CN109706375B - Production method of large-thickness low-alloy high-strength structural steel with thickness of 420-600mm - Google Patents
Production method of large-thickness low-alloy high-strength structural steel with thickness of 420-600mm Download PDFInfo
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Abstract
The invention discloses a large-thickness low-alloy high-strength structural steel with the thickness of 420-600mm, which comprises the following chemical components: c: 0.12 to 0.15%, Si: 0.20 to 0.5%, Mn: 1.50-1.60%, P: less than or equal to 0.013%, S: less than or equal to 0.001%, Nb: 0.04-0.06%, V: 0.03-0.05%, Als: 0.02-0.03%, and the balance of Fe and residual elements; the production method comprises the following process flows: molten iron → converter → LF refining → VD vacuum treatment → die casting and pouring → steel ingot cleaning → steel ingot is sent to the rolling and charging furnace within 12h after cleaning; the invention has reasonable chemical component dosage, and fully exerts the double effects of solid solution strengthening and fine grain strengthening on the premise of not reducing the ductility and toughness; the casting process is stable in casting and tight in following flow; the normalizing can be used for enhancing the toughness of steel, and the micro-alloy super-thick steel plate after being subjected to water cooling treatment is adopted, so that the phase change of the steel plate after being subjected to normalizing can be rapidly generated, crystal grains are refined, partial rolling stress is eliminated, and the plastic toughness of the steel plate is increased on the premise of ensuring the strength requirement of the steel plate.
Description
Technical Field
The invention belongs to the technical field of production of large-thickness low-alloy high-strength steel plates, and particularly relates to a production method of large-thickness low-alloy high-strength structural steel with the thickness of 420-600 mm.
Background
At present, fewer manufacturers are used for producing 420-plus-600 mm thick steel plates in China due to limitations of equipment and technology, the requirements of customers on use performance can be met, Nanyang and Han special steel in the factory is used as a product which is afraid of others and a product which is afraid of others, the company exerts the advantages of large die casting tonnage and stable internal quality, and continuously develops and develops a production process scheme for producing the extra-thick steel plates, so that a die casting production process for producing the 600mm thick low-alloy high-strength structural steel with the thickness exceeding the national standard range is invented.
Disclosure of Invention
In view of the above problems, the present invention provides a method for producing a high strength structural steel with large thickness of 420-600mm and low alloy.
In order to achieve the purpose, the technical scheme adopted by the invention is that the large-thickness low-alloy high-strength structural steel with the thickness of 420-600mm comprises the following chemical components in percentage by mass: c: 0.12 to 0.15%, Si: 0.20 to 0.5%, Mn: 1.50-1.60%, P: less than or equal to 0.013%, S: less than or equal to 0.001%, Nb: 0.04-0.06%, V: 0.03-0.05%, Als: 0.02-0.03%, and the balance of Fe and residual elements; carbon equivalent CEV 0.38-0.43; the production method comprises the following process flows: molten iron (KR desulfurization) → converter (argon station) → LF refining → VD vacuum treatment → die casting pouring (ingot type selection 50T constant scale) → steel ingot cleaning (cleaning of a die cast ingot within 12h after demolding) → steel ingot conveying to a rolling charging furnace within 12h after cleaning;
KR molten iron pretreatment: mg powder or Mg powder plus CaO is used as a desulfurizing agent, slag before and after molten iron arrives at a station must be removed, the thickness of a slag layer on the liquid surface is ensured to be less than or equal to 20mm, molten iron is stirred and desulfurized by KR to ensure that the S content of the molten iron is less than or equal to 0.005 percent, the desulfurization period is less than or equal to 21min and the desulfurization temperature is less than or equal to 20 ℃;
b. smelting in a converter: the S content of the molten iron fed into the furnace is less than or equal to 0.003 percent, the P content is less than or equal to 0.080 percent, the temperature of the molten iron is more than or equal to 1270 ℃, the loading error of the molten iron is controlled according to +/-1 t, the scrap steel strictly adopts high-quality leftover materials, and 4/5 of the total amount of lime is added into the first batch; taking the need of early dephosphorization into consideration, adding the light-burned dolomite according to the MgO content of 10-12% of the slag, and adding the light-burned dolomite at one time after blowing; the second batch of slag charge is added according to the temperature and the slagging condition in the process, the slag is melted and dephosphorized as early as possible at the high gun position in the early stage, the oxygen pressure is controlled according to 0.9MPa, and the gun is properly lowered after the second batch of slag charge is added into the melted slag, so that the blowing is stable; the end point carbon is controlled to be less than or equal to 0.06 percent of [ C ], less than or equal to 0.015 percent of S, less than or equal to 0.015 percent of P, and less than or equal to 0.0020 percent of [ N ]; the tapping temperature is 1640-1650 ℃, and the steel ladle temperature is 1570-1590 ℃;
