CN115094217A - 30CrMoA steel plate and production method thereof - Google Patents
30CrMoA steel plate and production method thereof Download PDFInfo
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- CN115094217A CN115094217A CN202210817044.8A CN202210817044A CN115094217A CN 115094217 A CN115094217 A CN 115094217A CN 202210817044 A CN202210817044 A CN 202210817044A CN 115094217 A CN115094217 A CN 115094217A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 116
- 239000010959 steel Substances 0.000 title claims abstract description 116
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 37
- 238000005096 rolling process Methods 0.000 claims abstract description 73
- 238000000034 method Methods 0.000 claims abstract description 64
- 230000008569 process Effects 0.000 claims abstract description 50
- 238000001816 cooling Methods 0.000 claims abstract description 39
- 238000005266 casting Methods 0.000 claims abstract description 30
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 66
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 44
- 229910052742 iron Inorganic materials 0.000 claims description 30
- 238000007670 refining Methods 0.000 claims description 28
- 229910052786 argon Inorganic materials 0.000 claims description 22
- 239000002893 slag Substances 0.000 claims description 22
- 230000009467 reduction Effects 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000001953 recrystallisation Methods 0.000 claims description 18
- 229910001566 austenite Inorganic materials 0.000 claims description 17
- 238000010079 rubber tapping Methods 0.000 claims description 16
- 238000010583 slow cooling Methods 0.000 claims description 13
- 238000006477 desulfuration reaction Methods 0.000 claims description 12
- 230000023556 desulfurization Effects 0.000 claims description 12
- 238000007664 blowing Methods 0.000 claims description 10
- 238000009749 continuous casting Methods 0.000 claims description 10
- 238000003723 Smelting Methods 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 4
- 238000005496 tempering Methods 0.000 abstract description 18
- 238000010791 quenching Methods 0.000 abstract description 8
- 230000000171 quenching effect Effects 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 7
- 230000003009 desulfurizing effect Effects 0.000 description 4
- 239000002918 waste heat Substances 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 229910000746 Structural steel Inorganic materials 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000033764 rhythmic process Effects 0.000 description 2
- -1 silicon-aluminum-barium-calcium Chemical compound 0.000 description 2
- 230000007480 spreading Effects 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000003137 locomotive effect Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000007306 turnover Effects 0.000 description 1
Classifications
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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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- 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
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- 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
-
- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
Abstract
The invention discloses a 30CrMoA steel plate and a production method thereof, belonging to the technical field of medium-thickness steel plate production. The method comprises the following steps: the casting blank is processed as follows: the method comprises the following steps of first-stage rolling, second-stage rolling, rapid cooling, third-stage rolling, ACC cooling and high-temperature stack cooling. The method adopts a mode of combining rolling with high-temperature heap cooling to replace the traditional normalizing, tempering or tempering process, the aim of on-line quenching is achieved by rapidly cooling the rolled steel plate by using the ACC, and the tempering effect is achieved by using the residual temperature of the steel plate in the heap cooling process, including the residual temperature of the steel plate and the residual temperature of other steel plates. The internal structure and mechanical property of the 30CrMoA steel plate produced by the method completely meet the use requirements, the production cost is reduced, and the process flow is shortened.
Description
Technical Field
The invention relates to the technical field of medium steel plate production, in particular to a 30CrMoA steel plate and a production method thereof.
Background
The 30CrMoA belongs to alloy structural steel, is mainly used for manufacturing parts with higher core strength requirement, surface abrasion resistance, complex shape and small load, such as: the gear of a gearbox of a machine tool, a large gear for locomotive traction, an operating wheel bearing high load, parts with larger stress and serious abrasion in engineering machinery and the like.
The market demand is increased in recent years, but at present, all production and use units basically adopt the processes of quenching and tempering and the like to produce the steel grade, and because the steel plate is subjected to two heat treatment processes of normalizing and tempering, the process flow is complex, the requirement on equipment is strict, the production and manufacturing cost is increased, and the steel grade is not in line with the current concepts of energy conservation, environmental protection, green and low carbon.
In view of this, the invention is particularly proposed.
Disclosure of Invention
One of the purposes of the invention is to provide a production method of a 30CrMoA steel plate to solve the technical problems.
