CN109321815B - Manufacturing method of high-heat input welding resistant high-strength thick steel plate - Google Patents
Manufacturing method of high-heat input welding resistant high-strength thick steel plate Download PDFInfo
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Abstract
The invention belongs to the technical field of low-alloy high-strength steel, and particularly relates to a manufacturing method of a high-heat input welding resistant high-strength thick steel plate. The steel plate comprises the chemical components of C, Si, Mn, Nb, V, Ti, P, S, Cu, Ni, Mo, B, N, O, Al and one of Mg, Ca, Zr and REM, the balance being Fe, and comprises special Ti-M-O inclusion distribution; the steel plate manufacturing steps comprise adopting an LD-LF-RH smelting process, pre-deoxidizing silicon and manganese in converter molten steel, LF refining and desulfurizing, RH vacuum degassing, blowing oxygen to the molten steel in an RH furnace, and adding Ti, Mg, Ca, Zr or REM for deoxidation; two-stage controlled rolling and controlled cooling are adopted. The yield strength of the steel plate reaches 500-700 MPa, and the steel plate has good low-temperature impact toughness under the welding line energy of 100-200 kJ/cm.
Description
Technical Field
The invention belongs to the technical field of low-alloy high-strength steel, and particularly relates to a manufacturing method of a high-heat input welding resistant high-strength thick steel plate.
Background
With the development of economic society, the structural structures in various fields such as high-rise buildings, energy storage and transportation, ships, ocean engineering and the like are continuously developed to be high in strength and large in size, the strength and the thickness of the required steel plate are greatly increased, the production scale is rapidly enlarged, and the welding workload for constructing the large-scale structure generally accounts for 30-40% of the total workload. Therefore, on the premise of ensuring the welding quality, how to improve the welding efficiency is the key for realizing low-cost economical rapid manufacturing. Under the background, the construction of large steel structures gradually adopts a single-pass welding process technology capable of implementing high heat input welding, so that the manufacturing efficiency is greatly improved. The performance of a welding joint of the traditional steel is seriously deteriorated under the condition of high heat input welding, and the traditional steel becomes a key problem which restricts the production efficiency and the reliability of engineering quality. Therefore, the development of high-strength steel which can bear high heat input welding becomes a very urgent task in the domestic steel industry at present.
The invention patent with the publication number of CN102312173A discloses steel with the tensile strength of 700MPa for a large heat input welding structure and a manufacturing method thereof, and the steel is characterized in that oxides of Ti, Zr and the like are formed through reasonable design of components, quenching and tempering are not needed, and the large heat input welding of 30-100 kJ/cm can be realized by adopting a TMCP process. The invention patent with the publication number of CN102041459A discloses a HT690 steel plate capable of being welded by large heat input and a manufacturing method thereof, which is characterized in that a low-C-high-Mn- (Nb + V + B) microalloying-ultramicro Ti processing component system is adopted, acid-soluble Al in steel is properly improved, the ratio relation among elements is controlled, a TMCP + tempering process is optimized, and fine tempered bainite is formed and has large heat input welding performance. The invention patent with the publication number of CN105256095A discloses a method for smelting a steel plate with excellent performance in a large heat input welding heat affected zone, which is characterized in that proper oxygen content control and alloy element control technologies are adopted, and Mg-Ti, Zr-Ti and Mg-Zr-Ti composite inclusions with the size less than 1 mu m are formed by reasonably controlling Ti/O and (Mg + Zr)/(Ti + Al) in the steel, so that the large heat input welding performance is improved, and the tensile strength of the steel plate is more than or equal to 550 MPa. The invention patent with publication number CN102286692A discloses a quenched and tempered steel for low temperature and a manufacturing method thereof, which is characterized in that excellent low temperature performance is obtained by controlling the ratio range of Mn/C, Ti/N, Ni/Cu and Ca/S and combining recrystallization control rolling, on-line direct quenching and tempering heat treatment processes, and the quenched and tempered steel can bear high-heat-input welding. The invention patent with the publication number of CN102839330A discloses a thick plate for 800 MPa-grade high-strength high heat input welding, which is characterized in that on the basis of low-carbon steel components, the Ni content is increased, meanwhile, a proper amount of alloy elements such as Cr, Mo and the like are added, the thickness of the steel plate is within 30mm, and the thick plate is suitable for welding heat input of 40-100 kJ/cm.
