CN116574978B - Multi-stage heat treatment fine grain pressure vessel steel plate and manufacturing method thereof - Google Patents

Multi-stage heat treatment fine grain pressure vessel steel plate and manufacturing method thereof Download PDF

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CN116574978B
CN116574978B CN202310439647.3A CN202310439647A CN116574978B CN 116574978 B CN116574978 B CN 116574978B CN 202310439647 A CN202310439647 A CN 202310439647A CN 116574978 B CN116574978 B CN 116574978B
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temperature
heat treatment
pressure vessel
fine grain
rolling
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CN116574978A (en
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欧阳鑫
胡昕明
王储
邢梦楠
孙殿东
高强
徐海健
刘晨希
赵启斌
王刚
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Angang Steel Co Ltd
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Angang Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
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    • 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
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D8/0231—Warm rolling
    • 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
    • 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
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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  • Heat Treatment Of Steel (AREA)

Abstract

The invention discloses a multi-stage heat treatment fine grain pressure vessel steel plate and a manufacturing method thereof, belonging to the technical field of steel preparation. The steel plate comprises the following chemical components in percentage by weight: c:0.20 to 0.30 percent of Si:4.0 to 5.0 percent of Mn:0.80 to 0.90 percent, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, and Cr:1.0% -2.0%, ni:0.10% -0.20%, mo:2.0 to 3.0 percent, nb:0.01 to 0.02 percent of Ti: 0.02-0.03%, cu:0.80 to 0.90 percent, V:0.02 to 0.03 percent, B: 0.001-0.002%, als:2% -3%, N:0.06% -0.08%, and the balance Fe and unavoidable impurities, the invention adopts micro-alloying, high-temperature short-time homogenization treatment, two-stage rolling, solution heat treatment, quenching heat treatment and other tissue refining technologies to realize the refinement of micro-composite tissue, so that the medium carbon steel has higher room temperature strength, good room temperature plasticity and higher hardness, and is expected to be widely applied in the field of pressure vessel equipment manufacturing.

Description

Multi-stage heat treatment fine grain pressure vessel steel plate and manufacturing method thereof
Technical Field
The invention belongs to the technical field of steel preparation, and particularly relates to a multi-stage heat treatment fine grain pressure vessel steel plate and a manufacturing method thereof.
Background
Conventionally, it is thought that medium carbon steel can obtain high hardness and strength, and is suitable for use in the production of tool steels and die steels which are not highly required to toughness, but cannot be used for the production of structural materials such as pressure vessels because of its high brittleness. Along with the continuous development of the industry, the development direction of equipment tends to be large-scale, two-stage heat treatment and long-term service are carried out, so that higher requirements are put on raw materials for equipment manufacture, and the toughness of the traditional low-carbon alloy container steel plate cannot meet the manufacturing requirements of high-end pressure container equipment. As is known, the performance of the material depends on the tissue type, the tissue is uniformly refined, the comprehensive mechanical property of the material is greatly improved, and the high matching degree of the toughness is realized.
The invention patent with the application number of 201710037112.8 discloses a manufacturing process of large-specification 42CrMo4 quenched and tempered steel for an outer main shaft of a wind power speed increasing box, wherein a die casting and 3500t rapid forging machine forging process is adopted in the patent, so that the manufacturing process has the advantages of higher production cost, high energy consumption, slow production rhythm and poorer plate shape and performance uniformity of products. The invention patent with the application number of CN201710919045.2 discloses a normalizing method for realizing the refinement of low-activation ferrite/martensitic steel structure, wherein the normalizing process is heated to 900-930 ℃ at 50-60 ℃/s, the temperature is kept for 1-2 s, and then the normalizing process is air-cooled to 20-25 ℃ at room temperature for refining the duplex stainless steel structure. The invention only provides a heat treatment process, does not definitely adopt a rolling process, and does not definitely propose the degree and grade of tissue refinement. At present, the tissue refinement of low carbon steel is successfully realized, but the related research of the tissue refinement of medium and high carbon steel is not reported yet.
