CN117305702A - Multiphase-structure FH40-HD50 high-ductility ship plate steel and preparation method thereof - Google Patents

Multiphase-structure FH40-HD50 high-ductility ship plate steel and preparation method thereof Download PDF

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CN117305702A
CN117305702A CN202311223215.5A CN202311223215A CN117305702A CN 117305702 A CN117305702 A CN 117305702A CN 202311223215 A CN202311223215 A CN 202311223215A CN 117305702 A CN117305702 A CN 117305702A
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steel
ship plate
plate steel
temperature
ductility
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张晓雪
王恩茂
王凌宇
武会宾
王光磊
刘金旭
李恒坤
陈林恒
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University of Science and Technology Beijing USTB
Nanjing Iron and Steel Co Ltd
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University of Science and Technology Beijing USTB
Nanjing 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
    • 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
    • C21D6/001—Heat treatment of ferrous alloys containing Ni
    • 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
    • C21D8/0205—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
    • 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
    • C22C38/04—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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The invention discloses a multiphase-structured FH40-HD50 high-ductility ship plate steel and a preparation method thereof; belongs to the field of ship plate steel manufacturing, and comprises the following chemical components: C. mn, si, ni, nb, alt, S, P the balance being Fe and unavoidable impurity elements. The FH40-HD50 high-ductility ship plate steel of the invention takes low C, nb microalloy as a core to carry out component design, and does not contain metal elements such as Cu, V, ti and the like; the preparation method mainly comprises the working procedures of smelting, continuous casting, hot rolling, cooling and the like, wherein the multiphase structure regulation and control of ferrite, pearlite and bainite are realized through the TMCP process of three-stage cooling of relaxation, ultra-fast cooling and air cooling, the FH40-HD50 high-ductility ship plate steel with the plasticity and toughness far higher than that of the traditional high-strength ship plate steel is obtained, and the preparation method aims at improving the collision resistance of large ships in China under the condition of not changing the structural design of the ships, and has excellent economic applicability and wide market application prospect.

Description

Multiphase-structure FH40-HD50 high-ductility ship plate steel and preparation method thereof
Technical Field
The invention belongs to the field of ship plate steel manufacturing, and relates to a multiphase-structure FH40-HD50 high-ductility ship plate steel and a preparation method thereof.
Background
Safety is a subject of the transportation industry which is unchanged from ancient, and along with the trend of increasing aging of ships, the potential safety hazard brought along with the trend seriously threatens the life and property safety and the marine ecological environment of people. The risk is greatly influencing the healthy development of the shipping industry under the superposition effect of the shipping digitization and decarburization transformation strategy, so that the novel high-grade ship plate steel and the novel fuel play an increasingly important role. As the 2023 carbon strength rating is put into effect, traffic safety accidents of ships at sea become more and more complex, and uncertainty increases, especially accidents mainly due to collisions and mechanical damages. Therefore, the ship plate steel of important parts such as the ship body, the cargo hold, the fuel tank and the like must have high strength and excellent plasticity and toughness, and have enough anti-collision performance so as to ensure the navigation safety of the ship.
At present, the patent with publication number CN 113957343A proposes a TMCP state EH830 ultra-high strength marine steel plate and a manufacturing method thereof, and the related steel is added with Nb, ti, ni, cu microalloying elements such as Mo and the like, so that the production cost is high, and the strength can reach the EH830 level, but the defects are that: poor in ductility and toughness, and the elongation is only about 14%;
the patent with publication number CN 108517462A proposes a high-ductility EH 40-grade ship plate steel and a preparation method thereof, the invention adopts water cooling, air cooling and water cooling three-section cooling, the prepared steel is a ferrite and bainite dual-phase structure, the strength is EH40 grade, the elongation rate is more than 30 percent, the low-temperature impact energy at minus 40 ℃ is more than 230J, but the defects are that: the structure type and the higher yield ratio are not beneficial to the production of the high-thickness high-ductility ship plate steel; the main steel prepared by the invention case is single-phase or double-phase steel, and the research on the high-ductility ship plate steel for improving the strength-plasticity matching by utilizing multiphase structure regulation is very little at present; multiphase structure regulation can enable dislocation engineering to break through the limit of strong-plastic balance, soft and hard phases can be mutually coordinated in the plastic deformation process, and steel with multiphase microstructure comprising soft and hard phases usually shows better strain hardening behavior; the appearance and the distribution of the hard phase are controlled by optimizing the volume fraction and the size of the multiphase tissue, so that better strong plastic matching can be obtained; multiphase structure regulation and control become an important development direction for improving strength and plasticity simultaneously in the development process of high-ductility ship plate steel.