Analysis on the prior art shows that in part of technical schemes, TiN particles are used for refining austenite grains, so that HAZ toughness is improved, but TiN is easy to decompose at high temperature, so that the structure refining effect is influenced. In the technology of improving HAZ toughness by using oxides or sulfides, the prior published technology does not clearly describe a deoxidation method of various elements under a refining condition, or has the disadvantages of high technical difficulty, complex process, difficult fine and uniform distribution of inclusions, influence on the actual effect of high heat input welding performance, and influence on the improvement of steel cleanliness and steel quality. In addition, the addition of higher Ni content improves the toughness and the high heat input welding performance of the steel plate, which increases the alloy cost and is not beneficial to popularization and application.
Disclosure of Invention
The invention aims to provide a method for manufacturing a high-strength thick steel plate resistant to high heat input welding, which solves the problem of low high heat input welding performance of the high-strength steel plate, and the manufactured steel plate has yield strength of 500-700 MPa and excellent low-temperature impact toughness under the welding heat input of 100-200 kJ/cm.
The invention adopts the following technical scheme:
a manufacturing method of a high-heat input welding resistant high-strength thick steel plate comprises the following chemical components in percentage by mass: 0.04 to 0.10% of C, 0.1 to 0.3% of Si, 1.0 to 1.8% of Mn, 0.01 to 0.05% of Nb, 0.01 to 0.05% of V, 0.005 to 0.025% of Ti, 0.001 to 0.008% of P, 0.0005 to 0.005% of S, 0.1 to 0.5% of Cu, 0.1 to 0.5% of Ni, 0.05 to 0.5% of Mo, 0.0005 to 0.0025% of B, 0.001 to 0.005% of N, 0.001 to 0.005% of O, 0.001 to 0.015% of Al, 0.0005 to 0.005% of Mg, 0.0005 to 0.005% of Ca, 0.001 to 0.025% of Zr, 0.001 to 0.025% of REM, and the balance Fe; the number of inclusions with the size of more than 4 mu m in the steel plate is less than or equal to 150/mm3(ii) a Inclusions with a size of 0.3 to 4 μm in the steel sheetIn the method, the number of Ti-M-O composite inclusions accounts for more than 10%, and the Ti-M-O inclusions averagely contain 1-50% of Ti and 1-50% of M, wherein M is one of Mg, Ca, Zr and REM;
the method comprises the following process steps:
(1) smelting: the molten steel adopts an LD-LF-RH smelting process, an LD converter is used for smelting the molten steel to perform silicon-manganese-aluminum deoxidation, and the content of dissolved oxygen after the converter is controlled to be less than or equal to 150 ppm; white slag desulfurization is carried out through LF refining, the alkalinity of final slag is 2-4, the oxidability FeO + MnO is less than or equal to 1.5 wt%, the white slag desulfurization retention time is more than or equal to 10min, the LF end point fixed oxygen is less than or equal to 20ppm, and S is less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag;
(2) refining: measuring temperature, sampling and determining oxygen after the RH arrives at the station, and keeping pure degassing time below 100Pa for more than or equal to 8 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen concentration is 10-100 ppm, adding Ti for deoxidation, simultaneously adding one of Mg, Ca, Zr and REM, adding in an alloy block or wire feeding mode, and blowing argon for more than or equal to 5min after deoxidation to ensure that the number of inclusions more than 5 mu m in the molten steel is less than or equal to 120 inclusions/mm3(ii) a Adjusting the content of other alloy elements according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet;
(3) rolling: heating the continuous casting slab to 1150-1260 ℃, preserving heat for 30-240 min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by spraying water, wherein the cooling speed is more than or equal to 10 ℃/s, and the final cooling temperature is 400-600 ℃.
According to the manufacturing method of the high-heat input welding resistant high-strength thick steel plate, the thickness of the steel plate is 20-60 mm, the yield strength is 500-700 MPa, the tensile strength is 600-800 MPa, and the impact toughness of a base metal and a heat affected zone at minus 40 ℃ is more than or equal to 70J under the welding input energy of 100-200 kJ/cm.
