CN113136530A - Corrosion-resistant steel and preparation method and application thereof - Google Patents
Corrosion-resistant steel and preparation method and application thereof Download PDFInfo
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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Abstract
The invention provides corrosion-resistant steel and a preparation method and application thereof, belonging to the technical field of steel material preparation, wherein the corrosion-resistant steel comprises the following chemical components in percentage by mass: c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities. The corrosion-resistant steel provided by the invention has the yield strength of 380-400MPa, the tensile strength of 420-475MPa, the elongation of 25-30%, the impact energy at-20 ℃ of 326-370J and good low-temperature toughness; under the condition that 3.5% NaCl solution flows at the speed of 1.2m/s, the average corrosion rate is 1.1-1.7mm/a, the corrosion rate is low, the corrosion is uniform, and the corrosion resistance is good.
Description
Technical Field
The invention belongs to the technical field of steel material preparation, and particularly relates to corrosion-resistant steel and a preparation method and application thereof.
Background
The corrosion-resistant steel can be applied to corrosive environments such as climatically humid areas, sea floors and the like due to corrosion resistance. Among them, the corrosion-resistant steel applied to the sea bottom is widely concerned by research and development personnel in the field because the corrosion-resistant steel can be used as a seawater desalination device and can solve the problem that the fresh water resources of the earth are increasingly exhausted. Because the normal operation of the seawater desalination device is a negative pressure environment, the salinity of seawater flowing in the device is between 3.5 and 7 percent, the working temperature is between 45 and 70 ℃, and the actual service environment of the corrosion-resistant steel applied to the device is as follows: long-term stress, concentrated seawater and medium-high temperature scouring corrosion, so the service environment of the corrosion-resistant steel is extremely harsh.
At present, corrosion-resistant steel used by a foreign seawater desalination device is duplex stainless steel, or key corrosion-resistant materials such as special protective coatings are coated on the corrosion-resistant steel, so that the corrosion-resistant steel with seawater scouring resistance is urgently needed to be developed to replace the existing imported duplex stainless steel and foreign special coatings, the service life of a core device is prolonged, the seawater desalination cost is reduced to better meet market demands, and the seawater desalination device is helpful for expanding the application field of seawater desalination.
Disclosure of Invention
In order to solve the problems, the invention provides corrosion-resistant steel, a preparation method and application thereof, so that the corrosion-resistant steel has good corrosion resistance, and the service life of a core device is prolonged.
In one aspect, an embodiment of the present invention provides a corrosion-resistant steel, where the corrosion-resistant steel is composed of the following chemical components by mass:
c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities.
Further, the ratio of the sum of the mass fractions of Ca and Mg to the mass fraction of O is more than or equal to 1.0.
Further, the ratio of the mass fraction of Mn to the mass fraction of carbon is not less than 14.0.
Furthermore, the metallographic structure of the corrosion-resistant steel consists of ferrite and pearlite, wherein the volume fraction of the ferrite is 85-90%, and the volume fraction of the pearlite is 5-10%.
Further, the grain size of the ferrite is 4-10 μm.
Further, the thickness of the corrosion-resistant steel is 5-20 mm.
In a second aspect, embodiments of the present invention provide a method for preparing corrosion-resistant steel, which includes,
obtaining a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities;
heating and rolling the plate blank to obtain corrosion-resistant steel; the rolling comprises finish rolling, the finish rolling finishing temperature is 830-860 ℃, the finish rolling is 2-4 passes of rolling, and the deformation of the last pass of the finish rolling is more than or equal to 20%.
Further, the rolling also comprises rough rolling, wherein the rough rolling starting temperature is 1080-.
Further, the heating temperature is 1150-1200 ℃.