Disclosure of Invention
The invention aims to: the invention aims to provide a multiphase-structure FH40-HD50 high-ductility ship plate steel and a preparation method thereof, which are characterized in that on the basis of low C, nb microalloying and low-cost component design without Cu, V, ti and other metal elements, the relaxation, ultra-fast cooling and air cooling three-section cooling TMCP process is optimized on line, so that multiphase-structure regulation and control with strong plastic matching gradient is realized, the structure type is ferrite, pearlite and bainite, and the FH40-HD50 high-ductility ship plate steel with plastic toughness far higher than that of the traditional high-strength ship plate steel is obtained.
The technical scheme is as follows: the invention relates to a multiphase-structured FH40-HD50 high-ductility ship plate steel, which comprises the following chemical components in percentage by weight: c:0.05 to 0.14 percent, mn:0.8 to 1.6 percent, si:0.12 to 0.28 percent of Ni:0.05 to 0.15 percent, nb:0.01 to 0.04 percent, alt: 0.02-0.05%, S is less than or equal to 0.01%, P is less than or equal to 0.001%, and the balance is Fe and unavoidable impurity elements.
Further, the chemical components of the paint are as follows by weight percent: c:0.05%, mn:0.8%, si:0.12%, ni:0.05%, nb:0.01%, alt:0.02%, S:0.005%, P:0.0005%, the balance of Fe and unavoidable impurity elements.
Further, the chemical components of the paint are as follows by weight percent: c:0.14%, mn:1.6%, si:0.28%, ni:0.15%, nb:0.04%, alt:0.05%, S:0.01%, P:0.001%, and the balance of Fe and unavoidable impurity elements.
Further, the chemical components of the paint are as follows by weight percent: c:0.10%, mn:1.2%, si:0.20%, ni:0.10%, nb:0.25%, alt:0.35%, S:0.007%, P:0.0008%, the balance being Fe and unavoidable impurity elements.
Further, the preparation method of the FH40-HD50 high-ductility ship plate steel with the multiphase structure specifically comprises the following steps:
step 1: smelting and casting into steel ingots by using a vacuum induction smelting furnace according to the design of each chemical component, cutting off a riser, and forging into steel billets with the thickness of 80-320 mm;
step 2: preserving the temperature of the billet at 1130-1220 ℃ for 1.2-2 h, then carrying out three times of rough rolling, wherein the accumulated rolling reduction is more than or equal to 60% in an austenite recrystallization region in the rough rolling stage, the rough rolling finishing temperature is 1000-1060 ℃, and the thickness of the intermediate billet is 40-160 mm; after rough rolling is finished, performing finish rolling twice, wherein the accumulated rolling reduction is more than or equal to 35% in an austenite non-recrystalization area in the finish rolling stage, and the finishing temperature is 830-920 ℃;
step 3: the three-stage cooling of relaxation, ultra-fast cooling and air cooling is carried out on the steel plate after hot rolling: first, the hot rolled steel sheet is relaxed to a temperature close to A r3 Temperature, as much as possible, of relaxation stageMade in austenite single-phase region, measured steel plate A r3 The temperature is 740-800 ℃; subsequently, the ultra-fast cooling system based on the hot rolling production line is utilized to cool at the cooling speed of 50-100 ℃ per second, and the final cooling temperature is close to A r1 Temperature, measured steel sheet A r1 The temperature is 600-630 ℃; and finally, air cooling the steel plate to room temperature to finish the preparation of the FH40-HD50 high-ductility ship plate steel, wherein the thickness of the finished steel plate is 16-50 mm.
