CN111286667A - Low-temperature toughness chromium-molybdenum steel plate and production method thereof - Google Patents
Low-temperature toughness chromium-molybdenum steel plate and production method thereof Download PDFInfo
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- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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Abstract
The invention provides low-temperature toughnessThe chromium-molybdenum steel plate and the production method thereof have the chemical components: 0.14 to 0.17 percent of C, 0.40 to 0.55 percent of Mn, 0.50 to 0.60 percent of Si, less than or equal to 0.008 percent of S, less than or equal to 0.015 percent of P, 1.15 to 1.35 percent of Cr, 0.45 to 0.55 percent of Mo, 0.02 to 0.04 percent of Alt, and the balance of Fe and inevitable impurities. According to the invention, no noble metal is added, no special process is needed to reduce the content of sulfur and phosphorus in the steel, the cost is low, and ferrite, pearlite and bainite tissues are obtained by controlling the finish rolling temperature, cooling after rolling, normalizing and tempering processes; tensile strength Rm: 550-650MPa, yield strength Rel: 350-450MPa, elongation A (L)0200mm) is more than or equal to 22 percent, and the average value of transverse V-shaped impact at minus 29 ℃ is more than or equal to 47J.
Description
Technical Field
The invention belongs to the technical field of alloy smelting, and particularly relates to a low-temperature tough chromium-molybdenum steel plate and a production method thereof.
Background
The SA387Gr.11Cl.2 steel is American standard container steel, has good high-temperature performance and heat strength performance due to the addition of Cr and Mo elements in the steel, belongs to II-class steel in American standard ASME SA387/SA387M, and is widely used for manufacturing thermal power equipment, nuclear power equipment, petroleum, chemical engineering, coal conversion equipment and other large-scale devices which are in contact with hydrogen. Because the material works under higher temperature and pressure and has poor service conditions, the material is required to have higher heat strength, good toughness and plasticity, corrosion resistance and welding performance. The container made of the steel grade runs at high temperature for a long time, and no reliable measure for preventing the temperature reduction from being too fast exists during parking, so that the thermal fatigue and the temperature difference stress are large, so that the toughness reserve of the steel grade is also considered during designing of the steel grade, and the deformation resistance and the temperature change resistance of the steel grade are enhanced.
The American standard ASME SA387/SA387M standard does not make a requirement for strengthening the impact of SA387Gr.11Cl.2 steel, and the standard is equal to the GB/T713-2014 standard with the same mark number of 14Cr1MoR, so that the transverse V-shaped impact absorption energy at 20 ℃ is required to be more than or equal to 47J, but a user can put forward the technical requirements of low-temperature impact (such as-29 ℃ or lower temperature) and 200mm gauge length stretching rate of more than or equal to 22.0 percent (the standard requirement is more than or equal to 18.0 percent), the one-time hit rate of product performance is reduced, and even the impact toughness does not meet the contract requirement.
In the patent CN105861946A publication No. CN 387Gr11Cl1 steel sheet for petrochemical lines and method for producing the same, published 8, 17, 2016, Ni element is added in the composition design, which increases the production cost, and this patent requires 0 ℃ impact in the delivery state, and at the same time, this patent employs air cooling while the heat treatment temperature is high.
In a patent publication No. CN 109881088A of 'low strength and high toughness SA387Gr11Cl1 steel plate and a production method thereof' published in 6, 14 and 6.2019, by reducing the contents of carbon and P, S elements, without adding noble alloy Ni element, a sub-temperature normalizing (water cooling after normalizing) and high-temperature tempering process is adopted for heat treatment, the steel plate with the thickness of 28-40mm can be produced to meet the requirement of tensile strength Rm: 450-585MPa, yield strength Rel: 300-450MPa, elongation A (L)0200mm) is more than or equal to 22 percent; the average impact value at minus 20 ℃ is more than or equal to 80J. The invention can improve the purity of molten steel and reduce the costLow sulfur and phosphorus contents and increased smelting cost.
