CN112795844B - Low-carbon Cr-Ni series high-strength corrosion-resistant steel and preparation method thereof - Google Patents
Low-carbon Cr-Ni series high-strength corrosion-resistant steel and preparation method 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- 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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- 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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- 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
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- 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
- 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
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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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
Abstract
The invention discloses low-carbon Cr-Ni series high-strength corrosion-resistant steel and a preparation method thereof, belongs to the technical field of corrosion-resistant steel, and solves the problem that the corrosion-resistant steel in the prior art cannot meet various corrosion environments. The low-carbon Cr-Ni series high-strength corrosion-resistant steel comprises the following alloy components in percentage by mass: c: 0.01% -0.03%, Cr: 3.0% -10.0%, Ni: 1.0% -2.0%, Si: 0.1% -0.5%, Mn: 0.5% -1.0%, P: 0.04% -0.10%, S: less than or equal to 0.005 percent, N: 0.02% -0.06%, Cu: 0.2 to 0.5 percent, and the balance of Fe and inevitable impurities. The low-carbon Cr-Ni series high-strength corrosion-resistant steel has excellent mechanical property, marine atmosphere corrosion resistance, industrial atmosphere corrosion resistance and seawater corrosion resistance.
Description
Technical Field
The invention belongs to the technical field of corrosion-resistant steel, and particularly relates to low-carbon Cr-Ni series high-strength corrosion-resistant steel and a preparation method thereof.
Background
Corrosion is one of the three major failure modes in the field of metallic materials, and according to macroscopic statistics, all metallic materials lose about 1% of their weight annually due to corrosion, which is more severe in tropical, marine environments. From the global perspective, the economic loss caused by corrosion accounts for about 3% -4% of the total national economy. Based on the huge economic loss caused by corrosion, researchers also propose a series of protective measures, such as means of corrosion resistant coatings (epoxy and metal coatings), corrosion inhibitors, electrochemical protection and the like, but the methods have more or less defects, such as the corrosion resistant coatings can effectively delay the corrosion process, but have higher cost, and once defects appear on the surfaces of the coatings, the corrosion can be further accelerated. Stainless steel has excellent corrosion resistance, but the addition of a large amount of alloy elements makes the stainless steel incapable of being widely applied in the huge engineering construction field of China, low-alloy corrosion-resistant steel receives more and more attention due to lower corrosion-resistant alloy content, excellent mechanical property and better corrosion resistance, the application field is continuously expanded, and higher requirements are provided for the corrosion resistance.
At present, a plurality of patents exist at home and abroad on the varieties of the weathering steel with good comprehensive performance and corresponding process flows, but most of the patents have the problems of insufficient corrosion resistance, overhigh cost, complex process and the like, so that the requirements of mass production and practical application cannot be met. For example, a high-resistance steel plate (JP04235250A Japanese patent 1992) and an ultra-low-carbon bainite weathering steel (US 6315946 US patent 2001) which are relatively early abroad, and a 'weathering steel Q345qDNH steel strip for bridges and a production method thereof' (CN 109097686A) which are published by domestic steel in 2018 are all low-Cr (<0.7 wt%) weathering steels which cannot meet the service requirements of more severe environments (such as marine atmospheric environment or coastal industrial atmospheric environment). Based on the defect of insufficient corrosion resistance of low-Cr weathering steel, the first domestic steel discloses 'a low-carbon high-Cr high-N steel for strong corrosion resistance and a production method thereof' in 2014 (CN 103540871A), the corrosion resistance of the weathering steel is greatly improved, but the addition amount of Cr is 6-13%, the alloy cost is improved, and the requirement of high N cannot be met by most steel mills. The analysis shows that the existing weathering steel variety still has great improvement space, simultaneously, with the development of the infrastructure business of China, the service environment of the steel structure also changes greatly, the corrosion resistance of the corrosion resistant steel is greatly influenced by external environmental factors such as temperature, humidity, pollutants and the like, but the early investment for developing the corrosion resistant steel variety special for each specific environment is large and the research and development period is long, so the corrosion resistant steel used in various corrosion environments has wide application prospect.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a low-carbon Cr-Ni series high-strength corrosion-resistant steel and a preparation method thereof, so as to solve the problem that the corrosion-resistant steel in the prior art cannot satisfy various corrosion environments, and ensure that the corrosion-resistant steel satisfies various corrosion environments on the basis of satisfying the mechanical properties.