In a third aspect, the embodiment of the present invention provides an application of the corrosion-resistant steel, wherein the corrosion-resistant steel is used in a seawater desalination plant environment or a seawater pipeline in an environment with a seawater flow rate of 0.5-2 m/s.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the invention provides a corrosion-resistant steel and a preparation method and application thereof.A chromium element is added in the composition design, and is dissolved in ferrite to inhibit an anode reaction and form carbide with carbon to inhibit a cathode reaction, thereby improving the corrosion resistance of the corrosion-resistant steel; controlling magnesium, calcium and oxygen, further controlling inclusions in the corrosion-resistant steel and refining ferrite grain size, thereby improving corrosion resistance and low-temperature toughness of the corrosion-resistant steel. The corrosion-resistant steel provided by the invention has the yield strength of 380-400MPa, the tensile strength of 420-475MPa, the elongation of 25-30%, the impact energy at-20 ℃ of 326-370J and good low-temperature toughness; under the condition that NaCl solution with the mass concentration of 3.5% flows at the speed of 1.2m/s, the average corrosion rate is 1.1-1.7mm/a, the corrosion rate is low, the corrosion is uniform, and the corrosion resistance is good.
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 image of corrosion resistant steel according to an embodiment of the present invention;
FIG. 2 shows the corrosion morphology of the corrosion-resistant steel provided by the embodiment of the present invention;
fig. 3 is a corrosion morphology of the corrosion resistant steel provided in comparative example 1.
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.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
in a first aspect, embodiments of the present invention provide a corrosion-resistant steel, which is composed of the following chemical components in parts by mass:
c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities.
The effect of each element in the invention is as follows:
carbon: carbon is the most key element for controlling the structure, the austenite phase region is enlarged by limited solid solution of the carbon and gamma-Fe, and meanwhile, chromium carbide is also beneficial to improving the corrosion resistance; however, the content of pearlite in steel is increased due to the excessively high carbon content, the corrosion resistance of alloy steel is reduced, and on the other hand, the welding performance of a steel matrix is influenced due to the increase of the carbon content; in order to avoid the adverse effect of carbon, the content of carbon is controlled between 0.04 and 0.12 percent;
silicon: the silicon element has the deoxidizing effect and can also ensure the strength of a matrix, but the welding performance of the steel is reduced due to the over-high silicon content, so the silicon content is controlled to be 0.01-1.0%;
manganese: the manganese element is the same as the silicon element and mainly plays a role in deoxidation and strength guarantee; meanwhile, manganese can weaken the phenomenon of sulfur brittleness and improve the processing performance of steel; manganese belongs to a weak carbide forming element, an alloy cementite with high manganese content is required to be formed during structure transformation, nucleation and growth of the alloy cementite during pearlite transformation can be slowed down, but when the content of manganese is higher than 2%, crystal grains can be coarsened obviously, low-temperature toughness of steel is also reduced obviously, and therefore the content of the manganese element is controlled to be 0.8-2.0%.
Sulfur: the sulfur element affects the strength and the weldability of steel, and the sulfur is easy to dissolve in an acid environment to form inclusion to induce pitting corrosion and reduce the corrosion resistance of a steel matrix, so the sulfur content is controlled to be below 0.005 percent;
phosphorus: the phosphorus element is a ferrite phase region forming element and can be limited in solid solution with alpha-Fe to reduce an austenite phase region; meanwhile, phosphorus is used as an anode depolarizer, which is beneficial to forming a uniform and compact rust layer on the surface of steel and hindering the occurrence of corrosion reaction; however, since too high a content of phosphorus deteriorates weldability and reduces toughness, the content of phosphorus should be controlled to 0.01% or less;
aluminum: the aluminum mainly plays a role of deoxidation, but the aluminum oxide inclusion in steel is easily increased due to the over-high aluminum content, and the aluminum oxide inclusion is an important starting point of corrosion, so the aluminum content is controlled to be below 0.02 percent;
chromium: the chromium element mainly plays a role in improving the corrosion resistance of the alloy steel, particularly the corrosion resistance of the alloy steel in a flowing seawater corrosion environment, and is an important alloy element in the invention. Chromium is dissolved in ferrite to form Cr oxide2O3The coating is enriched in a protective film close to the matrix to inhibit the anode reaction; on the other hand, form carbide (Cr) with carbon23C6) The cathode reaction is inhibited, but the content of chromium carbide is excessive, and the corrosion resistance is reduced; in addition, chromium can improve the stability of the super-cooled austenite, can delay the nucleation and growth of carbide during the transformation of pearlite, and can increase the bonding force among solid solution atoms and reduce the free diffusion coefficient of iron so as to inhibit the transformation from austenite to ferrite, and the chromium content is 0.5-3.5 percent in comprehensive consideration.
