CN111519101B - 1000 MPa-grade special marine atmospheric environment corrosion-resistant bolt steel and preparation method thereof - Google Patents

1000 MPa-grade special marine atmospheric environment corrosion-resistant bolt steel and preparation method thereof Download PDF

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CN111519101B
CN111519101B CN202010515776.2A CN202010515776A CN111519101B CN 111519101 B CN111519101 B CN 111519101B CN 202010515776 A CN202010515776 A CN 202010515776A CN 111519101 B CN111519101 B CN 111519101B
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steel
corrosion
marine atmospheric
atmospheric environment
special marine
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CN111519101A (en
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罗志俊
徐士新
孙齐松
吕迺冰
李舒笳
王晓晨
周洁
王翔
马跃
邱智捷
田志红
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Shougang Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0093—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for screws; for bolts
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Abstract

The invention discloses 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel, which comprises the following components in percentage by mass: c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01 percent; also comprises Ni: 2.5 to 5.5 percent; or further comprising: ni: 0.20-0.80%, Cr: 0.60-0.90%, Sb: 0.05-0.15, Sn: 0.06-0.15%, and the contents of Ni, Sb and Sn meet the following requirements: 2.5 [ Ni ]]+6[Sb]1/2+5.8[Sn]1/2≤5.5。

Description

1000 MPa-grade special marine atmospheric environment corrosion-resistant bolt steel and preparation method thereof
Technical Field
The invention relates to the technical field of steel preparation, in particular to 1000 MPa-grade special marine atmospheric environment corrosion resistant bolt steel and a preparation method thereof.
Background
With the decreasing of land oil reserves and the increasing difficulty of exploitation, marine oil will become the most important source of energy in the future. The large-scale exploration and development of the offshore oil depend on a large amount of offshore oil equipment, the main material of the offshore oil equipment is carbon steel, and the carbon steel is particularly easy to corrode in the atmosphere and the marine environment, so that huge loss is caused.
At present, the study of carbon steel corrosion in seawater by domestic and foreign scholars lags behind the study of carbon steel corrosion in atmosphere, the corrosion condition of carbon steel in marine environment is quite complex, and many factors can influence seawater corrosion, such as the dissolution of oxygen in seawater, the flow rate of seawater, temperature, salinity, pH value, contact with dissimilar metals, marine organisms and microorganisms and the like can influence steel corrosion, so that the corrosion resistance of steel can be influenced to a great extent. The south China sea island region has abundant ocean resources such as oil gas and the like, and is an important direction for future strategic development in China. Before large-scale development, a safe, reliable and long-service-life infrastructure needs to be built, but the south sea island has higher requirements on the service durability of the island engineering building due to the unique environments of offshore shore, high humidity and heat, strong radiation and high chloride ion concentration, and the corrosion resistance of the steel for the island engineering building is tested more seriously.
Patent application CN108754303A discloses a high strength bolt steel with excellent atmospheric corrosion resistance and delayed fracture resistance, which adopts the characteristics of Cr, Ni, Cu and Re components to improve the atmospheric corrosion resistance and delayed fracture resistance, but not marine atmospheric environment corrosion resistance. Patent application CN107022718A discloses a marine atmospheric corrosion resistant high-strength bolt steel for a coating-free bridge structure and a manufacturing method thereof, and the bolt steel is 10.9-grade (1000MPa) weather-resistant bolt steel for a bridge steel structure, is suitable for general marine environmental characteristics, and cannot meet the high-humidity heat, strong radiation and high chloride ion concentration environment like a south sea island reef.
Therefore, how to develop a high-strength bolt steel which is resistant to the corrosion of the marine atmospheric environment with high humidity, heat, radiation and chloride ion concentration becomes a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to provide 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel and a preparation method thereof, so as to obtain the 1000MPa grade bolt steel which is resistant to marine atmospheric environment corrosion with high damp heat, strong radiation and high chloride ion concentration.
In order to achieve the purpose, the invention provides 1000MPa grade special marine atmospheric environment corrosion resistant bolted steel, which comprises the following chemical components in percentage by mass:
c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01%, Ni: 2.5-5.5%, the balance being Fe and inevitable impurity elements; or the like, or, alternatively,
c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01%, Ni: 0.20-0.80%, Cr: 0.60-0.90%, Sb: 0.05-0.15, Sn: 0.06-0.15 percent, and the balance of Fe and inevitable impurity elements, wherein the mass fraction contents of Ni, Sb and Sn meet the following conditions:
2.5≤[Ni]+6[Sb]1/2+5.8[Sn]1/2≤5.5。
further, the contents of Al, Ti, B and N simultaneously meet the following conditions:
the content of (Al) + [ Ti ])/[ N ] is not less than 15.0,
([Al]+[Ti])·[N]≥2.25×10-4，
wherein, the [ Al ], [ Ti ] and [ N ] respectively represent the mass fraction contents of elements Al, Ti and N.