and d, LF refining: argon is blown in the whole refining process, slag is added, the alkalinity is controlled according to 4.0-6.0, the slag must turn white or yellow-white after the refining and heating are finished, the white slag holding time is more than or equal to 30min, and the final slag after the refining is required to be foamed white slag with good fluidity and proper viscosity; performing secondary desulfurization on the manufactured white slag, keeping the manufactured white slag for 20-25min, fully deoxidizing by adopting a high-temperature, high-alkalinity, high-slag-content and low-iron oxide slagging process, and adopting calcium carbide, aluminum wires or aluminum particles as a deoxidizing agent;
VD vacuum treatment: maintaining the pressure for 18-23min under the vacuum degree of less than or equal to 67Pa, immediately performing Ca treatment after vacuum breaking, and finally ensuring that the H content is less than or equal to 1.2 ppm;
f. die casting: before the upper line is used, the temperature of an ingot mould is less than or equal to 120 ℃, the distance between the upper opening of a middle pouring pipe and a lower water opening of a ladle is controlled to be less than or equal to 140mm during pouring, half of the die casting protective slag is hung in the ingot mould in a straw rope hanging mode before pouring, the hanging height is 300-400 mm higher than the bottom of the ingot mould, the pouring process is stable in pouring and tight in following flow, the pouring temperature is controlled at 1550-;
g. heating: the heating temperature and heating time were as follows: after steel is filled, the temperature of annealing steel is 600-;
h. rolling: after dephosphorization is carried out on steel ingot tapping, the initial rolling temperature is more than or equal to 1080 ℃, the steel feeding speed is 1.5m/s, the cumulative reduction rate is more than 45 percent, the steel is not cooled and hot rolled, and the final rolling temperature is 870-930 ℃;
i. and (3) cooling in a heaped mode: after the wire is off line, the clamp is used for high-temperature heap cooling, the heap cooling temperature is 600-750 ℃, after the heap cooling, other hot rolled steel plates are used for covering, the uncovering is forbidden, and the heap cooling time is more than or equal to 96 hours;
j. and (3) heat treatment: after finishing the steel ingot, carrying out heat treatment in an external furnace, wherein the heating temperature is 920-.
Wherein, C has the main function of improving the strength in the steel grade and is unfavorable for other properties, and the carbon content is favorably reduced in the low-alloy high-strength steel under the condition of ensuring certain strength; si can improve the strength limit, the yield limit and the hardness of the steel, and reduce the elongation, the shrinkage and the impact toughness of the steel but does not obviously show the elongation, the shrinkage and the impact toughness of the steel, so a small amount of silicon in the low-alloy high-strength steel can be used for improving the strength of the steel, and has little influence on other properties; mn is a strengthening alloy element of steel, the increase of Mn content can improve the stability of austenite, reduce the critical cooling speed, strengthen ferrite, improve the hardenability of steel, slow the decomposition and transformation speed of a structure in the tempering process after quenching, increase tempering resistance and improve the stability of a tempered structure, but the overhigh content can coarsen grains of the steel at high temperature and increase the tempering brittleness tendency of the steel, the brittleness transformation temperature of the steel is obviously reduced along with the increase of Mn/C, Mn/C is controlled to be between 18 and 19, in addition, the overhigh Mn content can improve the carbon equivalent and is unfavorable to the weldability, so the Mn is controlled to be between 1.50 and 1.60 percent; p, S: the silicon nitride is a harmful element, is easy to segregate in a grain boundary, reduces the surface energy of the grain boundary, reduces the brittle fracture stress and influences the ductile-brittle transition temperature, so the lower the content, the better, the P content is less than or equal to 0.018 percent, and the S content is less than or equal to 0.007 percent; nb: the niobium carbonitride precipitated in the solidification period is beneficial to forming a fine equiaxial casting structure, the fine original austenite grains can inhibit the growth of the austenite grains in the heating process, the recrystallization temperature of austenite is improved, and the desolventizing and strain-induced precipitation behavior of Nb in a low-temperature region can promote enrichment nucleation of gamma-alpha phase transformation; in the alpha region, ferrite grain growth is inhibited, and the addition amount of Nb is also controlled during composition design, because Nb exists in a solid solution form in the steel, precipitation of pro-eutectoid ferrite is delayed, and the time of transformation of austenite to pearlite is delayed; v has stronger affinity with nitrogen in steel, so V can greatly reduce the content of free N in steel, avoid the strain timeliness of steel, on the other hand, the precipitation strengthening effect of V can be fully exerted by adding a proper amount of N in the vanadium-containing steel, the precipitation strengthening effect of V (C, N) in steel is increased progressively with the increase of nitrogen content, the maximum strength increment can reach 300MPa, the strength can be increased by 6MPa when the nitrogen content of V is increased by 10 x 10 < -6 > in the vanadium-containing steel, the precipitation of V is optimized through vanadium-nitrogen microalloying, ferrite grains are refined, the fine-grain strengthening and precipitation strengthening effects are fully exerted, and the toughness of steel is obviously improved.