The second purpose of the invention is to provide a 30CrMoA steel plate produced by the production method.
The application can be realized as follows:
in a first aspect, the invention provides a method for producing a 30CrMoA steel plate, which comprises the following steps:
the casting blank is processed as follows:
rolling in the first stage: rolling in an austenite recrystallization region under the conditions that the initial rolling temperature is 1050-;
rolling in the second stage: rolling in an austenite recrystallization zone at the rolling temperature of 950 ℃ and 1000 ℃ and under the condition that the pass reduction is 10-30 mm; finishing the second-stage rolling until the thickness of the intermediate blank reaches 1.5-2.0 times of that of the finished product;
and (3) rapid cooling: rapidly cooling the intermediate blank obtained after the second-stage rolling until the temperature of the intermediate blank is 870-910 ℃, and carrying out third-stage rolling;
rolling in the third stage: rolling the austenite non-recrystallization region under the conditions that the stage accumulated reduction rate is more than or equal to 50 percent, the pass reduction rate is more than 15 percent and the final rolling temperature is 840-880 ℃;
the steel sheet obtained after the third stage rolling is ACC-cooled and then high-temperature stack-cooled.
In an alternative embodiment, the ACC cooling process is carried out at a cooling rate of 5-20 ℃/S and a temperature of 400-500 ℃ for red return.
In an alternative embodiment, before the slow cooling pile is cooled, 5-10 auxiliary steel plates with the temperature of more than 450 ℃ are paved at the bottom of the slow cooling pile, after the steel plates to be slowly cooled after the ACC is cooled enter the slow cooling pile, the upper part of the steel plates is covered with 5-10 auxiliary steel plates with the temperature of more than 450 ℃.
In an alternative embodiment, the casting blank is obtained by smelting molten iron in a furnace through a converter, LF refining, VD refining, continuous casting and heat treatment.
In an optional embodiment, in the smelting process of the converter, high-quality scrap steel is added into molten iron entering the converter, and the steel tapping targets are that P is less than or equal to 0.015 wt%, C is greater than or equal to 0.05 wt%, and S is less than or equal to 0.012 wt%.
In an optional embodiment, a slag-stopping tapping mode is adopted in the tapping process, and argon is blown in the whole process in the tapping process.
In an optional embodiment, P in the molten iron fed into the furnace is less than or equal to 0.01 wt% and S is less than or equal to 0.01 wt%.
In an optional embodiment, before entering the converter, the molten iron to be fed into the converter is pretreated.
In an alternative embodiment, the pretreatment of molten iron comprises: and carrying out slagging-off treatment on the molten iron to be charged into the furnace so as to enable the thickness of a liquid surface slag layer to be less than or equal to 20 mm.
In an optional embodiment, the molten iron after the slag skimming treatment is stirred by KR and then is subjected to desulfurization treatment, so that S in the molten iron after the desulfurization treatment is less than or equal to 0.005 wt%.
In an optional embodiment, the desulfurization period is less than or equal to 21min, and the desulfurization temperature is less than or equal to 20 ℃.
In an optional embodiment, argon is blown in the whole refining process to ensure that the exposed diameter of the molten steel is less than or equal to 200 mm.
In an alternative embodiment, the refining slag charge is added to make white slag during refining.
In an alternative embodiment, the alkalinity of the refining slag is 2.5-3, and the white slag holding time is more than or equal to 20 min.
In an alternative embodiment, a 100-200m calcium wire is added after the refining is complete.
In an alternative embodiment, the temperature of the molten steel leaving the refining apparatus is 1580-.
In an optional embodiment, in the VD refining process, the VD vacuum degree is below 67Pa, and the pressure maintaining time is more than or equal to 13 min.
In an alternative embodiment, after the vacuum is finished, argon gas is blown into the molten steel so that the molten steel does not tumble.
In an alternative embodiment, the covering agent is added after the argon blowing is finished and the temperature of the upper steel is 1540-1580 ℃.
In an alternative embodiment, the degree of superheat of the tundish during continuous casting is controlled to be 5-25 ℃.
In an alternative embodiment, the drawing speed during continuous casting is set to 0.55-0.95 m/min.
In an alternative embodiment, the casting is performed under electromagnetic stirring conditions.
