CN117127102B - Low-carbon equivalent high-strength steel casting for offshore floating platform and preparation method thereof - Google Patents

Low-carbon equivalent high-strength steel casting for offshore floating platform and preparation method thereof Download PDF

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CN117127102B
CN117127102B CN202310955864.8A CN202310955864A CN117127102B CN 117127102 B CN117127102 B CN 117127102B CN 202310955864 A CN202310955864 A CN 202310955864A CN 117127102 B CN117127102 B CN 117127102B
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steel casting
carbon equivalent
floating platform
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offshore floating
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CN117127102A (en
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熊六一
朱伟
魏红星
李凌羽
傅明康
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Ningbo Sun Yue Precision Manufacturing 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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C21C7/0645—Agents used for dephosphorising or desulfurising
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • 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
    • 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
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
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Abstract

The invention relates to a low-carbon equivalent high-strength steel casting for an offshore floating platform and a preparation method thereof, and belongs to the technical field of steel castings. The invention discloses a low-carbon equivalent high-strength steel casting for a marine floating platform, which comprises the following components in percentage by mass: 0.10 to 0.22 percent of C, 0.50 to 0.58 percent of Si, 1.10 to 1.45 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S, 0.13 to 0.37 percent of Ni, and the balance of iron and other unavoidable elements; the carbon equivalent CEV of the low-carbon equivalent high-strength steel casting for the offshore floating platform is less than or equal to 0.43 percent. The invention also discloses a preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform. According to the invention, the high strength and excellent weldability of the steel casting for the offshore floating platform are realized by adjusting the element composition of the steel casting and controlling the carbon equivalent CEV to be less than or equal to 0.43 and combining two heat treatments, and the steel casting can be produced in batches and has high qualification rate.

Description

Low-carbon equivalent high-strength steel casting for offshore floating platform and preparation method thereof
Technical Field
The invention belongs to the technical field of steel castings, and relates to a low-carbon equivalent high-strength steel casting for an offshore floating platform and a preparation method thereof.
Background
With the rapid development of the marine industry, more and more work needs to be done on maritime equipment or on an offshore floating platform. The existing offshore floating platform comprises an ultra-large floating platform, a large floating platform and a small floating platform; the ultra-large and large floating platform mainly comprises an offshore platform with the size larger than the wave wavelength, such as an offshore floating building, an offshore airplane field and the like; the small floating platform is mainly used for loading devices such as offshore wind power generation, tide observation, oil and gas exploration and the like. Almost all floating platforms need a large number of structural steel castings, lifting lug-shaped steel castings and the like to be connected with anchor chains and counterweights, so that the floating platforms stably stay in a calibration area, and in places with severe construction environments such as marine equipment, floating platforms and the like, no method is available for realizing integral preheating welding or tempering after welding, and welding cracks of the common steel castings are easy to occur; this requires that the steel castings used have sufficient strength and excellent welding properties to ensure the safety of the platform.
Carbon equivalent is an important factor in evaluating strength and weldability of steel pieces. For example, chinese patent application text (publication No. CN 105714202A) adopts a high-strength steel casting with carbon equivalent Ceq=0.61-0.75 for coal mining machinery; however, high carbon equivalent results in poor weldability and is not applicable to offshore floating platforms. Chinese patent application text (publication No. CN 103882190A) discloses that a steel casting with carbon content C less than or equal to 0.31% and carbon equivalent Ceq less than or equal to 0.42% is subjected to water quenching treatment, and the quenching phenomenon of the steel casting during water quenching is avoided by controlling the C content and the carbon equivalent Ceq (Ceq= [ C+Mn/5+Cr/4+Mo/3+Ni/10+V/5+ (Si-0.5)/5+Ti/5+W/10+Al/10 ]%; however, the process also needs to consider factors such as the maximum wall thickness of the workpiece, the radius of the transition fillet, the wall thickness ratio of the adjacent areas and the like; the wall thickness of the floating platform cannot meet the use requirements of the offshore floating platform.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a low-carbon equivalent high-strength steel casting for an offshore floating platform, which can ensure that the steel casting with large size has high strength and meets excellent weldability when the carbon equivalent CEV is less than or equal to 0.43% by controlling the raw material components.