In a patent CN 108359894A patent publication No. 8/3/2018, CN 108359894A, the contents of carbon and P, S elements are reduced, noble alloy Ni and Nb elements are added, and a sub-temperature normalizing (water cooling after normalizing) and high-temperature tempering process is adopted for heat treatment, so that a steel plate (1Cr0.5Mo) with the thickness of 90-110mm can be produced to meet the tensile strength Rm: 480-550MPa, yield strength Rel: not less than 310MPa, and the elongation not less than 22%; the average impact value at minus 38 ℃ is more than or equal to 150J. The invention adds noble alloy Ni and Nb elements, and has high production cost.
Patent publication No. CN 103334064A published in 2013, 10, month and 2, "a low yield ratio chromium-molybdenum steel plate and a production method thereof", adopts a heat treatment process of twice normalizing, accelerated cooling and tempering, and can produce a yield ratio of 30-70mm which is less than or equal to 0.80. The alloy of the patent has high cost, needs special normalizing furnace equipment and has high production cost.
Disclosure of Invention
The invention aims to provide a low-temperature toughness chromium-molybdenum steel plate, which optimally designs SA387Gr.11Cl.2 alloy components, does not add elements such as noble alloys Ni and Nb, and reduces smelting cost.
The invention also provides a production method of the low-temperature toughness chromium-molybdenum steel plate, which controls the structure of the hot rolled steel plate by designing heating and rolling processes, provides the hot rolled steel plate with a bainite + ferrite + a small amount of pearlite microstructure for heat treatment, avoids the limitation that an accelerated cooling device must be arranged after a hot-treatment furnace is fired, improves the heat treatment efficiency and reduces the manufacturing cost.
The specific technical scheme of the invention is as follows:
the low-temperature toughness chromium-molybdenum steel plate comprises the following chemical components in percentage by mass: 0.14 to 0.17 percent of C, 0.40 to 0.55 percent of Mn0.50 to 0.60 percent of Si, less than or equal to 0.008 percent of S, less than or equal to 0.015 percent of P, 1.15 to 1.35 percent of Cr, 0.45 to 0.55 percent of Mo, 0.02 to 0.04 percent of Alt, and the balance of Fe and inevitable impurities.
The thickness of the low-temperature toughness chromium-molybdenum steel plate is 6-50 mm.
The low-temperature toughness chromium-molybdenum steel plate meets the following requirements: resist againstTensile strength Rm: 550-650MPa, yield strength Rel: 350-450MPa, elongation A (L)0200mm) is more than or equal to 22 percent; the average value of transverse V-shaped impact at minus 29 ℃ is more than or equal to 47J.
The invention provides a production method of a low-temperature toughness chromium-molybdenum steel plate, which comprises steel making, blank heating, rolling and heat treatment.
Further, the steel making comprises the following processes:
when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process;
adding a deoxidizer into the LF furnace to make white slag, and electrifying to melt the slag for 6-8 minutes; the deoxidizer comprises ferrosilicon and Al particles.
In the RH vacuum process, the vacuum degree is less than or equal to 133Pa, the vacuum time is more than or equal to 15min, the pure degassing time is more than or equal to 10min, the calcium wire is fed for 80-150m after the RH vacuum degassing, and the soft argon blowing is more than or equal to 6min after the wire feeding.
The blank heating comprises the following processes:
the temperature of the blank preheating section is 700-; and rolling after reaching the temperature.
The rolling is carried out in two stages;
the initial rolling temperature of rough rolling is more than 1000 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%;
the initial rolling temperature of finish rolling is less than or equal to 950 ℃, and the finish rolling temperature is 800-840 ℃;
further, air cooling the steel plate with the thickness less than or equal to 8mm after rolling; after the steel plate with the thickness of more than 8mm is rolled, ACC cooling is adopted, the cooling speed is more than 10 ℃/s, and the temperature of the red returning is controlled to be 680-720 ℃. Because the ACC cooling device is arranged behind the rolling mill, the flashing temperature can be controlled by finish rolling.
The heat treatment comprises the following processes of normalizing and tempering:
and (3) normalizing process: the thickness of the steel plate is less than or equal to 12mm, the normalizing temperature is 920 +/-10 ℃, the furnace time is 4 XH minutes, and H is the thickness of the steel plate and is in mm; air cooling after normalizing discharge;
the steel plate with the thickness of more than 12mm and less than or equal to 50mm, the normalizing temperature is 940 +/-10 ℃, the furnace time is 1.9-2.1 multiplied by H minutes, and H is the thickness of the steel plate and the unit is mm; and air cooling after normalizing discharge.