In an optional embodiment, the post-casting blank unloading stack cooling is more than or equal to 24 hours.
In an alternative embodiment, the strand heating comprises: preheating at 850-1000 ℃, heating at 1220-1240 ℃, and preserving heat at 1200-1220 ℃;
wherein the heat preservation time is more than 40min, and the heating time of the whole casting blank is controlled according to 11-14 min/cm.
In a second aspect, the present application provides a 30CrMoA steel sheet produced by the production method according to any one of the preceding embodiments.
In an alternative embodiment, the 30CrMoA steel plate has a thickness of 20 to 100 mm.
In an alternative embodiment, the 30CrMoA steel plate has a chemical composition, in mass percent, including: 0.26-0.33% of C, 0.17-0.37% of Si, 0.4-0.7% of Mn, less than or equal to 0.02% of P, less than or equal to 0.015% of S, 0.8-1.1% of Cr, 0.15-0.25% of Mo, less than or equal to 0.05% of Als, and the balance of Fe and residual elements.
The beneficial effect of this application includes:
this application combines high temperature through adopting rolling to pile cold mode, replaces traditional normalizing + tempering or quenching and tempering process, and the steel sheet is rolled to finish utilizing the ACC to carry out the purpose that cools off fast and reach online quenching, piles cold in-process and utilizes the steel sheet residual temperature, reaches the effect of tempering. The method not only reduces the production cost and shortens the process flow, but also ensures that the internal structure and the mechanical property of the produced steel plate completely meet the use requirements.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.
The following is a detailed description of the 30CrMoA steel plate and the production method thereof provided in the present application.
The application provides a production method of a 30CrMoA steel plate, which comprises the following steps:
the casting blank is processed as follows:
rolling in the first stage: rolling in an austenite recrystallization region under the conditions that the initial rolling temperature is 1050-;
rolling in the second stage: rolling in an austenite recrystallization zone at the rolling temperature of 950 ℃ and 1000 ℃ and under the condition that the pass reduction is 10-30 mm; finishing the second-stage rolling until the thickness of the intermediate blank reaches 1.5-2.0 times of that of the finished product;
and (3) quick cooling: rapidly cooling the intermediate blank obtained after the second-stage rolling until the temperature of the intermediate blank is 870-910 ℃, and carrying out third-stage rolling;
rolling in the third stage: rolling the austenite non-recrystallization region under the conditions that the stage accumulated reduction rate is more than or equal to 50 percent, the pass reduction rate is more than 15 percent and the final rolling temperature is 840-880 ℃;
and (4) performing ACC cooling on the steel plate obtained after the third-stage rolling, and then performing high-temperature heap cooling in a slow cooling pile.
In the first stage pressing process, the initial rolling temperature can be set to 1050 ℃, 1075 ℃, 1100 ℃, 1125 ℃ or 1150 ℃, etc., or can be any other value within the range of 1050 ℃ and 1150 ℃.
The roll speed can be 12-20r/min, such as 20r/min, 19r/min, 18r/min, 17r/min, 16r/min, 15r/min, 14r/min, 13r/min, 12r/min, etc. Preferably, the rotation speed of the press rolls of the first stage pressing is 15-18 r/min.
The pass reduction may be 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, or the like. Preferably, the pass reduction of the first stage press is 40-50mm, such as 45mm or 50mm, the thicker the finished plate, the thicker the blank, the greater the pass reduction, and the more passes, as follows.
The first stage rolling is austenite recrystallization zone rolling, and the rolling force reaches the core part of the billet by adopting a high-temperature, low-speed and high-reduction process, so that the recrystallization of the core part of the casting blank is promoted, a foundation is laid for the refinement of core grains, the deformation of the core part of the billet is promoted, and the segregation and the defects of the core part of the casting blank are greatly improved.
In the second stage rolling process, the rolling temperature may be 950 ℃, 975 ℃, 980 ℃, 985 ℃, 990 ℃, 995 ℃ or 1000 ℃, or may be any other value within the range of 950 ℃ and 1000 ℃.
The pass reduction may be 10mm, 12mm, 15mm, 18mm, 30mm or the like, or may be any other value within the range of 10 to 30 mm.