The aim of the invention can be achieved by the following technical scheme:
a low carbon equivalent high strength steel casting for an offshore floating platform comprising, in mass percent: 0.10 to 0.22 percent of C, 0.50 to 0.58 percent of Si, 1.10 to 1.45 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S, 0.13 to 0.37 percent of Ni, and the balance of iron and other unavoidable elements; the carbon equivalent CEV of the low-carbon equivalent high-strength steel casting for the offshore floating platform is less than or equal to 0.43 percent.
The steel castings used by the marine equipment and the offshore floating platform are large in size and mass, so that most of low-alloy carbon steel with better weldability is selected; however, the construction environment is bad, so the weldability requirement on the material is higher, but the strength of the low-carbon low-alloy steel is lower, the load of the whole platform cannot be borne, and the strength requirement on the steel casting is higher; therefore, chromium, molybdenum, cobalt, tungsten, titanium, vanadium and other alloys need to be added for matrix reinforcement, and the preparation process is harsh, so that the mass production difficulty is high and the qualification rate is low. The invention adjusts the element composition of the steel casting and controls the carbon equivalent CEV to be less than or equal to 0.43 percent; the method has the advantages of controlling the types of key elements, reducing the cost, realizing high strength and excellent weldability of the steel casting for the offshore floating platform, along with mass production and high qualification rate.
Preferably, the offshore floating platform is composed of a low-carbon equivalent high-strength steel casting, and comprises the following components in percentage by mass: 0.19 to 0.22 percent of C, 0.50 to 0.55 percent of Si, 1.20 to 1.45 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.015 percent of S, 0.20 to 0.30 percent of Ni, and the balance of iron and other unavoidable elements.
Preferably, the carbon equivalent of the low-carbon equivalent high-strength steel casting for the offshore floating platform is more than or equal to 0.40% and less than or equal to 0.43% of CEV.
Further preferably, the carbon equivalent of the low carbon equivalent high strength steel casting for the offshore floating platform is more than or equal to 0.41% and less than or equal to 0.43%.
Preferably, the carbon equivalent CEV satisfies the following formula: cev=c+mn/6+ (cr+mo+v)/5+ (ni+cu)/15, wherein the element symbols represent mass percent.
Further preferably, the carbon equivalent CEV satisfies the following formula: cev=c+ (Mn/6) + (Ni/15), wherein the symbol of the element represents mass percent.
Preferably, the low carbon equivalent high strength steel casting for the offshore floating platform has a size of (1000-10000) x (500-10000) mm 3 。
Preferably, the mass of the low-carbon equivalent high-strength steel casting for the offshore floating platform is 1000-100000 kg.
Preferably, the yield strength of the low-carbon equivalent high-strength steel casting for the offshore floating platform is more than or equal to 330MPa, the tensile strength is more than or equal to 475MPa, the elongation is more than or equal to 20%, the reduction of area is more than or equal to 32%, and the low-temperature impact (-20 ℃) is more than or equal to 32J.
A method of preparing a low carbon equivalent high strength steel casting for an offshore floating platform, the method comprising: weighing raw materials, adding the raw materials into an electric arc furnace for melting, adding lithium element and modifier for modification treatment after melting to obtain molten steel, and refining, deoxidizing and casting the molten steel to obtain a steel casting intermediate; finally, the low-carbon equivalent high-strength steel casting for the offshore floating platform is obtained after heat treatment.
Preferably, the preparation method comprises the following steps:
s1, proportioning metal raw materials, and heating and melting in an electric arc furnace;
s2, adding lithium element and modifier into the molten steel after melting to carry out modification treatment;
s3, placing the molten steel in the step S2 into a vacuum refining furnace for refining;
s4, pouring the molten steel in the step S3 into a mold for molding to obtain a molded steel casting;
s5, placing the steel casting formed in the step S4 in a high-temperature furnace for first heating;
s6, water cooling the steel castings subjected to the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel castings subjected to the first heating is not more than 35 seconds;
s7, directly feeding the steel casting to a tempering furnace for secondary heating after the temperature of the steel casting is reduced to 100-120 ℃ and discharging water;
s8, taking out for air cooling after the second heating.