Disclosure of Invention
In view of the above, the present invention aims to provide a multi-stage heat-treated fine grain pressure vessel steel sheet and a method for manufacturing the same, which adopts a microstructure refining technique of microalloying, high-temperature short-time homogenizing treatment, two-stage rolling, solution heat treatment, quenching heat treatment, etc. to achieve refinement of a microcomposite structure, so that the medium carbon steel has high room temperature strength, good room temperature plasticity, and high hardness through heat treatment. The fully spheroidized microstructure can be obtained after the treatment, the grain size of pearlite reaches 1.0-3.0 mu m, the grain size of ferrite reaches 2.0-4.0 mu m, and the fully spheroidized microstructure has good comprehensive mechanical properties, and the medium carbon steel has good technological properties and mechanical properties, so that the fully spheroidized microstructure is expected to be widely applied to the field of pressure vessel equipment manufacturing.
The invention aims at realizing the following steps:
the invention provides a multi-stage heat treatment fine grain pressure vessel steel plate, which comprises the following chemical components in percentage by weight: c:0.20 to 0.30 percent of Si:4.0 to 5.0 percent of Mn:0.80 to 0.90 percent, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, and Cr:1.0% -2.0%, ni:0.10% -0.20%, mo:2.0 to 3.0 percent, nb:0.01 to 0.02 percent of Ti: 0.02-0.03%, cu:0.80 to 0.90 percent, V:0.02 to 0.03 percent, B: 0.001-0.002%, als:2% -3%, N:0.06% -0.08%, and the balance of Fe and unavoidable impurities.
The reason for adopting the above composition design is as follows:
c: c is a main constituent element of steel, the strength of the steel mainly depends on the content of C element in the steel, and the excessively high content of C element can lead to poor toughness, plasticity and welding performance of the steel; too low a content of C element results in lower strength of the steel and performance after simulated stress relief treatment. In order to ensure that the steel plate has good low-temperature impact toughness, strength and welding performance matching in the use process, the C content in the steel is required to be controlled within the range of 0.20-0.30 percent.
Si: si is added to the medium carbon steel, which affects the thermodynamics of the iron-carbon system and the kinetics of carbide formation and dissolution. Silicon as a pearlite stabilizing element will raise the Ac1 point of the steel. The addition of silicon causes the carbon content of the eutectoid composition to decrease, thereby increasing the amount of pre-eutectoid carbide, such that the volume fraction of carbide used to pin the grain boundaries in the gamma + theta two-phase region increases. Thus, not only the growth of pearlite and austenite grains is suppressed. Silicon is insoluble in carbide and when carbide precipitates, silicon is distributed around the carbide, locally forming a high concentration zone of silicon. Silicon is in turn an element that increases the activity of carbon. In the high concentration region of silicon, the activity of carbon is also improved correspondingly, so that the diffusion flow rate of carbon to carbide is reduced, and therefore, coarsening of carbide can be inhibited, and the Si content of the invention is controlled to be 4.0-5.0%.
Mn: mn element can strengthen pearlite in steel grade through solid solution strengthening, C-Mn strengthening is also a main mode for improving strength of low-carbon steel, but Mn content is too high, mn element is easy to combine with S element to generate MnS while increasing production cost, hydrogen-induced cracking resistance of the material is reduced, and simultaneously too high Mn content can reduce activity of carbon element, so that the Mn content in the steel is required to be controlled to be 0.80-0.90%.
P: phosphorus is a harmful element in steel, increases cold brittleness of the steel, worsens welding performance, reduces plasticity, worsens cold bending performance, and is particularly sensitive to irradiation embrittlement. Therefore, the lower the P content in the steel, the better, the lower the P content in the steel, the invention is required to be less than 0.015%.
S: sulfur is a hazardous element in the usual case. S generally tends to form brittle sulfides with alloying elements in the steel, causing hot shortness to the steel, reducing the ductility and toughness of the steel, and S also tends to accelerate irradiation embrittlement. Therefore, the S content in the steel is required to be limited to below 0.005%.
