CN115110005A - Production method of large-thickness steam pocket steel plate - Google Patents
Production method of large-thickness steam pocket steel plate Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 119
- 239000010959 steel Substances 0.000 title claims abstract description 119
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000005096 rolling process Methods 0.000 claims abstract description 48
- 238000001816 cooling Methods 0.000 claims abstract description 26
- 238000010438 heat treatment Methods 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000009847 ladle furnace Methods 0.000 claims abstract description 12
- 238000007670 refining Methods 0.000 claims abstract description 12
- 238000009849 vacuum degassing Methods 0.000 claims abstract description 12
- 238000003723 Smelting Methods 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 238000004512 die casting Methods 0.000 claims abstract description 7
- 238000007689 inspection Methods 0.000 claims abstract description 3
- 238000005266 casting Methods 0.000 claims description 30
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 16
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 16
- 229910052791 calcium Inorganic materials 0.000 claims description 16
- 239000011575 calcium Substances 0.000 claims description 16
- 239000003795 chemical substances by application Substances 0.000 claims description 14
- 238000004321 preservation Methods 0.000 claims description 14
- 239000002893 slag Substances 0.000 claims description 14
- 238000005496 tempering Methods 0.000 claims description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 8
- 229910052786 argon Inorganic materials 0.000 claims description 8
- 238000007664 blowing Methods 0.000 claims description 8
- 239000001257 hydrogen Substances 0.000 claims description 8
- 229910052739 hydrogen Inorganic materials 0.000 claims description 8
- 238000010079 rubber tapping Methods 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000003892 spreading Methods 0.000 claims description 2
- 238000003466 welding Methods 0.000 abstract description 5
- 238000005520 cutting process Methods 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000004925 denaturation Methods 0.000 description 2
- 230000036425 denaturation Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000009966 trimming Methods 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/04—Making ferrous alloys by melting
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- C21—METALLURGY OF IRON
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- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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Abstract
A production method of a large-thickness steam pocket steel plate comprises the following process flows of converter smelting, ladle furnace refining, vacuum degassing treatment, die casting, two-fire rolling and controlled rolling, cooling, heat treatment, inspection and warehousing. The steel comprises, by mass, C = 0.16-0.18, Si = 0.20-0.25, Mn = 1.40-1.45, P ≤ 0.015, S ≤ 0.003, Nb = 0.014-0.019, Ti = 0.012-0.018, Al = 0.020-0.045, Cr = 0.15-0.20, Mo = 0.50-0.55, and the balance Fe and unavoidable impurities. The steel produced by the method has high strength, good short-time high-temperature strength performance, good toughness, certain low-temperature toughness, excellent processability and welding performance; the delivery state yield strength of the steel is more than or equal to 450MPa, the tensile strength is 560-660 MPa, and the elongation is more than or equal to 18%; the impact toughness of the core part of the plate is 0 ℃, Akv is more than or equal to 110J, the low-temperature impact toughness is-20 ℃, and Akv is more than or equal to 85J; the tensile yield strength at 400 ℃ is more than or equal to 380Mpa, and the tensile strength is more than or equal to 500 Mpa.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a large-thickness steam drum steel plate with good strength and toughness and a production method thereof.
Background
In recent years, there has been an increasing demand for drum steels, particularly drum steel sheets of extra thick gauge, in many international areas and countries. The large-thickness drum steel plate with good strength and toughness is a new steel type with high technical content and high added value, has high yield strength and tensile strength, and also has good extensibility, cold bending property, welding property and impact toughness.
Disclosure of Invention
The invention aims to provide a production method of a large-thickness American-standard GrB-grade steam drum steel plate with good strength and toughness, and the produced steel has the strength of 560-660 Mpa, excellent impact toughness at 20 ℃, 0 ℃ and-20 ℃, good high-temperature tensile property at 400 ℃ in a short time, good processing and welding properties and the thickness of 145 mm.