The purpose of the invention is mainly realized by the following technical scheme:
in one aspect, the invention provides a low-carbon Cr-Ni series high-strength corrosion-resistant steel, which comprises the following alloy components in percentage by mass: c: 0.01% -0.03%, Cr: 3.0% -10.0%, Ni: 1.0% -2.0%, Si: 0.1% -0.5%, Mn: 0.5% -1.0%, P: 0.04% -0.10%, S: less than or equal to 0.005 percent, N: 0.02% -0.06%, Cu: 0.2 to 0.5 percent, and the balance of Fe and inevitable impurities.
Further, the low-carbon Cr-Ni series high-strength corrosion-resistant steel comprises the following alloy components in percentage by mass: c: 0.015% -0.027%, Cr: 3.3% -9.8%, Ni: 1.1% -1.9%, Si: 0.1% -0.40%, Mn: 0.5% -1.0%, P: 0.04% -0.09%, S: less than or equal to 0.005 percent, N: 0.025% -0.058%, Cu: 0.25 to 0.48 percent, and the balance of Fe and inevitable impurities.
Further, the microstructure of the low-carbon Cr-Ni-based high-strength corrosion-resistant steel is a ferrite + tempered martensite structure.
On the other hand, the invention provides a preparation method of low-carbon Cr-Ni series high-strength corrosion-resistant steel, which comprises the following steps:
step 1: smelting and casting to obtain a casting blank;
step 2: homogenizing the casting blank, namely heating to an austenite homogenization temperature and preserving heat;
and step 3: after the heat-preserved casting blank is discharged from a furnace, removing oxide skin, directly rolling, wherein the rolling process adopts two sections of rolling, namely recrystallization rough rolling and non-recrystallization finish rolling; wherein the accumulated deformation of rough rolling is more than or equal to 65 percent;
and 4, step 4: after rolling to the target thickness in the step 3, carrying out laminar cooling to 550-750 ℃ for coiling to obtain a plate coil;
and 5: the coil is annealed.
Further, in the step 2, the austenite homogenization temperature is controlled to 1150-1250 ℃.
Further, in the step 2, when the Cr content of the low-carbon Cr-Ni series high-strength corrosion-resistant steel is 7-10%, the austenite homogenization temperature is controlled to 1150-1200 ℃.
Furthermore, in the step 2, the heat preservation time is 0.5-3 h.
Further, in the step 3, when the Cr content of the low-carbon Cr-Ni series high-strength corrosion-resistant steel is 3% -7%, the recrystallization rough rolling temperature is controlled to 1100-.
Further, in the step 3, when the Cr content of the low-carbon Cr-Ni series high-strength corrosion-resistant steel is 7-10%, the recrystallization rough rolling temperature is controlled to be 1100-1000 ℃, and the finish rolling temperature is controlled to be 1000-900 ℃.
Further, in the step 5, the annealing step is: the coiled plate coil is cooled to below 100 ℃ and then heated to 550 ℃ and 700 ℃ again, and the temperature is kept for 0.5-5 h.
Compared with the prior art, the invention can at least realize one of the following technical effects:
1) in the steel, the ultra-low carbon component design ensures that carbides are not easily formed in the steel, the occurrence of local corrosion is avoided, the initial corrosion resistance is greatly improved by adding high N and high content Cr, the corrosion resistance is further improved by alloying Ni, Cu and P, the compactness of a rust layer is enhanced by increasing the content of alpha-FeOOH in the rust layer, the grain boundary corrosion resistance is enhanced by the composite segregation of Cu and P interfaces, and the trend that the long-term corrosion rate of the Cr alloy steel is gradually reduced by more than 3 percent is ensured.
