CN115807194A - Production method of Q345B steel plate with thickness of 150-250mm - Google Patents
Production method of Q345B steel plate with thickness of 150-250mm Download PDFInfo
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- CN115807194A CN115807194A CN202211640430.0A CN202211640430A CN115807194A CN 115807194 A CN115807194 A CN 115807194A CN 202211640430 A CN202211640430 A CN 202211640430A CN 115807194 A CN115807194 A CN 115807194A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 72
- 239000010959 steel Substances 0.000 title claims abstract description 72
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 238000005096 rolling process Methods 0.000 claims abstract description 42
- 238000001816 cooling Methods 0.000 claims abstract description 30
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000126 substance Substances 0.000 claims abstract description 4
- 208000020990 adrenal cortex carcinoma Diseases 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 238000005507 spraying Methods 0.000 claims description 6
- 230000035515 penetration Effects 0.000 claims description 4
- 238000003825 pressing Methods 0.000 claims description 4
- 238000004512 die casting Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 12
- 238000010438 heat treatment Methods 0.000 abstract description 10
- 229910045601 alloy Inorganic materials 0.000 abstract description 3
- 239000000956 alloy Substances 0.000 abstract description 3
- 238000003466 welding Methods 0.000 abstract description 2
- 239000002994 raw material Substances 0.000 abstract 1
- 230000001172 regenerating effect Effects 0.000 abstract 1
- 238000001514 detection method Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 5
- 230000000630 rising effect Effects 0.000 description 4
- 238000003723 Smelting Methods 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000009659 non-destructive testing Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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Abstract
The invention belongs to the field of production of extra-thick plates, and particularly relates to a production method of a Q345B steel plate with the thickness of 150-250mm, wherein the steel plate comprises the following chemical components in percentage by mass (unit, wt%): c:0.12 to 0.18%, si: less than or equal to 0.50%, mn:1.40 to 1.60%, P: less than or equal to 0.015%, S: less than or equal to 0.005 percent, ti: less than or equal to 0.020%, als:0.030 to 0.060%, the balance being Fe and residual elements, carbon equivalent CEV: c + Mn/6+ (Cr + Mo + V)/5 + (Ni + Cu)/15 is less than or equal to 0.45; according to the scheme, conventional alloy elements such as C, mn and ALs are adopted, steel ingots produced by a water-cooling mold are used as raw materials on the basis of no addition of other micro-alloy elements, a low-temperature heating process of a regenerative heating furnace is adopted, and a special high-temperature controlled rolling process, a plurality of intermittent rapid cooling processes and a reddening (TM + NCP + BT) process are adopted to produce the extra-thick plate with good strength, plasticity and toughness, excellent lamellar tearing resistance and good welding performance.
Description
Technical Field
The invention belongs to the field of production of extra-thick plates, and particularly relates to a production method of a Q345B steel plate with the thickness of 150-250 mm.
Background
The Q345B belongs to the most widely used steel grade of low alloy series, and the steel plate has good strength, impact toughness, welding performance and cutting performance and is mainly used in industries such as factory building structures, buildings, vehicles, machining and the like. At present, steel plates with the thickness of more than 150mm sold in the market are delivered in a normalized state, the main reasons are influenced by the thickness of steel billets, the heating temperature of hot steel and the rolling mode, and if the steel plates are not subjected to heat treatment, the tensile strength and the impact absorption power cannot meet the standard requirements. In recent years, the competition of the steel industry is increasingly intense, and the production of steel plates, which is energy-saving, emission-reducing, capacity-improving and production cost-reducing, is an important means for improving the market share of steel enterprises.
In view of this, the present invention is proposed.
Disclosure of Invention
In order to meet the technical requirements, the invention aims to provide the production method of the Q345B steel plate with the thickness of 150-250mm, the performance requirement of the Q345B can be met without heat treatment in the production process, and the low cost is realized.
In order to achieve the purpose, the invention adopts the technical scheme that: a production method of a Q345B steel plate with the thickness of 150-250mm comprises the following chemical components in percentage by mass (unit, wt%): c:0.12 to 0.18%, si: less than or equal to 0.50 percent, mn:1.40 to 1.60%, P: less than or equal to 0.015%, S: less than or equal to 0.005%, ti: less than or equal to 0.020%, als:0.030 to 0.060%, the others are Fe and residual elements, the carbon equivalent CEV: c + Mn/6+ (Cr + Mo + V)/5 + (Ni + Cu)/15 is less than or equal to 0.45;
according to the thickness of the finished steel plate, producing a 500-950mm cast ingot in a water-cooling die casting mode, wherein the rolling ratio is more than 3;
high-pressure water spraying is started once when a high-temperature casting blank enters a rolling mill for rolling, rolling is stopped for 1-2 times when each rolling is carried out for one time, the rolling blank only passes through the rolling mill for 1-2 times in a reciprocating way, and only high-pressure water spraying cooling is carried out for 1-2 times in the reciprocating way, wherein the initial rolling temperature is 950-980 ℃, the reduction of normal times is as follows: 40-50 mm/pass, the combination of the rolling and cooling modes, compared with the core temperature, the surface temperature of the steel plate is obviously lower than the core temperature, the temperature difference is more than or equal to 50 ℃, and the penetration of the rolling mill pressing force to 1/2 part is facilitated;
entering ACC laminar cooling within 30 seconds after the steel plate is rolled, and rapidly cooling at the cooling speed of 4-6 ℃/S; according to the different thicknesses of the steel plates, the ACC reciprocating times are different, and the specific times refer to the table 1:
slowly cooling the steel plate: the steel plates are fully reddened after ACC treatment, so that the temperature difference between the inside and the outside of the steel plates tends to be consistent, then the steel plates are stacked in a concentrated manner, the stack cooling temperature is 350-420 ℃, the coverage is neat, and the stack cooling time is more than or equal to 72 hours.