The invention has reasonable chemical component dosage, fully exerts the double effects of solid solution strengthening and fine grain strengthening on the premise of not reducing the plastic toughness, and the obtained high-strength and high-toughness steel plate has the thickness of 420-600mm and belongs to an extra-thick die casting plate; the casting process is stable in casting and tight in follow-up flow, and the steel plate is ensured to be free of microcracks, looseness, cavities and the like, namely soundness; macroscopic segregation, semi-macroscopic segregation and large-area microscopic segregation, namely homogeneity, do not exist in the steel plate; the steel plate has no macroscopic and semi-macroscopic non-metallic inclusions, namely: the product is pure. The normalizing can be used for enhancing the toughness of steel, and the micro-alloy super-thick steel plate after being subjected to water cooling treatment is adopted, so that the phase change of the steel plate after being subjected to normalizing can be rapidly generated, crystal grains are refined, partial rolling stress is eliminated, and the plastic toughness of the steel plate is increased on the premise of ensuring the strength requirement of the steel plate.
Detailed Description
The 420-600mm large-thickness low-alloy high-strength structural steel comprises the following chemical components in percentage by mass:
c: 0.12 to 0.15%, Si: 0.20 to 0.5%, Mn: 1.50-1.60%, P: less than or equal to 0.013%, S: less than or equal to 0.001%, Nb: 0.04-0.06%, V: 0.03-0.05%, Als: 0.02-0.03%, and the balance of Fe and residual elements; carbon equivalent CEV 0.38-0.43; the production method comprises the following process flows: molten iron (KR desulfurization) → converter (argon station) → LF refining → VD vacuum treatment → die casting pouring (ingot type selection 50T constant scale) → steel ingot cleaning (cleaning of a die cast ingot within 12h after demolding) → steel ingot conveying to a rolling charging furnace within 12h after cleaning;
KR molten iron pretreatment: mg powder or Mg powder plus CaO is used as a desulfurizing agent, slag before and after molten iron arrives at a station must be removed, the thickness of a slag layer on the liquid surface is ensured to be less than or equal to 20mm, molten iron is stirred and desulfurized by KR to ensure that the S content of the molten iron is less than or equal to 0.005 percent, the desulfurization period is less than or equal to 21min and the desulfurization temperature is less than or equal to 20 ℃;
b. smelting in a converter: the S content of the molten iron fed into the furnace is less than or equal to 0.003 percent, the P content is less than or equal to 0.080 percent, the temperature of the molten iron is more than or equal to 1270 ℃, the loading error of the molten iron is controlled according to +/-1 t, the scrap steel strictly adopts high-quality leftover materials, and 4/5 of the total amount of lime is added into the first batch; taking the need of early dephosphorization into consideration, adding the light-burned dolomite according to the MgO content of 10-12% of the slag, and adding the light-burned dolomite at one time after blowing; the second batch of slag charge is added according to the temperature and the slagging condition in the process, the slag is melted and dephosphorized as early as possible at the high gun position in the early stage, the oxygen pressure is controlled according to 0.9MPa, and the gun is properly lowered after the second batch of slag charge is added into the melted slag, so that the blowing is stable; the end point carbon is controlled to be less than or equal to 0.06 percent of [ C ], less than or equal to 0.015 percent of S, less than or equal to 0.015 percent of P, and less than or equal to 0.0020 percent of [ N ]; the tapping temperature is 1640-1650 ℃, and the steel ladle temperature is 1570-1590 ℃;
and d, LF refining: argon is blown in the whole refining process, slag is added, the alkalinity is controlled according to 4.0-6.0, the slag must turn white or yellow-white after the refining and heating are finished, the white slag holding time is more than or equal to 30min, and the final slag after the refining is required to be foamed white slag with good fluidity and proper viscosity; performing secondary desulfurization on the manufactured white slag, keeping the manufactured white slag for 20-25min, fully deoxidizing by adopting a high-temperature, high-alkalinity, high-slag-content and low-iron oxide slagging process, and adopting calcium carbide, aluminum wires or aluminum particles as a deoxidizing agent;
VD vacuum treatment: maintaining the pressure for 18-23min under the vacuum degree of less than or equal to 67Pa, immediately performing Ca treatment after vacuum breaking, and finally ensuring that the H content is less than or equal to 1.2 ppm;