Magnesium, calcium, oxygen are also key elements in the present invention. Magnesium and calcium are strong deoxidizing elements in steel, and are combined with oxygen in the steel to form fine composite spherical oxide particles, and the composite particles can better inhibit strip-shaped MnS and off-specification Al in the steel2O3The formation of inclusions improves the corrosion resistance of the steel. Meanwhile, the grain size of ferrite is refined by the composite oxide particles, and the low-temperature toughness of the material is obviously improved. In order to ensure the precipitation of a large amount of fine particles, the lower limits of magnesium, calcium and oxygen are controlled to be 0.001 percent. However, excessive magnesium, calcium and oxygen can increase the amount of oxide inclusions in the steel, increase the size, obviously reduce the corrosion resistance of the corrosion-resistant steel in a flowing seawater corrosion environment, and cannot refineThe organization function in the steel reduces the low-temperature toughness of the steel. Therefore, the upper limits of the contents of magnesium, calcium and oxygen in the steel are all controlled to be 0.01%.
As an implementation manner of the embodiment of the invention, the ratio of the sum of the mass fractions of the Ca and the Mg to the mass fraction of the O is more than or equal to 1.0. When the ratio (Mg + Ca)/O of the sum of the mass fractions of Ca and Mg and the mass fraction of O is more than or equal to 1, the amount of the oxide formed in the steel is large, the size of the oxide is small, the final microstructure is obviously refined, and meanwhile, the corrosion resistance and the low-temperature toughness are improved.
As an implementation manner of the embodiment of the invention, the ratio of the mass fraction of the Mn to the mass fraction of the carbon is more than or equal to 14.0. When the ratio of the mass fraction of Mn to the mass fraction of carbon, that is, Mn/C, is less than 14.0, a small amount of granular bainite structure will appear in the structure, thereby degrading the corrosion resistance of the steel matrix.
In one embodiment of the present invention, the metallographic structure of the corrosion-resistant steel comprises ferrite and pearlite, wherein the volume fraction of the ferrite is 85 to 90%, and the volume fraction of the pearlite is 5 to 10%.
Ferrite: ferrite is an interstitial solid solution of carbon in alpha-Fe and is also a main composition phase in a low alloy steel hot rolled and annealed structure; since the lattice spacing in α -Fe is very small, the carbon-dissolving ability is very poor, and thus its properties are almost the same as those of pure iron. The ferrite has single component, higher electrode potential and good corrosion resistance. When the ferrite content is low, the number of other structures such as pearlite, bainite and the like in the structure is relatively large, and the corrosion resistance of the steel in a flowing seawater environment is remarkably reduced. Therefore, the volume fraction of the ferrite structure is not less than 85 percent and is controlled between 85 and 90 percent.
Pearlite: the pearlite is a lamellar complex phase object with a ferrite thin layer and a cementite thin layer which are alternately overlapped; in the case of ferrite and cementite which are alternately distributed in pearlite, the electrode potential of ferrite becomes negative and becomes positive due to the difference in electrode potential, and the electrode potential of cementite becomes positive and becomes negative, so that in a corrosive environment, a corrosion cell formed of ferrite and cementite is likely to cause local corrosion. When the pearlite structure content is higher than 10%, micro corrosion cells are easily formed in the structure, and the corrosion resistance of the steel in a flowing seawater corrosion environment is obviously reduced. Therefore, the volume fraction of the pearlite structure is 6 to 10%.