2) The high Cr and Ni alloying of the invention can be realized by adopting the medium Cr low Ni Mn-containing molten iron smelted by the laterite-nickel ore, the high N content can be realized by combining the nitrogen-blowing smelting process, and the alloy cost is more economic than that of the conventional intermediate alloy or pure metal addition alloying mode.
3) Because the steel has higher hardenability, the coiling at 750 ℃ can obtain higher strength basically equivalent to that obtained when coiling at 550 ℃, and the coiling temperature window is wide and the coiling temperature is high, so that the load of a coiler can be reduced.
4) The steel of the invention is in Cl-Or SO4 -The steel has better corrosion resistance under existing conditions, ensures that the marine atmospheric corrosion resistance, the industrial atmospheric corrosion resistance and the seawater corrosion resistance of the steel are all superior to 09CuPCrNi commercial low-alloy weathering steel, and can meet the service requirements of various corrosion environments.
5) The invention accurately controls the mass percentage of C, N, Cr, Ni, Cu, P and Mn elements in the steel, can obtain a ferrite and tempered martensite dual-phase structure after rolling and annealing processes, not only ensures high strength, but also has good plasticity, and is easy to control lower yield ratio, so that the yield strength of the steel can be ensured to be more than 360MPa (for example 361-512MPa), the tensile strength is more than 570MPa (for example 579.5-745MPa), and the elongation is 20.0% -29.0%.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a metallographic structure diagram of example 1;
FIG. 2 is a metallographic structure chart of example 4;
FIG. 3 is a metallographic structure diagram of comparative example 1;
FIG. 4 is a metallographic structure diagram of comparative example 2;
FIG. 5 is a metallographic structure diagram of comparative example 3.
Detailed Description
A low-carbon Cr-Ni based high-strength corrosion-resistant steel and a method for manufacturing the same will be described in further detail with reference to specific examples, which are provided for comparison and explanation purposes only, and the present invention is not limited to these examples.
The alloy components of the low-carbon Cr-Ni series high-strength corrosion-resistant steel are calculated by mass percent: c: 0.01% -0.03%, Cr: 3.0% -10.0%, Ni: 1.0% -2.0%, Si: 0.1% -0.5%, Mn: 0.5% -1.0%, P: 0.04% -0.10%, S: less than or equal to 0.005 percent, N: 0.02% -0.06%, Cu: 0.2 to 0.5 percent, and the balance of Fe and inevitable impurities.
The function and amount of the components contained in the present invention are specifically described below:
c: c is an effective interstitial solid solution strengthening element in steel, but in the corrosion-resistant steel, the total content of Cr + Ni + Mn is high, the hardenability is good, so the upper limit of the content of C must be strictly limited, too high content of C can be combined with Cr to generate larger and more carbides, the corrosion resistance is reduced, but the strength is insufficient due to too low content of C, and the content of C is controlled to be 0.01-0.03%.
N: n is also an effective interstitial solid solution strengthening element in steel, and N and main alloy elements such as Cr, Ni, Mn and the like are difficult to form or do not form nitride or carbonitride, but the corrosion resistance can be improved by properly high N content, and simultaneously a low-cost nitrogen blowing process is allowed to be adopted during smelting, and the N content is controlled to be 0.02-0.06%.
Si: the strongest replacement solid solution strengthening element in the steel can obviously reduce the ductility and toughness when the content is higher, and the content is controlled to be 0.1-0.5 percent.
