austenite recrystallization is inhibited and structure grains grow up in the rolling process, so that ferrite grains are refined, and the strength and the toughness of the steel are improved. Under the condition of high-temperature tempering, V (C, N) is dispersed and separated out, so that the precipitation strengthening effect can be achieved, and the strength and the toughness of the steel are further improved. The content of V is 0.12-0.18%.
Boron: the trace B element can obviously improve the hardenability of the steel plate, and for the quenched thick steel plate, the addition of B can obviously promote the formation of martensite or bainite, thereby improving the strength of the steel plate. However, excessive B precipitates at austenite grain boundaries in the steel to cause hot embrittlement. The content of B is 0.0010-0.0020%.
The invention adopts the design of low C, low Mn, high Cr and high V components and the production of on-line quenching and tempering processes; the molten steel is purified by various means during smelting, such as self-produced molten steel and low-sulfur waste steel, the contents of harmful elements and impurity elements are strictly controlled, and [ P ] is strictly controlled]Less than or equal to 0.010 percent; during refining, desulfurizing agent is used to further desulfurizing deeply and control S]Less than or equal to 0.003 percent; Si-Mn alloy is adopted for deoxidation, the content of Als is strictly controlled, and Al in molten steel is reduced2O3Harmful impurities are formed, and the molten steel is vacuum treated to form O]≤10ppm、[N]≤35ppm、[H]Less than or equal to 1 ppm. The purification of the molten steel can obviously improve the low-temperature toughness of the steel plate. During on-line quenching, the matching of the temperature, the cooling speed and the like of the steel plate is fully ensured, elements such as Cr, B and the like which improve the hardenability of the steel are utilized to promote the formation of hard phase structures such as bainite, martensite and the like in the steel, the finish rolling temperature of the steel is properly improved, the temperature of the steel plate is ensured to be higher than the Ac3 point of the steel plate during on-line quenching, a certain amount of bainite is formed at the position of 1/4 of the super-thick steel plate thickness, after high-temperature tempering, the low-temperature toughness of the steel is further improved, and meanwhile, the dispersion strengthening effect of V (C, N) is fully utilized to weaken the great reduction of the strength caused by the reduction of dislocation density and other; and meanwhile, after the finish rolling, the watering is strictly controlled for two times, so that the condition that the temperature of the steel plate is not uniform due to the watering is avoided, and the structure and the performance of the steel plate are not uniform during the on-line quenching. The rolling reduction of the last pass is less than or equal to 5mm, and the plate type and the flatness of the steel plate can be ensured.
Advantageous effects
Compared with the prior art, the invention has the following advantages.
1. The steel is designed by adopting C + Mn + Cr + V components, so that the components are simpler, the Ceq and Pcm values are lower, and the weldability is better; meanwhile, an on-line quenching and tempering process is adopted, so that the process flow is short, the operability is strong, and the production cost is low;
2. the invention produces the ultra-thick hydroelectric high-strength steel with the thickness of 80-150 mm and the low yield ratio, and the performance meets the yield strength ReLNot less than 560MPa, tensile strength RmMore than or equal to 700MPa, the elongation A more than or equal to 18 percent, the yield ratio less than or equal to 0.83, and the transverse impact energy KV at-20 DEG C2More than or equal to 60J; 5% strain aging impact energy-20 deg.C KV2Not less than 47J; has the characteristics of lower yield ratio, better toughness matching, weldability and the like.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings.
FIG. 1 shows the 1/4 metallographic structure of the steel plate with a thickness of 80mm according to example 2 of the present invention, mainly comprising bainite + ferrite;
FIG. 2 shows the metallurgical structure at 1/4 points of a 150mm thick steel plate according to example 2 of the present invention, mainly comprising bainite + ferrite.
Detailed Description
The invention is further described with reference to the following examples and the accompanying drawings.
The low-yield-ratio ultra-thick hydroelectric high-strength steel comprises the following chemical components in percentage by mass: c: 0.03 to 0.08%, Si: 0.05 to 0.35%, Mn: 0.60-1.00%, P is less than or equal to 0.012%, S is less than or equal to 0.005%, Cr: 0.50 to 1.00%, Ni: 0.10-0.30%, V: 0.12-0.18%, B: 0.0010-0.0020%, and the balance of Fe and inevitable impurity elements.
The low yield ratio ultra-thick hydroelectric high-strength steel simultaneously satisfies the following requirements:
Ceq=C+Si/24+Mn/6+Cr/5+Mo/4+V/14≤0.42%，
Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B≤0.20%。
the thickness of the low-yield-ratio ultra-thick hydroelectric high-strength steel is 80-150 mm.
The mechanical properties of the low yield ratio ultra-thick hydroelectric high-strength steel meet the following requirements: the yield strength ReL is more than or equal to 560MPa, the tensile strength Rm is more than or equal to 700MPa, the elongation A is more than or equal to 18 percent, the yield ratio is less than or equal to 0.83, and the transverse impact energy KV2 at the temperature of-20 ℃ is more than or equal to 60J; 5% strain aging impact energy-20 ℃ KV2 is more than or equal to 47J.