The second stage rolling is still austenite recrystallization region rolling, and the rolling temperature and the pass reduction are controlled in the ranges, so that the rolling force reaches the position of about 1/4 thickness of the cast slab, the 1/4 position is promoted to deform, and finally the aims of recrystallization at the position of the cast slab 1/4 and creating conditions for grain refinement are achieved.
The second stage of rolling is terminated when the intermediate billet thickness reaches 1.5-2.0 times (e.g., 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, or 2 times) the finished product thickness. The intermediate blank is then introduced into an IC device for rapid cooling.
When the intermediate blank is cooled to 870-.
In the third-stage rolling process, the cumulative reduction ratio at this stage may be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any other value within a range of not less than 50%.
The finishing temperature can be 840 ℃, 845 ℃, 850 ℃, 855 ℃, 860 ℃, 865 ℃, 870 ℃, 875 ℃ or 880 ℃, etc., and can also be any other value within the range of 840 ℃ and 880 ℃.
The rolling in the third stage is the rolling in an austenite non-recrystallization region, and the rolling in the third stage can effectively increase the effective area of austenite grain boundaries, provide more nucleation points for austenite transformation and achieve the effect of grain refinement.
In the ACC cooling process, the cooling speed can be controlled to be 5-20 ℃/S, such as 5 ℃/S, 8 ℃/S, 10 ℃/S, 12 ℃/S, 15 ℃/S, 18 ℃/S or 20 ℃/S, and the like, and can also be any other value within the range of 5-20 ℃/S. It should be noted that the larger the thickness of the sheet, the lower the cooling rate and the longer the cooling time.
The temperature for the re-annealing can be controlled at 400-500 deg.C, such as 400 deg.C, 420 deg.C, 450 deg.C, 480 deg.C or 500 deg.C, and can be any other value within the range of 400-500 deg.C.
Further, the steel plate after the ACC cooling is straightened and quickly hung into a slow cooling pit for stack cooling.
In the application, before the slow cooling pile is cooled, 5-10 auxiliary steel plates (such as other steel plates) with the temperature being more than 450 ℃ (preferably 510 plus 580 ℃) are laid at the bottom of the slow cooling pile, after the steel plates to be slowly cooled after the ACC is cooled are placed in the slow cooling pile, 5-10 auxiliary steel plates (other steel plates) with the temperature being more than 450 ℃ (preferably 510 plus 580 ℃) are covered at the upper part of the steel plates to be slowly cooled.
The dump cooling mode can fully utilize the residual temperature of the steel plate, and achieves the aims of saving energy, protecting environment and reducing subsequent heat treatment processes on the premise of meeting the tempering temperature requirement. If the bottom paved steel plate or the covered steel plate is less, the temperature drop is too fast to meet the heat preservation time and the tempering effect, and too many paved steel plates are not beneficial to production organization.
Bearing, this application replaces traditional normalizing + tempering or quenching and tempering process through adopting rolling + high temperature heap cold mode, and the steel sheet is rolled to finish utilizing the ACC to carry out the purpose that cools off fast and reach online quenching, piles cold in-process and utilizes the steel sheet waste heat, including the waste heat of steel sheet self surplus temperature and other steel sheets, reaches the effect of tempering. The method not only reduces the production cost and shortens the process flow, but also ensures that the internal structure and the mechanical property of the produced steel plate completely meet the use requirements.
In the application, the casting blank is obtained by smelting molten iron in a furnace through a converter, LF refining, VD refining, continuous casting and heat treatment.
For reference, in the converter smelting process, high-quality scrap steel is added into molten iron in the furnace, wherein P in the molten iron in the furnace is less than or equal to 0.01 wt%, S in the molten iron in the furnace is less than or equal to 0.01 wt%, and the steel tapping targets are that P is less than or equal to 0.015 wt%, C is more than or equal to 0.05 wt%, and S in the molten iron in the furnace is less than or equal to 0.012 wt%.
Before entering the converter, the molten iron to be entered into the converter is pretreated, and the pretreatment comprises the following steps: and carrying out slagging-off treatment on the molten iron to be charged into the furnace to ensure that the thickness of a slag layer on the liquid surface is less than or equal to 20 mm. And stirring and desulfurizing the molten iron subjected to slag skimming by KR to ensure that S in the molten iron subjected to desulfurization is less than or equal to 0.005 wt%.