f. die casting: before the upper line is used, the temperature of an ingot mould is less than or equal to 120 ℃, the distance between the upper opening of a middle pouring pipe and a lower water opening of a ladle is controlled to be less than or equal to 140mm during pouring, half of the die casting protective slag is hung in the ingot mould in a straw rope hanging mode before pouring, the hanging height is 300-400 mm higher than the bottom of the ingot mould, the pouring process is stable in pouring and tight in following flow, the pouring temperature is controlled at 1550-;
g. heating: the heating temperature and heating time were as follows: after steel is filled, the temperature of annealing steel is 600-;
h. rolling: after dephosphorization is carried out on steel ingot tapping, the initial rolling temperature is more than or equal to 1080 ℃, the steel feeding speed is 1.5m/s, the cumulative reduction rate is more than 45 percent, the steel is not cooled and hot rolled, and the final rolling temperature is 870-930 ℃;
i. and (3) cooling in a heaped mode: after the wire is off line, the clamp is used for high-temperature heap cooling, the heap cooling temperature is 600-750 ℃, after the heap cooling, other hot rolled steel plates are used for covering, the uncovering is forbidden, and the heap cooling time is more than or equal to 96 hours;
j. and (3) heat treatment: after finishing the steel ingot, carrying out heat treatment in an external furnace, wherein the heating temperature is 920-.
Wherein, C has the main function of improving the strength in the steel grade and is unfavorable for other properties, and the carbon content is favorably reduced in the low-alloy high-strength steel under the condition of ensuring certain strength; si can improve the strength limit, the yield limit and the hardness of the steel, and reduce the elongation, the shrinkage and the impact toughness of the steel but does not obviously show the elongation, the shrinkage and the impact toughness of the steel, so a small amount of silicon in the low-alloy high-strength steel can be used for improving the strength of the steel, and has little influence on other properties; mn is a strengthening alloy element of steel, the increase of Mn content can improve the stability of austenite, reduce the critical cooling speed, strengthen ferrite, improve the hardenability of steel, slow the decomposition and transformation speed of a structure in the tempering process after quenching, increase tempering resistance and improve the stability of a tempered structure, but the overhigh content can coarsen grains of the steel at high temperature and increase the tempering brittleness tendency of the steel, the brittleness transformation temperature of the steel is obviously reduced along with the increase of Mn/C, Mn/C is controlled to be between 18 and 19, in addition, the overhigh Mn content can improve the carbon equivalent and is unfavorable to the weldability, so the Mn is controlled to be between 1.50 and 1.60 percent; p, S: the silicon nitride is a harmful element, is easy to segregate in a grain boundary, reduces the surface energy of the grain boundary, reduces the brittle fracture stress and influences the ductile-brittle transition temperature, so the lower the content, the better, the P content is less than or equal to 0.018 percent, and the S content is less than or equal to 0.007 percent; nb: the niobium carbonitride precipitated in the solidification period is beneficial to forming a fine equiaxial casting structure, the fine original austenite grains can inhibit the growth of the austenite grains in the heating process, the recrystallization temperature of austenite is improved, and the desolventizing and strain-induced precipitation behavior of Nb in a low-temperature region can promote enrichment nucleation of gamma-alpha phase transformation; in the alpha region, ferrite grain growth is inhibited, and the addition amount of Nb is also controlled during composition design, because Nb exists in a solid solution form in the steel, precipitation of pro-eutectoid ferrite is delayed, and the time of transformation of austenite to pearlite is delayed; v has stronger affinity with nitrogen in steel, so V can greatly reduce the content of free N in steel, avoid the strain timeliness of steel, on the other hand, the precipitation strengthening effect of V can be fully exerted by adding a proper amount of N in the vanadium-containing steel, the precipitation strengthening effect of V (C, N) in steel is increased progressively with the increase of nitrogen content, the maximum strength increment can reach 300MPa, the strength can be increased by 6MPa when the nitrogen content of V is increased by 10 x 10 < -6 > in the vanadium-containing steel, the precipitation of V is optimized through vanadium-nitrogen microalloying, ferrite grains are refined, the fine-grain strengthening and precipitation strengthening effects are fully exerted, and the toughness of steel is obviously improved.