In the preparation process, the time from the opening of the furnace door to the complete water entering of the steel casting after the first heating in the S6 can not exceed 35 seconds, and if the time is too long, the steel casting can be cracked or deformed.
Preferably, the melting temperature is 1620-1750 ℃ and the time is 50-200 minutes.
Preferably, the lithium element includes one or more of metallic lithium and a lithium-containing compound.
The addition of lithium element reacts with gases such as hydrogen, oxygen, nitrogen, chlorine and the like in molten steel to form lithium hydride, lithium oxide, lithium chloride and lithium nitride, and reacts with sulfur and phosphorus to form lithium sulfide and lithium phosphide, so that the effect of purifying impurities and gases in molten steel is achieved, and the overall performance of the steel casting is improved.
Further preferably, the lithium-containing compound includes, but is not limited to, one or more of lithium carbonate, lithium sulfide, lithium nitride, lithium hydroxide, and is reduced prior to use.
Preferably, the amount of the lithium element to be added is 0.001 to 0.1g/kg.
Preferably, the modifier comprises silicon-barium alloy and/or silicon-aluminum-barium-calcium alloy, and the addition amount is 0.1-20 g/kg.
According to the invention, through the addition of lithium element, silicon-barium alloy and silicon-aluminum-barium-calcium alloy, deoxidation, desulfurization and dephosphorization are realized, the property and distribution of nonmetallic inclusion are changed, and the influence on the performance of the casting after molten steel molding is reduced, so that better low-temperature toughness is obtained.
Preferably, the refining temperature is 1650 to 1800 ℃ and the time is 15 to 50 minutes.
Preferably, the first heating temperature is 900-930 ℃, the heating speed is 10-120 ℃/h, and the heat preservation time is 20-35 mm/h according to the thickest wall thickness.
Preferably, the ratio of the total water content of the water tank in water cooling to the weight of the steel casting is more than or equal to 20.
If the ratio of the total water content of the pool to the weight of the steel casting is lower than 20, the cooling effect is reduced, and the performance of the steel casting is affected.
Further preferably, the water temperature is 35+ -5 deg.C, the water is running water, and the water flow rate is greater than 0.5m/s.
When cooling in stationary water, the vapor film adheres to the surface of the workpiece for a long time, which may cause insufficient cooling or uneven cooling to generate "soft spots"; therefore, the circulating water is used or the workpiece moves in the water, and the steam film on the surface of the workpiece is destroyed by the water flow, so that the cooling capacity of a high-temperature area can be improved, and the non-uniformity of the cooling of the workpiece can be improved; meanwhile, the water circulation can also quickly reduce the temperature of the water.
Preferably, the second heating temperature is 530-580 ℃, the heating speed is 10-80 ℃/h, and the heat preservation time is 20-35 mm/h according to the thickest wall thickness.
Preferably, the steel casting obtained in S8 may further be subjected to post-treatment including one or more of shot blasting, grinding, NDT detection, repair welding, painting, roughing, finishing.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, the high strength and excellent weldability of the steel casting for the offshore floating platform are realized by adjusting the element composition of the steel casting and controlling the carbon equivalent CEV to be less than or equal to 0.43 and combining two heat treatments, and the steel casting can be produced in batches and has high qualification rate.
2. According to the invention, other alloys are not required to be added in the raw material formula, so that the cost is reduced, and meanwhile, the stress generated by matrix reinforcement is reduced in the use process of the steel casting, thereby achieving better comprehensive use performance.
3. Compared with the performance of the steel casting before heat treatment, the performance of the steel casting after heat treatment twice has higher mechanical performance.
Detailed Description
The following are specific examples of the present invention, and the technical solutions of the present invention are further described, but the present invention is not limited to these examples.
The materials adopted by the invention are conventional commercial products, and the adopted method is conventional technical means unless specified.