The manufacturing method of the high-heat input welding resistant high-strength thick steel plate preferably comprises the following steps that under the welding heat input of 100-200 kJ/cm, the base material-40 ℃ impact toughness of the steel plate is 150-250J, and the heat affected zone-40 ℃ impact toughness of the steel plate is 100-200J.
According to the manufacturing method of the high heat input resistant welding high-strength thick steel plate, the steel plate is subjected to quenching and tempering treatment, the quenching heating temperature is 900-950 ℃, the heat preservation time is 20-40 min, the quenching cooling temperature of the steel plate is below 100 ℃, the quenching cooling speed is not less than 15 ℃/s, the tempering heating temperature is 500-700 ℃, and the tempering time is 30-90 min.
The method for manufacturing the high-strength thick steel plate resistant to high heat input welding preferably comprises the step of selecting 10-100 inclusions with the size of more than 4 mu m per mm in the steel plate3。
In the method for manufacturing the high-strength thick steel plate capable of resisting the high heat input welding, the number of Ti-M-O composite inclusions in inclusions with the size of 0.3-4 mu M in the steel plate is preferably 30-50%.
In the method for producing a high-strength thick steel sheet resistant to high heat input welding, the Ti-M-O inclusions preferably contain Ti 10-30% and M10-30% on average.
Preferably, in the step (1), the content of dissolved oxygen after the furnace is controlled to be 10-50 ppm, the oxidability FeO + MnO of the refining slag is less than or equal to 1 wt%, the white slag desulfurization retention time is 12-20 min, the oxygen content at the LF end point is 1-10 ppm, and the S content is 0.001-0.004 wt%.
Preferably, in the step (2), pure degassing time is 10-15 min when the vacuum degree is kept below 100Pa, blowing is stopped when the oxygen concentration is 20-80 ppm, and argon blowing time is 10-20 min after deoxidation, so that the number of inclusions with the size of more than 5 mu m in molten steel is 10-100/mm3。
The manufacturing method of the high-heat input welding resistant high-strength thick steel plate preferably comprises the steps of heating a continuous casting billet to 1180-1230 ℃, keeping the temperature for 100-150 min, cooling at a speed of 20-40 ℃/s and cooling at a final temperature of 500-550 ℃.
The design idea of the invention is as follows:
aiming at a 500-700 MPa high-strength steel plate, the scheme of the invention adopts lower C and higher Mn to reduce carbide and high-carbon martensite islands in the steel and ensure the hardenability and the toughness of a matrix; the alloy components are optimized by combining the requirements of high heat input welding performance, the combination of Nb, V, Cu, Ni, Mo and B elements is selected and respectively controlled within the optimal content range, and the comprehensive improvement of the toughness and the high heat input welding performance of the steel plate is realized; meanwhile, the control of microelements such as Ti, Mg, N, O and the like is carried out, the distribution of special composite oxides and fine TiN particles is promoted, a refined HAZ microstructure is obtained, and the remarkable improvement of the large-linear energy welding performance is realized. On the other important aspect, when the welding performance of the general steel for large heat input welding is improved by using special inclusions, the micro-uniform dispersion distribution of the inclusions is difficult to ensure, and the product performance and the quality are reduced due to the fact that the high-strength steel with higher requirement on steel cleanliness is particularly used. Aiming at the problem, the invention specially controls the production process, reduces the content of harmful inclusions, promotes the fine dispersion distribution of beneficial inclusions and improves the comprehensive performance of the product.
The invention has the advantages and beneficial effects that:
1. according to the invention, through reasonable component design and special control of a key smelting production process, the steel plate obtains comprehensive properties of high strength, high toughness and high heat input welding resistance. The scheme of the invention is different from the deoxidation process in the smelting of the conventional large heat input welding steel, the fine and uniform special type inclusions are formed in the steel through LF refining and RH oxygen blowing and deoxidation operations, the components and distribution of the inclusions have better effect of promoting the nucleation of the acicular ferrite in the crystal, the low-temperature toughness of the HAZ in the large heat input welding can be obviously improved, and the defects in the prior art are overcome.