In the desulfurization treatment process, the desulfurization period is less than or equal to 21min (preferably 16-20min), and the desulfurization temperature is less than or equal to 20 ℃ (preferably 10-18 ℃).
And in the tapping process after the converter smelting, adding a silicon-aluminum-barium-calcium block and an aluminum wire into a ladle for deoxidation. The slag blocking mode is adopted for tapping, and argon is blown in the whole process during tapping.
In the LF refining process, argon is blown in the whole process, the argon blowing strength is based on the condition that the exposed diameter of molten steel is less than or equal to 200mm, secondary oxidation of the molten steel is avoided, meanwhile, in order to ensure the argon blowing effect, refining slag is added to produce white slag, the alkalinity is controlled to be 2.5-3.0, and the white slag holding time is more than or equal to 20min (preferably 20-25 min). The heating process can select proper current to heat according to rhythm surplus and temperature conditions, aluminum wires, aluminum particles and the like are added in the heating process according to slagging conditions, argon is closed before leaving the station, 100-plus-200 m (such as 100m, 120m, 150m, 180m or 200m and the like) calcium wires are added, and the temperature of molten steel leaving the station (the temperature leaving the refining equipment) is controlled at 1600 +/-20 ℃ (such as 1580 ℃, 1590 ℃, 1600 ℃, 1610 ℃ or 1620 ℃ and the like).
In the VD refining process, the VD vacuum degree is below 67Pa (preferably 56-66Pa), and the dwell time is more than or equal to 13min (preferably 13-16 min). And blowing argon into the molten steel after the vacuum is finished, wherein the strength is based on that the molten steel does not tumble. Closing argon before leaving the station, spreading covering agent on the molten steel surface, and ensuring the steel feeding temperature to be 1560 + -20 deg.C (such as 1540 deg.C, 1550 deg.C, 1560 deg.C, 1570 deg.C or 1580 deg.C).
In the continuous casting process, the superheat degree of the tundish is controlled to be 5-25 ℃ (namely 15 +/-10 ℃). The pulling speed is set to be the pulling speed (the pulling speed is constant) corresponding to the casting blank with the thickness of 300-450mm and is about 0.55-0.95m/min, so that the rolling compression ratio requirement of the thick plate and the internal structure thinning condition are ensured. It should be noted that the constant drawing speed varies with the thickness of the slab, for example: when the thickness of the casting blank is 300mm, the pulling speed is 0.85-0.95m/min, and when the thickness of the casting blank is 450mm, the pulling speed is 0.55-0.65 mm. That is, when the thickness of the cast slab is relatively small, the pulling rate is relatively high, and when the thickness of the cast slab is relatively large, the pulling rate is relatively small.
Electromagnetic stirring is started in the casting process, and the casting is protected in the whole process. The argon blowing amount of the stopper rod is reasonably controlled in the steel casting process, and slight fluctuation of the liquid level of the crystallizer is ensured. And the casting blank is cooled in a heap after being off line for more than or equal to 24 hours (preferably 24-36 hours). The dump cooling time is related to the slab thickness, and the thicker the cast slab, the longer the dump cooling time is.
The casting blank heating process comprises the following steps: preheating at 850-.
Wherein the heat preservation time is more than 40min (preferably 42-48min), and the heating time of the whole casting blank is controlled according to 11-14 min/cm.
It should be noted that, the contents that are not expanded and described in detail in the present application can refer to the related prior art, and are not described in detail herein.
Correspondingly, the application also provides a 30CrMoA steel plate produced by the production method.
The thickness of the 30CrMoA steel plate is 20-100mm, such as 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, and the like, and can also be any other value within the range of 20-100 mm.
The 30CrMoA steel plate comprises the following chemical components in percentage by mass: 0.26-0.33% of C, 0.17-0.37% of Si, 0.4-0.7% of Mn, less than or equal to 0.02% of P, less than or equal to 0.015% of S, 0.8-1.1% of Cr, 0.15-0.25% of Mo, less than or equal to 0.05% of Als (acid-melted aluminum), and the balance of Fe and residual elements.