The invention relates to a low-carbon equivalent high-strength steel casting for an offshore floating platform, which comprises the following components in percentage by mass: 0.10 to 0.22 percent of C, 0.50 to 0.58 percent of Si, 1.10 to 1.45 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S, 0.13 to 0.37 percent of Ni, and the balance of iron and other unavoidable elements;
the carbon equivalent CEV is less than or equal to 0.43 percent;
the carbon equivalent CEV satisfies the following formula: cev=c+ (Mn/6) + (Ni/15), wherein the symbol of the element represents mass percent;
the dimension of the low-carbon equivalent high-strength steel casting for the offshore floating platform is (1000-10000) multiplied by (500-10000) mm 3 The method comprises the steps of carrying out a first treatment on the surface of the The mass is 1000-100000 kg;
the preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform comprises the following steps:
s1, proportioning metal raw materials, and heating and melting in an electric arc furnace;
the melting temperature is 1620-1750 ℃ and the time is 50-200 minutes;
s2, adding lithium element and modifier into the molten steel after melting to carry out modification treatment;
the lithium element comprises one or more of metallic lithium and lithium-containing compounds, and the addition amount of the lithium element is 0.001-0.1 g/kg;
the modifier comprises silicon-barium alloy and/or silicon-aluminum-barium-calcium alloy, and the addition amount is 0.1-20 g/kg;
s3, placing the molten steel in the step S2 into a vacuum refining furnace for refining;
refining temperature is 1650-1800 ℃ and refining time is 15-50 minutes;
s4, pouring the molten steel in the step S3 into a mold for molding to obtain a molded steel casting;
a mold release agent can be coated in the mold;
s5, placing the steel casting formed in the step S4 in a high-temperature furnace for first heating;
the first heating temperature is 900-930 ℃, the heating speed is 10-120 ℃/h, and the heat preservation time is 20-35 mm/h according to the thickest wall thickness;
s6, water cooling the steel castings subjected to the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel castings subjected to the first heating is not more than 35 seconds;
the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20; the water temperature is 35+/-5 ℃, the water is flowing water, and the water flow rate is more than 0.5m/s;
s7, directly feeding the steel casting to a tempering furnace for secondary heating after the temperature of the steel casting is reduced to 100-120 ℃ and discharging water;
the second heating temperature is 530-580 ℃, the heating speed is 10-80 ℃/h, and the heat preservation time is 20-35 mm/h according to the thickest wall thickness;
s8, taking out for air cooling after the second heating.
The yield strength of the low-carbon equivalent high-strength steel casting for the offshore floating platform is more than or equal to 330MPa, the tensile strength is more than or equal to 475MPa, the elongation is more than or equal to 20%, the reduction of area is more than or equal to 32%, and the low-temperature impact (-20 ℃) is more than or equal to 32J.
Example 1
The preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform in the embodiment comprises the following steps:
the metal raw materials are mixed according to the following components: 0.19% of C, 0.55% of Si, 1.25% of Mn, 0.018% of P, 0.01% of S, 0.24% of Ni and the balance of iron and other unavoidable elements; its carbon equivalent cev=0.414%;
heating and melting in an electric arc furnace, wherein the melting temperature is 1670 ℃ and the time is 70 minutes; adding 0.007g/kg of metallic lithium (white wax wrapping) and 3g/kg of silicon-barium alloy and 3g/kg of silicon-aluminum-barium-calcium alloy into the molten steel for modification treatment; then placing the molten steel into a vacuum refining furnace for refining, wherein the refining temperature is 1680 ℃ and the refining time is 20 minutes; pouring molten steel into a mold coated with a release agent for molding, and placing the molded steel casting into a high-temperature furnace for first heating; the first heating temperature is 920+/-10 ℃ (the temperature difference in the furnace is +/-10 ℃), the heating speed is 80 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; water cooling is carried out on the steel casting after the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel casting after the first heating is not more than 35 seconds; the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20; the water temperature is 35+/-5 ℃, the water is flowing water, and the water flow rate is more than 0.5m/s; when the temperature of the steel casting is reduced to 110+/-5 ℃, water is discharged, and the steel casting is directly fed into a tempering furnace for secondary heating; the second heating temperature is 550+/-5 ℃ (the temperature difference in the furnace is +/-5 ℃), the heating speed is 60 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; and taking out for air cooling after the second heating.
The properties of the prepared low-carbon equivalent high-strength steel casting body test bar for the offshore floating platform are shown in Table 1.
