CN115418460A - FH32-HD50 high-ductility ship plate steel and preparation method thereof - Google Patents
FH32-HD50 high-ductility ship plate steel and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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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
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Abstract
The invention discloses FH32-HD50 high-ductility ship plate steel and a preparation method thereof, and belongs to the technical field of ship plate steel development. The ship plate steel comprises the following chemical components in percentage by mass: c:0.06 to 0.10%, mn:1.20 to 1.60%, si:0.20 to 0.26%, ni:0.07 to 0.10%, alt:0.03 to 0.05 percent, ti:0.008 to 0.013%, nb:0.01 to 0.03 percent, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.36 percent of Ceq, and the balance of Fe and inevitable impurities. The preparation method comprises the steps of heating, heat preservation, rough rolling, finish rolling and cooling to obtain a finished steel plate with the thickness of 12-34 mm. The method adopts a preparation process with high finish rolling temperature, the cooling stage is a relaxation-laminar cooling-air cooling three-stage cooling mode, the obtained tissues are soft-phase ferrite and hard-phase lamellar pearlite, two phases have large hardness difference, high ductility is obtained while the strength and low-temperature toughness are ensured, an A5 proportion sample with full thickness is adopted in a tensile test, the elongation is more than 35%, and the preparation method is simple, economic and efficient and has good industrial application prospect.
Description
Technical Field
The invention belongs to the technical field of ship plate steel development, and particularly relates to FH32-HD50 high-ductility ship plate steel and a preparation method thereof.
Background
In recent years, the shipbuilding industry and the marine oil industry of various countries around the world have been developed at a high speed, the yield and demand of ships have been increasing, and the large-scale, high-speed and automatic ship building industry has become the development direction of the shipbuilding industry. With the rapid development of marine economy, the scale of ships is continuously enlarged, the navigation speed of the ships is continuously improved, the navigation environment is increasingly complex, the occurrence of marine traffic accidents is high, and the life and property safety of people is seriously threatened. Accident category analysis shows that marine traffic accidents are mainly collision, touch and grounding, wherein the damage caused by collision accidents is the most serious. In order to improve the safety of ships in marine accidents, the International Maritime Organization (IMO) sets forth new standards, new specifications and new convention for environmental protection and safety, and puts forward higher requirements for ship enterprises, and also puts forward more strict standards for the quality of ship plate steel, and the proportion of steel for high-end ship models in the ship industry will gradually increase.
In the prior art, methods such as double hulls are often adopted to deal with the problem of environmental pollution caused by leakage of loaded substances after gas transport ships and crude oil tankers for transporting LNG (liquefied natural gas) and LPG (liquefied petroleum gas) touch reefs or are impacted.
In addition, high Ductility (HD) steel sheets may be used to increase the impact energy absorbed upon impact while ensuring the strength of the steel sheets, thereby improving the safety of the impact.
In the plastic deformation process of the multi-phase structure, the soft phase and the hard phase are matched with each other, and the ferrite of the soft phase is preferentially yielded, so that the material is ensured to have good plasticity; the hard phase pearlite can in turn act to increase the strength during subsequent deformation. Better strong plastic matching can be obtained by optimizing the volume fraction and the size of the soft and hard phases and controlling the distribution of the hard phases.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problem of the existing ship collision, the invention aims to provide a preparation method of FH32-HD50 high-ductility ship plate steel, which can obtain the ship plate steel with good strength and plasticity matching degree and improve the collision resistance of the ship under the condition of not increasing the weight of the ship.