Als: the Ac1 point of the steel can be increased by aluminum alloying, the proeutectoid cementite is thinned and uniformly distributed, the formation of network carbide is inhibited, and after aluminum is added, both grain boundary carbide and widmannstatten structure carbide disappear, so that a thinned complete pearlite structure is obtained. Therefore, the Al content in the steel is required to be 2% -3%.
V: v belongs to microalloy elements, and V microalloy in steel can form tiny second phase particles, plays roles of pinning grain boundary and precipitation strengthening, can effectively refine grains, and greatly improves comprehensive mechanical properties of steel such as strength, toughness, ductility, thermal fatigue resistance and the like, so that the range of V added in the steel is 0.02-0.03%.
Ni: ni is a solid solution strengthening element in steel, so that the strength of the steel can be improved, the Ni reduces dislocation movement resistance of steel types, so that stress is relaxed, and the substructure of a matrix structure is changed, so that the toughness of the steel, particularly the low-temperature toughness, is improved, but the transformation temperature is improved due to the fact that the excessive Ni content in medium-carbon steel is controlled to be 0.10-0.20%.
Cr: chromium is an element that stabilizes the carbide, and the addition of chromium reduces the dissolution rate of the carbide. Therefore, when the thermal deformation tissue refining process is adopted, eutectoid transformation can be avoided even if the heating temperature is increased or the heating time is prolonged, and the refined tissue can be obtained. Chromium also inhibits graphitization of the silicon-containing, aluminum ultra-high carbon steel. The present invention therefore requires that the Cr content in the steel be controlled to 1.0-2.0%.
Cu: the outstanding effect of Cu in steel is to improve the corrosion resistance of common carbon low alloy steel, and also to improve the strength and yield ratio of steel without adversely affecting the welding performance. When the copper content exceeds 0.75%, the aging strengthening effect can be generated after solution treatment and aging. Meanwhile, the effect is similar to nickel, and the nickel-saving and cost-reducing effects can be achieved. However, when the content is high, copper embrittlement occurs during heat deformation processing. The present invention therefore requires that the Cu content in the steel be controlled to 0.80-0.90%.
Nb: nb is used as a strong carbide forming element to form NbC phase with large dispersity and good high-temperature stability in steel grade, plays a role of precipitation strengthening, can effectively refine grains through multi-stage rolling, and improves the toughness reduction caused by precipitation strengthening, so that the steel plate has the comprehensive performance of high strength and high toughness. In addition, in the steel added by Nb-Mo composite, mo can be partially polymerized on an NbC matrix interface, so that coarsening of NbC particles is prevented, and the high-temperature strength of the steel is greatly improved, and therefore, the Nb content is controlled to be 0.01-0.02%.
Mo: mo mainly relies on solid solution strengthening and grain boundary strengthening to improve the strength of steel; secondly, mo increases the stability of supercooled austenite, so that the transformation curve of the austenite to pearlite moves to the right, and finer pearlite structure is obtained after transformation; in addition, ti and Mo are combined, a large amount of nano-sized Ti-Mo (CN) carbide is precipitated in the steel, and the refined carbide pins dislocation, so that the toughness of the steel is greatly improved, and the Mo content in the steel is required to be controlled to be 2.0-3.0%.
Ti: adding proper amount of Ti to form a large amount of dispersed fine TiN or Ti 2 O 3 Particles which act as heterogeneous nucleation cores for needle-like pearlite in tissue solidification, thereby refining the tissue. Ti also has deoxidizing effect, and ensures that B is not oxidized and nitrided. And B can reduce the transformation temperature from austenite to pearlite, promote the formation of needle-shaped pearlite in the grains, and play a role in refining the grains. However, when w (Ti) is not less than 0.09%, the needle-like pearlite content is reduced to deteriorate the low-temperature toughness of the steel sheet, so that the Ti content in the steel is required to be controlled to 0.02 to 0.03% in the present invention.