2. The invention can obviously reduce the contents of impurity elements and harmful impurities in the steel, compared with the common steel for large heat input welding, the cleanliness of the steel plate is obviously improved, the micro distribution of beneficial impurities can be obtained, and the comprehensive performance and the product quality of the steel plate can be obviously improved while the large heat input welding performance is stably improved.
3. The technical scheme of the invention has the advantages of clear process, obvious effect and strong feasibility, is beneficial to popularization and application, and can meet the urgent requirements on high-quality high-strength steel plates for high-heat input welding.
Drawings
FIGS. 1-2 are the morphology and composition spectra of typical inclusions in example 1, which are Ti-Mg-O composite inclusions. Wherein, FIG. 1 shows typical inclusion morphology; FIG. 2 is a component spectrum.
FIGS. 3 to 4 are energy spectra of morphology and composition of typical inclusions in example 3, which are Ti-Zr-O composite inclusions. Wherein, FIG. 3 is a typical inclusion morphology; FIG. 4 is a component spectrum.
Detailed Description
The present invention will be explained in further detail below by way of examples and figures.
Example 1
In the embodiment, the manufacturing method of the high heat input welding resistant high-strength thick steel plate comprises the following chemical components in percentage by mass: 0.1% of C, 0.2% of Si, 1.2% of Mn, 0.015% of Nb, 0.02% of V, 0.01% of Ti, 0.005% of P, 0.001% of S, 0.2% of Cu, 0.2% of Ni, 0.2% of Mo, 0.0005% of B, 0.001% of N, 0.005% of O, 0.01% of Al, 0.001% of Mg and the balance of Fe; the number of inclusions with a size of 4 μm or more in the steel sheet is 100 to 150/mm3(ii) a In the inclusions with the size of 0.3-4 mu m in the steel plate, the number of Ti-Mg-O composite inclusions accounts for 12%, and the Ti-Mg-O inclusions averagely contain 10% of Ti and 15% of Mg according to the mass fraction;
the method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 10 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.6 wt%, the holding time is 15min, the LF end point oxygen is 5ppm, and the S is less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 80Pa for 20 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen content is determined to be 10ppm, adding Ti and Mg in an alloy block mode for deoxidation, blowing argon for 5min, wherein the number of inclusions with the size of more than 5 mu m in the molten steel is 80-120/mm3(ii) a Adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1150 ℃, preserving heat for 200min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by water spraying at a cooling speed of 15 ℃/s and at a final cooling temperature of 600 ℃.
The thickness of the produced steel plate is 20mm, the yield strength is 520MPa, the tensile strength is 650MPa, the impact toughness at minus 40 ℃ is 260J, and the impact toughness at minus 40 ℃ of a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
Example 2
In the embodiment, the manufacturing method of the high heat input welding resistant high-strength thick steel plate comprises the following chemical components in percentage by mass: 0.05% of C, 0.1% of Si, 1.0% of Mn, 0.05% of Nb, 0.05% of V, 0.02% of Ti, 0.001% of P, 0.0008% of S, 0.5% of Cu, 0.5% of Ni, 0.05% of Mo, 0.001% of B, 0.005% of N, 0.001% of O, 0.001% of Al, 0.001% of Ca and the balance of Fe; the number of inclusions with the size of more than 4 mu m in the steel plate is 80-120/mm3(ii) a In the inclusions with the size of 0.3-4 mu m in the steel plate, the number of Ti-Ca-O composite inclusions accounts for 20%, and the Ti-Ca-O inclusions averagely contain 20% of Ti and 12% of Ca in mass fraction;
the method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 50 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.7 wt%, the holding time is 12min, the LF end point oxygen is 9ppm, and the S is less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 90Pa for 15 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen content is determined to be 20ppm, adding Ti and Ca for deoxidation in a wire feeding mode, and blowing argon for 10min to ensure that the number of inclusions with the size of more than 5 mu m in the molten steel is 70-100/mm3(ii) a Adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1250 ℃, preserving heat for 100min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by water spraying at a cooling speed of 10 ℃/s and a final cooling temperature of 650 ℃. Quenching and tempering are carried out on the steel plate, the quenching heating temperature is 910 ℃, the heat preservation is carried out for 30min, the steel plate is quenched and cooled to be below 100 ℃, the quenching cooling speed is 18 ℃/s, the tempering heating temperature is 550 ℃, and the tempering time is 40 min.