Further, the internal microstructure of the 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel is ferrite plus pearlite.
Furthermore, the 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel is suitable for marine environments with high damp heat, strong radiation and high chloride ion concentration.
Specifically, the special marine atmospheric environment refers to: chloride ion deposition rate > 0.6mdd, including simultaneous SO2Marine industrial atmospheric region with deposition rate > 2.0 mdd. The special marine atmospheric environment includes, but is not limited to, the environment of the south sea island reef.
Furthermore, the 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel is suitable for marine environments in island and reef areas in the south China sea.
The invention also provides a preparation method of the 1000 MPa-grade special marine atmospheric corrosion resistant bolt steel, which comprises the steps of molten iron pretreatment, converter or electric furnace smelting, refining, vacuum degassing, continuous casting, rolling, material modification, cold heading manufacturing into bolts and quenching and tempering heat treatment.
Further, the quenching and tempering heat treatment includes: oil quenching at 850-950 ℃ and high-temperature tempering at 550-650 ℃.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
according to the 1000 MPa-grade special marine atmosphere environment corrosion-resistant bolt steel and the preparation method thereof, a passivation film is formed by matching high-content Ni (2.5-5.5%) with Cu element to block strong radiation and high chloride ion permeation in the environment of the island reef in the south China sea; or a small amount of Ni (0.20-0.80%) is cooperated with Cr, Sb and Sn elements to prevent strong radiation and high chloride ion permeation in the south sea island reef environment, so that the corrosion performance of the marine atmospheric environment characteristics of high damp heat resistance, strong radiation and high chloride ion concentration is met.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a metallographic structure diagram of 1000MPa grade corrosion-resistant bolted steel resistant to special marine atmospheric environment prepared in the examples;
FIG. 2 is a graph comparing the corrosion rate and the relative corrosion percentage of the 1000MPa class of bolting steel for corrosion in special marine atmosphere in examples 7, 8 and 12 of the present invention and the 1000MPa class of general bolting steel in comparative example 1 after corrosion in 20% HCl (80 ℃) solution + 2% NaCl solution for different periods of time;
FIG. 3 is a comparison graph of work hardening at a cold deformation ratio of 0 to 77% for a 1000MPa class bolt steel in example 8 of the present invention, which is resistant to corrosion in a special marine atmosphere environment, and a 1000MPa class ordinary bolt steel in a comparative example.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
The technical scheme provided by the embodiment of the invention aims to provide the high-strength bolt steel which can resist the corrosion of the marine atmospheric environment with high damp heat, strong radiation and high chloride ion concentration, and the general idea is as follows:
in order to achieve the above purpose, the embodiment provides 1000MPa grade special marine atmospheric corrosion resistant bolted steel, which includes the following two technical solutions:
the first scheme is as follows:
according to the mass fraction, the 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel comprises the following chemical components:
c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01%, Ni: 2.5-5.5%, the balance being Fe and inevitable impurity elements;
scheme II:
according to the mass fraction, the 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel comprises the following chemical components:
c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01%, Ni: 0.20-0.80%, Cr: 0.60-0.90%, Sb: 0.05-0.15, Sn: 0.06-0.15% of Fe and inevitable impurity elements as the rest; and the contents of Ni, Sb and Sn meet the following conditions:
2.5≤[Ni]+6[Sb]1/2+5.8[Sn]1/2≤5.5，
wherein [ Ni ], [ Sb ] and [ Sn ] represent the mass fraction contents of the elements Ni, Sb and Sn, respectively.
The 1000 MPa-grade special marine atmospheric environment corrosion-resistant bolt steel with the chemical components is formed by optimizing the constituent elements, and is based on the following principle:
the control principle in the chemical composition design of the invention is as follows:
c: in order to improve the hardenability of the bolting steel in the quenching and tempering heat treatment process, the C content is controlled to be 0.20% or more, but since increasing the C content increases carbides and deteriorates the atmospheric corrosion resistance and the cold deformation resistance, the C content is controlled to be 0.30% or less.