B: the B can reduce the transformation temperature from austenite to pearlite, promote the formation of needle-shaped pearlite in the grains, and play a role in refining the grains. Therefore, the present invention requires that the B content in the steel be controlled to 0.001-0.002%.
N: n can be combined with Ti to form a large amount of tiny TiN which is dispersed and distributed, and the tiny TiN can be used as heterogeneous nucleation cores of needle-shaped pearlite when the tissue is solidified, so that the tissue is refined. The present invention therefore requires that the N content in the steel be controlled to 0.06-0.08%.
Based on the technical scheme, the microstructure of the steel plate is a fully spheroidized microstructure, the grain size of pearlite reaches 1.0-3.0 mu m, and the grain size of ferrite reaches 2.0-4.0 mu m.
Based on the technical scheme, further, the tensile strength of the steel plate is 650-790 MPa, the yield strength is 425-625 MPa, the elongation after fracture is 20-30%, the impact power at 0 ℃ is 260-360J, the surface Brinell hardness is 340-440 HBW, and the high-temperature tensile yield strength at 450 ℃ is 315-455 MPa.
The second technical scheme of the invention is to provide a manufacturing method of the multi-stage heat treatment fine grain pressure vessel steel plate, which mainly comprises high-temperature short-time homogenization treatment, two-stage rolling, solution heat treatment and quenching heat treatment, and comprises the following steps:
(1) High-temperature short-time homogenization treatment: preserving heat of the continuous casting blank for 1-2h at 1130-1170 ℃, carrying out homogenizing annealing in a single-phase austenite region, and fully dissolving carbon elements;
(2) Two-stage rolling: the homogenized continuous casting billet is sent to a rolling mill for rolling at a rough rolling start temperature of 1080-1110 ℃ and a finish rolling temperature of 810-840 ℃ and a reduction rate of 15-25% in each pass, and is subjected to air cooling to 600-650 ℃ for finish rolling at a finish rolling temperature of 510-620 ℃ and a reduction rate of 5-15% in each pass until the thickness of a final finished product is reached;
(3) Solution heat treatment: the solid solution heat treatment system is 1040-1060 ℃, the clean heat preservation is carried out for 50-70min, and finally the water cooling is carried out to room temperature;
(4) Quenching heat treatment: austenitizing at 10-30 deg.c higher than Ac1 for 20-40 min, water cooling to room temperature.
Based on the technical scheme, the thickness of the continuous casting billet in the step (1) is 150-350mm.
Based on the technical scheme, the homogenization temperature in the step (1) is 1140-1160 ℃.
Based on the technical scheme, the thickness of the intermediate blank in the step (2) is 2-3 times of the thickness of the finished steel plate.
Based on the technical scheme, further, in the step (2), the rough rolling start temperature is 1094-1109 ℃, the finish rolling temperature is 812-839 ℃, the finish rolling start temperature is 640-650 ℃, and the finish rolling temperature is 524-617 ℃.
Based on the technical scheme, further, the solution heat treatment temperature in the step (3) is 1041-1058 ℃, and the net heat preservation time is 52-69min.
Based on the technical scheme, the austenitizing temperature in the step (4) is 960-980 ℃.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts high-temperature short-time homogenization treatment to carry out homogenization annealing in a single-phase austenite region, and fully dissolves carbon elements; then adopting two-stage rolling to help to break the proeutectoid cementite separated out from austenite, avoiding forming netlike carbide; the solution treatment heats the alloy element to a high-temperature single-phase region and maintains the temperature, so that the excessive alloy element compound is fully dissolved into the solid solution and then is rapidly cooled, supersaturated solid solution is obtained, crystal grains are refined, and meanwhile, the plasticity and toughness of the product are improved; finally, the prior austenite grains are further refined by quenching heat treatment, so that the pearlite grains after phase transformation are fully refined, the fully spheroidized microstructure can be obtained after the treatment, the grain size of the pearlite reaches 1.0-3.0 mu m, and the grain size of the ferrite reaches 2.0-4.0 mu m. Finally, the finished steel plate has the tensile strength of 650-790 MPa, the yield strength of 425-625 MPa, the elongation after fracture of 20-30%, the impact energy of 0 ℃ of 260-360J, the surface Brinell hardness of 340-440 HBW and the high-temperature tensile yield strength of 315-455 MPa at 450 ℃.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings to which the embodiments relate will be briefly described.