The thickness of the produced steel plate is 40mm, the yield strength is 680MPa, the tensile strength is 750MPa, the impact toughness at minus 40 ℃ is 210J, and the impact toughness at minus 40 ℃ in a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
Example 3
In this embodiment, the wire resistance is highThe manufacturing method of the welded high-strength thick steel plate comprises the following chemical components in percentage by mass: 0.06% of C, 0.15% of Si, 1.6% of Mn, 0.04% of Nb, 0.03% of V, 0.025% of Ti, 0.006% of P, 0.003% of S, 0.2% of Cu, 0.3% of Ni, 0.4% of Mo, 0.002% of B, 0.002% of N, 0.003% of O, 0.015% of Al, 0.01% of Zr and the balance of Fe; the number of inclusions with a size of 4 μm or more in the steel sheet is 50 to 100/mm3(ii) a In the inclusions with the size of 0.3-4 mu M in the steel plate, the number of Ti-Zr-O composite inclusions accounts for 50%, and the Ti-M-O composite inclusions contain 15% of Ti and 10% of Zr on average according to mass fraction.
The method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 100 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.8 wt%, the holding time is 20min, the LF end point oxygen accounts for 8ppm, and the S accounts for less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 70Pa for 18 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen concentration is 50ppm, adding Ti and Zr in an alloy block mode for deoxidation, and blowing argon for 15min to ensure that the number of inclusions with the size of more than 5 mu m in the molten steel is 50-80/mm3(ii) a Adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1200 ℃, preserving heat for 120min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by water spraying at a cooling speed of 18 ℃/s and a final cooling temperature of 550 ℃.
The thickness of the produced steel plate is 30mm, the yield strength is 580MPa, the tensile strength is 690MPa, the impact toughness at minus 40 ℃ is 200J, and the impact toughness at minus 40 ℃ in a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
Example 4
In the embodiment, the manufacturing method of the high heat input welding resistant high-strength thick steel plate comprises the following chemical components in percentage by mass: 0.08% of C, 0.25% of Si, 1.15% of Mn, 0.01% of Nb, 0.015% of V, 0.015% of Ti, 0.007% of P, 0.004% of S, 0.3% of Cu, 0.4% of Ni, 0.1% of Mo, 0.0025% of B, 0.004% of N, 0.004% of O, 0.007% of Al, 0.01% of REM (rare earth element), and the balanceThe amount is Fe; the number of inclusions with the size of more than 4 mu m in the steel plate is 10-30/mm3(ii) a In the inclusions with the size of 0.3-4 mu m in the steel plate, the number of Ti-REM-O composite inclusions accounts for 38%, and the Ti-REM-O inclusions contain 18% of Ti and 30% of REM on average in mass fraction;
the method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 100 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.9 wt%, the retention time is 18min, the LF end point oxygen is 7ppm, and the S is less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 60Pa for 12 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen is determined to be 100ppm, adding Ti and REM for deoxidation in a wire feeding mode, and blowing argon for 20min to ensure that the number of inclusions with the diameter of more than 5 mu m in the molten steel is 5-30/mm3(ii) a Adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1200 ℃, preserving heat for 60min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by water spraying at a cooling speed of 10 ℃/s and at a final cooling temperature of 500 ℃.
The thickness of the produced steel plate is 60mm, the yield strength is 525MPa, the tensile strength is 650MPa, the impact toughness at minus 40 ℃ is 205J, and the impact toughness at minus 40 ℃ in a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
As shown in FIGS. 1 to 2, typical inclusions in example 1 were Ti-Mg-O composite inclusions. As shown in FIGS. 3 to 4, typical inclusions in example 3 were Ti-Zr-O composite inclusions. The method is easy to form the Ti-M-O composite inclusion with the size of 0.3-4 mu M in the steel, and is beneficial to comprehensively improving the strength and toughness of the steel plate and the high heat input welding performance.