Si: the common deoxidizing element in steel, the solid solution strengthening of Si element, improves the work hardening rate of steel, can obviously deteriorate the cold workability of steel, promotes the grain boundary segregation of element P, S, and controls the content of the element not to exceed 0.30%.
Mn: the common deoxidizing elements in the steel can improve the hardenability of the steel in the quenching and high-temperature tempering and tempering processes, but the continuous casting process has the risk of center segregation and strong grain boundary segregation tendency in the tempering process, the tempering brittleness is promoted, and the content of Mn is controlled to be 0.70-1.20%.
P: the micro segregation is formed when the molten steel is solidified, and the micro segregation is gathered at a crystal boundary in the tempering process of quenching and tempering, so that the brittleness of the steel is obviously improved, and the P is controlled to be below 0.025 percent.
S: MnS inclusions with Mn in the steel and grain boundary segregation cause hot brittleness of the steel, deteriorating the workability of the steel. The reduction of the S content in the steel can improve the deformation performance of the steel, reduce the non-metallic inclusions in the steel, improve the processing performance and the toughness of the steel and the like, and control the S content to be below 0.015 percent.
Cu: the Cu element can obviously improve the weather resistance and the acid resistance of the steel, the effect is more obvious when the content is more than 0.2 percent, but the effect is saturated when the content is more than 0.6 percent, the high-temperature plasticity of the steel is reduced, cracks are easy to generate in the hot working process, and the Cu content is controlled to be 0.2-0.6 percent.
B: the trace B can greatly improve the hardenability of the steel, has low price and replaces precious elements such as Mo, Ni, Cr and the like, and reduces the cost. When the content of B is less than 0.0003%, the effect cannot be achieved, the content of B is more than 0.0050%, and excessive B element forms NB to provide a phase transition nucleation point, so that the transformation of medium-high temperature structure is promoted, and the hardenability of steel grades is reduced. Therefore, the B content is controlled to be 0005-0.0050%.
Al: the common deoxidizing elements in the steel, acid-soluble Al in the steel is precipitated in the rolling process to fix free N elements, the work hardening rate is reduced, the cold processing performance of the steel is improved, and the effects of fixing N and protecting B are achieved. The Al content is lower than 0.025 percent and does not play a role of fixing N and protecting B, and the Al content is higher than 0.065 percent, so that the problems of trepanning, straightening cracks and the like in the process of protecting and pouring small square billets are obvious, and the Al content is controlled to be 0.025-0.065 percent.
Ti: the Ti element is more active in the steel, has strong binding capacity with the N element, plays a role in fixing N and protecting B, and is difficult to fix the N content in the steel when the Ti content is lower than 0.03 percent; the Ti content is higher than 0.085 percent, the large size TiN in the steel can greatly reduce the low-temperature impact property of the steel, and the Ti content is controlled to be 0.03-0.085 percent.
In the first scheme, Ni can improve the hardenability and the low-temperature toughness of steel, the phenomenon of copper brittleness is eliminated by adding Ni and Cu which are matched, Ni is uniformly distributed on the surface of the steel to form a passive film, the content of Ni is in the high content range of 2.5-5.5%, and the passive film formed by matching with Cu can also block strong radiation and high chloride ion permeation in the south sea island reef environment and meet the corrosion performance of the south sea special environment characteristics. If the Ni content is lower than 2.5%, the corrosion resistance is difficult to meet the requirement of high chloride ion corrosion in south China sea; if the Ni content is more than 5.5%, the material cost is high.
In the second scheme, a small amount of Ni (0.20-0.80%) cooperates with Cr, Sb and Sn elements to prevent strong radiation and high chloride ion penetration in the environment of the island and reef in the south China sea. Through verification of matching relations among a large number of laboratory full-immersion corrosion results, elements and actual service environment corrosion results, researches show that the elements Ni, Sb and Sn need to be added in a proper proportion, and the content of the elements needs to meet a parameter theta relational expression: 2.5 [ Ni ]]+6[Sb]1/2+5.8[Sn]1/25.5 or less, and when the theta value is less than 2.5, although the contents of the single elements are all in the range, excellent strong radiation resistance and high chloride ion penetration resistance of the south sea island environment corrosion performance cannot be obtained; when the value of θ is more than 5.5, the effect is saturated and the cost of steel is increased.