Mn: stabilizing austenite elements can enlarge the austenite phase region, compensate the reduction of the austenite phase region caused by the overhigh Cr content, and is also an effective solid solution strengthening element. In addition, from the perspective of reducing hardenability, on the premise of adding 3% -10% of Cr, the lower the Mn content is, the better the Mn content is, but based on the consideration that the cost is reduced by adopting the molten iron containing Mn with low Cr and low Ni smelted by the laterite-nickel ore, the Mn content in the steel is controlled to be 0.5% -1.0%.
Cr, Ni, Cu: when the Cr content in the steel is more than 3 percent, the initial corrosion resistance of the steel is much better than that of Corten A, SPA-H or 09CuPCrNi commercial low-alloy weathering steel in the atmosphere or humid environment containing chloride ions, but the long-term corrosion rate is reduced and then improved, which is inconsistent with the phenomenon that the long-term corrosion rate of Corten A, SPA-H or 09CuPCrNi commercial low-alloy weathering steel is gradually reduced. The research of the invention shows that the corrosion resistance in the initial stage is further improved and the initial rust layer is more compact by adding a certain content of Ni and Cu, so that the long-term corrosion rate is gradually reduced. Therefore, on the basis of 3.0-10.0% of Cr content, the composite addition of Ni and Cu is controlled simultaneously, wherein the Ni content is 1.0-2.0%, and the Cu content is 0.2-0.5%. The component design is also suitable for smelting medium-Cr low-Ni molten iron containing Mn, which is smelted by adopting laterite-nickel ore as a smelting raw material, so that the cost is reduced.
P: p can further improve the corrosion resistance of Cr and Cu-based corrosion-resistant and weather-resistant steel grain boundaries, but too high P content reduces the ductility and toughness. The content of P in the steel is controlled to be 0.04-0.10%.
S: the ductility and toughness of the steel are reduced, and the large-particle MnS inclusion can be used as a pitting corrosion source, and the content of Mn in the steel is controlled to be not more than 0.005% in consideration of higher content of Mn in the steel.
In order to further improve the overall performance of the low-carbon Cr-Ni based high-strength corrosion-resistant steel, the composition of the low-carbon Cr-Ni based high-strength corrosion-resistant steel may be further adjusted. Illustratively, the composition comprises the following components in percentage by mass: c: 0.015% -0.027%, Cr: 3.3% -9.8%, Ni: 1.1% -1.9%, Si: 0.1% -0.35%, Mn: 0.5% -1.0%, P: 0.04% -0.09%, S: less than or equal to 0.005 percent, N: 0.025% -0.058%, Cu: 0.25 to 0.48 percent, and the balance of Fe and inevitable impurities.
A preparation method of low-carbon Cr-Ni series high-strength corrosion-resistant steel comprises the following steps:
step 1: smelting and casting to obtain a casting blank;
step 2: homogenizing the casting blank, namely heating to an austenite homogenization temperature and preserving heat;
and step 3: after the heat-preserved casting blank is discharged from a furnace, removing oxide skin, directly rolling, wherein the rolling process adopts two sections of rolling, namely recrystallization rough rolling and non-recrystallization finish rolling; wherein the accumulated deformation of rough rolling is more than or equal to 65 percent;
and 4, step 4: after rolling to the target thickness in the step 3, carrying out laminar cooling to 550-750 ℃ for coiling to obtain a plate coil;
and 5: the coil is annealed.
Specifically, in the step 1, the cast ingot is formed by vacuum induction smelting and die casting according to the components of the corrosion-resistant steel.
Specifically, in the step 1, a converter or an electric furnace is adopted for smelting, LF refining and continuous casting to form a casting blank.
In order to reduce the manufacturing cost of the high-strength corrosion-resistant steel, in the step 1, Cr low-Ni Mn-containing molten iron in the laterite-nickel ore and an alloy melted on an intermediate frequency furnace are injected into an AOD furnace through a steel ladle, and are subjected to nitrogen-blowing smelting, LF refining and continuous casting to form a casting blank.
