CN110983175A - Steel plate for hot-rolled weldable pressure-bearing equipment and production method thereof - Google Patents

Steel plate for hot-rolled weldable pressure-bearing equipment and production method thereof Download PDF

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CN110983175A
CN110983175A CN201911123332.8A CN201911123332A CN110983175A CN 110983175 A CN110983175 A CN 110983175A CN 201911123332 A CN201911123332 A CN 201911123332A CN 110983175 A CN110983175 A CN 110983175A
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steel plate
hot
rolled
equal
rolling
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李建朝
石莉
李�杰
赵国昌
龙杰
刘生
林明新
张海军
张萌
谢东
刘印子
李肖
朱宜进
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Wuyang Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

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  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
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  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The invention discloses a steel plate for hot rolling weldable pressure-bearing equipment and a production method thereof, wherein the steel plate comprises the following chemical components in percentage by mass: c: 0.06-0.12%, Si: 0.20 to 0.50%, Mn: 1.40-1.60%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, Ni: 0.25 to 0.50%, Nb: 0.020-0.050%, Alt is more than or equal to 0.020%, and the balance of Fe and inevitable impurities, wherein the carbon equivalent CEV: 0.35-0.37%; the production method comprises smelting and billet rolling. The steel plate obtained by the invention has good weldability, can simultaneously meet the normal-temperature stretching and low-temperature impact performance of-50 ℃ in a delivery state and a simulated postweld heat treatment state, has uniform and fine structure, is a ferrite and pearlite structure, and has the grain size reaching 8-10 grade.

Description

Steel plate for hot-rolled weldable pressure-bearing equipment and production method thereof
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a steel plate for hot-rolled weldable pressure-bearing equipment and a production method thereof.
Background
With the rapid development of economy in China in recent years, the pressure-bearing equipment technology develops towards the directions of high parameter, large size and complexity, the technical progress relates to that the material of the equipment must have better mechanical property and extreme environment service performance (such as ultralow temperature service environment and the like), and the development of the pressure-bearing equipment material towards high grade is promoted, wherein the high strength, high toughness and easy weldability are the key directions of the current development and research. On the other hand, the controlled rolling technology can shorten the process flow and reduce the use of precious alloys, and the controlled rolling technology is developed rapidly in recent years and has been successfully applied to a plurality of steel grades. However, the hot rolled steel plate produced by the controlled rolling technology has the defects of large internal stress, poor weldability and the like, so that the application of the hot rolled steel plate to pressure-bearing equipment is limited.
The steel plate for the hot rolling weldable pressure-bearing equipment and the production method thereof have the advantages that on the premise of ensuring the good weldability of the steel plate, the steel plate obtains two sets of performances of a delivery state and a simulated postweld heat treatment state by using a controlled rolling technology, the requirements of the steel plate market of the pressure-bearing equipment are better met, the process is simplified, and the cost is saved.
Disclosure of Invention
The invention aims to solve the technical problem of providing a steel plate for hot-rolled weldable pressure-bearing equipment and a production method thereof; the steel plate for the hot-rolling weldable pressure-bearing equipment ensures two sets of performances of a delivery state and a simulated postweld heat treatment state.
In order to solve the technical problems, the invention adopts the technical scheme that: the steel plate for the hot-rolled weldable pressure-bearing equipment comprises the following chemical components in percentage by mass: c: 0.06-0.12%, Si: 0.20 to 0.50%, Mn: 1.40-1.60%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, Ni: 0.25 to 0.50%, Nb: 0.020-0.050%, Alt is more than or equal to 0.020%, and the balance is Fe and inevitable impurities.
The carbon equivalent CEV of the steel plate is as follows: 0.35-0.37%, wherein the carbon equivalent is calculated by CEV (%) = C + Mn/6+ (Cr + Mo + V)/5+ (Ni + Cu)/15.
The thickness specification of the steel plate is 12-63 mm.
The mechanical properties of the steel plate in the delivery state and the simulated postweld heat treatment state meet the following requirements: stretching at normal temperature: ReH is more than or equal to 355MPa, Rm: 450-610 MPa, A is more than or equal to 22.0%; the average value of the transverse impact energy AKV at minus 50 ℃ is more than or equal to 150J.