The invention has the beneficial effects that: the high-pressure water spraying is started once when a high-temperature casting blank enters a rolling mill for rolling, the rolling is stopped for 1-2 times when the high-temperature casting blank is rolled for one time, the rolling blank only passes through the rolling mill for 1-2 times, and the rolling blank is only cooled by the high-pressure water spraying after 1-2 times of reciprocating, wherein the rolling temperature is 950-980 ℃, and the rolling reduction in normal times is as follows: 40-50 mm/pass, the combination of the rolling and cooling modes, compared with the core temperature, the surface temperature of the steel plate is obviously lower than the core temperature, the temperature difference is more than or equal to 50 ℃, the penetration of the pressing force of the rolling mill to 1/2 part is facilitated, the shrinkage cavity and shrinkage porosity of the core are eliminated, the segregation phenomenon is dispersed, and the internal and external tissues tend to be homogenized.
The high-temperature controlled-rolling steel plate is repeatedly cooled by ACC to inhibit the grain growth and recrystallization of austenite to form super-cooled austenite, and the super-cooled austenite enters a phase transformation region by controlling the temperature of red returning so as to obtain a fine F + P two-phase structure, ensure the obdurability matching of the steel plate and have the lamellar tearing resistance.
A heap cooling process: the concentrated heap cooling can also fully release the internal stress of the steel plate, reduce the strength and ensure the toughness matching of the steel plate.
The performance of the steel plate is as follows: the steel plate has good strength-toughness matching and lamellar tearing resistance, can completely replace the performance of a normalized steel plate, and reduces the heat treatment benefit by 80 yuan/ton.
Drawings
FIG. 1 shows a metallographic structure (metallographic microscope,. Times.100) of a portion having a thickness of 1/4 of a head part in an example of the invention
FIG. 2 is a metallographic structure (metallographic microscope, X200) of a 1/2 part of the head thickness according to an example of the present invention
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 conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The present invention is described in further detail below with reference to production examples.
The scheme provides a Q345B steel plate with the thickness of 150-250mm, and the steel plate comprises the following chemical components: c:0.15%, si:0.40%, mn:1.55%, P:0.009%, S:0.002%, als:0.035%, ti:0.015% and carbon equivalent CEV =0.42%.
The production method comprises the following steps:
1) Clean steel smelting and casting: clean steel smelting and casting: the steel-making adopts a clean steel smelting process, the finished product P is less than or equal to 100ppm, S is less than or equal to 17ppm, H is less than or equal to 1.0ppm, O is less than or equal to 30ppm, N is less than or equal to 50ppm, the water-cooling mould of Chinese metallurgy independent property is combined with a microdefect pouring technology, molten steel is solidified to form a feeding channel with a large upper part and a small lower part, the solidification is rapid, the internal porosity of a steel ingot is reduced, the original crystal grains are finer, the ingot shape is adjusted according to the thickness of the steel plate, and the steel plate is compressed by 3-6;
2) Heating a steel ingot: the method comprises five stages of steel stewing, temperature rising, heat preservation, secondary temperature rising and heat soaking, wherein the steel stewing temperature is less than 650 ℃, the temperature rising speed is controlled to be less than 80 ℃/h in the temperature rising stage, the heat preservation temperature of the middle section is 900 ℃, the low-temperature heating is adopted in the heat soaking section, the temperature is controlled to be 1220-1240 ℃, and the ingot temperature fluctuation of the heat soaking section is less than 15 ℃. According to the thickness of 500-950mm of the blank, the heating temperature uniformity of the blank is ensured, and the total heating time is controlled to be 22-34 hours, so that the energy loss is reduced, and the original crystal grains of the blank are ensured;
3) Rolling: the process adopts high-temperature controlled rolling and multiple intermittent quick cooling processes, the steel plate rolling adopts high-temperature controlled rolling, and the process has the following key points: rolling temperature is 950-980 ℃, rolling reduction: 40-50 mm per pass, 2-3 times of high-pressure water is used in each pass, the temperature difference between the surface of the steel plate and the core part in continuous block rolling is more than or equal to 50 ℃, and the penetration of the rolling machine pressing force to 1/2 part is facilitated;
4) The steel controlled cooling process comprises the following steps: entering ACC laminar cooling within 30 seconds after the steel plate is rolled, and rapidly cooling at the cooling speed of 5 ℃/S;
5) The red returning time of the steel plate is 30-60S every time the steel plate is cooled, so that the uniform temperature of the whole plate and the flat plate shape are ensured;
6) Slowly cooling the steel plate: the steel plate fully turns red after entering a cooling bed, and is slowly heated, so that the temperature of the core part of the steel plate is fully released, the temperature of the pile cooling is 350-420 ℃, the steel plate is intensively stacked and is regularly covered, and the pile cooling time is not less than 72 hours.