The embodiment result shows that the yield strength of the steel plate reaches 500-700 MPa, and the steel plate has good low-temperature impact toughness under the welding line energy of 100-200 kJ/cm.
Claims (4)
1. A method for manufacturing a high-strength thick steel plate resistant to high heat input welding is characterized in thatCharacterized in that the steel plate comprises the following chemical components in percentage by mass: 0.1% of C, 0.2% of Si, 1.2% of Mn, 0.015% of Nb, 0.02% of V, 0.01% of Ti, 0.005% of P, 0.001% of S, 0.2% of Cu, 0.2% of Ni, 0.2% of Mo, 0.0005% of B, 0.001% of N, 0.005% of O, 0.01% of Al, 0.001% of Mg and the balance of Fe; the number of inclusions with a size of 4 μm or more in the steel sheet is 100 to 150/mm3(ii) a In the inclusions with the size of 0.3-4 mu m in the steel plate, the number of Ti-Mg-O composite inclusions accounts for 12%, and the Ti-Mg-O inclusions averagely contain 10% of Ti and 15% of Mg according to the mass fraction;
the method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 10 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.6 wt%, the holding time is 15min, the LF end point oxygen is 5ppm, and the S is less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 80Pa for 20 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen content is determined to be 10ppm, adding Ti and Mg in an alloy block mode for deoxidation, blowing argon for 5min, wherein the number of inclusions with the size of more than 5 mu m in the molten steel is 80-120/mm3(ii) a Adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1150 ℃, preserving heat for 200min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by water spraying at a cooling speed of 15 ℃/s and a final cooling temperature of 600 ℃;
the thickness of the produced steel plate is 20mm, the yield strength is 520MPa, the tensile strength is 650MPa, the impact toughness at minus 40 ℃ is 260J, and the impact toughness at minus 40 ℃ of a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
2. The manufacturing method of the high-heat input welding resistant high-strength thick steel plate is characterized in that the steel plate comprises the following chemical components in percentage by mass: 0.05% of C, 0.1% of Si, 1.0% of Mn, 0.05% of Nb, 0.05% of V, 0.02% of Ti, 0.001% of P, 0.0008% of S, 0.5% of Cu, 0.5% of Ni, 0.05% of Mo, 0.001% of B, 0.005% of N, 0.001% of O, 0.001% of Al, 0.001% of Ca and the balance of Fe; the number of inclusions with a size of 4 μm or more in the steel sheet is 80 to 120 inclusions/mm3(ii) a In the inclusions with the size of 0.3-4 mu m in the steel plate, the number of Ti-Ca-O composite inclusions accounts for 20%, and the Ti-Ca-O inclusions averagely contain 20% of Ti and 12% of Ca in mass fraction;
the method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 50 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.7 wt%, the holding time is 12min, the LF end point oxygen is 9ppm, and the S is less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 90Pa for 15 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen is determined to be 20ppm, adding Ti and Ca for deoxidation in a wire feeding mode, and blowing argon for 10min to ensure that the number of inclusions with the size of more than 5 mu m in the molten steel is 70-100/mm < 3 >; adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1250 ℃, preserving heat for 100min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, cooling the rolled steel plate by water spraying at a cooling speed of 10 ℃/s and a final cooling temperature of 650 ℃. Quenching and tempering the steel plate, wherein the quenching and heating temperature is 910 ℃, the heat preservation is carried out for 30min, the steel plate is quenched and cooled to be below 100 ℃, the quenching and cooling speed is 18 ℃/s, the tempering and heating temperature is 550 ℃, and the tempering time is 40 min;
the thickness of the produced steel plate is 40mm, the yield strength is 680MPa, the tensile strength is 750MPa, the impact toughness at minus 40 ℃ is 210J, and the impact toughness at minus 40 ℃ in a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
3. The manufacturing method of the high-heat input welding resistant high-strength thick steel plate is characterized in that the steel plate comprises the following chemical components in percentage by mass: 0.06% of C, 0.15% of Si, 1.6% of Mn, 0.04% of Nb, 0.03% of V, 0.025% of Ti, 0.006% of P, 0.003% of S, 0.2% of Cu, 0.3% of Ni, 0.4% of Mo, 0.002% of B, 0.002% of N, 0.003% of O, 0.015% of Al, 0.01% of Zr and the balance of Fe; the number of inclusions with a size of 4 μm or more in the steel sheet is 50 to 100/mm3(ii) a In the inclusions with the size of 0.3-4 mu M in the steel plate, the number of Ti-Zr-O composite inclusions accounts for 50 percent, and the average Ti-M-O composite inclusions in mass fractionContains 15% of Ti and 10% of Zr.