The steel plate has uniform and fine structure which is ferrite plus pearlite structure, and the grain size can reach 8-10 grades.
The invention also provides a production method of the steel plate for the hot-rolled weldable pressure-bearing equipment, which is characterized by comprising the working procedures of billet smelting and billet rolling.
The smelting process adopts primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is more than or equal to 50 minutes, and good argon blowing in the whole process is ensured; when VD vacuum treatment is carried out, the vacuum degree is less than or equal to 66Pa, and the vacuum holding time is more than or equal to 20 minutes.
The billet rolling procedure of the invention is a two-stage controlled rolling process. And (3) performing temperature-controlled rolling in the first stage, wherein the final rolling temperature is more than or equal to 950 ℃, the total deformation is 55-60%, the final reduction is 25-30mm, and the billet is cooled to 880-900 ℃ after the first stage. The rolling temperature at the stage II is 830-850 ℃, the final rolling temperature is 790-810 ℃, and the water cooling is carried out to 650-700 ℃ after the stage II.
The steel plate of the invention simulates the heat treatment process after welding, the steel plate is taken out of a furnace at 400 ℃, and the temperature rise and fall rate of the steel plate is more than 400 ℃: 55-80 ℃/h, the heat preservation temperature is 570-590 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The steel plate product standard for the hot-rolled weldable pressure-bearing equipment is referred to EN10028-5, and the product performance detection method is referred to EN ISO6892-1 and EN ISO 148-1.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:
1. the invention optimizes the component design: the toughness of the matrix is improved by adding a small amount of Ni alloy, and the grain is refined by adding a trace amount of Nb alloy.
2. The invention adopts a two-stage controlled rolling process, the temperature and the rolling reduction are reasonably distributed at the stage I, austenite grains are refined, and water cooling is carried out after the stage I rolling: firstly, inhibiting the growth of crystal grains in the cooling process, and secondly forming a hardened layer on the surface of the billet so as to transmit the rolling force to the center of the billet during the II-stage rolling; and in the stage II, rolling is carried out in a slightly lower temperature range, the breaking degree of austenite grains is increased, and phase change nucleation points are increased.
3. The invention meets the increasingly strict requirements of the steel plate for the pressure-bearing equipment, the obtained steel plate has good weldability, the steel plate simultaneously meets the normal-temperature stretching of a delivery state and a simulated postweld heat treatment state and the low-temperature impact performance of 50 ℃ below zero, the structure is uniform and fine, the steel plate is a ferrite and pearlite structure, and the grain size can reach 8-10 grades.
4. The invention adopts a hot rolling process, does not need heat treatment, has simple process, low cost, stable performance and market competitiveness, and can be widely used for manufacturing domestic and foreign pressure-bearing equipment.
Drawings
FIG. 1 is a metallographic structure diagram of a steel sheet for a hot-rolled weldable pressure-bearing apparatus according to example 1 of the present invention.
FIG. 2 is a metallographic structure diagram of a steel sheet for hot-rolling weldable pressure-bearing apparatus according to example 2.
FIG. 3 is a metallographic structure diagram of a steel sheet for a hot-rolled weldable pressure-bearing apparatus according to example 3 of the present invention.
FIG. 4 is a metallographic structure diagram of a steel sheet for a hot-rolled weldable pressure-bearing apparatus according to example 4 of the present invention.
FIG. 5 is a metallographic structure diagram of a steel sheet for a hot-rolled weldable pressure-bearing apparatus according to example 5 of the present invention.
FIG. 6 is a metallographic structure diagram of a steel sheet for a hot-rolled weldable pressure-bearing apparatus according to comparative example 1 of the present invention.
FIG. 7 is a metallographic structure diagram of a steel sheet for a hot-rolled weldable pressure-bearing apparatus according to comparative example 2 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
The thickness of the steel plate for the hot rolling weldable pressure-bearing equipment is 12mm, and the steel plate comprises the following chemical components in percentage by mass: c: 0.06%, Si: 0.20%, Mn: 1.60%, P: 0.006%, S: 0.003%, Ni: 0.41%, Nb: 0.020%, Alt: 0.020%, the balance being Fe and unavoidable impurities, carbon equivalent CEV = 0.35%.