The invention is realized by the following technical scheme:
a production method of a large-thickness steam pocket steel plate comprises the following process flows of converter smelting, ladle furnace refining, vacuum degassing treatment, die casting, two-fire rolling and controlled rolling, cooling, heat treatment, inspection and warehousing. The steel comprises, by mass, C = 0.16-0.18, Si = 0.20-0.25, Mn = 1.40-1.45, P ≤ 0.015, S ≤ 0.003, Nb = 0.014-0.019, Ti = 0.012-0.018, Al = 0.020-0.045, Cr = 0.15-0.20, Mo = 0.50-0.55, and the balance of unavoidable impurities of Fe; the key process steps comprise:
(1) smelting in a converter: the steel tapping C is more than or equal to 0.08 percent and less than or equal to 0.012 percent;
(2) ladle furnace refining: the molten steel is fed into a ladle furnace to carry out white slag making and heating temperature rise operation, the white slag is kept for more than 15min, and argon is blown from the bottom in the whole process; performing calcium treatment operation after refining is finished, wherein the calcium feeding line is more than or equal to 150 m;
(3) vacuum degassing: the molten steel enters a VD furnace or an RH furnace for vacuum degassing operation, the vacuum is kept for more than 12min under the condition of the working vacuum degree of 0.5tor, the molten steel is subjected to denitrification, hydrogen and oxygen treatment, and the hydrogen content is controlled to be less than or equal to 2.0 ppm; after vacuum breaking, feeding pure calcium wires for 300m twice at an interval of about 30 seconds; after calcium wires are fed, the soft blowing time of the molten steel is more than or equal to 12 min; adding a molten steel covering agent before the molten steel is discharged out of the station, and spreading the molten steel covering agent on the surface of the molten steel for molten steel heat preservation; covering the big bag;
(4) die casting: adding 120kg of covering slag into each riser 1h before casting, controlling the superheat degree of molten steel to be 42-45 ℃ for casting operation, and casting a large ladle deviating from a middle casting pipe; argon blowing is carried out in the whole process to protect casting, and casting operation is carried out by combining early-stage full-open flow control and later-stage low-temperature fast casting; after the pouring is finished, 60kg of heating agent is added into each riser of the steel ingot to reduce the molten steel cooling rate of the riser, and in addition, 12kg of molten steel covering agent is added into each riser to carry out heat preservation and insulation; after the steel ingot is demoulded, the pile cooling is more than or equal to 24 hours;
(5) rolling: adopting secondary heating forming and controlled rolling, firstly cogging a steel ingot to a secondary heating ingot with the thickness of 350mm, and cleaning the surface temperature of the steel ingot when the surface temperature of the secondary heating ingot is more than or equal to 200 ℃; the initial rolling temperature of the rough rolling stage of the secondary heating finished product is more than or equal to 1050 ℃, and the final rolling temperature is more than or equal to 980 ℃; the rough rolling adopts a high reduction system, and the final continuous two-pass reduction rate is more than or equal to 10 percent; the thickness of the intermediate blank = the thickness of the finished product + 40-60 mm; the finish rolling initial rolling temperature is 800-820 ℃ of a steel plate pyrometer; straightening the steel plate by hot straightening; after rolling, the thick plates are piled for more than 24 hours, and after unstacking, the thick plates are heated, and the edges and the ends are cut at the temperature of more than 100 ℃;
(6) and (3) heat treatment: normalizing, fast cooling and tempering heat treatment, wherein the normalizing temperature is 880-910 ℃, the heat preservation time is 260-270 min, and then fast water cooling is carried out; tempering at 670-710 ℃, keeping the temperature for 430-450 min, and then air cooling.
The invention has the beneficial effects that: the steel strictly controls the content of each harmful element through reasonable chemical composition design, and ensures the cleanliness of steel through converter smelting, ladle furnace refining, vacuum degassing treatment, external casting of a middle casting pipe and protective casting processes; the method comprises the following steps of secondary-fire cogging, rough-rolling under high pressure, controlled rolling, heap cooling, normalizing, fast cooling and tempering, and finally obtains the American-standard GrB-grade steel for the steam pocket, wherein the structure of the American-standard GrB-grade steel is ferrite, pearlite and tempered bainite, the grain size of the American-standard GrB-grade steel reaches 7.5-8.5 grades, the strength of the American-standard GrB-grade steel reaches 560-660 Mpa, the American-standard GrB-grade steel has excellent impact toughness at 20 ℃, good 0 ℃ and good-20 ℃, and has good short-time high-temperature tensile property at 400 ℃, good processing and welding performance and the thickness of the American-standard GrB-grade steel is 145 mm. The delivery state yield strength of the steel is more than or equal to 450MPa, the tensile strength is 560-660 MPa, and the elongation is more than or equal to 18%; the impact toughness of the core part of the plate is 0 ℃, Akv is more than or equal to 110J, the low-temperature impact toughness is-20 ℃, and Akv is more than or equal to 85J; the tensile yield strength at the high temperature of 400 ℃ is more than or equal to 380Mpa, and the tensile strength is more than or equal to 500 Mpa; the yield strength of the steel in a die-welding state is more than or equal to 440MPa, the tensile strength is more than or equal to 560MPa, and the elongation is more than or equal to 24 percent when the steel is kept at 610 ℃ for 10 hours; the plate thickness core part has the impact toughness of 0 ℃, Akv more than or equal to 120J, the low-temperature impact toughness of-20 ℃ and Akv more than or equal to 70J; the tensile yield strength at 400 ℃ is more than or equal to 360MPa, and the tensile strength is more than or equal to 470 MPa.