Example 2
The preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform in the embodiment comprises the following steps:
the metal raw materials are mixed according to the following components: 0.20% of C, 0.52% of Si, 1.28% of Mn, 0.016% of P, 0.009% of S, 0.22% of Ni and the balance of iron and other unavoidable elements; its carbon equivalent cev=0.428%;
heating and melting in an electric arc furnace, wherein the melting temperature is 1670 ℃ and the time is 70 minutes; adding 0.009g/kg metallic lithium (white wax wrapped) and 3g/kg silicon-barium alloy and 3g/kg silicon-aluminum-barium-calcium alloy into molten steel for modification treatment; then placing the molten steel into a vacuum refining furnace for refining, wherein the refining temperature is 1680 ℃ and the refining time is 20 minutes; pouring molten steel into a mold coated with a release agent for molding, and placing the molded steel casting into a high-temperature furnace for first heating; the first heating temperature is 920+/-10 ℃ (the temperature difference in the furnace is +/-10 ℃), the heating speed is 80 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; water cooling is carried out on the steel casting after the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel casting after the first heating is not more than 35 seconds; the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20; the water temperature is 35+/-5 ℃, the water is flowing water, and the water flow rate is more than 0.5m/s; when the temperature of the steel casting is reduced to 110+/-5 ℃, water is discharged, and the steel casting is directly fed into a tempering furnace for secondary heating; the second heating temperature is 550+/-5 ℃ (the temperature difference in the furnace is +/-5 ℃), the heating speed is 60 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; and taking out for air cooling after the second heating.
The properties of the prepared low-carbon equivalent high-strength steel casting body test bar for the offshore floating platform are shown in Table 1.
Example 3
The preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform in the embodiment comprises the following steps:
the metal raw materials are mixed according to the following components: 0.20% of C, 0.54% of Si, 1.22% of Mn, 0.016% of P, 0.008% of S, 0.26% of Ni and the balance of iron and other unavoidable elements; its carbon equivalent cev=0.421%;
heating and melting in an electric arc furnace, wherein the melting temperature is 1670 ℃ and the time is 70 minutes; adding 0.006g/kg of metallic lithium (white wax wrapping) and 3g/kg of silicon-barium alloy and 3g/kg of silicon-aluminum-barium-calcium alloy into molten steel for modification treatment; then placing the molten steel into a vacuum refining furnace for refining, wherein the refining temperature is 1680 ℃ and the refining time is 20 minutes; pouring molten steel into a mold coated with a release agent for molding, and placing the molded steel casting into a high-temperature furnace for first heating; the first heating temperature is 920+/-10 ℃ (the temperature difference in the furnace is +/-10 ℃), the heating speed is 80 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; water cooling is carried out on the steel casting after the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel casting after the first heating is not more than 35 seconds; the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20; the water temperature is 35+/-5 ℃, the water is flowing water, and the water flow rate is more than 0.5m/s; when the temperature of the steel casting is reduced to 110+/-5 ℃, water is discharged, and the steel casting is directly fed into a tempering furnace for secondary heating; the second heating temperature is 550+/-5 ℃ (the temperature difference in the furnace is +/-5 ℃), the heating speed is 60 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; and taking out for air cooling after the second heating.
The properties of the prepared low-carbon equivalent high-strength steel casting body test bar for the offshore floating platform are shown in Table 1.
Example 4
The preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform in the embodiment comprises the following steps:
the metal raw materials are mixed according to the following components: 0.19% of C, 0.52% of Si, 1.26% of Mn, 0.017% of P, 0.011% of S, 0.28% of Ni and the balance of iron and other unavoidable elements; its carbon equivalent cev=0.419%;
heating and melting in an electric arc furnace, wherein the melting temperature is 1670 ℃ and the time is 70 minutes; adding 0.008g/kg of metallic lithium (white wax wrapping) and 3g/kg of silicon-barium alloy and 3g/kg of silicon-aluminum-barium-calcium alloy into molten steel for modification treatment; then placing the molten steel into a vacuum refining furnace for refining, wherein the refining temperature is 1680 ℃ and the refining time is 20 minutes; pouring molten steel into a mold coated with a release agent for molding, and placing the molded steel casting into a high-temperature furnace for first heating; the first heating temperature is 920+/-10 ℃ (the temperature difference in the furnace is +/-10 ℃), the heating speed is 80 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; water cooling is carried out on the steel casting after the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel casting after the first heating is not more than 35 seconds; the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20; the water temperature is 35+/-5 ℃, the water is flowing water, and the water flow rate is more than 0.5m/s; when the temperature of the steel casting is reduced to 110+/-5 ℃, water is discharged, and the steel casting is directly fed into a tempering furnace for secondary heating; the second heating temperature is 550+/-5 ℃ (the temperature difference in the furnace is +/-5 ℃), the heating speed is 60 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; and taking out for air cooling after the second heating.