The production method of the steel plate for the hot-rolled weldable pressure-bearing equipment comprises the processes of steel billet smelting and steel billet rolling, and the specific process steps are as follows:
(1) smelting: carrying out primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is 50 minutes, and the argon blowing is good in the whole process; when VD is carried out, the vacuum degree is 60Pa, and the vacuum maintaining time is 20 minutes;
(2) rolling a steel billet: two-stage controlled rolling is adopted, the first stage is temperature controlled rolling, the final rolling temperature is 965 ℃, the total deformation is 60 percent, the final pass reduction is 25mm, and the billet after the first stage is cooled to 900 ℃ by water. The initial rolling temperature of the second stage is 850 ℃, the final rolling temperature is 790 ℃, and water cooling is carried out to 650 ℃ after the second stage to obtain a steel plate with the thickness of 12 mm;
the simulated postweld heat treatment process of the steel plate comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 55 ℃/h, the heat preservation temperature is 570 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The results of examining the physical and chemical properties of the steel sheet for hot-rolled weldable pressure-bearing equipment of this example having a thickness of 12mm in the delivery state and the simulated postweld heat treatment state are shown in Table 1.
Table 1 example 1 mechanical properties of steel sheet for hot-rolled weldable bearing device
Figure 1
The steel plate for the hot-rolled weldable pressure-bearing equipment with the thickness of 12mm in the embodiment has a uniform and fine structure which is a ferrite plus pearlite structure and has a grain size of 10 grades, and the steel plate is shown in figure 1.
Example 2
The thickness of the steel plate for the hot-rolling weldable pressure-bearing equipment is 28mm, and the steel plate comprises the following chemical components in percentage by mass: c: 0.09%, Si: 0.31%, Mn: 1.43%, P: 0.020%, S: 0.007%, Ni: 0.50%, Nb: 0.032%, Alt: 0.0380%, the balance being Fe and unavoidable impurities, carbon equivalent CEV = 0.36%.
The production method of the steel plate for the hot-rolled weldable pressure-bearing equipment comprises the processes of steel billet smelting and steel billet rolling, and the specific process steps are as follows:
(1) smelting: carrying out primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is 55 minutes, and the argon blowing is good in the whole process; when VD is used for vacuum treatment, the vacuum degree is 62Pa, and the vacuum maintaining time is 25 minutes;
(2) rolling a steel billet: two-stage controlled rolling is adopted, the temperature is controlled to be controlled in the first stage, the finish rolling temperature is 950 ℃, the total deformation is 58%, the final pass reduction is 30mm, and the billet is cooled to 885 ℃ after the first stage. The initial rolling temperature in the stage II is 835 ℃, the final rolling temperature is 797 ℃, and water cooling is carried out to 665 ℃ after the stage II to obtain a steel plate with the thickness of 28 mm;
the simulated postweld heat treatment process of the steel plate comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 60 ℃/h, the heat preservation temperature is 575 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The results of examining the physical and chemical properties of the steel sheet for hot-rolled weldable pressure-bearing apparatus of 28mm thickness in the delivered state and the simulated postweld heat treatment state are shown in Table 2.
Table 2 example 2 mechanical properties of steel sheet for hot-rolled weldable bearing device
Figure 2
The steel plate for the hot-rolled weldable pressure-bearing equipment with the thickness of 28mm in the embodiment has a uniform and fine structure which is a ferrite plus pearlite structure and has a grain size of 9.5 grades, and is shown in figure 2.
Example 3
The thickness of the steel plate for the hot-rolling weldable pressure-bearing equipment is 40mm, and the steel plate comprises the following chemical components in percentage by mass: c: 0.10%, Si: 0.44%, Mn: 1.51%, P: 0.016%, S: 0.012%, Ni: 0.32%, Nb: 0.041%, Alt: 0.0450%, the balance being Fe and unavoidable impurities, the carbon equivalent CEV = 0.37%.