FIG. 1 is a golden phase diagram of a steel sheet prepared in example 1.
Detailed Description
The following detailed description of the invention is provided in connection with examples, but the implementation of the invention is not limited thereto, and it is obvious that the examples described below are only some examples of the invention, and that it is within the scope of protection of the invention to those skilled in the art to obtain other similar examples without inventive faculty.
Examples 1 to 6
The embodiment provides a manufacturing method of a two-stage heat treatment fine grain pressure vessel steel plate, wherein the chemical compositions and weight percentages of the steel plate are shown in table 1;
TABLE 1 chemical composition and weight percent (wt%) of billets of examples 1-6
The method comprises the following steps:
(1) High-temperature short-time homogenization treatment: directly hot-charging a continuous casting billet with the thickness of 150-350mm into a heating furnace, preserving heat for 1.2-1.8h at 1145-1160 ℃ and carrying out homogenizing annealing in a single-phase austenite region to fully dissolve carbon elements;
(2) Two-stage rolling: after homogenization treatment, the continuous casting blank is hot-rolled by a double-frame rolling mill, firstly, the continuous casting blank is rough-rolled and cogged, the proeutectoid cementite is formed in the form of fine particles in an austenite grain boundary and a high-density dislocation area in crystal, the rough rolling start temperature is 1094-1109 ℃, the finish rolling temperature is 812-839 ℃, the reduction rate of each pass is ensured to be 16-25%, the thickness of an intermediate blank is 2-3 times of the thickness of a finished steel plate, the intermediate blank roller way after rough rolling is reciprocally swung and air-cooled to be at 640-650 ℃ for continuous multi-pass quick finish rolling, the finish rolling temperature is 524-617 ℃, the reduction rate of each pass is ensured to be 5-15%, and the thermal deformation in the process is beneficial to breaking the proeutectoid cementite precipitated in the austenite, and the main technological parameters of the high-temperature short-time homogenization treatment and two-stage rolling are shown in table 2 are avoided;
TABLE 2 essential process parameters for high temperature short time homogenization treatment and two stage rolling of examples 1-6
(3) Solution heat treatment: the solid solution heat treatment system is that the solution heat treatment is carried out for 52-69min at 1041-1058 ℃ and finally water cooling is carried out to room temperature. The alloy element is heated to a high-temperature single-phase region and kept at a constant temperature through solution treatment, so that excessive alloy element compounds are fully dissolved into the solid solution and then are rapidly cooled, supersaturated solid solution is obtained, crystal grains are refined, and meanwhile, the plasticity and toughness of the product are improved.
(4) Quenching heat treatment: austenitizing in a range of 10-30 ℃ higher than Ac1 temperature (950 ℃ measured), net heat preservation for 20-40 min, discharging water to room temperature, carrying out short-time quenching heat treatment to further refine original austenite grains, so that the grains of pearlite are refined after phase transformation, a fully spheroidized microstructure can be obtained after the treatment, the grain size of pearlite reaches 1.0-3.0 mu m, the grain size of ferrite reaches 2.0-4.0 mu m, the steel plate has good mechanical properties, main technological parameters of solution heat treatment and quenching heat treatment are shown in table 3, and the grain sizes and comprehensive mechanical properties of the prepared steel plate are shown in table 4.
TABLE 3 major process parameters for solution heat treatment and quenching heat treatment of steels of examples 1-6
TABLE 4 grain size and comprehensive mechanical Properties of Steel sheets of examples 1-6
The present invention has been properly and fully described in the above embodiments by way of example only, and the present invention is not limited thereto, but various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention, and any modifications, equivalents, improvements, etc. should be included in the scope of the present invention.