The 30CrMoA steel plate has better mechanical properties such as yield strength, tensile strength, elongation, average impact energy, reduction of area, Brinell hardness and the like.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The embodiment provides a 30CrMoA steel plate with the thickness of 30mm, which comprises the following chemical components in percentage by mass:
c: 0.27%, Si: 0.19%, Mn: 0.56%, P is less than or equal to 0.016%, S is less than or equal to 0.010%, Cr: 0.89%, Mo: 0.18%, Als: 0.023 percent, and the balance of Fe and residual elements.
Example 2
The embodiment provides a 30CrMoA steel plate with the thickness of 70mm, which comprises the following chemical components in percentage by mass:
c: 0.30%, Si: 0.23%, Mn: 0.62 percent, P is less than or equal to 0.012 percent, S is less than or equal to 0.009 percent, Cr: 1.01%, Mo: 0.20%, Als: 0.030%, the balance being Fe and residual elements.
Example 3
The embodiment provides a 30CrMoA steel plate with the thickness of 100mm, which comprises the following chemical components in percentage by mass:
c: 0.32%, Si: 0.35%, Mn: 0.68%, P is less than or equal to 0.010%, S is less than or equal to 0.005%, Cr: 1.09%, Mo: 0.24%, Als: 0.039%, the balance being Fe and residual elements.
The main production process of the 30CrMoA steel plate corresponding to the above examples 1-3 is as follows:
(1) pretreating molten iron: slagging off the molten iron, wherein the thickness of a slag layer on the liquid surface is 15-20mm, stirring and desulfurizing the molten iron by KR to ensure that S in the molten iron is less than or equal to 0.005 percent, the desulfurizing period is 16-21min, and the desulfurizing temperature is reduced by 16-20 ℃.
(2) Smelting in a converter: the S content of the charged molten iron is less than or equal to 0.010 percent and the P content is less than or equal to 0.010 percent, high-quality scrap steel is added in the smelting process, the tapping target P content is less than or equal to 0.015 percent, the C content is more than or equal to 0.05 percent and the S content is less than or equal to 0.012 percent, and silicon-aluminum-barium-calcium blocks and aluminum wires are added into a ladle for deoxidation in the tapping process. And (4) slag stopping and tapping, and blowing argon in the whole tapping process.
(3) LF refining: argon is blown in the whole refining process, the argon blowing strength is based on the condition that the exposed diameter of the molten steel is less than or equal to 200mm, and refining slag (the alkalinity is 2.5-3.0) is added. And in the heating process, proper current is selected according to rhythm surplus and temperature conditions for heating, aluminum wires, aluminum particles and the like are supplemented according to slagging conditions in the heating process, argon is closed before leaving the station, 160m calcium wires are added, and the leaving temperature of molten steel is controlled to be 1600 +/-20 ℃.
(4) VD refining: VD, the vacuum degree is 56-66Pa, the dwell time is 13-16min, soft blowing is carried out after vacuum breaking, and the strength is based on that molten steel does not turn over. And (3) closing argon before leaving the station, fully spreading a covering agent on the surface of the molten steel, and ensuring the temperature of feeding the steel to be 1560 +/-20 ℃.
(5) Continuous casting: the tundish superheat degree is 15 +/-10 ℃, the constant drawing speed is 0.55-0.95m/min according to different slab thicknesses, electromagnetic stirring is adopted, and the whole process protection casting is required for continuous casting steel casting. The argon blowing amount of the stopper rod is reasonably controlled in the steel casting process, and slight fluctuation of the liquid level of the crystallizer is ensured. And (5) performing stack cooling for 24-36h after the casting blank is drawn off the line.
(6) A casting blank heating process: the temperature of the preheating section is 850-.
(7) Rolling: the first stage is austenite recrystallization zone rolling, and adopts a process of high temperature, low speed and large reduction, wherein the rolling temperature is 1050-; the second stage is still rolling in an austenite recrystallization region, the rolling temperature is controlled to be 950-1000 ℃, the pass reduction is controlled according to 10-30mm, the rolling force reaches the position of 1/4 thickness of a casting blank, the position of 1/4 is promoted to deform, and the aims of recrystallization at the position of 1/4 and creating conditions for grain refinement are finally achieved, when the thickness of an intermediate blank reaches 1.5-2.0 times of the thickness of a finished product, the second stage rolling is finished, and the intermediate blank enters an IC device for rapid cooling; when the temperature of the intermediate billet is 870-910 ℃, the third-stage austenite non-recrystallization zone rolling is started, the accumulated reduction rate of the stages is 50-100%, and the final rolling temperature is 840-880 ℃. And after rolling, the steel plate enters ACC for cooling, the cooling speed is controlled to be 5-20 ℃/S, and the temperature of red returning is controlled to be 400-500 ℃.