The production method of the steel plate for the hot-rolled weldable pressure-bearing equipment comprises the processes of steel billet smelting and steel billet rolling, and the specific process steps are as follows:
(1) smelting: carrying out primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is 60 minutes, and the argon blowing is good in the whole process; when VD is used for vacuum treatment, the vacuum degree is 66Pa, and the vacuum maintaining time is 29 minutes;
(2) rolling a steel billet: two-stage controlled rolling is adopted, the first stage is temperature controlled rolling, the final rolling temperature is 984 ℃, the total deformation is 55 percent, the last secondary rolling amount is 28mm, and the billet is cooled to 880 ℃ by water after the first stage. The initial rolling temperature at stage II is 842 ℃, the final rolling temperature is 805 ℃, and water cooling is carried out to 674 ℃ after stage II, so as to obtain a steel plate with the thickness of 40 mm;
the simulated postweld heat treatment process of the steel plate comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 62 ℃/h, the heat preservation temperature is 581 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The results of examining the physical and chemical properties of the steel sheet for a hot-rolled weldable pressure-bearing apparatus having a thickness of 40mm in this example in the delivery state and the simulated postweld heat treatment state are shown in Table 3.
Table 3 example 3 mechanical properties of steel sheet for hot-rolled weldable bearing device
Figure 3
The steel plate for the hot-rolled weldable pressure-bearing equipment with the thickness of 28mm in the embodiment has a uniform and fine structure which is a ferrite plus pearlite structure and has a grain size of 9 grades, and particularly shown in figure 3.
Example 4
The thickness of the steel plate for the hot-rolling weldable pressure-bearing equipment is 52mm, and the steel plate comprises the following chemical components in percentage by mass: c: 0.12%, Si: 0.50%, Mn: 1.40%, P: 0.010%, S: 0.015%, Ni: 0.25%, Nb: 0.050%, Alt: 0.052%, the balance being Fe and unavoidable impurities, carbon equivalent CEV = 0.37%.
The production method of the steel plate for the hot-rolled weldable pressure-bearing equipment comprises the processes of steel billet smelting and steel billet rolling, and the specific process steps are as follows:
(1) smelting: carrying out primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is 60 minutes, and the argon blowing is good in the whole process; when VD is carried out, the vacuum degree is 65Pa, and the vacuum maintaining time is 32 minutes;
(2) rolling a steel billet: two-stage controlled rolling is adopted, the temperature is controlled to be rolled in the first stage, the finish rolling temperature is 979 ℃, the total deformation is 57%, the final reduction amount is 26mm, and the billet is cooled to 892 ℃ by water after the first stage. The initial rolling temperature at stage II is 830 ℃, the final rolling temperature is 810 ℃, and water cooling is carried out to 700 ℃ after stage II to obtain a steel plate with the thickness of 52 mm;
the simulated postweld heat treatment process of the steel plate comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 75 ℃/h, the heat preservation temperature is 590 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The results of examining the physical and chemical properties of the steel sheet for hot-rolled weldable pressure-bearing apparatus of 52mm thickness in the delivery state and the simulated postweld heat treatment state are shown in Table 4.
Table 4 example 4 mechanical properties of steel sheets for hot-rolled weldable bearing devices
Figure 4
The steel plate for the hot-rolled weldable pressure-bearing equipment with the thickness of 28mm in the embodiment has a uniform and fine structure which is a ferrite plus pearlite structure and has a grain size of 8 grades, and particularly is shown in figure 4.
Example 5
The thickness of the steel plate for the hot-rolling weldable pressure-bearing equipment is 63mm, and the steel plate comprises the following chemical components in percentage by mass: c: 0.08%, Si: 0.38%, Mn: 1.55%, P: 0.012%, S: 0.009%, Ni: 0.38%, Nb: 0.027%, Alt: 0.068%, the balance being Fe and unavoidable impurities, carbon equivalent CEV = 0.36%.