Drawings
FIG. 1 is a metallographic structure chart of a steel plate according to example 1.
Detailed Description
The invention is further illustrated by the following examples:
example 1: production of 145mmSA302GrB steel
The alloy elements comprise the following chemical components, by weight, C =0.16, Si =0.23, Mn =1.41, P =0.014, S =0.002, Nb =0.014, Al =0.035, Cr =0.17, Mo =0.51, and the balance of Fe and inevitable impurities; the key process steps are as follows:
(1) smelting in a converter: tapping C =0.08%, and tapping P is less than or equal to 0.012%;
(2) ladle furnace refining: the molten steel is put into a ladle furnace to carry out white slag making and heating temperature rise operation, the white slag keeping time is more than 15min, and argon is blown at the bottom in the whole process. Performing calcium treatment operation after refining is finished, wherein the calcium feeding line is more than or equal to 150m, and controlling impurities in molten steel;
(3) vacuum degassing treatment: the molten steel enters a VD furnace or an RH furnace for vacuum degassing operation, the vacuum is kept for more than 12min under the condition of the working vacuum degree of 0.5tor, and the molten steel is subjected to denitrification, hydrogen and oxygen treatment, wherein the hydrogen content is less than or equal to 2.0 ppm; after vacuum breaking, feeding pure calcium wires for 300m twice at an interval of 30 seconds to ensure complete denaturation of molten steel inclusions; after calcium wire feeding, the soft blowing time of the molten steel is more than or equal to 12min to ensure that impurities in the molten steel fully float upwards and are absorbed by slag, and the molten steel is purified; before the molten steel is discharged, a molten steel covering agent is added to spread the molten steel surface, and the molten steel is subjected to heat preservation. The ladle is covered with a cover, so that the heat preservation effect of the molten steel is further improved;
(4) die casting: adding 120kg of covering slag into each riser 1h before casting, controlling the superheat degree of molten steel to be 42-45 ℃ for casting, and casting a large ladle deviating from a middle pouring pipe to prevent drainage sand from rolling into polluted molten steel; and (3) blowing argon in the whole process to protect casting, and performing casting operation by combining early-stage full-open flow control and later-stage low-temperature fast casting. After the pouring is finished, 60kg of exothermic agent is added into each riser of the steel ingot to reduce the molten steel cooling rate of the riser, and 12kg of molten steel covering agent is added into each riser to carry out heat preservation and insulation. After the steel ingot is demoulded, the steel ingot is cooled in a heaping way for more than or equal to 24 hours;
(5) rolling: in order to ensure the stability and good control of the rolling process, the two-fire forming and controlled rolling are adopted. Firstly, cogging a steel ingot to a second hot ingot with the thickness of 350mm, and cleaning the surface temperature of the steel ingot when the surface temperature of the second hot ingot is more than or equal to 200 ℃ to ensure the surface quality of the steel ingot. The initial rolling temperature of the rough rolling stage of the secondary heating finished product is more than or equal to 1050 ℃, and the final rolling temperature is more than or equal to 980 ℃; a large reduction system is adopted for rough rolling, and the reduction rate of the last two continuous passes is ensured to be more than or equal to 10 percent; the thickness of the intermediate blank = the thickness of the finished product + 40-60 mm. And (3) finish rolling initial rolling temperature, and a steel plate pyrometer is 800-820 ℃. Straightening the steel plate by hot straightening to ensure that the plate shape meets the requirement; after rolling, the thick plates are piled for more than 24 hours, and after unstacking, trimming and cutting the ends and the tails with temperature (the temperature of hot cutting is more than 100 ℃);
(6) and (3) heat treatment: normalizing, fast cooling and tempering heat treatment, wherein the normalizing temperature is 880-910 ℃, the heat preservation time is 260-270 min, and then fast cooling (water cooling) is carried out; tempering at 670-710 ℃, keeping the temperature for 430-450 min, and then air cooling.
The product performance was examined as in table 1.