The properties of the prepared low-carbon equivalent high-strength steel casting body test bar for the offshore floating platform are shown in Table 1.
Example 5
The preparation method of the low-carbon equivalent high-strength steel casting for the offshore floating platform in the embodiment comprises the following steps:
the metal raw materials are mixed according to the following components: 0.19% of C, 0.54% of Si, 1.28% of Mn, 0.018% of P, 0.012% of S, 0.25% of Ni and the balance of iron and other unavoidable elements; its carbon equivalent cev=0.420%;
heating and melting in an electric arc furnace, wherein the melting temperature is 1670 ℃ and the time is 70 minutes; adding 0.007g/kg of metallic lithium (white wax wrapping) and 3g/kg of silicon-barium alloy and 3g/kg of silicon-aluminum-barium-calcium alloy into the molten steel for modification treatment; then placing the molten steel into a vacuum refining furnace for refining, wherein the refining temperature is 1680 ℃ and the refining time is 20 minutes; pouring molten steel into a mold coated with a release agent for molding, and placing the molded steel casting into a high-temperature furnace for first heating; the first heating temperature is 920+/-10 ℃ (the temperature difference in the furnace is +/-10 ℃), the heating speed is 80 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; water cooling is carried out on the steel casting after the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel casting after the first heating is not more than 35 seconds; the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20; the water temperature is 35+/-5 ℃, the water is flowing water, and the water flow rate is more than 0.5m/s; when the temperature of the steel casting is reduced to 110+/-5 ℃, water is discharged, and the steel casting is directly fed into a tempering furnace for secondary heating; the second heating temperature is 550+/-5 ℃ (the temperature difference in the furnace is +/-5 ℃), the heating speed is 60 ℃/h, and the heat preservation time is 25mm/h according to the thickest wall thickness; and taking out for air cooling after the second heating.
The properties of the prepared low-carbon equivalent high-strength steel casting body test bar for the offshore floating platform are shown in Table 1.
Comparative example 1
Compared with the example 1, the metal raw materials are proportioned according to the following components: 0.22% of C, 0.55% of Si, 1.30% of Mn, 0.018% of P, 0.01% of S, 0.31% of Ni and the balance of iron and other unavoidable elements; its carbon equivalent cev=0.457%.
The properties of the prepared cast steel body test bar for the offshore floating platform are shown in Table 1.
Table 1, performance data sheet of low carbon equivalent high strength steel casting body test bar for offshore floating platform
(impact values are typically tested three times so there are three impact values in the table above)
The invention also provides a welding experiment with different carbon equivalent, the raw material composition is shown in table 2, and the preparation process is the same as that of the example 1; the number of defects with the same size (30×20×10 mm) welded in the welding process is 5 (1 # to 5 #), the welding environment temperature is 25 ℃, and the welding performance results are shown in table 3.
TABLE 2 raw material composition Table for cast steel products having different carbon equivalent
C(％) Si(％) Mn(％) P(％) S(％) Ni(％) CEV(％)
Example 6 0.18 0.55 1.24 0.018 0.008 0.20 0.400
Example 7 0.20 0.53 1.24 0.016 0.013 0.21 0.421
Comparative example 2 0.22 0.55 1.27 0.018 0.009 0.29 0.451
Comparative example 3 0.22 0.53 1.44 0.016 0.010 0.30 0.480
Comparative example 4 0.28 0.54 1.50 0.019 0.012 0.35 0.553
TABLE 3 welding results Table of bulk samples with different carbon equivalent
(MT: magnetic particle detection, national standard GB/T9444-2019)
As can be seen from tables 1 and 3, when the carbon equivalent CEV is less than or equal to 0.43%, the cast steel has high strength and low-temperature impact resistance although the cast steel has fluctuation; in contrast, in comparative example 1, when the carbon equivalent CEV is more than 0.43%, the strength of the steel casting is increased, but the low-temperature impact resistance and the weldability are reduced; and when the carbon equivalent CEV is more than 0.43%, the weldability is continuously deteriorated with the continuous improvement of the carbon equivalent.