Specifically, in the step 2, the austenite homogenization temperature T1 is controlled to 1150-1250 ℃, because when T1 is too high, austenite grains of the cast slab are too coarse, which increases energy cost, and when T1 is too low, the solid solution of alloy elements in the steel is insufficient and the homogenization is insufficient, thereby affecting the performance of subsequent finished products.
It should be noted that, in the step 2, as the Cr content increases from 3% to 10%, the upper heating limit temperature needs to be decreased synchronously, where the control range of the austenite homogenization temperature T1 is 1150-1200 ℃ when Cr is 7% -10%. This is because Cr shrinks the austenite region, and an excessively high heating temperature adversely causes δ -Fe, which prevents complete austenitization, and further affects subsequent structure control.
Specifically, in the step 2, the heat preservation time t1 is too long, the energy cost is increased, the production efficiency is not facilitated, the t1 is too short, and the uniformity of the thickness and the temperature of the casting blank is difficult to guarantee. Therefore, t1 is controlled to be 0.5-3 h.
Specifically, in the step 3, for corrosion-resistant steel with 3% -7% of Cr, the recrystallization rough rolling temperature is controlled at 1100-; the finish rolling temperature is controlled at 970-900 ℃, and the flat austenite can be rolled without recrystallization in the section, so that the subsequent ferrite transformation is promoted.
Specifically, in the step 3, for the corrosion-resistant steel with 7-10% of Cr, the recrystallization rough rolling temperature is controlled at 1100-.
It should be noted that, in the step 4, the laminar flow is cooled to 550-; when the temperature is too low, the coiling stress is too large, and coiling is not facilitated.
Specifically, in step 4, the room-temperature microstructure of the hot-rolled corrosion-resistant steel is ferrite + martensite, wherein the volume fraction of the ferrite microstructure is 15% to 40%.
Specifically, in step 5, in order to reduce the hardness and strength of the martensite structure and improve the ductility and toughness of the coil, the corrosion-resistant hot-rolled steel coil is subjected to whole-coil annealing or continuous annealing, specifically, the annealing step is as follows: and cooling the coiled plate coil to below 100 ℃, then reheating to the temperature of T2, and keeping the temperature for T2 time.
Specifically, T2 temperature is too low, softening effect is not good or holding time is too long, temperature is too high, and control of oxide skin, strength and structure is not facilitated. Therefore, the temperature range of T2 is controlled to be 550-700 ℃; t2 time is too short, softening effect is not good, time is too long, energy cost is increased, and excessive softening can be caused; therefore, the time t2 is controlled to be 0.5-5 h.
By the preparation method, the microstructure of the low-carbon Cr-Ni series high-strength corrosion-resistant steel prepared by the invention is a ferrite and tempered martensite structure, wherein the volume fraction of ferrite is 15-40%. The yield strength is more than 360MPa (for example 361-512MPa), the tensile strength is more than 570MPa (for example 579.5-745MPa), the elongation is 20.0% -29.0%, and the marine atmospheric corrosion resistance, the industrial atmospheric corrosion resistance and the seawater corrosion resistance of the steel are all obviously superior to the commercial low-alloy weathering steel of Corten A, SPA-H or 09CuPCRNi and the like.
The advantages of the steel according to the invention with regard to the precise control of the composition and process parameters will be shown in the following in the specific examples and comparative examples. The chemical compositions of the steels of examples 1-4 and comparative examples 1-3 are shown in Table 1, the specific rolling process parameters are shown in Table 2, and the mechanical properties of examples 1-4 and comparative examples 1-3 are shown in Table 3.
A commercial low alloy weathering steel sheet of 09CuPCrNi was selected as comparative example 1 for corrosion performance of the examples, and the remaining comparative examples 2-3 were produced in a similar process or composition to example 1, as described below.