TABLE 1145 mmSA302GrB Performance Table
Example 2: production of 120mmSA302GrB steel
The chemical composition weight percentage of the alloy elements is C =0.19, Si =0.22, Mn =1.43, P =0.011, S =0.002, Nb =0.016, Al =0.031, Cr =0.17, Mo =0.49, and the balance is Fe and inevitable impurities, and the key process steps are as follows:
(1) smelting in a converter: the steel tapping C is =0.08%, and the steel tapping P is less than or equal to 0.012%.
(2) Ladle furnace refining: the molten steel is put into a ladle furnace to carry out white slag making and heating temperature rise operation, the white slag keeping time is more than 15min, and argon is blown at the bottom in the whole process. And performing calcium treatment operation after refining is finished, wherein the calcium feeding line is more than or equal to 150m, and controlling inclusions in molten steel.
(3) Vacuum degassing treatment: the molten steel enters a VD furnace or an RH furnace for vacuum degassing operation, the vacuum is kept for more than 12min under the condition of the working vacuum degree of 0.5tor, and the molten steel is subjected to denitrification, hydrogen and oxygen treatment, wherein the hydrogen content is less than or equal to 2.0 ppm; after vacuum breaking, feeding pure calcium wires for 300m twice at an interval of 32 seconds to ensure complete denaturation of molten steel inclusions; after calcium wire feeding, the soft blowing time of the molten steel is more than or equal to 12min to ensure that impurities in the molten steel fully float upwards and are absorbed by slag, and the molten steel is purified; before the molten steel is discharged, a molten steel covering agent is added to spread the molten steel surface, and the molten steel is subjected to heat preservation. The ladle is covered with a cover, so that the heat preservation effect of the molten steel is further improved.
(4) Die casting: and adding 120kg of covering slag into each riser 1 hour before casting, controlling the superheat degree of molten steel to be 42-45 ℃ for casting, and casting a large ladle deviating from a middle casting pipe to prevent drainage sand from rolling into and polluting the molten steel. And (3) blowing argon in the whole process to protect casting, and performing casting operation by combining early-stage full-open flow control and later-stage low-temperature fast casting. After the pouring is finished, 60kg of exothermic agent is added into each riser of the steel ingot to reduce the molten steel cooling rate of the riser, and 12kg of molten steel covering agent is added into each riser to carry out heat preservation and insulation. And after the steel ingot is demoulded, the pile cooling is more than or equal to 24 hours.
(5) Rolling: in order to ensure the stability and good control of the rolling process, the two-fire forming and controlled rolling are adopted. Firstly, cogging a steel ingot to a second fire ingot with the thickness of 350mm, and cleaning the surface of the steel ingot with temperature when the surface temperature of the second fire ingot is more than or equal to 200 ℃ to ensure the surface quality of the steel ingot. The initial rolling temperature of the rough rolling stage of the two-fire finished product is more than or equal to 1050 ℃, and the final rolling temperature is more than or equal to 980 ℃. The rough rolling adopts a high reduction system, and the final continuous two-pass reduction rate is ensured to be more than or equal to 12 percent. The thickness of the intermediate blank = the thickness of the finished product + 40-60 mm. And (3) finish rolling initial rolling temperature, and a steel plate pyrometer is 810-830 ℃. The hot straightening must straighten the steel plate to ensure that the plate shape meets the requirements. And (3) stacking and cooling the thick plates for more than 24 hours after rolling, and trimming and cutting the ends of the thick plates with temperature (the temperature of hot cutting is more than 100 ℃) after unstacking.
(6) And (3) heat treatment: normalizing, fast cooling and tempering heat treatment, wherein the normalizing temperature is 880-910 ℃, the heat preservation time is 220-230 min, and then fast cooling (water cooling) is carried out; tempering at 670-710 ℃, keeping the temperature for 350-370 min, and then air cooling.
The product performance was examined as in table 2.