The invention discloses a preparation method of FH32-HD50 high-ductility ship plate steel, which is characterized by comprising the following steps:
step 1: heating the steel billet which is smelted and cast according to the component design to 1150-1200 ℃ at the speed of 10 ℃/s, and preserving the heat for 1-2 h;
step 2: the billet is taken out of the furnace and then is subjected to multi-pass rough rolling, the single pass adopts the reduction rate of more than or equal to 20 percent, the accumulated reduction rate is more than or equal to 50 percent, the rough rolling finishing temperature is more than 1000 ℃, and an intermediate billet with the thickness not less than 2 times of the thickness of a finished product is obtained;
and step 3: after the intermediate billet is heated, performing multi-pass finish rolling, wherein the finish rolling initial rolling temperature is 920-930 ℃, the single-pass rolling adopts the reduction rate which is more than or equal to 16 percent, the accumulated reduction rate is more than or equal to 40 percent, and the final rolling temperature is controlled at 820-860 ℃;
and 4, step 4: then, performing relaxation-laminar cooling-air cooling three-stage cooling on the steel plate: relaxing to 700-740 ℃ after rolling in the first stage, carrying out laminar flow cooling to 600-650 ℃ in the second stage at the cooling speed of 6-15 ℃/s, and carrying out air cooling to room temperature in the third stage to finish the preparation of the FH32-HD50 high-ductility ship plate steel.
Preferably, in the step 1, the thickness of the steel billet is 60 to 150mm.
Preferably, in the step 2, the rough rolling stage belongs to austenite recrystallization zone rolling, the number of passes of the rough rolling stage is 2-3, the single-pass reduction rate is 20-35%, and the thickness of the intermediate billet is 25-75 mm.
Preferably, in the step 3, the finish rolling stage belongs to austenite non-recrystallization region rolling, the number of passes in the finish rolling stage is 2-3, the single pass reduction rate is 16-34%, and the thickness of the finished steel plate is 12-34 mm.
The invention further provides FH32-HD50 high-ductility ship plate steel prepared according to the method, which is characterized in that the chemical components of the ship plate steel are as follows by mass percent: c:0.06 to 0.10%, mn:1.20 to 1.60%, si:0.20 to 0.26%, ni:0.07 to 0.10%, alt:0.03 to 0.05 percent, ti:0.008 to 0.013%, nb:0.01 to 0.03 percent of Fe, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.36 percent of Ceq, and the balance of Fe and inevitable impurities; the ship plate steel structure is a ferrite-pearlite structure, the hardness difference between two phases of ferrite and pearlite is 24-35 HV, wherein the volume fraction of soft phase ferrite is 74-80%, the volume fraction of hard phase pearlite is 20-26%, and the average grain size of the ferrite is 16-20 mu m.
Preferably, the yield strength of the ship plate steel is 332-356 MPa, the tensile strength is 474-490 MPa, the impact energy at-60 ℃ is 194-333J, and the elongation after fracture is 36.6-37.7%.
The invention relates to a production standard and a performance detection method of FH32-HD50 high-DUCTILITY ship plate steel, which refer to the guidance of MATERIAL REQUERNEMENTS FOR HIGHER-DUCTILITY HULL STRUCTURAL STEEL PLATES AND SECTIONS of American ABS classification society.
Compared with the prior art, the preparation method provided by the invention has the following beneficial effects:
the preparation method of the FH32-HD50 high-ductility ship plate steel adopts a three-section cooling method of higher finish rolling temperature to reduce the load of a rolling mill, relaxation, laminar cooling and air cooling, so that the prepared ship plate steel has soft phase ferrite and hard phase pearlite structures with larger hardness difference, the volume fraction and the size of the soft and hard phases and the distribution of the hard phases are optimized, the ship plate steel has good strength and plasticity, the structure performance is uniform along the thickness direction, and the anti-collision performance of a ship is improved. The ship plate steel is designed by adopting low-carbon microalloy components, so that the production cost is lower, the steel plate has excellent performance, has good low-temperature impact toughness and the characteristics of high strength and high plasticity, and has the carbon equivalent Ceq of less than or equal to 0.36 percent and good welding performance.
Drawings
FIG. 1 is a drawing of a process for preparing the FH32-HD50 high ductility boat deck steel of example 1;
FIG. 2 is a stress-strain curve of the high ductility ship plate steel of example 1FH32-HD 50;
FIG. 3 shows the tensile fracture morphology of the high ductility ship plate steel of FH32-HD50 in example 1;
FIG. 4 is a typical metallographic structure of the high ductility ship plate steels of FH32-HD50 in example 1.
Detailed Description
In order to better explain the method for preparing FH32-HD50 high ductility ship plate steel of the present invention, the following detailed description is provided with reference to the attached drawings and preferred embodiments.