(8) And (3) cooling in a stacking manner: after the steel plate is straightened out of the ACC, the steel plate is quickly hung into a slow cooling pit and then is piled and cooled in the slow cooling pit, before the piling and cooling, 5-10 auxiliary steel plates with the temperature of 510-.
Test examples
The mechanical properties of the 30CrMoA steel plates produced according to the above examples 1-3 were tested according to the method provided in GB3077-2015, wherein the mechanical properties of the products of each example correspond to 20 batches, the mechanical properties are shown in table 1, and the values in table 1 are the total average values of the products of 3 examples after 20 batches of tests.
TABLE 1 mechanical Property results
As can be seen from table 1:
the method is used for trial production of 20 batches of 30CrMoA with the thickness of 30mm, 70mm and 100mm respectively, and the novel alloy structural steel 30CrMoA steel plate is successfully developed through reasonable chemical composition design and production process control.
The average value of the yield strength of the obtained 30CrMoA steel plates with different thicknesses is 915MPa, and the average value is 180MPa more than the standard value; the average value of the tensile strength is 1141.6MPa, which is 211.6MPa more than the standard, and the average value of the elongation is 18 percent, which is 6 percent more than the standard; the average value of the average impact energy is 164.3J, the average value of the reduction of area is 57.6 percent, and the average value of the Brinell hardness is HB 400.
Performing external inspection on the obtained steel plate, wherein the rate of qualified products is 100%; flaw detection is carried out according to GB/T47030, the first-grade rate is 80%, the third-grade rate is 100% (namely, the flaw detection grade reaches 80% of the first grade, and the rest 20% reaches the third grade), and the expected effect is achieved.
Comparative example
Steel sheets having the same chemical composition as those of examples 1 to 3 were produced under the following conditions, i.e., the present comparative example provides a plurality of steel sheets having the same chemical composition as those of examples 1 to 3, respectively, except that the production process was different.
The steel billet rolling temperature is 980-:
TABLE 2 mechanical Property results
Through the comparison of the data, the mechanical properties of the steel plate produced by the method are basically the same as those of the steel plate produced by the traditional hardening and tempering process, but the method provided by the application can greatly shorten the process flow compared with the hardening and tempering process, improve the production efficiency and meet the mechanical properties of the steel plate. To sum up, this application replaces traditional normalizing + tempering or quenching and tempering process through the mode that adopts rolling + high temperature heap cold, and the steel sheet is rolled to finish utilizing the ACC to cool off fast and reach the purpose of online quenching, piles cold in-process and utilizes the steel sheet waste heat, including the waste heat of steel sheet self surplus warm sum other steel sheets, reaches the effect of tempering. The method not only reduces the production cost, shortens the process flow and improves the production efficiency, but also ensures that the internal structure and the mechanical property of the produced steel plate completely meet the use requirements.
The present invention has been described in terms of the preferred embodiment, and it is not intended to be limited to the embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The production method of the 30CrMoA steel plate is characterized by comprising the following steps:
the casting blank is processed as follows:
rolling in the first stage: rolling in an austenite recrystallization region under the conditions that the initial rolling temperature is 1050-;
rolling in the second stage: rolling in an austenite recrystallization zone at the rolling temperature of 950 ℃ and 1000 ℃ and under the condition that the pass reduction is 10-30 mm; finishing the second stage of rolling until the thickness of the intermediate blank reaches 1.5-2.0 times of that of the finished product;
and (3) rapid cooling: rapidly cooling the intermediate blank obtained after the second-stage rolling until the temperature of the intermediate blank is 870-910 ℃, and performing third-stage rolling;
rolling in the third stage: rolling the austenite non-recrystallization region under the conditions that the accumulated reduction rate is more than or equal to 50 percent, the pass reduction rate is more than 15 percent and the final rolling temperature is 840-880 ℃;
and (4) carrying out ACC cooling on the steel plate obtained after the third-stage rolling is finished, and then carrying out high-temperature heap cooling.