As an embodiment of the present invention, the ferrite has a grain size of 4 to 10 μm. The grain size of the ferrite in the microstructure can significantly affect the service properties of the steel. When the ferrite grain size is relatively large, the yield strength and low-temperature toughness of the steel are reduced; when ferrite grains are too fine, corrosive media easily permeate into the grains along grain boundaries, the corrosion resistance is obviously reduced, and the low-temperature toughness of a welding heat affected zone is also obviously reduced due to the fine grains. Therefore, the present invention controls the ferrite grain size to 4-10 μm.
As an implementation mode of the embodiment of the invention, the thickness of the corrosion-resistant steel is 5-20 mm.
In a second aspect, embodiments of the present invention provide a method for preparing corrosion-resistant steel, which includes,
s1, obtaining a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities;
s2, heating and rolling the plate blank to obtain corrosion-resistant steel; the rolling comprises finish rolling, the finish rolling finishing temperature is 830-860 ℃, the finish rolling is 2-4 passes of rolling, and the deformation of the last pass of the finish rolling is not less than 20%.
The final ferrite grain size can be obviously refined by controlling the finish rolling temperature and the deformation of the last pass, and the low-temperature toughness is improved. After finishing rolling, air cooling is adopted, so that the final ferrite grain size can be further refined, and the corrosion resistance and the low-temperature toughness of the steel are improved. When the finish rolling finishing temperature is too high, the crystal grains are coarse, and the plasticity and toughness of the material are poor; when the finish rolling temperature is too low, the steel enters an austenite and ferrite two-phase region, and the structure is uneven after cooling is finished, so that the toughness of the material can be reduced; the dislocation deformation generated by the over-small final deformation amount is less, so that the nucleation points are less, and the crystal grains grow unevenly, thereby reducing the plasticity and toughness of the material.
As an implementation manner of the embodiment of the present invention, the rolling further includes rough rolling, where the rough rolling start temperature is 1080-.
As an implementation manner of the embodiment of the invention, the heating temperature is 1150-1200 ℃. The heating temperature is controlled mainly to prevent the prior austenite grain size from being significantly coarsened.
In addition, the control of slab components can be completed through steel making, when the content of oxygen in molten steel is controlled to be 10-100ppm in the steel making process, Mg-Ca alloy wires are fed into the molten steel to obtain a large amount of fine spherical Mg and Ca oxide particles, the number of irregular inclusions in the steel is reduced, and the corrosion resistance of the steel is obviously improved. The argon stirring can be adopted to lead the oxide particles to be evenly and finely distributed in the molten steel.
It should be noted that the above-mentioned process for producing corrosion-resistant steel is also applicable to steel sheets, i.e., steel sheets are produced without coiling.
In a third aspect, the embodiment of the present invention provides an application of the corrosion-resistant steel, wherein the corrosion-resistant steel is used in a seawater desalination plant environment or a seawater pipeline in an environment with a seawater flow rate of 0.5-2 m/s.
A corrosion-resistant steel of the present invention, a method for manufacturing the same, and applications thereof will be described in detail with reference to examples, comparative examples, and experimental data.
Examples 1 to 7 and comparative examples 1 to 4
Examples 1 to 7 and comparative examples 1 to 4 provide a method of manufacturing corrosion resistant steel, the method comprising: smelting, heating a casting blank, rough rolling, finish rolling, air cooling and coiling;
the chemical components of the cast slab are shown in table 1, the balance being Fe and inevitable impurities, and the process control of each step is shown in table 2.