Example 1
The preparation method of the FH32-HD50 high-ductility ship plate steel with the thickness of 12mm is shown in the table 1 in terms of chemical components and mass percent, and comprises the following specific steps:
step 1: heating a 60mm thick steel billet which is smelted and cast according to the component design to 1200 ℃ at the speed of 10 ℃/s, and preserving heat for 1h;
and 2, step: and (3) immediately carrying out 3 times of rough rolling after the heated and heat-preserved steel billet is taken out of the furnace, wherein the 3 times of rough rolling sequentially comprise: 60mm → 48mm → 38mm → 30mm, the accumulated reduction rate is 50%, and the rough rolling finishing temperature is 1080 ℃, so as to obtain an intermediate blank with the thickness of 30 mm;
and 3, step 3: after the intermediate billet is heated, performing 3 times of finish rolling, wherein the 3 times are sequentially as follows: 30mm → 24mm → 18mm → 12mm, the start rolling temperature of finish rolling is 930 ℃, the cumulative reduction rate is 60%, and the finish rolling temperature is 840 ℃, so as to obtain a steel plate with the thickness of 12 mm;
and 4, step 4: performing relaxation-laminar cooling-air cooling three-stage cooling on a steel plate: and air cooling to 740 ℃ after the first stage of rolling, carrying out laminar flow cooling to 650 ℃ at the cooling speed of 6 ℃/s in the second stage, and then carrying out air cooling to room temperature in the third stage to finish the preparation of the FH32-HD50 high-ductility ship plate steel.
The tensile test of the ship plate steel prepared in the embodiment adopts a full-thickness A5 proportion sample, the stress-strain curve is shown in figure 2, the tensile fracture morphology is shown in figure 3 (the stress-strain curve and the tensile fracture morphology of the steel plates of the embodiments 2-6 are similar and are omitted), and the mechanical properties are shown in table 2. The microstructure of the steel sheet was a ferrite-pearlite structure, and a typical metallographic structure is shown in FIG. 4 (typical metallographic structures of steel sheets of examples 2 to 6 are similar to those of the steel sheets, and therefore, omitted), and the differences in the two-phase microhardness and hardness are shown in Table 3, and the phase ratios and the ferrite average grain sizes are shown in Table 4.
Example 2
The preparation method of the FH32-HD50 high-ductility ship plate steel with the thickness of 14mm comprises the following specific steps, wherein the chemical components and the mass percentages are shown in Table 1:
step 1: heating a 60mm thick steel billet which is smelted and cast according to the component design to 1150 ℃ at the speed of 10 ℃/s, and preserving heat for 1.5h;
step 2: and (3) immediately carrying out 2 times of rough rolling after the heated and heat-preserved steel billet is taken out of the furnace, wherein the 2 times of rough rolling sequentially comprise: 60mm → 44mm → 29mm, the accumulated reduction rate is 52%, and the rough rolling finishing temperature is 1060 ℃, so as to obtain an intermediate blank with the thickness of 29 mm;
and 3, step 3: after the intermediate billet is warmed, performing 2-pass finish rolling, wherein the 2-pass finish rolling sequentially comprises the following steps: 29mm → 20mm → 14mm, the initial rolling temperature of finish rolling is 925 ℃, the cumulative reduction rate is 52%, and the final rolling temperature is 820 ℃ to obtain a steel plate with the thickness of 14 mm;
and 4, step 4: performing relaxation-laminar cooling-air cooling three-section cooling on the steel plate: and air cooling to 740 ℃ after the first stage of rolling, carrying out laminar flow cooling to 600 ℃ at the cooling speed of 10 ℃/s in the second stage, and then carrying out air cooling to room temperature in the third stage to finish the preparation of the FH32-HD50 high-ductility ship plate steel.
The tensile test of the ship plate steel prepared by the embodiment adopts a full-thickness A5 proportion sample, and the mechanical properties are shown in Table 2; the structure of the steel plate is a ferrite-pearlite structure, the two-phase microhardness and hardness difference are shown in table 3, and the phase proportion and the ferrite average grain size are shown in table 4.