Claims (9)

1. The multi-stage heat treatment fine grain pressure vessel steel plate is characterized by comprising the following chemical components in percentage by weight: c: 0.20-0.30%, si:4.0% -5.0%, mn:0.80% -0.90%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, cr:1.0% -2.0%, ni:0.10% -0.20%, mo:2.0% -3.0%, nb: 0.01-0.02%, ti: 0.02-0.03%, cu: 0.80-0.90%, V: 0.02-0.03%, B: 0.001-0.002%, als:2% -3%, N:0.06% -0.08%, and the balance being Fe and unavoidable impurities;
the manufacturing method of the multi-stage heat treatment fine grain pressure vessel steel plate mainly comprises high-temperature short-time homogenization treatment, two-stage rolling, solution heat treatment and quenching heat treatment, and comprises the following steps of:
(1) High-temperature short-time homogenization treatment: preserving heat of the continuous casting blank for 1-2h at 1130-1170 ℃, carrying out homogenizing annealing in a single-phase austenite region, and fully dissolving carbon elements;
(2) Two-stage rolling: the homogenized continuous casting billet is hot-fed to a rolling mill for rolling, the initial rolling temperature of rough rolling is 1080-1110 ℃, the final rolling temperature is 810-840 ℃, the reduction rate of each pass is 15-25%, the rolling mill is air-cooled to 600-650 ℃ for finish rolling, the final rolling temperature is 510-620 ℃, and the reduction rate of each pass is 5-15%, and the thickness of a final finished product is reached;
(3) Solution heat treatment: the solid solution heat treatment system is 1040-1060 ℃, the clean heat preservation is carried out for 50-70min, and finally the water cooling is carried out to room temperature;
(4) Quenching heat treatment: austenitizing at a temperature 10-30 ℃ higher than Ac1, keeping the temperature for 20-40 min, discharging, and cooling to room temperature.
2. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the microstructure of the steel sheet is a fully spheroidized microstructure, the grain size of pearlite is 1.0 to 3.0 μm, and the grain size of ferrite is 2.0 to 4.0 μm.
3. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the steel sheet has a tensile strength of 650-460 mpa, a yield strength of 425-245 mpa, a post-fracture elongation of 20-30%, an impact power of 260-360 j at 0 ℃, a surface brinell hardness of 340-440 hbw, and a high temperature tensile yield strength of 315-45 mpa at 450 ℃.
4. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the thickness of the continuous casting billet in step (1) is 150 to 350mm.
5. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the homogenization temperature in step (1) is 1140-1160 ℃.
6. The multi-stage heat treated fine grain pressure vessel steel sheet as claimed in claim 1, wherein the thickness of the intermediate billet of step (2) is 2 to 3 times the thickness of the finished steel sheet.
7. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the rough rolling start temperature is 1094 to 1109 ℃, the finish rolling temperature is 812 to 839 ℃, the finish rolling start temperature is 640 to 650 ℃, and the finish rolling temperature is 524 to 617 ℃ in the step (2).
8. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the solution heat treatment in step (3) is performed at a temperature of 1041 to 1058 ℃ and a net heat preservation time of 52 to 69min.
9. The multi-stage heat-treated fine grain pressure vessel steel sheet according to claim 1, wherein the austenitizing temperature in step (4) is 960 to 980 ℃.
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CN107532255A (en) * 2015-04-08 2018-01-02 新日铁住金株式会社 Heat- treated steel board member and its manufacture method
CN113166838A (en) * 2019-04-08 2021-07-23 日本制铁株式会社 Cold-rolled steel sheet and method for producing same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1106981A (en) * 1993-03-31 1995-08-16 日立金属株式会社 Wear- and seizure-resistant roll for hot rolling
TW201432061A (en) * 2012-09-14 2014-08-16 Ilsenburger Grobblech Gmbh Steel alloy for a low alloy high-strength steel
CN107406953A (en) * 2015-04-08 2017-11-28 新日铁住金株式会社 steel plate for heat treatment
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CN113166838A (en) * 2019-04-08 2021-07-23 日本制铁株式会社 Cold-rolled steel sheet and method for producing same

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