TABLE 2120 mmSA302GrB Performance Table
Claims (1)
1. A production method of a large-thickness steam pocket steel plate comprises the following process flows of converter smelting, ladle furnace refining, vacuum degassing treatment, die casting, two-fire rolling and controlled rolling, cooling, heat treatment and inspection and warehousing, and is characterized in that: the steel comprises the following chemical components, by weight, 0.16-0.18% of C, 0.20-0.25% of Si, 1.40-1.45% of Mn, 0.015% or less of P, 0.003% or less of S, 0.014-0.019% of Nb, 0.012-0.018% of Ti, 0.020-0.045% of Al, 0.15-0.20% of Cr, 0.50-0.55% of Mo, and the balance of Fe and inevitable impurities; the key process steps comprise:
(1) smelting in a converter: the tapping C is more than or equal to 0.08 percent and less than or equal to 0.012 percent;
(2) ladle furnace refining: the molten steel is fed into a ladle furnace to carry out white slag making and heating temperature rise operation, the white slag is kept for more than 15min, and argon is blown from the bottom in the whole process; performing calcium treatment operation after refining is finished, wherein the calcium feeding line is more than or equal to 150 m;
(3) vacuum degassing: the molten steel enters a VD furnace or an RH furnace for vacuum degassing operation, the vacuum is kept for more than 12min under the condition of the working vacuum degree of 0.5tor, the molten steel is subjected to denitrification, hydrogen and oxygen treatment, and the hydrogen content is controlled to be less than or equal to 2.0 ppm; after the vacuum is broken, feeding pure calcium wires for two times by 300m at an interval of about 30 seconds; after calcium wires are fed, the soft blowing time of the molten steel is more than or equal to 12 min; adding a molten steel covering agent before the molten steel is discharged out of the station, and spreading the molten steel covering agent on the surface of the molten steel for molten steel heat preservation; covering the big bag;
(4) die casting: adding 120kg of covering slag into each riser 1h before casting, controlling the superheat degree of molten steel to be 42-45 ℃ for casting operation, and casting a large ladle deviating from a middle casting pipe; argon blowing is carried out in the whole process to protect casting, and casting operation is carried out by combining early-stage full-open flow control and later-stage low-temperature fast casting; after the pouring is finished, 60kg of heating agent is added into each riser of the steel ingot to reduce the molten steel cooling rate of the riser, and in addition, 12kg of molten steel covering agent is added into each riser to carry out heat preservation and insulation; after the steel ingot is demoulded, the steel ingot is cooled in a heaping way for more than or equal to 24 hours;
(5) rolling: adopting secondary heating forming and controlled rolling, firstly cogging a steel ingot to a secondary heating ingot with the thickness of 350mm, and cleaning the surface temperature of the steel ingot when the surface temperature of the secondary heating ingot is more than or equal to 200 ℃; the initial rolling temperature of the rough rolling stage of the secondary heating finished product is more than or equal to 1050 ℃, and the final rolling temperature is more than or equal to 980 ℃; the rough rolling adopts a high reduction system, and the final continuous two-pass reduction rate is more than or equal to 10 percent; the thickness of the intermediate blank = the thickness of the finished product + 40-60 mm; the finish rolling initial rolling temperature is 800-820 ℃ of a steel plate pyrometer; straightening the steel plate by hot straightening; after rolling, the thick plates are piled for more than 24 hours, and after unstacking, the thick plates are heated, and the edges and the ends are cut at the temperature of more than 100 ℃;
(6) and (3) heat treatment: normalizing, fast cooling and tempering heat treatment, wherein the normalizing temperature is 880-910 ℃, the heat preservation time is 260-270 min, and then fast water cooling is carried out; tempering at 670-710 ℃, keeping the temperature for 430-450 min, and then air cooling.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116970865A (en) * | 2023-07-22 | 2023-10-31 | 湖南华菱湘潭钢铁有限公司 | Production method of aluminum-free pipe fitting steel Q555PF |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102080185A (en) * | 2010-12-21 | 2011-06-01 | 南阳汉冶特钢有限公司 | High-tensile quenched and tempered steel plate for large-thickness structures and production method thereof |
| CN103160740A (en) * | 2013-03-16 | 2013-06-19 | 南阳汉冶特钢有限公司 | Steel 18MnMoNbR for pressure vessel and process for producing 18MnMoNbR steel plate with thickness of 100mm |
| CN105296731A (en) * | 2015-11-12 | 2016-02-03 | 内蒙古包钢钢联股份有限公司 | Production method capable of improving impact toughness of thick-specification high-strength steel plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102080185A (en) * | 2010-12-21 | 2011-06-01 | 南阳汉冶特钢有限公司 | High-tensile quenched and tempered steel plate for large-thickness structures and production method thereof |
| CN103160740A (en) * | 2013-03-16 | 2013-06-19 | 南阳汉冶特钢有限公司 | Steel 18MnMoNbR for pressure vessel and process for producing 18MnMoNbR steel plate with thickness of 100mm |
| CN105296731A (en) * | 2015-11-12 | 2016-02-03 | 内蒙古包钢钢联股份有限公司 | Production method capable of improving impact toughness of thick-specification high-strength steel plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116970865A (en) * | 2023-07-22 | 2023-10-31 | 湖南华菱湘潭钢铁有限公司 | Production method of aluminum-free pipe fitting steel Q555PF |
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