Example 3
The preparation method of the FH32-HD50 high-ductility ship plate steel with the thickness of 16mm comprises the following specific steps, wherein the chemical components and the mass percentages are shown in Table 1:
step 1: heating a 150mm thick steel billet which is smelted and cast according to the component design to 1200 ℃ at the speed of 10 ℃/s, and preserving heat for 1.2h;
and 2, step: immediately carrying out 3 times of rough rolling after the heated and heat-preserved billet is taken out of the furnace, wherein the 3 times are as follows: 150mm → 115mm → 76mm → 50mm, the accumulated reduction rate is 67%, and the rough rolling finishing temperature is 1100 ℃, so as to obtain an intermediate blank with the thickness of 50 mm;
and step 3: after the intermediate billet is heated, performing 3 times of finish rolling, wherein the 3 times are sequentially as follows: 50mm → 34mm → 24mm → 16mm, the start rolling temperature of finish rolling is 920 ℃, the cumulative reduction rate is 68%, and the finish rolling temperature is 835 ℃, so as to obtain a steel plate with the thickness of 16 mm;
and 4, step 4: performing relaxation-laminar cooling-air cooling three-section cooling on the steel plate: and air cooling to 740 ℃ after the first stage of rolling, carrying out laminar flow cooling to 550 ℃ at the cooling speed of 12 ℃/s in the second stage, and then carrying out air cooling to room temperature in the third stage to finish the preparation of the FH32-HD50 high-ductility ship plate steel.
The tensile test of the ship plate steel prepared by the embodiment adopts a full-thickness A5 proportion sample, and the mechanical properties are shown in Table 2; the structure of the steel plate is a ferrite-pearlite structure, the two-phase microhardness and hardness difference are shown in table 3, and the phase ratio and the ferrite average grain size are shown in table 4.
Example 4
The preparation method of FH32-HD50 high-ductility ship plate steel with the thickness of 23mm comprises the following steps of:
step 1: heating a 150mm thick steel billet which is smelted and cast according to the component design to 1180 ℃ at the speed of 10 ℃/s, and preserving heat for 1.5 hours;
and 2, step: immediately carrying out 3 times of rough rolling after the heated and heat-preserved billet is taken out of the furnace, wherein the 3 times are as follows: 150mm → 120mm → 80mm → 58mm, the accumulated reduction rate is 61%, the rough rolling finishing temperature is 1040 ℃, and an intermediate blank with the thickness of 58mm is obtained;
and step 3: after the intermediate billet is warmed, performing 3-pass finish rolling, wherein the 3-pass finish rolling sequentially comprises the following steps: 58mm → 42mm → 31mm → 23mm, the start rolling temperature of finish rolling is 926 ℃, the cumulative reduction rate is 60%, and the finish rolling temperature is 850 ℃, so as to obtain a steel plate with the thickness of 23 mm;
and 4, step 4: performing relaxation-laminar cooling-air cooling three-section cooling on the steel plate: and air cooling to 700 ℃ after the first stage of rolling, carrying out laminar flow cooling to 650 ℃ at the second stage, carrying out air cooling to room temperature at the third stage, and completing the preparation of the FH32-HD50 high-ductility ship plate steel.
The tensile test of the ship plate steel prepared by the embodiment adopts a full-thickness A5 proportion sample, and the mechanical properties are shown in Table 2; the structure of the steel plate is a ferrite-pearlite structure, the two-phase microhardness and hardness difference are shown in table 3, and the phase ratio and the ferrite average grain size are shown in table 4.