Further, the prepared ship plate steel has a multiphase structure of ferrite, pearlite and bainite, wherein the volume fraction of soft ferrite is 60-75%, the volume fraction of hard pearlite is 15-25%, the volume fraction of hard bainite is 10-15%, the average grain size of ferrite is 8.5-11.5 mu m, and the bainite is mainly granular bainite and a small amount of lath-shaped bainite.
Furthermore, the invention relates to a production standard and performance detection method of the FH40-HD50 high-ductility ship plate steel with multiphase structure, and a tensile sample is a full-thickness A5 proportion sample by referring to the guidelines of MATERIAL REQUIREMENTS FOR HIGHER-DUCTILITY HULL STRUCTURAL STEEL PLATES AND SECTINS of American ABS class society.
Further, the yield strength of the prepared ship plate steel is 410-500 MPa, the tensile strength is 520-645 MPa, the elongation after fracture is 32% -38%, and the impact energy at minus 60 ℃ is more than 280J.
The beneficial effects are that: compared with the prior art, the invention has the characteristics that: 1. according to the FH40-HD50 high-ductility ship plate steel, 0.01% -0.04% of Nb is added only on the basis of the conventional C, mn component, so that the production cost is greatly reduced; 2. the invention optimizes TMCP process on line based on actual industrial production conditions, regulates and controls 60-75% of ferrite, 15-25% of pearlite and 10-15% of bainite (granular bainite is the main) in a three-stage cooling mode of relaxation, ultra-fast cooling and air cooling, and the produced FH40-HD50 high-ductility ship plate steel has the yield strength of 410-500 MPa, the tensile strength of 520-645 MPa, the elongation after break of 32-38%, the impact power of-60 ℃ of more than 280J, which is far higher than the performance index of the traditional high-strength ship plate steel and the high-ductility ship plate steel specified by the classification society, and greatly improves the anti-collision property of ships; 3. the FH40-HD50 high-ductility ship plate steel has high strength and excellent ductility and toughness, on one hand, precipitation strengthening and fine crystal strengthening effects brought by Nb element are achieved, fine crystal is beneficial to improving the ductility and toughness, on the other hand, the coordination deformation capacity of phase change strengthening and soft and hard phases is fully utilized, and the high-ductility ship plate steel has important significance for development of the high-ductility ship plate steel.
Drawings
FIG. 1 is an SEM micrograph of a multiphase structured FH40-HD50 high-ductility ship plate steel according to example 1 of the present invention;
FIG. 2 is a graph showing the engineering stress-strain curve of a multiphase structured FH40-HD50 high-ductility ship plate steel according to example 1 of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
The FH40-HD50 high-ductility ship plate steel with multiphase structure in each embodiment of the invention comprises chemical components and mass percentages shown in table 1, wherein the balance of the components is Fe and unavoidable impurities.
TABLE 1 chemical compositions (mass fraction/wt%) of FH40-HD50 high-ductility ship plate steel for each example
Example 1
The chemical compositions and mass percentages of the FH40-HD50 high-ductility ship plate steel with multiphase structures are shown in the table 1, and the preparation method specifically comprises the following steps:
step 1: smelting and casting into steel ingots by using a vacuum induction melting furnace according to the composition design of the table 1, cutting off a riser, and forging into steel billets with the thickness of 150 mm;
step 2: preserving the temperature of the billet at 1150 ℃ for 1.5h, and then carrying out three times of rough rolling, wherein the accumulated rolling reduction rate is 76% in an austenite recrystallization region in the rough rolling stage, the rough rolling finishing temperature is 1030 ℃, and the thickness of the intermediate billet is 36mm; performing finish rolling twice after rough rolling is finished, wherein the accumulated rolling reduction rate is 50% in an austenite non-recrystalized region in the finish rolling stage, and the finish rolling temperature is 850 ℃;
step 3: the three-stage cooling of relaxation, ultra-fast cooling and air cooling is carried out on the steel plate after hot rolling: first, the hot rolled steel sheet is relaxed to a temperature close to A r3 Temperature, the relaxation stage is controlled to be in an austenite single-phase region as far as possible, and the measured steel plate A r3 The temperature is 760 ℃; subsequently, the ultra-fast cooling system based on the hot rolling production line is used for cooling at the cooling speed of 80 ℃ per second, and the final cooling temperature is close to A r1 Temperature, measured steel sheet A r1 The temperature is 614 ℃; and finally, air cooling the steel plate to room temperature to finish the preparation of the FH40-HD50 high-ductility ship plate steel, wherein the thickness of the finished steel plate is 18mm.