The normalizing temperature is high, the structure and the performance of the formed steel plate are ensured within the steel plate forming temperature range, and the safe operation of equipment is facilitated. And air cooling is carried out after normalizing, special equipment is not required to be arranged behind the normalizing furnace, and the cost is low.
The tempering process comprises the following steps: the tempering temperature is 720-; discharging and air cooling.
And normalizing and tempering the steel plate to obtain the SA387Gr.11Cl.2 steel plate with good low-temperature toughness and plasticity.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: 1. the invention optimizes and accurately controls the steelmaking components, does not add elements such as noble alloys Ni, Nb and the like, does not need to adopt a special process to reduce the contents of sulfur and phosphorus in steel, and reduces the smelting cost (the dephosphorization rate of a common converter is about 88 percent, the phosphorus content is less than or equal to 0.010 percent, the phosphorus content in molten iron is required to be low, or the two methods are adopted for smelting, and the manufacturing cost is increased). 2. The invention obtains good hot rolling microstructure (bainite, ferrite and a small amount of pearlite) of the steel plate by controlling the finish rolling temperature and cooling after rolling. 3. The invention adopts the normalizing and tempering processes to obtain the steel plate with ferrite, pearlite and bainite tissues (the ferrite content is 70-75 percent, and the grain size is 8.0-9.0 grade), and the different tissue contents and grain sizes are key factors for ensuring the toughness of the steel plate. 4. The steel plate has the following performances: tensile strength Rm: 550-650MPa, yield strength Rel: 350-450MPa, elongation A (L)0200mm) is more than or equal to 22 percent, the average value of horizontal V-shaped impact at minus 29 ℃ is more than or equal to 47J, the strength of the steel plate is moderate, the low-temperature impact performance is good, the design requirement is completely met, and the stable control of the strength of the steel plate is realized. 5. The invention has low cost and stable mechanical property, completely meets the requirement of the steel plate for the pressure container, has the normalizing temperature of the steel plate of 910-950 ℃, improves the forming temperature of the steel plate, reduces the forming resistance, ensures the structure and the performance of the formed steel plate, and is suitable for manufacturing and using the pressure container.
Drawings
FIG. 1 example 4 Hot rolled Steel sheet Structure;
FIG. 2 is a structure of a hot rolled steel sheet of comparative example;
FIG. 3 example 4 microstructure of normalized + tempered steel sheet;
FIG. 4 shows the microstructure of a normalized and tempered steel sheet.
Detailed Description
Example 1
The low-temperature toughness chromium-molybdenum steel plate comprises the following chemical components in percentage by mass: see table 1 below; the balance of Fe and inevitable impurities.
The production method of the low-temperature toughness chromium-molybdenum steel plate comprises the following processes:
1) a steel making process: when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process; adding deoxidizing agents such as silicon carbide, calcium carbide and Al particles into the LF furnace to produce white slag, and electrifying to melt the slag for 6 minutes; RH vacuum process, vacuum degree 43Pa, vacuum time 16min, pure degassing time 10min, feeding calcium wire 110m after RH vacuum degassing, and soft argon blowing for 8min after feeding;
2) a blank heating procedure: the temperature of a preheating section of the blank with the thickness of 210mm is 750-;
3) a rolling procedure: two-stage rolling is adopted, wherein the initial rolling temperature of rough rolling is 1058 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%; the initial rolling temperature of finish rolling is 950 ℃, the thickness of the steel plate is 50mm, the final rolling temperature is 835 ℃, and the steel plate is rolled by 6 mm; air cooling is carried out after rolling;
4) a heat treatment process: normalizing the steel plate, keeping the temperature at 912 ℃ for 24 minutes in the furnace, and cooling the steel plate in air after discharging; the tempering temperature is 725 ℃ and the furnace time is 86 minutes, and the air cooling is carried out after the furnace is taken out.
Example 2
The low-temperature toughness chromium-molybdenum steel plate comprises the following chemical components in percentage by mass: see table 1 below; the balance of Fe and inevitable impurities.