Further, in order to further improve the cold deformation performance of the steel, the requirement of cold heading continuous processing of a user can be met, so that the method is favorable for popularization of engineering application. Through verification of a large number of matching relations between laboratory cold deformation simulation and result comparison elements and results of actual cold machining, researches show that Al, Ti, B and N elements also need to be added in a proper proportion, and the contents of Al, Ti, B and N simultaneously meet the following conditions:
the content of (Al) + [ Ti ])/[ N ] is not less than 15.0,
([Al]+[Ti])·[N]≥2.25×10-4，
wherein [ Al ], [ Ti ] and [ N ] respectively represent the mass fraction contents of the elements Al, Ti and N, and are numerical values before "%".
When ([ Al ] is present]+[Ti])/[N]Content < 15, ([ A ]l]+[Ti])·[N]＜2.25×10-4In the case where the contents of the individual elements are all within the above ranges, excellent cold deformation properties cannot be obtained, and the continuous operation requirements for cold heading cannot be satisfied.
The invention also provides a preparation method of the 1000 MPa-grade special marine atmospheric corrosion resistant bolt steel, which comprises the steps of molten iron pretreatment, converter or electric furnace smelting, refining, vacuum degassing, continuous casting, rolling, drawing, bolt manufacturing by cold heading, and quenching and tempering heat treatment, and specifically comprises the following steps:
and smelting molten iron in a converter or an electric furnace, refining, forming a square billet by adopting a conventional continuous casting method, and adopting the formula of the scheme I or the scheme II according to the chemical components of the square billet in percentage by mass.
Continuous casting: carrying out RH vacuum degassing and then continuously casting the billet, wherein pure degassing time is more than or equal to 15 minutes during RH vacuum degassing, and the content of [ H ] after vacuum treatment is ensured; the square billet continuous casting comprises: the target temperature of ladle molten steel is controlled to be 10-40 ℃ above the liquidus temperature, and 150 or 200mm square billets are continuously cast.
Rolling: the square billet rolling comprises the following steps: and heating the square billet in a heating furnace, and rolling into a phi 18-25 hot rolled coil or a 25-42 large coil.
Quenching and tempering heat treatment: quenching at 850-950 ℃, oil cooling, tempering at 500-650 ℃, and air cooling. By adopting the quenching and tempering heat treatment process system, all indexes of the strength, the plasticity and the toughness which meet the performance of the bolt with the 1000MPa level can be obtained, and the all-section structure is stable and the consistency performance is higher.
According to the above contents, the 1000MPa grade special marine atmospheric environment corrosion resistant bolted steel and the preparation method thereof provided by the invention achieve the purposes of enhancing the strength of the bolted steel and the corrosion performance of the environmental characteristics of high humid heat resistance, strong radiation resistance and high chloride ion concentration in south China sea by the synergistic cooperation of all elements and limiting the proportion of all elements, and specifically: a passivation film is formed by matching high-content Ni (2.5-5.5%) with Cu to prevent strong radiation and high chloride ion permeation in the environment of the island in the south China sea; or a small amount of Ni (0.20-0.80%) is cooperated with Cr, Sb and Sn elements to prevent strong radiation and high chloride ion permeation in the south sea island reef environment, so that the corrosion performance of the marine atmospheric environment characteristics of high damp heat resistance, strong radiation and high chloride ion concentration is met.
The 1000MPa grade special marine atmosphere corrosion resistant bolted steel and the preparation method thereof will be described in detail below with reference to examples, comparative examples and experimental data.
Molten iron enters an LF furnace fire RH furnace for refining treatment after being smelted by a converter, and a slab with chemical components shown as 1-2 is formed by adopting a conventional continuous casting method.
TABLE 1
Figure BDA0002529272260000061
Figure BDA0002529272260000071
TABLE 2
Figure BDA0002529272260000072
The mechanical properties and the corrosion rates of the south sea island reef against strong radiation and high chloride ion penetration environment of the bolted steel prepared by the preparation method of the invention (the quenching and tempering heat treatment comprises oil quenching at 850-950 ℃ and high-temperature tempering at 500-650 ℃) in the examples 1-14 and the comparative examples 1-5 are shown in the table 3.
TABLE 3
Figure BDA0002529272260000073
Figure BDA0002529272260000081
As can be seen from Table 3, in comparison with comparative examples 1 to 5, the 1000 MPa-class Nanhai island of examples 1 to 14 of the present invention is resistant to corrosion by a special marine atmosphere environmentThe corrosion rate of bolted steel is slower. The 1000 MPa-grade south sea island corrosion-resistant bolt steel for the 1000 MPa-grade south sea island in the embodiments 1-14 of the invention has the highest yield strength of 1050MPa, the tensile strength of 1150MPa, the elongation of 16%, the impact energy AKV (40 ℃ below zero) of 145, the corrosion rate (20% HCl (80 ℃) and 2% NaCl) of 30.5g/m2·h。
In the bolt steel of the invention in examples 7, 8 and 12, the 1000MPa class bolt steel resisting corrosion in special marine atmospheric environment and the plain carbon steel bolt steel of comparative example 1 are corroded for 24 hours in 20% HCl (80 ℃) and 2% NaCl, and the bolt corrosion conditions of 6h, 12h, 18h and 24h are respectively observed, and the results are shown in figure 2. It can be seen that the corrosion rates of examples 7, 8, 12 are slower than the corrosion rate of comparative example 1 over the entire period of 6-24 h.