The production method of the steel plate for the hot-rolled weldable pressure-bearing equipment comprises the processes of steel billet smelting and steel billet rolling, and the specific process steps are as follows:
(1) smelting: carrying out primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is 58 minutes, and the argon blowing is good in the whole process; when VD is carried out, the vacuum degree is 64Pa, and the vacuum maintaining time is 35 minutes;
(2) rolling a steel billet: two-stage controlled rolling is adopted, temperature control rolling is carried out in the first stage, the final rolling temperature is 957 ℃, the total deformation is 58%, the final pass reduction is 25mm, and the billet is cooled to 899 ℃ after the first stage. The initial rolling temperature of the second stage is 847 ℃, the final rolling temperature is 792 ℃, and the steel plate with the thickness of 63mm is obtained after the second stage by water cooling to 687 ℃;
the simulated postweld heat treatment process of the steel plate comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 80 ℃/h, the heat preservation temperature 586 ℃, the heat preservation time: and 6h, discharging and then air-cooling to room temperature.
The results of examining the physical and chemical properties of the steel sheet for hot-rolled weldable pressure-bearing apparatus of this example having a thickness of 63mm in the delivery state and the simulated postweld heat treatment state are shown in Table 5.
Table 5 example 5 mechanical properties of steel sheets for hot-rolled weldable bearing devices
Figure 5
The steel plate for the hot-rolled weldable pressure-bearing equipment with the thickness of 63mm in the embodiment has a uniform and fine structure which is a ferrite plus pearlite structure and has a grain size of 8.5 grades, and is shown in figure 5.
Comparative example 1
This comparative example is the same as example 5: the same components and the same thickness specification; the difference from the embodiment 5 is the production process, and the process flow is as follows: the method comprises the following steps of billet smelting, billet rolling procedure and steel plate normalizing heat treatment, and comprises the following specific process steps:
(1) smelting: carrying out primary smelting, LF furnace refining and VD vacuum treatment; pre-deoxidation technology is adopted for primary smelting tapping; the total refining time of the LF furnace is 58 minutes, and the argon blowing is good in the whole process; when VD is carried out, the vacuum degree is 64Pa, and the vacuum maintaining time is 35 minutes;
(2) rolling a steel billet: two-stage controlled rolling is adopted, temperature control rolling is carried out in the first stage, the final rolling temperature is 957 ℃, the total deformation is 58%, the final pass reduction is 25mm, and the billet is cooled to 899 ℃ after the first stage. The initial rolling temperature of the second stage is 847 ℃, the final rolling temperature is 792 ℃, and the steel plate with the thickness of 63mm is obtained after the second stage by water cooling to 687 ℃;
(3) normalizing heat treatment of the steel plate: heating the steel plate to 900 +/-10 ℃, preserving heat for 40min, and air-cooling to room temperature after discharging.
The simulated postweld heat treatment process of the steel plate of the comparative example comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 55 ℃/h, the heat preservation temperature is 570 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The results of the physical and chemical property tests of the normalized steel sheet of this comparative example are shown in Table 6.
TABLE 6 mechanical Properties of normalized Steel sheet of comparative example 1
Figure 6
The structure of the normalized steel plate of the comparative example is uniform and fine, is a ferrite plus pearlite structure, and has the grain size of 7 grades, and concretely shown in figure 6.
The steel sheet of this comparative example was compared with example 5: in performance, the ductility and toughness are similar, the strength is low compared with that of the embodiment 5 of the patent, and the strength of the normalized steel plate after die welding can not meet the standard requirement. In texture, the grain size is slightly coarser in comparative example 1. The reason for this difference is that: the rolled steel plate has more substructures, is easy to nucleate, refines grains, and has certain contribution to strength due to the deformation of rolled tissues. After the normalizing treatment, the substructure disappears, the deformed tissue disappears, and the strength is low. To ensure strength, the carbon equivalent needs to be increased, which entails an increase in cost and a decrease in weldability.
Comparative example 2
This comparative example is the same as example 5: the same process flow and the same thickness specification; the difference from the embodiment 5 is that the chemical components comprise the following components in percentage by mass: c: 0.14%, Si: 0.32%, Mn: 1.41%, P: 0.011%, S: 0.008%, Ni: 0.31%, Nb: 0.025%, Alt: 0.068%, the balance being Fe and unavoidable impurities, carbon equivalent CEV = 0.40%.