The method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 100 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.8 wt%, the holding time is 20min, the LF end point oxygen accounts for 8ppm, and the S accounts for less than or equal to 0.005 wt%; after LF refining is finished, completely removing desulfurized white slag, and secondarily producing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 70Pa for 18 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen is determined to be 50ppm, adding Ti and Zr in an alloy block mode for deoxidation, and blowing argon for 15min to ensure that the number of inclusions with the size of more than 5 mu m in the molten steel is 50-80/mm < 3 >; adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1200 ℃, preserving heat for 120min, controlling rolling in an austenite recrystallization area and a non-recrystallization area, cooling the rolled steel plate by water spraying at a cooling speed of 18 ℃/s and a final cooling temperature of 550 ℃;
the thickness of the produced steel plate is 30mm, the yield strength is 580MPa, the tensile strength is 690MPa, the impact toughness at minus 40 ℃ is 200J, and the impact toughness at minus 40 ℃ in a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
4. The manufacturing method of the high-heat input welding resistant high-strength thick steel plate is characterized in that the steel plate comprises the following chemical components in percentage by mass: 0.08% of C, 0.25% of Si, 1.15% of Mn, 0.01% of Nb, 0.015% of V, 0.015% of Ti, 0.007% of P, 0.004% of S, 0.3% of Cu, 0.4% of Ni, 0.1% of Mo, 0.0025% of B, 0.004% of N, 0.004% of O, 0.007% of Al, 0.01% of REM (rare earth element) and the balance of Fe; the number of inclusions with the size of more than 4 mu m in the steel plate is 10-30/mm < 3 >; in the inclusions with the size of 0.3-4 mu m in the steel plate, the number of Ti-REM-O composite inclusions accounts for 38%, and the Ti-REM-O inclusions contain 18% of Ti and 30% of REM on average in mass fraction;
the method comprises the following process steps: carrying out silicon-manganese-aluminum deoxidation on the converter molten steel, wherein the dissolved oxygen behind the converter is 100 ppm; desulfurizing the LF white slag, wherein the alkalinity of the final slag is 2-4, the FeO + MnO accounts for 0.9 wt%, the retention time is 18min, the LF end point oxygen is 7ppm, and the S is less than or equal to 0.005 wt%; after LF refining is finished, the desulfurized white slag is completely removed, andsecondarily manufacturing high-alkalinity low-sulfur slag; RH keeps the vacuum degree below 60Pa for 12 min; blowing oxygen to molten steel in a vacuum tank by using a top-blowing oxygen lance, stopping blowing when the oxygen is determined to be 100ppm, adding Ti and REM for deoxidation in a wire feeding mode, and blowing argon for 20min to ensure that the number of inclusions with the diameter of more than 5 mu m in the molten steel is 5-30/mm3(ii) a Adjusting the content of other alloy elements such as Nb, V, Cu, Ni and the like according to the component requirements of the steel plate, and casting molten steel with qualified components into a continuous casting billet; heating the continuous casting slab to 1200 ℃, preserving heat for 60min, controlling rolling in two stages of an austenite recrystallization zone and a non-recrystallization zone, and cooling the rolled steel plate by water spraying at a cooling speed of 10 ℃/s and a final cooling temperature of 500 ℃;
the thickness of the produced steel plate is 60mm, the yield strength is 525MPa, the tensile strength is 650MPa, the impact toughness at minus 40 ℃ is 205J, and the impact toughness at minus 40 ℃ in a heat affected zone is 70-200J under the welding line energy of 100-200 kJ/cm.
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