FIG. 3 is a comparison graph of work hardening at a cold deformation ratio of 0 to 77% for a 1000MPa class bolt steel in example 8 of the present invention and a 1000MPa class bolt steel in comparative example 1. As can be seen from FIG. 2, compared with comparative example 1, the 1000MPa grade special marine atmospheric corrosion resistant bolting steel of the example of the invention can satisfy excellent cold deformation performance.
In conclusion, the 1000MPa grade special marine atmospheric environment corrosion resistant bolt steel and the preparation method thereof provided by the invention can block strong radiation and high chloride ion permeation, thereby meeting the corrosion performance of marine atmospheric environment characteristics of high damp heat resistance, strong radiation and high chloride ion concentration.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (7)

1. The 1000 MPa-grade special marine atmospheric environment corrosion resistant bolt steel is characterized by comprising the following chemical components in parts by mass:
c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01%, Ni: 2.5-5.5%, the balance being Fe and inevitable impurity elements; or the like, or, alternatively,
c: 0.20-0.30%, Si: 0.10-0.30%, Mn: 0.70-1.20%, Cu: 0.20-0.60%, Al: 0.025 to 0.065%, Ti: 0.030-0.085%, B: 0.0003-0.0050%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, N: 0.003-0.01%, Ni: 0.20-0.80%, Cr: 0.60-0.90%, Sb: 0.05-0.15, Sn: 0.06-0.15 percent, and the balance of Fe and inevitable impurity elements, wherein the mass fraction contents of Ni, Sb and Sn meet the following conditions:
2.5≤[Ni]+6[Sb]1/2+5.8[Sn]1/2≤5.5，
and the contents of Al, Ti, B and N simultaneously meet the following conditions:
the content of (Al) + [ Ti ])/[ N ] is not less than 15.0,
([Al]+[Ti])·[N]≥2.25×10-4，
wherein, the [ Al ], [ Ti ] and [ N ] respectively represent the mass fraction contents of elements Al, Ti and N;
the internal microstructure of the 1000 MPa-grade bolt steel resistant to corrosion in the special marine atmospheric environment is ferrite plus pearlite, and the fluorine ion deposition rate in the special marine atmospheric environment>0.6mdd, including simultaneous SO2Deposition rate>2.0mdd。
2. The 1000MPa grade special marine atmospheric corrosion resistant bolted steel according to claim 1, characterized in that the 1000MPa grade special marine atmospheric corrosion resistant bolted steel is suitable for marine environments with high damp heat, strong radiation and high chloride ion concentration.
3. The 1000MPa grade special marine atmospheric corrosion resistant bolted steel according to claim 1, wherein the 1000MPa grade special marine atmospheric corrosion resistant bolted steel is suitable for marine environments in island and reef areas in south China sea.
4. The preparation method of the 1000MPa grade bolt steel with the special marine atmospheric environment corrosion resistance according to any one of claims 1 to 3 is characterized by comprising the steps of molten iron pretreatment, converter or electric furnace smelting, refining, vacuum degassing, continuous casting, rolling, material modification, cold heading for manufacturing bolts and quenching and tempering heat treatment.
5. The preparation method of the 1000MPa grade bolt steel resisting corrosion in special marine atmospheric environment as claimed in claim 3, wherein the pure degassing time is more than or equal to 15min during vacuum degassing.
6. The method for preparing 1000MPa grade bolting steel with special marine atmospheric environment corrosion resistance according to claim 3, wherein said continuous casting includes square billet continuous casting, said square billet continuous casting includes: controlling the target temperature of the ladle molten steel to be 10-40 ℃ above the liquidus temperature.
7. The method for preparing the 1000MPa grade bolt steel resisting the corrosion in the special marine atmospheric environment as claimed in claim 3, wherein the quenching and tempering heat treatment comprises the following steps: oil quenching at 850-950 ℃ and high-temperature tempering at 500-650 ℃.
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