In conclusion, the invention realizes the high strength and excellent weldability of the steel castings for the offshore floating platform by adjusting the element composition of the steel castings and controlling the carbon equivalent CEV to be less than or equal to 0.43 percent and combining two heat treatments, and has the advantages of mass production and high qualification rate; in addition, other alloys are not needed to be added in the formula, so that the cost is reduced, and the stress generated by matrix reinforcement is reduced in the use process of the steel casting, thereby achieving better comprehensive use performance.
The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions thereof without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims (12)

1. A low carbon equivalent high strength steel casting for an offshore floating platform, comprising, in mass percent: 0.10-0.22% of C, 0.50-0.58% of Si, 1.10-1.45% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 0.13-0.37% of Ni, and the balance of iron and other unavoidable impurity elements;
the carbon equivalent CEV of the low-carbon equivalent high-strength steel casting for the offshore floating platform is less than or equal to 0.43%;
the dimension of the low-carbon equivalent high-strength steel casting for the offshore floating platform is (1000-10000) multiplied by (500-10000) mm 3 ；
The yield strength of the low-carbon equivalent high-strength steel casting for the offshore floating platform is more than or equal to 330MPa, the tensile strength is more than or equal to 475MPa, the elongation is more than or equal to 20%, the reduction of area is more than or equal to 32%, and the low-temperature impact at minus 20 ℃ is more than or equal to 32J.
2. The low carbon equivalent high strength steel casting for an offshore floating platform according to claim 1, wherein the offshore floating platform is composed of the low carbon equivalent high strength steel casting, comprising, in mass percent: 0.19-0.22% of C, 0.50-0.55% of Si, 1.20-1.45% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, 0.22-0.30% of Ni, and the balance of iron and other unavoidable impurity elements.
3. The low carbon equivalent high strength steel casting for an offshore floating platform according to claim 1 or 2, wherein the carbon equivalent CEV satisfies the following formula: cev=c+ (Mn/6) + (Ni/15), wherein the symbol of the element represents mass percent.
4. A method of producing a low carbon equivalent high strength steel casting for an offshore floating platform as claimed in claim 1, comprising:
s1, proportioning metal raw materials, and heating and melting in an electric arc furnace;
s2, adding lithium element and modifier into the molten steel after melting to carry out modification treatment; the modifier comprises silicon-barium alloy and/or silicon-aluminum-barium-calcium alloy;
s3, placing the molten steel in the step S2 into a vacuum refining furnace for refining;
s4, pouring the molten steel in the step S3 into a mold for molding to obtain a molded steel casting;
s5, placing the steel casting formed in the step S4 in a high-temperature furnace for first heating;
s6, water cooling the steel castings subjected to the first heating, wherein the time from the opening of the furnace door to the complete water feeding of the steel castings subjected to the first heating is not more than 35 seconds; the ratio of the total water quantity of the water cooling medium water tank to the weight of the steel casting is more than or equal to 20, and the water is running water;
s7, directly feeding the steel casting to a tempering furnace for secondary heating after the temperature of the steel casting is reduced to 100-120 ℃ and discharging water;
s8, taking out for air cooling after the second heating.
5. The method for manufacturing the low-carbon equivalent high-strength steel casting for the offshore floating platform, which is disclosed in claim 4, is characterized in that the melting temperature is 1620-1750 ℃ and the time is 50-200 minutes.
6. The method for producing a low carbon equivalent high strength steel casting for an offshore floating platform according to claim 4, wherein the lithium element comprises one or more of metallic lithium and a lithium-containing compound.
7. The method of producing a low carbon equivalent high strength steel casting for use on an offshore floating platform according to claim 6, wherein the lithium-containing compound includes, but is not limited to, one or more of lithium carbonate, lithium sulfide, lithium nitride, lithium hydroxide, and the reduction is performed prior to use.