By the production method, the quality of the rolled steel plate is as follows:
(1) Mechanical property detection
The sampling position and the preparation of the mechanical property test piece of the steel plate are carried out according to the GB/T2975 and GB/T5313, the impact toughness test is carried out according to the GB/T229 standard, and the tensile property test is carried out according to the GB/T228 standard.
The results of the mechanical property tests are shown in the following table:
(2) Metallographic structure detection
The metallographic structure is evaluated according to the standard of GB/T13299 'method for evaluating microstructure of steel' and GB/T6394 'method for measuring average grain size of metal', the matrix structure mainly comprises ferrite and pearlite, and the grain size is 8-9 grade. The Z-direction tensile fracture is macroscopically cup-cone-shaped, mainly comprises a central fiber area and a shearing lip on the periphery, and is mainly a dimple-shaped fracture with better plasticity under a scanning electron microscope.
(3) Inclusion detection
The inclusion rating is carried out according to GB/T10561 microscopic examination method of determination standard rating chart of the content of non-metallic inclusions in steel, and the detection results are shown in the following table:
(4) Nondestructive inspection
According to NB/T47013.3-2015' third section of nondestructive testing of pressure-bearing equipment: the ultrasonic detection standard is used for nondestructive inspection, and the grade I is combined.
According to the test results, the Q345B steel plate with the thickness of 150-250mm produced by the embodiment of the invention has excellent flaw detection quality, and the flaw detection meets NB/T47013.3-2015I level; the grain structure is uniform and fine, the main grain structure is ferrite and pearlite, the lamellar tearing resistance is excellent, the strength, the elongation and the impact toughness of the steel plate are good, and the normalized steel plate can be completely replaced.
Claims (1)
1. A production method of a Q345B steel plate with the thickness of 150-250mm is characterized by comprising the following steps: the steel plate comprises the following chemical components in percentage by mass (unit, wt%): c:0.12 to 0.18%, si: less than or equal to 0.50%, mn:1.40 to 1.60%, P: less than or equal to 0.015%, S: less than or equal to 0.005 percent, ti: less than or equal to 0.020%, als:0.030 to 0.060%, the balance being Fe and residual elements, carbon equivalent CEV: c + Mn/6+ (Cr + Mo + V)/5 + (Ni + Cu)/15 is less than or equal to 0.45;
according to the thickness of the finished steel plate, producing a 500-950mm cast ingot in a water-cooling die casting mode, wherein the rolling ratio is more than 3;
the high-pressure water spraying is started once when a high-temperature casting blank enters a rolling mill for rolling, the rolling is stopped for 1-2 times when the high-temperature casting blank is rolled for one time, the rolling blank only passes through the rolling mill for 1-2 times, and the rolling blank is only cooled by the high-pressure water spraying after 1-2 times of reciprocating, wherein the rolling temperature is 950-980 ℃, and the rolling reduction in normal times is as follows: 40-50 mm/pass, the combination of the rolling and cooling modes, compared with the core temperature, the surface temperature of the steel plate is obviously lower than the core temperature, the temperature difference is more than or equal to 50 ℃, and the penetration of the rolling mill pressing force to 1/2 part is facilitated;
entering ACC laminar cooling within 30 seconds after the steel plate is rolled, and rapidly cooling at the cooling speed of 4-6 ℃/S; according to the different thicknesses of the steel plates, the ACC reciprocating times are different, and the specific times refer to the table 1:
slowly cooling the steel plate: the steel plates are fully reddened after ACC treatment, so that the temperature difference between the inside and the outside of the steel plates tends to be consistent, then the steel plates are stacked in a concentrated mode, the stacking temperature is 350-420 ℃, the covering is neat, and the stacking time is more than or equal to 72 hours.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211640430.0A CN115807194B (en) | 2022-12-20 | 2022-12-20 | Production method of Q345B steel plate with thickness of more than 150mm and less than or equal to 250mm |
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| CN202211640430.0A CN115807194B (en) | 2022-12-20 | 2022-12-20 | Production method of Q345B steel plate with thickness of more than 150mm and less than or equal to 250mm |
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Citations (9)
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| WO2019105055A1 (en) * | 2017-11-29 | 2019-06-06 | 南京钢铁股份有限公司 | S355g10+m wide and heavy steel plate having low-temperature toughness for ocean engineering, and method for manufacturing same |
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2022
- 2022-12-20 CN CN202211640430.0A patent/CN115807194B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101871083A (en) * | 2010-06-14 | 2010-10-27 | 南阳汉冶特钢有限公司 | Ultra-thick low-alloy high-strength Q345-series steel plate and production method thereof |
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