Example 5
The preparation method of the FH32-HD50 high-ductility ship plate steel with the thickness of 28mm comprises the following steps of:
step 1: heating a 150mm thick steel billet which is smelted and cast according to the component design to 1175 ℃ at the speed of 10 ℃/s, and preserving heat for 1.8h;
step 2: immediately carrying out 2-pass rough rolling after the heated and heat-preserved billet is taken out of the furnace, wherein the 2-pass rough rolling comprises the following steps: 150mm → 112mm → 74mm, the accumulated reduction rate is 51%, the rough rolling finishing temperature is 1045 ℃, and an intermediate blank with the thickness of 74mm is obtained;
and step 3: after the intermediate billet is heated, performing 3 times of finish rolling, wherein the 3 times are sequentially as follows: 74mm → 51mm → 36mm → 28mm, the start rolling temperature of finish rolling is 930 ℃, the cumulative reduction rate is 62%, and the finish rolling temperature is 860 ℃ to obtain a steel plate with the thickness of 28 mm;
and 4, step 4: performing relaxation-laminar cooling-air cooling three-section cooling on the steel plate: and air cooling to 700 ℃ after the first stage of rolling, carrying out laminar flow cooling to 600 ℃ at the second stage, carrying out cooling at the speed of 13 ℃/s, and then carrying out air cooling to room temperature in the third stage, thus completing the preparation of the FH32-HD50 high-ductility ship plate steel.
The tensile test of the ship plate steel prepared by the embodiment adopts a full-thickness A5 proportion sample, and the mechanical properties are shown in Table 2; the structure of the steel plate is a ferrite-pearlite structure, the two-phase microhardness and hardness difference are shown in table 3, and the phase ratio and the ferrite average grain size are shown in table 4.
Example 6
The preparation method of the FH32-HD50 high-ductility ship plate steel with the thickness of 34mm comprises the following steps of:
step 1: heating a 150mm thick steel billet which is smelted and cast according to the component design to 1160 ℃ at the speed of 10 ℃/s, and preserving heat for 2 hours;
step 2: immediately carrying out 2-pass rough rolling after the heated and heat-preserved billet is taken out of the furnace, wherein the 2-pass rough rolling comprises the following steps: 150mm → 104mm → 70mm, the accumulated reduction rate is 53%, and the rough rolling finishing temperature is 1075 ℃, so as to obtain an intermediate blank with the thickness of 70 mm;
and step 3: after the intermediate billet is warmed, performing 2-pass finish rolling, wherein the 2-pass finish rolling sequentially comprises the following steps: 70mm → 48mm → 34mm, the initial rolling temperature of finish rolling is 926 ℃, the cumulative reduction rate is 51%, and the final rolling temperature is 855 ℃, so as to obtain a steel plate with the thickness of 34 mm;
and 4, step 4: performing relaxation-laminar cooling-air cooling three-section cooling on the steel plate: and air cooling to 700 ℃ after the first stage of rolling, carrying out laminar flow cooling to 600 ℃ at the second stage, carrying out cooling at the speed of 13 ℃/s, and then carrying out air cooling to room temperature in the third stage, thus completing the preparation of the FH32-HD50 high-ductility ship plate steel.
The tensile test of the ship plate steel prepared by the embodiment adopts a full-thickness A5 proportion sample, and the mechanical properties are shown in Table 2; the structure of the steel plate is a ferrite-pearlite structure, the two-phase microhardness and hardness difference are shown in table 3, and the phase ratio and the ferrite average grain size are shown in table 4.
The steel sheets according to the examples of the present invention contain chemical components in the mass percentages shown in table 1, and the balance of Fe and inevitable impurities are not shown in the table. The mechanical properties of the steel sheets of the examples of the present invention are shown in Table 2. The two-phase microhardness and hardness difference of the steel sheets according to the examples of the present invention are shown in Table 3. The phase ratio and ferrite average grain size of the steel sheets according to the examples of the present invention are shown in Table 4. The preparation process of each embodiment of the invention is shown in figure 1.
TABLE 1 chemical composition of FH32-HD50 boat deck steel of each example (mass fraction/wt%)
TABLE 2 mechanical properties of FH32-HD50 ship plate steels of various embodiments
TABLE 3 micro-hardness and hardness difference of FH32-HD50 ship plate steels of various examples
TABLE 4 comparative examples and ferritic average grain sizes of FH32-HD50 boat plate steels of various examples
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above examples, and it should be noted that, for those skilled in the art, several attempts and modifications can be made without departing from the preparation method of the present invention, and these attempts and modifications should also fall into the protection scope of the present invention.