8. The method for producing a low-carbon equivalent high-strength steel casting for a marine floating platform according to claim 4, wherein the amount of the lithium element added is 0.001 to 0.1g/kg, and the amount of the modifier added is 0.1 to 20g/kg.
9. The method for manufacturing the low-carbon equivalent high-strength steel casting for the offshore floating platform, which is disclosed in claim 4, is characterized in that the refining temperature is 1650-1800 ℃ and the refining time is 15-50 minutes.
10. The method for preparing the low-carbon equivalent high-strength steel casting for the offshore floating platform, which is disclosed in claim 4, is characterized in that the first heating temperature is 900-930 ℃, the heating speed is 10-120 ℃/h, and the heat preservation time is 20-35 mm/h according to the thickest wall thickness.
11. The method for producing a low carbon equivalent high strength steel casting for a floating platform on the sea according to claim 4, wherein the water temperature in the water cooling is 35+ -5 degrees, the water is running water, and the water flow rate is more than 0.5m/s.
12. The method for preparing the low-carbon equivalent high-strength steel casting for the offshore floating platform, which is disclosed in claim 4, is characterized in that the second heating temperature is 530-580 ℃, the heating speed is 10-80 ℃/h, and the heat preservation time is 20-35 mm/h according to the thickest wall thickness.
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08243793A (en) * 1995-03-03 1996-09-24 Sunouchi:Kk Cast steel end tab for welding
JP2003253379A (en) * 2002-02-27 2003-09-10 Jfe Steel Kk Steel plank superior in toughness and weld characteristic, and manufacturing method therefor
JP2006104506A (en) * 2004-10-01 2006-04-20 Kobe Steel Ltd Method for producing high cleanness steel excellent in fatigue strength or cold workability
JP2007169769A (en) * 2005-12-26 2007-07-05 Kobe Steel Ltd High cleanliness steel having excellent fatigue strength
JP2009228040A (en) * 2008-03-21 2009-10-08 Jfe Steel Corp Low yield ratio high strength steel plate and method for producing the same
CN104726767A (en) * 2013-12-23 2015-06-24 鞍钢股份有限公司 High-strength cold-rolled steel plate with TRIP (transformation induced plasticity) effect and production method thereof
CN114381662A (en) * 2021-12-13 2022-04-22 首钢京唐钢铁联合有限责任公司 Low-cost steel for pressure vessel and preparation method thereof
CN114959453A (en) * 2022-04-29 2022-08-30 宁波日月精华精密制造有限公司 Thin-wall steel casting for offshore wind power coupler and preparation method thereof
CN116162864A (en) * 2022-11-28 2023-05-26 重庆钢铁股份有限公司 09MnNiDR steel plate with low-temperature impact of-70 ℃ and manufacturing method thereof

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08243793A (en) * 1995-03-03 1996-09-24 Sunouchi:Kk Cast steel end tab for welding
JP2003253379A (en) * 2002-02-27 2003-09-10 Jfe Steel Kk Steel plank superior in toughness and weld characteristic, and manufacturing method therefor
JP2006104506A (en) * 2004-10-01 2006-04-20 Kobe Steel Ltd Method for producing high cleanness steel excellent in fatigue strength or cold workability
JP2007169769A (en) * 2005-12-26 2007-07-05 Kobe Steel Ltd High cleanliness steel having excellent fatigue strength
JP2009228040A (en) * 2008-03-21 2009-10-08 Jfe Steel Corp Low yield ratio high strength steel plate and method for producing the same
CN104726767A (en) * 2013-12-23 2015-06-24 鞍钢股份有限公司 High-strength cold-rolled steel plate with TRIP (transformation induced plasticity) effect and production method thereof
CN114381662A (en) * 2021-12-13 2022-04-22 首钢京唐钢铁联合有限责任公司 Low-cost steel for pressure vessel and preparation method thereof
CN114959453A (en) * 2022-04-29 2022-08-30 宁波日月精华精密制造有限公司 Thin-wall steel casting for offshore wind power coupler and preparation method thereof
CN116162864A (en) * 2022-11-28 2023-05-26 重庆钢铁股份有限公司 09MnNiDR steel plate with low-temperature impact of-70 ℃ and manufacturing method thereof

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