The ship plate steel prepared in this example has a multiphase structure of ferrite, pearlite and bainite, wherein the volume fraction of ferrite in the soft phase is 72%, the volume fraction of pearlite in the hard phase is 16%, the volume fraction of bainite in the hard phase is 12%, the average grain size of ferrite is 11.2 μm, and bainite is mainly granular bainite, and a small amount is lath-shaped bainite. The ship plate steel prepared in the embodiment is subjected to full thickness tensile test and low temperature impact test, engineering stress-strain curves are shown in figure 2, and specific mechanical properties are shown in table 2.
Example 2
The chemical compositions and mass percentages of the FH40-HD50 high-ductility ship plate steel with multiphase structures are shown in the table 1, and the preparation method specifically comprises the following steps:
step 1: smelting and casting into steel ingots by using a vacuum induction melting furnace according to the composition design of the table 1, cutting off a riser, and forging into steel billets with the thickness of 300 mm;
step 2: preserving the heat of the billet at 1180 ℃ for 1.3 hours, and then carrying out three times of rough rolling, wherein the accumulated reduction rate is 68% in an austenite recrystallization region in the rough rolling stage, the rough rolling finishing temperature is 1050 ℃, and the thickness of an intermediate billet is 96mm; performing finish rolling twice after rough rolling is finished, wherein the finish rolling stage is performed in an austenite non-recrystallization region, the accumulated rolling reduction is 56%, and the final rolling temperature is 870 ℃;
step 3: the three-stage cooling of relaxation, ultra-fast cooling and air cooling is carried out on the steel plate after hot rolling: first, the hot rolled steel sheet is relaxed to a temperature close to A r3 Temperature, the relaxation stage is controlled to be in an austenite single-phase region as far as possible, and the measured steel plate A r3 The temperature is 780 ℃; subsequently, the ultra-fast cooling system based on the hot rolling production line is used for cooling at the cooling speed of 60 ℃ per second, and the final cooling temperature is close to A r1 Temperature, measured steel sheet A r1 The temperature is 622 ℃; and finally, air cooling the steel plate to room temperature to finish the preparation of the FH40-HD50 high-ductility ship plate steel, wherein the thickness of the finished steel plate is 42mm.
The ship plate steel prepared in this example has a multiphase structure of ferrite, pearlite and bainite, wherein the volume fraction of ferrite in the soft phase is 65%, the volume fraction of pearlite in the hard phase is 21%, the volume fraction of bainite in the hard phase is 14%, the average grain size of ferrite is 9.7 μm, and bainite is mainly granular bainite, and a small amount is lath-shaped bainite. The ship plate steel prepared in the embodiment is subjected to full thickness tensile test and low temperature impact test, and specific mechanical properties are shown in Table 2.
Example 3
The chemical compositions and mass percentages of the FH40-HD50 high-ductility ship plate steel with multiphase structures are shown in the table 1, and the preparation method specifically comprises the following steps:
step 1: smelting and casting into steel ingots by using a vacuum induction melting furnace according to the composition design of the table 1, cutting off a riser, and forging into steel billets with the thickness of 320 mm;
step 2: preserving the temperature of the billet at 1210 ℃ for 1.2 hours, and then carrying out three times of rough rolling, wherein the accumulated reduction rate is 64% in an austenite recrystallization zone in the rough rolling stage, the rough rolling finishing temperature is 1055 ℃, and the thickness of the intermediate billet is 115mm; performing finish rolling twice after rough rolling is finished, wherein the finish rolling stage is performed in an austenite non-recrystallization region, the accumulated rolling reduction is 44%, and the final rolling temperature is 840 ℃;
step 3: the three-stage cooling of relaxation, ultra-fast cooling and air cooling is carried out on the steel plate after hot rolling: first, the hot rolled steel sheet is relaxed to a temperature close to A r3 Temperature, the relaxation stage is controlled to be in an austenite single-phase region as far as possible, and the measured steel plate A r3 The temperature is 750 ℃; subsequently, the ultra-fast cooling system based on the hot rolling production line is used for cooling at the cooling speed of 90 ℃ per second, and the final cooling temperature is close to A r1 Temperature, measured steel sheet A r1 The temperature is 608 ℃; and finally, air cooling the steel plate to room temperature to finish the preparation of the FH40-HD50 high-ductility ship plate steel, wherein the thickness of the finished steel plate is 64mm.