A manufacturing method of low yield ratio ultra-thick hydroelectric high-strength steel comprises the following process flows: KR treatment of blast furnace molten iron and molten iron, smelting in a 150t oxygen converter, refining in an LF ladle furnace, RH vacuum furnace treatment, continuous casting, heating of casting blanks, controlled rolling, online quenching, flaw detection, tempering and inspection; the method comprises the following specific operation steps:
(1) smelting: the blast furnace molten iron is desulfurized by KR and then smelted by an oxygen converter, and the content of [ P ] is controlled to be less than or equal to 0.010 percent and the content of [ C ] is controlled to be less than or equal to 0.04 percent; refining in a ladle furnace, adding ferrochromium, ferrovanadium, ferronickel, ferromanganese and other alloys at the same time, adjusting the components to target values, and simultaneously ensuring that [ S ] is less than or equal to 0.004%; refining in an RH vacuum furnace, and adding ferroboron after 1 cycle of vacuum treatment;
(2) continuous casting: casting the casting blank with the thickness of 450mm or above by adopting matched pulling speed and temperature, whole-process protective casting, electromagnetic stirring technology and the like, stacking the casting blank for slow cooling for 48 hours, and transferring to the next procedure when the temperature of the casting blank is lower than 300 ℃;
(3) rolling: heating the casting blank to 1170-1250 ℃, wherein the furnace time is 0.6-1.2 min/mm multiplied by the thickness of the plate, and removing iron scales on the surface of the casting blank by using high-pressure water after the casting blank is discharged from the furnace; then, controlled rolling is carried out in two stages, the final rolling temperature in the stage I is controlled to be 970-1010 ℃, and the rolling reduction of the first 3 passes is more than or equal to 35 mm; the initial rolling temperature in the stage II is not more than 930 ℃, the final rolling temperature is 900-920 ℃, the final reduction of 1 pass is not more than 5mm, the straightness of the steel plate is strictly controlled, and the steel plate is rolled into a steel plate with the thickness of 80-150 mm;
(4) online quenching: after finishing rolling in the stage II, performing temperature correction, controlling the temperature of the steel plate to be 890-910 ℃ after temperature correction, directly performing online quenching on the steel plate with the thickness of 80-150 mm to a lower temperature by using an online accelerated cooling device, wherein the temperature of the steel plate does not exceed 60 ℃, and performing flaw detection to ensure that the steel plate has no inherent quality problem and then transferring to the next process;
(5) tempering: the high-strength steel plate for the ultra-thick hydropower station with the thickness of 80-150 mm is tempered at 500-580 ℃, the in-furnace time is 240-450 minutes, and the steel plate is taken out of the furnace and cooled to room temperature in an air cooling mode to form a finished steel plate.
The melting chemistry of the specific examples and comparative examples of the invention is shown in Table 1(wt%), the remainder being Fe and unavoidable impurity elements.
TABLE 1
In the above examples, the steel is smelted in a 150t converter, molten iron is desulfurized by KR, further desulfurized and refined in a ladle furnace, degassed in a vacuum furnace, and then cast into a 450mm thick casting blank under light pressure and under electromagnetic stirring and under protection of the whole process.
Heating a casting blank with the thickness of 450mm to 1180-1240 ℃, keeping the furnace time at 0.8-1.2 min/mm multiplied by the thickness (mm), and descaling through high-pressure water after discharging to remove iron oxide scales on the surface of the casting blank; then rolling is controlled, the final rolling temperature is controlled to 970-1010 ℃, and the rolling reduction of the first 3 passes is 35-40 mm; the final rolling temperature is 900-920 ℃, after on-line quenching, the temperature of the test steel plate is lower than 60 ℃, and the steel plate is rolled into a finished steel plate with the thickness of 80-150 mm; and then carrying out tempering treatment at 500-580 ℃, wherein the furnace time is 240-420 min, and air cooling to room temperature after discharging.
Table 2 shows the main rolling and tempering process parameters for each example:
the steel sheets after the tempering heat treatment were subjected to transverse sampling at a sheet thickness of 1/4 to obtain tensile specimens and impact specimens, and surface layer sampling was conducted to obtain strain aging impact specimens, and mechanical properties were measured, and the results are shown in Table 3.
TABLE 3 results of mechanical properties of parent metal
As can be seen from Table 3, the steel sheets tested in the examples of the present invention satisfy the yield strength ReLNot less than 560MPa, tensile strength RmMore than or equal to 700MPa, the elongation A more than or equal to 18 percent, the yield ratio less than or equal to 0.83, and the transverse impact energy KV at-20 DEG C2More than or equal to 60J; 5% strain aging impact energy-20 deg.C KV2Not less than 47J, large allowance of strength, elongation and impact toughness, low yield ratio and excellent low-temperature toughness at 1/4 plate thickness.
The above shows that the steel has the strength of over 700MPa, excellent toughness matching and low-temperature toughness, and the actual yield ratio of not more than 0.80; the carbon equivalent Ceq and Pcm values are lower, which indicates that the welding material has better weldability; in addition, the steel has the advantages of simple production control, short process flow, low production cost and wide market prospect.