The simulated postweld heat treatment process of the steel plate of the comparative example comprises the following steps: charging and discharging at 400 ℃, and increasing and decreasing the temperature rate above 400 ℃: 55 ℃/h, the heat preservation temperature is 570 ℃, and the heat preservation time is as follows: and 6h, discharging and then air-cooling to room temperature.
The results of the physical and chemical property tests of the steel sheets of this comparative example are shown in Table 7.
TABLE 7 mechanical Properties of the comparative example 2 steel sheet
Figure 7
The steel plate structure of the comparative example is a ferrite + pearlite structure with a grain size of grade 8, and is shown in figure 7 in detail.
The steel sheet of this comparative example was compared with example 5: in terms of performance, comparative example 2 shows high strength, poor ductility and toughness, and particularly lower impact energy after die welding. The grain size is somewhat coarser in texture and the pearlite content is significantly higher than in example 5. the reason for this difference is: comparative example 2 has a high carbon equivalent, the second phase particles increase in size and number after rolling, the increase in number causes dispersion strengthening, and the increase in size causes a decrease in toughness. And an increase in the carbon content entails an increase in the pearlite content.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.

Claims (8)

1. The steel plate for the hot-rolled weldable pressure-bearing equipment is characterized by comprising the following chemical components in percentage by mass: c: 0.06-0.12%, Si: 0.20-0.50%, 0.50%, Mn: 1.40-1.60%, P is less than or equal to 0.020%, S is less than or equal to 0.015%, Ni: 0.25 to 0.50%, Nb: 0.020-0.050%, Alt is more than or equal to 0.020%, and the balance is Fe and inevitable impurities.
2. The steel plate for a hot-rolled weldable pressure-bearing apparatus according to claim 1, wherein the steel plate has a chemical composition of carbon equivalent CEV: 0.35-0.37%.
3. The steel plate for a hot-rolled weldable pressure-bearing apparatus according to claim 1 or 2, wherein the steel plate has a thickness of 12 to 63 mm.
4. The steel plate for a hot-rolled weldable pressure-bearing device according to claim 1 or 2, wherein the steel plate in a delivery state and a simulated post-weld heat treatment state have mechanical properties satisfying: normal temperature stretching ReH is more than or equal to 355MPa, Rm: 450-610 MPa, A is more than or equal to 22.0%; the average value of the transverse impact energy AKV at minus 50 ℃ is more than or equal to 150J.
5. The steel plate for a hot-rolled weldable pressure-bearing apparatus according to claim 1 or 2, wherein the steel plate has a uniform structure of ferrite plus pearlite and a grain size of 8 to 10 grades.
6. A method of producing a steel sheet for a hot-rolled weldable bearing device according to any one of claims 1 to 5, characterized in that it comprises a billet smelting and billet rolling process; the billet smelting process adopts primary smelting, LF furnace refining and VD vacuum treatment; the billet rolling procedure is a two-stage controlled rolling process.
7. The method for producing a steel plate for a hot-rolled weldable pressure-bearing apparatus according to claim 6, wherein the preliminary smelting steel is performed by a pre-deoxidation process; the total refining time of the LF furnace is more than or equal to 50 minutes, and the argon blowing is good in the whole process; when VD vacuum treatment is carried out, the vacuum degree is less than or equal to 66Pa, and the vacuum holding time is more than or equal to 20 minutes.
8. The method of producing a steel sheet for a hot rolled weldable pressure bearing device according to claim 6, wherein the two-stage controlled rolling process; the first stage of temperature-controlled rolling, wherein the final rolling temperature is more than or equal to 950 ℃, the total deformation is 55-60%, the final reduction is 25-30mm, and the steel billet is cooled to 880-900 ℃ after the first stage; the rolling temperature at the stage II is 830-850 ℃, the final rolling temperature is 790-810 ℃, and the water cooling is carried out to 650-700 ℃ after the stage II.
CN201911123332.8A 2019-11-16 2019-11-16 Steel plate for hot-rolled weldable pressure-bearing equipment and production method thereof Pending CN110983175A (en)

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