The production method of the low-temperature toughness chromium-molybdenum steel plate comprises the following processes:
1) a steel making process: when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process; adding deoxidizing agents such as ferrosilicon and Al particles into the LF furnace to produce white slag, and electrifying to melt the slag for 6 minutes; RH vacuum process, vacuum degree 37Pa, vacuum time 17min, pure degassing time 11min, feeding calcium wire 120m after RH vacuum degassing, and soft argon blowing 7min after feeding;
2) a blank heating procedure: the temperature of a preheating section of the blank with the thickness of 210mm is 750-;
3) a rolling procedure: two-stage rolling is adopted, wherein the initial rolling temperature of rough rolling is 1062 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%; the initial rolling temperature of finish rolling is 930 ℃, the thickness of the steel plate is 65mm, the final rolling temperature is 838 ℃, the steel plate is rolled to 10mm, ACC is used for cooling, the cooling speed is 15 ℃/s, and the steel plate reddening temperature is 706 ℃;
4) a heat treatment process: normalizing the steel plate, keeping the temperature of 915 ℃ for 40 minutes in the furnace, and cooling the steel plate in air after discharging; the tempering temperature is 728 ℃ and the furnace time is 90 minutes, and the air cooling is carried out after the furnace is taken out.
Example 3
The low-temperature toughness chromium-molybdenum steel plate comprises the following chemical components in percentage by mass: see table 1 below; the balance of Fe and inevitable impurities.
The production method of the low-temperature toughness chromium-molybdenum steel plate comprises the following processes:
1) a steel making process: when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process; adding deoxidizing agents such as ferrosilicon and Al particles into the LF furnace to produce white slag, and electrifying to melt the slag for 7 minutes; RH vacuum process, vacuum degree 27Pa, vacuum time 16min, pure degassing time 11min, feeding calcium wire 115m after RH vacuum degassing, and soft argon blowing for 9min after feeding;
2) a blank heating procedure: the temperature of a preheating section of a blank with the thickness of 250mm is 750-;
3) a rolling procedure: two-stage rolling is adopted, wherein the initial rolling temperature of rough rolling is 1025 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%; the initial rolling temperature of finish rolling is 902 ℃, the thickness of a steel plate is 70mm, the final rolling temperature is 835 ℃, the steel plate is rolled to 25mm, ACC is used for cooling, the cooling speed is 13 ℃/s, and the reddening temperature after rolling is 695 ℃;
4) a heat treatment process: normalizing and preserving heat of the steel plate at 935 ℃ for 48 minutes in the furnace, and air cooling after discharging; the tempering temperature is 729 ℃ and the furnace time is 105 minutes, and the air cooling is carried out after the furnace is taken out.
Example 4
The low-temperature toughness chromium-molybdenum steel plate comprises the following chemical components in percentage by mass: see table 1 below; the balance of Fe and inevitable impurities.
The production method of the low-temperature toughness chromium-molybdenum steel plate comprises the following processes:
1) a steel making process: when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process; adding deoxidizing agents such as carbon iron and Al particles into the LF furnace to produce white slag, and electrifying to melt the slag for 8 minutes; RH vacuum process, vacuum degree 55Pa, vacuum time 16min, pure degassing time 10min, feeding calcium wire 135m after RH vacuum degassing, and soft argon blowing for 7min after feeding;
2) a blank heating procedure: the temperature of a preheating section of the blank with the thickness of 250mm is 750-;
3) a rolling procedure: two-stage rolling is adopted, the initial rolling temperature of rough rolling is 1029 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%; the initial rolling temperature of finish rolling is 890 ℃, the initial rolling temperature is 85mm, the final rolling temperature is 825 ℃, the initial rolling temperature is 35mm, ACC is used for cooling, the cooling speed is 12 ℃/s, and the reddening temperature is 695 ℃;
4) a heat treatment process: normalizing and preserving heat of the steel plate at 937 ℃ for 70 minutes in the furnace, and air-cooling after discharging; the tempering temperature is 729 ℃ and the furnace time is 115 minutes, and the air cooling is carried out after the furnace is taken out.
Example 5
The low-temperature toughness chromium-molybdenum steel plate comprises the following chemical components in percentage by mass: see table 1 below; the balance of Fe and inevitable impurities.