FIG. 1 is a structural view showing the structure of an 80mm thick steel plate in example 2 at 1/4 thickness, the structure being bainite + ferrite. FIG. 2 is a structural view showing the structure of a 150mm thick steel plate in example 2 at 1/4 thickness, the structure being bainite + ferrite. The tissue matching enables the steel to have better obdurability, and simultaneously enables the steel to have lower yield ratio.
The steel has simple process flow, strong operability and lower cost, and can be implemented in medium and heavy plate factories in the steel industry. The steel has wide application, can be applied to the industries of hydropower, buildings, bridges, engineering machinery and the like, and is more suitable for building pressure steel pipes, volutes, branch pipes, engine bases and the like for large and super-large hydropower stations.
Claims (5)
1. The low yield ratio ultra-thick hydroelectric high-strength steel is characterized by comprising the following chemical components in percentage by mass: c: 0.03 to 0.08%, Si: 0.05 to 0.35%, Mn: 0.60-1.00%, P is less than or equal to 0.012%, S is less than or equal to 0.005%, Cr: 0.50 to 1.00%, Ni: 0.10-0.30%, V: 0.12-0.18%, B: 0.0010-0.0020%, and the balance of Fe and inevitable impurity elements.
2. The low yield ratio ultra-thick hydroelectric high-strength steel according to claim 1, which simultaneously satisfies:
Ceq=C+Si/24+Mn/6+Cr/5+Mo/4+V/14≤0.42%，
Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B≤0.20%。
3. the low yield ratio ultra-thick hydroelectric high-strength steel as claimed in claim 1, wherein the thickness of the low yield ratio ultra-thick hydroelectric high-strength steel is 80-150 mm.
4. The low yield ratio ultra-thick hydroelectric high-strength steel as claimed in claim 1, wherein the mechanical properties of the low yield ratio ultra-thick hydroelectric high-strength steel satisfy: the yield strength ReL is more than or equal to 560MPa, the tensile strength Rm is more than or equal to 700MPa, the elongation A is more than or equal to 18 percent, the yield ratio is less than or equal to 0.83, and the transverse impact energy KV2 at the temperature of-20 ℃ is more than or equal to 60J; 5% strain aging impact energy-20 ℃ KV2 is more than or equal to 47J.
5. The method of manufacturing a low yield ratio ultra thick hydroelectric high strength steel according to claim 1, comprising the steps of:
(1) smelting: the blast furnace molten iron is desulfurized by KR and then smelted by an oxygen converter, and the content of [ P ] is controlled to be less than or equal to 0.010 percent and the content of [ C ] is controlled to be less than or equal to 0.04 percent; refining in a ladle furnace, simultaneously adding ferrochromium, ferrovanadium, ferronickel and ferromanganese alloy, adjusting the components to target values, and simultaneously ensuring that [ S ] is less than or equal to 0.004%; refining in an RH vacuum furnace, and adding ferroboron after 1 cycle of vacuum treatment;
(2) continuous casting: casting the casting blank with the thickness of 450mm or above by adopting the matched drawing speed and temperature and the whole-process protective casting and electromagnetic stirring technology, stacking the casting blank and slowly cooling for 48 hours, and transferring to the next procedure when the temperature of the casting blank is lower than 300 ℃;
(3) rolling: heating the casting blank to 1170-1250 ℃, wherein the furnace time is 0.6-1.2 min/mm multiplied by the thickness of the plate, and removing iron scales on the surface of the casting blank by using high-pressure water after the casting blank is discharged from the furnace; then, controlled rolling is carried out in two stages, the final rolling temperature in the stage I is controlled to be 970-1010 ℃, and the rolling reduction of the first 3 passes is more than or equal to 35 mm; the initial rolling temperature in the stage II is not more than 930 ℃, the final rolling temperature is 900-920 ℃, the final reduction of 1 pass is not more than 5mm, the straightness of the steel plate is strictly controlled, and the steel plate is rolled into a steel plate with the thickness of 80-150 mm;
(4) online quenching: after finishing rolling in the stage II, performing temperature correction, controlling the temperature of the steel plate to be 890-910 ℃ after temperature correction, directly performing online quenching on the steel plate with the thickness of 80-150 mm to a lower temperature by using an online accelerated cooling device, wherein the temperature of the steel plate does not exceed 60 ℃, and performing flaw detection to ensure that the steel plate has no inherent quality problem and then transferring to the next process;
(5) tempering: the high-strength steel plate for the ultra-thick hydropower station with the thickness of 80-150 mm is tempered at 500-580 ℃, the in-furnace time is 240-450 minutes, and the steel plate is taken out of the furnace and cooled to room temperature in an air cooling mode to form a finished steel plate.
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| CN113512682A (en) * | 2021-07-02 | 2021-10-19 | 东北大学 | High-strength and high-toughness ultra-thick quenched and tempered hydroelectric steel plate and preparation method thereof |
| CN114134407A (en) * | 2021-06-04 | 2022-03-04 | 江阴兴澄特种钢铁有限公司 | Easy-to-weld steel plate with excellent low-temperature toughness at core for volute and manufacturing method thereof |
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