TABLE 1
TABLE 2
The corrosion-resistant steels of examples 1 to 7 and comparative examples 1 to 4 were sampled for mechanical property inspection, structure inspection under an optical microscope, and corrosion resistance inspection. The corrosion resistance is characterized in that a sample is processed into a standard corrosion sample, a scouring corrosion simulation device set up in a laboratory is adopted, a pipe flow test method is used for testing the seawater scouring corrosion resistance of the seawater scouring corrosion resistant steel, the solution is a NaCl solution with the mass fraction of 3.5%, the flow rate of the solution is 1.2m/s, and the corrosion time is 768 hours (32d 24 hours). The corrosion resistant steels of examples 1-7 and comparative examples 1-4 corroded for 768 hours in the above environment, and the average corrosion rates are shown in table 4. The seawater erosion corrosion resistance test described above was also conducted while using Q345E as a reference, whereby the relative corrosion rates of examples 1 to 7 and comparative examples 1 to 4 were calculated, and the results are shown in table 4.
TABLE 3
TABLE 4
| Numbering | Impact work at-20 ℃ J | Relative rate of corrosion | Average corrosion rate mm/a | Morphology of corrosion |
| Example 1 | 368 | 0.68 | 1.5 | Little rust |
| Example 2 | 355 | 0.59 | 1.3 | Little rust |
| Example 3 | 326 | 0.50 | 1.1 | Little rust |
| Example 4 | 347 | 0.77 | 1.7 | Little rust |
| Example 5 | 345 | 0.73 | 1.6 | Little rust |
| Example 6 | 335 | 0.64 | 1.4 | Little rust |
| Example 7 | 370 | 0.55 | 1.2 | Little rust |
| Comparative example 1 | 36 | 2.05 | 4.5 | Relatively thick loose rust layer |
| Comparative example 2 | 67 | 1.36 | 3.0 | Relatively thick loose rust layer |
| Comparative example 3 | 145 | 1.45 | 3.2 | Little rust |
| Comparative example 4 | 89 | 1.05 | 2.3 | Little rust |
In Table 4, the average corrosion rate refers to the average corrosion depth per unit time.
The relative corrosion rate refers to a ratio of the average corrosion rate of the samples of examples 1 to 7 and comparative examples 1 to 4 to the average corrosion rate of reference sample Q345E, and a smaller ratio indicates better corrosion resistance.
As can be seen from the data in tables 3 and 4, the volume fraction of pearlite in the corrosion-resistant steels prepared in examples 1-7 is 4.8-9.7%, the volume fraction of ferrite is 90.3-95.2%, the average grain size of ferrite is 4.98-7.16 μm, the yield strength is 380-400MPa, the tensile strength is 420-475MPa, the elongation is 25-30%, the impact work at-20 ℃ is 326-370J, and the low-temperature toughness is good; the average corrosion rate is 1.1-1.7mm/a, the corrosion rate is low, the corrosion is uniform, and the corrosion resistance is good as shown in figure 2.
Comparative example 1 is corrosion resistant steel under the conditions that (Mg + Ca)/O is too small and Mn/C is too small, the volume fraction of pearlite is 22.6%, the volume fraction of ferrite is 77.4%, the average grain size of ferrite is 20.7 μm, the yield strength is 352MPa, the tensile strength is 446MPa, the elongation is 32.8%, the impact work at-20 ℃ is 36J, and the low-temperature toughness is poor; the average corrosion rate is 4.5mm/a, the corrosion rate is high, and the local corrosion is obvious, as shown in figure 3, the corrosion resistance is poor.
Comparative example 2 is a corrosion-resistant steel in the case where (Mg + Ca)/O is excessively small, the volume fraction of pearlite is 17.8%, the volume fraction of ferrite is 82.2%, the average grain size of ferrite is 18.9 μm, the yield strength is 365MPa, the tensile strength is 502MPa, the elongation is 31.2%, the impact work at-20 ℃ is 67J, and the low-temperature toughness is poor; the average corrosion rate was 3.0mm/a, the corrosion rate was high, local corrosion was significant, and the corrosion resistance was poor because of the large number of inclusions in the steel grade.