The steel plate has the advantages that the effects of various elements are integrated, the strength of the steel plate is ensured, and meanwhile, the steel plate has good plasticity and low-temperature toughness, and the following chemical components are formulated:
(Note: CEV. C + Mn/6+ (Mo + V + Cr)/5+ (Ni + Cu)/15, balance Fe and residual elements)
The invention has reasonable chemical component dosage, fully exerts the double effects of solid solution strengthening and fine grain strengthening on the premise of not reducing the plastic toughness, and the obtained high-strength and high-toughness steel plate has the thickness of 420-600mm and belongs to an extra-thick die casting plate; the casting process is stable in casting and tight in follow-up flow, and the steel plate is ensured to be free of microcracks, looseness, cavities and the like, namely soundness; macroscopic segregation, semi-macroscopic segregation and large-area microscopic segregation, namely homogeneity, do not exist in the steel plate; the steel plate has no macroscopic and semi-macroscopic non-metallic inclusions, namely: the product is pure. The normalizing can be used for enhancing the toughness of steel, and the micro-alloy super-thick steel plate after being subjected to water cooling treatment is adopted, so that the phase change of the steel plate after being subjected to normalizing can be rapidly generated, crystal grains are refined, partial rolling stress is eliminated, and the plastic toughness of the steel plate is increased on the premise of ensuring the strength requirement of the steel plate.
Examples of the invention
The low-temperature impact Q345E-grade extra-thick die casting plate is obtained by KR molten iron pretreatment, converter smelting, argon blowing treatment, LF refining, VD refining, die casting, heating, hot rolling, stack cooling and heat treatment processes and comprises the following chemical components in percentage by mass (unit, wt%): c: 0.14, Si: 0.26, Mn: 1.58, P: 0.012, S: 0.001, Als: 0.021, V: 0.040, Nb: 0.040, CEV: 0.41, and the balance Fe and residual elements.
Mechanical Property analysis
The components and the mechanical properties are implemented according to GB/T1591-
Mechanical properties of 500mm low alloy series Q345E
Standard requirements (performance reference GB-T1591 + 2008 400mm thickness performance because thickness exceeds national standard)
Performance of the produced steel plate
| Sample batches | Thickness/mm | Rel/MPa | Rm/MPa | A％ | KV2/J(-40℃) |
| 1 | 500 | 341 | 498 | 27 | 277、232、262 |
| 2 | 500 | 342 | 542 | 22 | 286、232、211 |
| 3 | 500 | 348 | 498 | 25 | 259、251、245 |
This trial production Q345E with the thickness of 500mm adopts hot rolling + normalizing fast cooling technology, wherein: the yield strength is controlled to be 341-348 MPa, the tensile strength is controlled to be 498-542 MPa, the elongation is controlled to be 22% -27%, the V-shaped impact energy at the temperature of minus 40 ℃ is controlled to be 211-286J, and the standard of Q345E with the thickness of 500mm is completely met according to the maximum thickness performance requirement of Q345E in GB/T1591-2008 standard.
External inspection and flaw detection: the quality control product rate of the steel plate is 100 percent, the flaw detection is carried out according to JB/T47030, and the grade is closed.