2. The production method according to claim 1, wherein the cooling rate is controlled to be 5-20 ℃/S and the temperature for red-back is controlled to be 400-500 ℃ during the ACC cooling process.
3. The production method according to claim 2, wherein before the slow cooling pile, 5-10 auxiliary steel plates with the temperature of more than 450 ℃ are laid at the bottom of the slow cooling pile, and after the steel plate to be slowly cooled after the ACC cooling is placed in the slow cooling pile, 5-10 auxiliary steel plates with the temperature of more than 450 ℃ are covered at the upper part of the steel plate to be slowly cooled.
4. The production method according to any one of claims 1 to 3, wherein the cast slab is obtained by converter smelting, LF refining, VD refining, continuous casting and slab heating of charged molten iron;
preferably, in the converter smelting process, high-quality scrap steel is added into molten iron entering a converter, and the steel tapping targets are that P is less than or equal to 0.015 wt%, C is more than or equal to 0.05 wt%, and S is less than or equal to 0.012 wt%;
preferably, in the tapping process, a slag stopping tapping mode is adopted, and argon is blown in the whole process in the tapping process;
preferably, P in the molten iron fed into the furnace is less than or equal to 0.01wt percent, and S is less than or equal to 0.01wt percent;
preferably, before entering the converter, the molten iron to be charged into the converter is pretreated;
preferably, the molten iron pretreatment includes: carrying out slagging-off treatment on molten iron to be charged into the furnace so as to enable the thickness of a liquid surface slag layer to be less than or equal to 20 mm;
preferably, the molten iron after the slag skimming treatment is stirred by KR and then is subjected to desulfurization treatment, so that S in the molten iron after the desulfurization treatment is less than or equal to 0.005 wt%;
preferably, the desulfurization period is less than or equal to 21min, and the desulfurization temperature is less than or equal to 20 ℃.
5. The production method according to claim 4, wherein during the refining process, argon is blown in the whole process to ensure that the bare diameter of the molten steel is less than or equal to 200 mm;
preferably, refining slag charge is added in the refining process to make white slag;
preferably, the alkalinity of the refining slag is 2.5-3, and the white slag holding time is more than or equal to 20 min;
preferably, a 100- & ltSP & gt and 200m calcium wire is added after the refining is finished;
preferably, the temperature of the molten steel leaving the refining equipment is 1580-1620 ℃.
6. The production method according to claim 4, wherein in the VD refining process, the VD vacuum degree is below 67Pa, and the pressure maintaining time is more than or equal to 13 min;
preferably, after the vacuum is finished, argon is blown into the molten steel so that the molten steel is not overturned;
preferably, the covering agent is added after the argon blowing is finished, and the temperature of the upper steel is 1540-1580 ℃.
7. The production method according to claim 4, wherein the degree of superheat of the tundish during continuous casting is controlled to be 5-25 ℃;
preferably, the drawing speed is set to be 0.55-0.95m/min in the continuous casting process;
preferably, the casting is performed under electromagnetic stirring conditions;
preferably, the post-cooling of the casting blank is more than or equal to 24 hours after the casting blank is off line.
8. The production method according to claim 4, wherein the slab heating includes: preheating at 850-1000 ℃, heating at 1220-1240 ℃, and preserving heat at 1200-1220 ℃;
wherein the heat preservation time is more than 40min, and the heating time of the whole casting blank is controlled according to 11-14 min/cm.
9. A 30CrMoA steel sheet produced by the production method according to any one of claims 1 to 8;
preferably, the thickness of the 30CrMoA steel plate is 20-100 mm.
10. The 30CrMoA steel sheet according to claim 9, characterized in that said 30CrMoA steel sheet has a chemical composition comprising, in mass%: 0.26-0.33% of C, 0.17-0.37% of Si, 0.4-0.7% of Mn, less than or equal to 0.02% of P, less than or equal to 0.015% of S, 0.8-1.1% of Cr, 0.15-0.25% of Mo, less than or equal to 0.05% of Als, and the balance of Fe and residual elements.
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