Comparative example 3 is a corrosion-resistant steel in the case where the chromium content is excessively low (Mg + Ca)/O, the volume fraction of pearlite is 8.9%, the volume fraction of ferrite is 91.1%, the average grain size of ferrite is 13.4 μm, the yield strength is 376MPa, the tensile strength is 389MPa, the elongation is 28.4%, the impact work at-20 ℃ is 145J, and the low-temperature toughness is poor; the average corrosion rate is 3.2mm/a, the corrosion rate is high, and the seawater scouring corrosion resistance is poor.
Comparative example 4 is seawater erosion corrosion resistant steel in the case where the Mn/C ratio is too small, 3.1% of granular bainite appears in the structure, the volume fraction of pearlite is 10.4%, the volume fraction of ferrite is 86.5%, the average grain size of ferrite is 14.6 μm, the yield strength is 285MPa, the tensile strength is 305MPa, the elongation is 24.3%, the impact work at-20 ℃ is 89J, and the low-temperature toughness is poor; the average corrosion rate is 2.3mm/a, the corrosion rate is high, and the seawater scouring corrosion resistance is poor.
The invention has at least the following advantages:
1. the corrosion-resistant steel provided by the invention has the yield strength of 380-400MPa, the tensile strength of 420-475MPa, the elongation of 25-30%, the impact energy at-20 ℃ of 326-370J and good low-temperature toughness; under the condition that NaCl solution with the mass concentration of 3.5% flows at the speed of 1.2m/s, the average corrosion rate is 1.1-1.7mm/a, the corrosion rate is low, the corrosion is uniform, and the corrosion resistance is good.
2. The preparation method of the seawater scouring corrosion resistant steel is simple and convenient in operation process, and is particularly suitable for producing steel pipe steel requiring high strength, high low-temperature toughness and high corrosion resistance.
3. The seawater scouring corrosion resistant steel can be applied to the environment of a seawater desalination device or the environment of a seawater pipeline, can be directly used in an exposed mode, and can obviously prolong the service life of a steel matrix and improve the service safety under the condition of not increasing the cost to a great extent.
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 (10)
1. The corrosion-resistant steel is characterized by comprising the following chemical components in percentage by mass:
c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities.
2. The corrosion-resistant steel as claimed in claim 1, wherein the ratio of the sum of the mass fractions of Ca and Mg to the mass fraction of O is not less than 1.0.
3. The corrosion-resistant steel as claimed in claim 1, wherein the ratio of the mass fraction of Mn to the mass fraction of carbon is 14.0 or more.
4. The corrosion-resistant steel according to claim 1, wherein a metallographic structure of the corrosion-resistant steel consists of ferrite and pearlite, wherein a volume fraction of the ferrite is 85 to 90%, and a volume fraction of the pearlite is 5 to 10%.
5. A corrosion resistant steel according to claim 4, wherein the ferrite grain size is 4-10 μm.
6. A corrosion resistant steel according to claim 1, wherein said corrosion resistant steel has a thickness of 5-20 mm.
7. The method of producing a corrosion resistant steel according to any one of claims 1 to 6, comprising,
obtaining a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.04-0.12%, Si: 0.01-1.0%, Mn: 0.8-2.0%, S is less than or equal to 0.005%, P is less than or equal to 0.01%, Als is less than or equal to 0.02%, Cr: 0.5-3.5%, Mg: 0.001-0.01%, Ca: 0.001-0.01%, O: 0.001-0.01%, and the balance of Fe and inevitable impurities;
heating and rolling the plate blank to obtain corrosion-resistant steel; the rolling comprises finish rolling, the finish rolling finishing temperature is 830-860 ℃, the finish rolling is 2-4 passes of rolling, and the deformation of the last pass of the finish rolling is more than or equal to 20%.
8. The method as claimed in claim 7, wherein the rolling further comprises rough rolling, the rough rolling start temperature is 1080-.
9. The method for preparing corrosion-resistant steel according to claim 7, wherein the heating temperature is 1150-1200 ℃.
10. Use of a corrosion resistant steel according to any one of claims 1 to 6 in a seawater desalination plant environment or seawater pipeline in an environment with a seawater flow rate of 0.5 to 2 m/s.
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