The production method of the low-temperature toughness chromium-molybdenum steel plate comprises the following processes:
1) a steel making process: when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process; adding deoxidizing agents such as carbon iron and Al particles into the LF furnace to produce white slag, and electrifying to melt the slag for 8 minutes; RH vacuum process, vacuum degree of 45Pa, vacuum time of 16min, pure degassing time of 10min, feeding calcium wire 121m after RH vacuum degassing, and soft argon blowing for 6min after feeding;
2) a blank heating procedure: the temperature of a preheating section of a blank with the thickness of 250mm is 750 plus 850 ℃, the temperature of a first heating section is 1150 plus 1200 ℃, the temperature of a second heating section is 1230 plus 1250 ℃, the temperature of soaking is 1220 plus 1240 ℃, the furnace time is 289 minutes, and rolling is carried out after reaching the temperature;
3) a rolling procedure: two-stage rolling is adopted, wherein the initial rolling temperature of rough rolling is 1030 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%; the initial rolling temperature of finish rolling is 860 ℃, the thickness is 110mm, the final rolling temperature is 827 ℃, the finish rolling is carried out until the finish rolling reaches 50mm, ACC is used for cooling, the cooling speed is 11 ℃/s, and the reddening temperature is 690 ℃;
4) a heat treatment process: normalizing the steel plate, keeping the temperature of 942 ℃ for 105 minutes in the furnace, and cooling in air after discharging; the tempering temperature is 730 ℃, the furnace time is 130 minutes, and the air cooling is carried out after the furnace is taken out.
Comparative example
The paint comprises the following chemical components in percentage by mass: see table 1 below; the balance of Fe and inevitable impurities.
The production method of the SA387Gr.11cl.2 steel plate comprises the following steps:
1) a steel making process: when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process; adding deoxidizing agents such as carbon iron and Al particles into the LF furnace to produce white slag, and electrifying to melt the slag for 8 minutes; RH vacuum process, vacuum degree 55Pa, vacuum time 16min, pure degassing time 10min, feeding calcium wire 135m after RH vacuum degassing, and soft argon blowing for 7min after feeding;
2) a blank heating procedure: the temperature of a preheating section of the blank with the thickness of 250mm is 750-;
3) a rolling procedure: two-stage rolling is adopted, the initial rolling temperature of rough rolling is 1029 ℃, high-temperature low-speed high-pressure rolling is adopted, the rolling speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12%; the initial rolling temperature of finish rolling is 890 ℃, the rolling temperature is 865 ℃ when the thickness is 85mm, the finish rolling temperature is 35mm, air cooling is carried out after rolling, and the flashing temperature is 695 ℃;
4) a heat treatment process: normalizing and preserving heat of the steel plate at 937 ℃ for 70 minutes in the furnace, and air-cooling after discharging; the tempering temperature is 729 ℃ and the furnace time is 115 minutes, and the air cooling is carried out after the furnace is taken out.
Table 1 examples 1-5 low temperature tough chrome molybdenum steel plates and comparative examples chemical composition and mass percent (wt%) thereof
| Examples | C | Mn | Si | S | P | Alt | Cr | Mo |
| 1 | 0.15 | 0.43 | 0.52 | 0.005 | 0.012 | 0.031 | 1.18 | 0.46 |
| 2 | 0.15 | 0.46 | 0.55 | 0.003 | 0.013 | 0.029 | 1.20 | 0.48 |
| 3 | 0.16 | 0.48 | 0.57 | 0.004 | 0.011 | 0.025 | 1.22 | 0.50 |
| 4 | 0.15 | 0.50 | 0.55 | 0.006 | 0.015 | 0.030 | 1.19 | 0.49 |
| 5 | 0.16 | 0.52 | 0.53 | 0.007 | 0.014 | 0.035 | 1.21 | 0.51 |
| Comparative example | 0.14 | 0.42 | 0.55 | 0.002 | 0.015 | 0.029 | 1.23 | 0.46 |
Note: not listed in table 1 are Fe and inevitable impurities.
The properties of the low temperature toughness chrome molybdenum steel plates described in examples 1 to 5 and the mechanical properties of the comparative steel plates are shown in the following table 2.