Claims (1)
1. The production method of the 420-600mm large-thickness low-alloy high-strength structural steel is characterized in that the 420-600mm large-thickness low-alloy high-strength structural steel comprises the following chemical components in percentage by mass: c: 0.12 to 0.15%, Si: 0.20 to 0.5%, Mn: 1.50-1.60%, P: less than or equal to 0.013%, S: less than or equal to 0.001%, Nb: 0.04-0.06%, V: 0.03-0.05%, Als: 0.02-0.03%, and the balance of Fe and residual elements; carbon equivalent CEV0.38 to 0.43; the production method comprises the following process flows: molten iron → converter → LF refining → VD vacuum treatment → die casting and pouring → steel ingot cleaning → steel ingot is sent to the rolling and charging furnace within 12h after cleaning; KR molten iron pretreatment: mg powder or Mg powder + CaO is used as a desulfurizing agent, slag before and after molten iron arrives at a station must be removed, the thickness of a slag layer on the liquid surface is ensured to be less than or equal to 20mm, molten iron is stirred and desulfurized by KR to ensure that the S content of the molten iron is less than or equal to 0.005 percent, the desulfurization period is less than or equal to 21min and the desulfurization temperature is reduced to be less than or equal to 20 ℃;
b. smelting in a converter: the S content of the molten iron fed into the furnace is less than or equal to 0.003 percent, the P content is less than or equal to 0.080 percent, the temperature of the molten iron is more than or equal to 1270 ℃, the loading error of the molten iron is controlled according to +/-1 t, the scrap steel strictly adopts high-quality leftover materials, and 4/5 of the total amount of lime is added into the first batch; taking the need of early dephosphorization into consideration, adding the light-burned dolomite according to the MgO content of 10-12% of the slag, and adding the light-burned dolomite at one time after blowing; the second batch of slag charge is added according to the temperature and the slagging condition in the process, the slag is melted and dephosphorized as early as possible at the high gun position in the early stage, the oxygen pressure is controlled according to 0.9MPa, and the gun is properly lowered after the second batch of slag charge is added into the melted slag, so that the blowing is stable; the end point carbon is controlled to be less than or equal to 0.06 percent of [ C ], less than or equal to 0.015 percent of S, less than or equal to 0.015 percent of P and less than or equal to 0.0020 percent of [ N ]; the tapping temperature is 1640-1650 ℃, and the steel ladle temperature is 1570-1590 ℃;
and d, LF refining: argon is blown in the whole refining process, slag is added, the alkalinity is controlled according to 4.0-6.0, the slag must turn white or yellow-white after the refining and heating are finished, the white slag holding time is more than or equal to 30min, and the final slag after the refining is required to be foamed white slag with good fluidity and proper viscosity; performing secondary desulfurization on the manufactured white slag, keeping the manufactured white slag for 20-25min, fully deoxidizing by adopting a high-temperature, high-alkalinity, high-slag-content and low-iron oxide slagging process, and adopting calcium carbide, aluminum wires or aluminum particles as a deoxidizing agent;
VD vacuum treatment: maintaining the pressure for 18-23min under the vacuum degree of less than or equal to 67Pa, immediately performing Ca treatment after vacuum breaking, and finally ensuring that the H content is less than or equal to 1.2 ppm;
f. die casting: before the upper line is used, the temperature of an ingot mould is less than or equal to 120 ℃, the distance between the upper opening of a middle pouring pipe and a lower water opening of a ladle is controlled to be less than or equal to 140mm during pouring, half of the die casting protective slag is hung in the ingot mould in a straw rope hanging mode before pouring, the hanging height is 300-400 mm higher than the bottom of the ingot mould, the pouring process is stable in pouring and tight in following flow, the pouring temperature is controlled at 1550-;
g. heating at the following temperature for the following time: after steel is filled, the temperature of annealing steel is 600-;
h. rolling, namely after dephosphorization is carried out on steel ingot tapping, keeping the initial rolling temperature to be more than or equal to 1080 ℃, the steel feeding speed to be 1.5m/s, the cumulative reduction rate to be more than 45 percent, carrying out hot rolling on uncooled steel, and keeping the final rolling temperature to be 870-930 ℃;
i. performing stack cooling, namely performing high-temperature stack cooling by using a clamp after the wire is taken off, wherein the stack cooling temperature is 600-750 ℃, covering the cooled stack by using other hot rolled steel plates after the stack cooling, and forbidding the stack cooling to be exposed, wherein the stack cooling time is more than or equal to 96 hours;
j. and (3) heat treatment: after finishing the steel ingot, carrying out heat treatment in an external furnace, wherein the heating temperature is 920-plus 930 ℃, the heating coefficient T =2.4mm/min, and after tapping, carrying out water cooling, wherein the water inlet temperature is more than 785 ℃, the water cooling is 300-plus 400s, and the flashing temperature is 550-plus 600 ℃.
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| CN101487069A (en) * | 2008-01-18 | 2009-07-22 | 上海梅山钢铁股份有限公司 | Foam slag inhibitor for converter |
| CN105506454A (en) * | 2015-12-21 | 2016-04-20 | 南阳汉冶特钢有限公司 | Q460GJE-Z35 steel plate with thickness of 60-80 mm and low cost and production method thereof |
| CN108149135A (en) * | 2017-12-08 | 2018-06-12 | 南阳汉冶特钢有限公司 | A kind of Q390E grades of molding steel plates of 420mm thickness low-temperature impact and its production method |
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