The ship plate steel prepared in this example has a multiphase structure of ferrite, pearlite and bainite, wherein the volume fraction of ferrite in the soft phase is 67%, the volume fraction of pearlite in the hard phase is 20%, the volume fraction of bainite in the hard phase is 13%, the average grain size of ferrite is 8.9 μm, and bainite is mainly granular bainite, and a small amount is lath bainite. The ship plate steel prepared in the embodiment is subjected to full thickness tensile test and low temperature impact test, and specific mechanical properties are shown in Table 2.
Example 4
The chemical compositions and mass percentages of the FH40-HD50 high-ductility ship plate steel with multiphase structures are shown in the table 1, and the preparation method specifically comprises the following steps:
step 1: smelting and casting into steel ingots by using a vacuum induction melting furnace according to the composition design of the table 1, cutting off a riser, and forging into steel billets with the thickness of 280 mm;
step 2: preserving the heat of the billet at 1170 ℃ for 1.8 hours, and then carrying out three times of rough rolling, wherein the accumulated rolling reduction is 74% in an austenite recrystallization zone in the rough rolling stage, the rough rolling finishing temperature is 1020 ℃, and the thickness of the intermediate billet is 72mm; performing finish rolling twice after rough rolling is finished, wherein the finish rolling stage is performed in an austenite non-recrystallization region, the accumulated rolling reduction rate is 53%, and the finish rolling temperature is 900 ℃;
step 3: the three-stage cooling of relaxation, ultra-fast cooling and air cooling is carried out on the steel plate after hot rolling: first, the hot rolled steel sheet is relaxed to a temperature close to A r3 Temperature, the relaxation stage is controlled to be in an austenite single-phase region as far as possible, and the measured steel plate A r3 The temperature is 785 ℃; subsequently, the ultra-fast cooling system based on the hot rolling production line is used for cooling at the cooling speed of 75 ℃ per second, and the final cooling temperature is close to A r1 Temperature, measured steel sheet A r1 The temperature is 617 ℃; finally, the steel plate is air-cooled to room temperature to finish the preparation of the FH40-HD50 high-ductility ship plate steel,the thickness of the finished steel plate is 34mm.
The ship plate steel prepared in this example has a multiphase structure of ferrite, pearlite and bainite, wherein the volume fraction of ferrite in the soft phase is 62%, the volume fraction of pearlite in the hard phase is 23%, the volume fraction of bainite in the hard phase is 15%, the average grain size of ferrite is 10.3 μm, and bainite is mainly granular bainite, and a small amount is lath-shaped bainite. The ship plate steel prepared in the embodiment is subjected to full thickness tensile test and low temperature impact test, and specific mechanical properties are shown in Table 2.
TABLE 2 mechanical Properties of the FH40-HD50 high-ductility ship plate Steel of each example
Examples Yield strength/MPa Tensile strength/MPa A5 elongation/% Impact energy/J at-60 DEG C
1 433 631 37.5 318
2 465 639 34.3 295
3 427 645 36.8 334
4 472 628 33.7 301

Claims (10)

1. The FH40-HD50 high-ductility ship plate steel with the multiphase structure is characterized by comprising the following chemical components in percentage by weight: c:0.05 to 0.14 percent, mn:0.8 to 1.6 percent, si:0.12 to 0.28 percent of Ni:0.05 to 0.15 percent, nb:0.01 to 0.04 percent, alt: 0.02-0.05%, S is less than or equal to 0.01%, P is less than or equal to 0.001%, and the balance is Fe and unavoidable impurity elements.