TABLE 2 EXAMPLES 1-5 Properties of Low temperature tough chrome molybdenum steel sheets and comparative steel sheets
The steel plate has the following performances: tensile strength Rm: 550-650MPa, yield strength Rel: 350-450MPa, elongation A (L)0200mm) is more than or equal to 22 percent, the average value of horizontal V-shaped impact at minus 29 ℃ is more than or equal to 47J, the strength of the steel plate is moderate, the low-temperature impact performance is good, the design requirement is completely met, and the stable control of the strength of the steel plate is realized.
Claims (10)
1. The low-temperature toughness chromium-molybdenum steel plate is characterized by comprising the following chemical components in percentage by mass: : 0.14 to 0.17 percent of C, 0.40 to 0.55 percent of Mn, 0.50 to 0.60 percent of Si, less than or equal to 0.008 percent of S, less than or equal to 0.015 percent of P, 1.15 to 1.35 percent of Cr1, 0.45 to 0.55 percent of Mo, 0.02 to 0.04 percent of Alt, and the balance of Fe and inevitable impurities.
2. A method of producing a low temperature tough chromium molybdenum steel sheet as claimed in claim 1, which comprises steel making, billet heating, rolling and heat treatment;
the rolling is carried out in two stages;
the initial rolling temperature of rough rolling is more than 1000 ℃, the roller speed is less than or equal to 2.5m/s, and the pass reduction rate is more than 12 percent.
3. The production method as claimed in claim 2, wherein the finish rolling start temperature is not more than 950 ℃ and the finish rolling temperature is 800-840 ℃.
4. The production method according to claim 2 or 3, wherein the steel plate with the thickness of less than or equal to 8mm is air-cooled after rolling; or after rolling the steel plate with the thickness of more than 8mm, adopting ACC for cooling, wherein the cooling speed is more than 10 ℃/s, and controlling the temperature of the red returning to be 680-720 ℃.
5. The production method according to claim 2, characterized in that the heat treatment comprises a normalizing and tempering process, in particular: the thickness of the steel plate is less than or equal to 12mm, the normalizing temperature is 920 +/-10 ℃, the furnace time is 4 XH minutes, and H is the thickness of the steel plate and is in mm; air cooling after normalizing discharge;
or the steel plate with the thickness of more than 12mm and less than or equal to 50mm has the normalizing temperature of 940 +/-10 ℃ and the furnace time of 1.9-2.1 XH minutes, wherein H is the thickness of the steel plate and the unit is mm; and air cooling after normalizing discharge.
6. The production method as claimed in claim 2 or 5, wherein the tempering process is a tempering temperature of 720-; discharging and air cooling.
7. The production method according to claim 2, characterized in that said steelmaking comprises the following processes:
when 1/4 weight of molten steel is discharged, adding ferromanganese, ferrosilicon and aluminum blocks in sequence, and controlling Al to be 0.020-0.040% in the whole process;
adding a deoxidizer into the LF furnace to make white slag, and electrifying to melt the slag for 6-8 minutes;
in the RH vacuum process, the vacuum degree is less than or equal to 133Pa, the vacuum time is more than or equal to 15min, the pure degassing time is more than or equal to 10min, the calcium wire is fed for 80-150m after the RH vacuum degassing, and the soft argon blowing is more than or equal to 6min after the wire feeding.
8. The production method according to claim 2, characterized in that the blank is heated, comprising the following processes:
the temperature of the blank preheating section is 700-; and rolling after reaching the temperature.
9. The production method according to any one of claims 2 to 8, wherein the steel sheet produced has a structure of ferrite + pearlite + bainite.
10. The production method according to any one of claims 2 to 9, wherein the steel sheet produced has a tensile strength Rm: 550-650MPa, yield strength Rel: 350-450MPa, elongation A (L)0200mm) is more than or equal to 22 percent, and the average value of transverse V-shaped impact at minus 29 ℃ is more than or equal to 47J.
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| CN112921239A (en) * | 2021-01-22 | 2021-06-08 | 新余钢铁股份有限公司 | Low-yield-ratio 12MnNiVR steel plate and production method thereof |
| CN114395725A (en) * | 2021-11-29 | 2022-04-26 | 安阳钢铁股份有限公司 | Production method for producing steel plate with yield of 300MPa grade by adopting chromium-molybdenum alloy |
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