Claims (6)
1. A preparation method of FH32-HD50 high-ductility ship plate steel is characterized by comprising the following steps:
step 1: heating a steel blank which is smelted and cast according to the component design to 1150 to 1200 ℃ at the speed of 10 ℃/s, and preserving heat for 1 to 2 hours;
step 2: the billet is taken out of the furnace and then is subjected to multi-pass rough rolling, the single pass adopts the reduction rate of more than or equal to 20 percent, the accumulated reduction rate is more than or equal to 50 percent, the rough rolling finishing temperature is more than 1000 ℃, and an intermediate billet with the thickness not less than 2 times of the thickness of a finished product is obtained;
and step 3: after the intermediate billet is warmed, carrying out multi-pass finish rolling at the rolling start temperature of 920-930 ℃, adopting the reduction rate of more than or equal to 16% for a single pass, controlling the cumulative reduction rate of more than or equal to 40% and controlling the final rolling temperature at 820-860 ℃;
and 4, step 4: then, performing relaxation-laminar cooling-air cooling three-section cooling on the steel plate: and (3) relaxing to 700-740 ℃ after rolling in the first stage, carrying out laminar flow cooling to 600-650 ℃ in the second stage at the cooling speed of 6-15 ℃/s, and then carrying out air cooling to room temperature in the third stage to finish the preparation of the FH32-HD50 high-ductility ship plate steel.
2. The method of claim 1, wherein in step 1, the thickness of the steel billet is 60 to 150mm.
3. The method for preparing FH32-HD50 high ductility ship plate steel according to claim 1, wherein in the step 2, the rough rolling stage belongs to rolling in an austenite recrystallization zone, the number of rough rolling stages is 2~3 passes, the single-pass reduction rate is 20-35%, and the thickness of the intermediate billet is 25-75 mm.
4. The method for preparing FH32-HD50 high ductility ship plate steel according to claim 1, wherein in the step 3, the finish rolling stage belongs to rolling in an austenite non-recrystallization zone, the number of passes in the finish rolling stage is 2~3, the single pass reduction rate is 16-34%, and the thickness of a finished steel plate is 12-34 mm.
5. A FH32-HD50 high ductility ship plate steel prepared according to the method of any one of claims 1 to 4, characterized in that the chemical composition of the ship plate steel is as follows by mass percent: c:0.06 to 0.10%, mn:1.20 to 1.60%, si:0.20 to 0.26%, ni:0.07 to 0.10%, alt:0.03 to 0.05 percent, ti:0.008 to 0.013%, nb:0.01 to 0.03 percent, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.36 percent of Ceq, and the balance of Fe and inevitable impurities; the ship plate steel structure is a ferrite-pearlite structure, the hardness difference of two phases of ferrite and pearlite is 24-35 HV, the volume fraction of soft phase ferrite is 74-80%, the volume fraction of hard phase pearlite is 20-26%, and the average grain size of the ferrite is 16-20 μm.
6. The FH32-HD50 high ductility ship plate steel of claim 5, characterized in that the yield strength of the ship plate steel is 332 to 356MPa, the tensile strength is 474 to 490MPa, the impact work at-60 ℃ is 194 to 333J, and the elongation after fracture is 36.6 to 37.7%.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211045377.XA CN115418460A (en) | 2022-08-30 | 2022-08-30 | FH32-HD50 high-ductility ship plate steel and preparation method thereof |
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| CN202211045377.XA CN115418460A (en) | 2022-08-30 | 2022-08-30 | FH32-HD50 high-ductility ship plate steel and preparation method thereof |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012172258A (en) * | 2011-02-24 | 2012-09-10 | Nippon Steel Corp | Method for manufacturing thick steel plate |
| CN114807761A (en) * | 2022-04-28 | 2022-07-29 | 鞍钢股份有限公司 | EH36 grade ocean engineering steel with high ductility and manufacturing method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012172258A (en) * | 2011-02-24 | 2012-09-10 | Nippon Steel Corp | Method for manufacturing thick steel plate |
| CN114807761A (en) * | 2022-04-28 | 2022-07-29 | 鞍钢股份有限公司 | EH36 grade ocean engineering steel with high ductility and manufacturing method thereof |
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