2. The multi-phase structured FH40-HD50 high ductility ship plate steel of claim 1, comprising the chemical composition in weight percent: c:0.05%, mn:0.8%, si:0.12%, ni:0.05%, nb:0.01%, alt:0.02%, S:0.005%, P:0.0005%, the balance of Fe and unavoidable impurity elements.
3. The multi-phase structured FH40-HD50 high ductility ship plate steel of claim 1, comprising the chemical composition in weight percent: c:0.14%, mn:1.6%, si:0.28%, ni:0.15%, nb:0.04%, alt:0.05%, S:0.01%, P:0.001%, and the balance of Fe and unavoidable impurity elements.
4. The multi-phase structured FH40-HD50 high ductility ship plate steel of claim 1, comprising the chemical composition in weight percent: c:0.10%, mn:1.2%, si:0.20%, ni:0.10%, nb:0.25%, alt:0.35%, S:0.007%, P:0.0008%, the balance being Fe and unavoidable impurity elements.
5. The method for producing a multiphase structured FH40-HD50 high ductility ship plate steel according to any one of claims 1 to 4, comprising the steps of:
(1): preparing each compound according to a proportion, smelting and casting into steel ingots by using a vacuum induction smelting furnace, cutting off a riser, and forging into steel billets;
(2): preserving the temperature of the billet at 1130-1220 ℃ for 1.2-2 h, and then performing three times of rough rolling;
(3): and (3) performing three-stage cooling of relaxation, ultra-fast cooling and air cooling on the hot rolled steel plate.
6. The method for producing a multiphase structured FH40-HD50 high ductility ship plate steel according to claim 5, wherein in step (1), the thickness of said steel slab is: 80-320 mm.
7. The method for producing a multiphase structured FH40-HD50 high ductility ship plate steel according to claim 5, wherein in step (2), said three roughings are: in the austenite recrystallization region in the rough rolling stage, the accumulated reduction rate is more than or equal to 60 percent, the rough rolling finishing temperature is 1000-1060 ℃, and the thickness of the intermediate billet is 40-160 mm; and after finishing rough rolling, performing finish rolling twice, wherein the accumulated rolling reduction is more than or equal to 35% in an austenite non-recrystallization region in the finish rolling stage, and the finishing rolling temperature is 830-920 ℃.
8. The method for producing a multiphase structured FH40-HD50 high ductility ship plate steel according to claim 5, wherein in step (3), said three-stage cooling process is specifically: first, the hot rolled steel sheet is relaxed to a temperature close to A r3 Temperature, control the relaxation stage in austenite single-phase region, measured steel plate A r3 The temperature is 740-800 DEG CThe method comprises the steps of carrying out a first treatment on the surface of the Subsequently, the ultra-fast cooling system based on the hot rolling production line is utilized to cool at the cooling speed of 50-100 ℃ per second, and the final cooling temperature is close to A r1 Temperature, measured steel sheet A r1 The temperature is 600-630 ℃; and finally, air cooling the steel plate to room temperature to finish the preparation of the FH40-HD50 high-ductility ship plate steel, wherein the thickness of the finished steel plate is 16-50 mm.
9. The method for producing a multiphase structured FH40-HD50 high ductility ship plate steel according to claim 5, wherein the ship plate steel is produced by: a multiphase structure of ferrite, pearlite and bainite;
wherein, the volume fraction of soft phase ferrite is 60-75%, the volume fraction of hard phase pearlite is 15-25%, the volume fraction of hard phase bainite is 10-15%, and the average grain size of ferrite is 8.5-11.5 μm.
10. The method for producing a multi-phase structured FH40-HD50 high ductility ship plate steel according to claim 5, wherein the yield strength of the prepared ship plate steel is 410-500 MPa, the tensile strength is 520-645 MPa, the elongation after break is 32% -38%, and the impact energy at-60 ℃ is > 280J.
CN202311223215.5A 2023-09-21 2023-09-21 Multiphase-structure FH40-HD50 high-ductility ship plate steel and preparation method thereof Pending CN117305702A (en)

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