The example 1 and the rest of the comparative examples 2-3 are subjected to vacuum smelting and continuous casting to form a blank with the specification of 60mm (thickness) x 70mm (width), 1 block with the size of 60mm (thickness) x 70mm (width) x 100mm is cut, the blank is heated to 1150 plus 1250 ℃ and is subjected to heat preservation for 1h, oxide skin is removed after the blank is taken out of a furnace, rough rolling is carried out according to the positive tolerance of 60mm-48mm-38mm-32mm-25mm-20mm, finish rolling is carried out according to the positive tolerance of 16mm-13mm-11mm, the finished product is about 1m long, the finish rolling temperature is not lower than 900 ℃, laminar flow cooling is carried out to 550 plus 750 ℃ for coiling, a hot rolled coil is cooled to below 100 ℃ and is then heated again to 550 plus 700 ℃ and is subjected to heat preservation for 0.5-5 h. The steel of the invention has higher hardenability, so the strength basically consistent with the relatively lower coiling temperature can be obtained by adopting higher coiling temperature, and the coiling temperature window is wide. The reason for cooling the hot rolled coil to 100 ℃ or less is to complete the martensitic transformation and then to reheat the coil to temper the martensitic structure. Because the medium and high Cr alloy steel has good thermal stability, the medium and high Cr alloy steel can be heated to the temperature of 700 ℃ for short tempering such as 0.5h, and if the reheating is controlled to 550 ℃ at least, the heat preservation time can reach 5h to achieve the effect.
In the embodiment 2-4, the Cr low Ni Mn-containing molten iron in the laterite-nickel ore and the alloy melted on the medium frequency furnace are injected into the AOD furnace through a ladle, and are subjected to nitrogen blowing smelting, LF refining and continuous casting to form a casting blank. The remaining steps are similar to example 1.
Table 1 chemical composition wt% of examples and comparative examples
| Numbering | C | Cr | Si | Mn | P | S | Ni | Cu | N |
| Example 1 | 0.025 | 4.3 | 0.30 | 0.5 | 0.04 | 0.004 | 1.5 | 0.48 | 0.044 |
| Example 2 | 0.020 | 7.5 | 0.24 | 0.8 | 0.09 | 0.005 | 1.1 | 0.30 | 0.025 |
| Example 3 | 0.027 | 3.3 | 0.40 | 1.0 | 0.05 | 0.005 | 1.6 | 0.35 | 0.030 |
| Example 4 | 0.015 | 9.8 | 0.35 | 0.7 | 0.03 | 0.002 | 1.9 | 0.25 | 0.058 |
| Comparative example 1 | 0.09 | 0.34 | 0.44 | 0.3 | 0.09 | 0.003 | 0.02 | 0.28 | 0.004 |
| Comparative example 2 | 0.005 | 9.0 | 0.30 | 0.2 | 0.01 | 0.009 | 0.04 | / | 0.004 |
| Comparative example 3 | 0.025 | 4.5 | 0.3 | 1.2 | 0.04 | 0.005 | 1.5 | / | 0.005 |
TABLE 2 specific hot-Rolling Process parameters of examples and comparative examples
TABLE 3 mechanical Properties of examples and comparative examples
TABLE 4 metallographic structure of examples and comparative examples
| Microstructure of | |
| Example 1 | Ferrite 16% + tempered martensite 84% |
| Example 2 | Ferrite 25% + tempered martensite 75% |
| Example 3 | Ferrite 37% + tempered martensite 63% |
| Example 4 | Ferrite 29% + tempered martensite 71% |
| Comparative example 1 | Ferrite 91% + pearlite 9% |
| Comparative example 2 | Ferrite 100% |
| Comparative example 3 | Ferrite 2% + martensite 98% |
As can be seen from Table 3, examples 1 to 4 all satisfied the objectives of yield strength of more than 360MPa (e.g., 361-512MPa), tensile strength of more than 570MPa (e.g., 579.5-745MPa), and elongation of 20.0% to 29.0%, while comparative example 2 too reduced the C content and Ni content, and low hardenability to obtain a single ferrite structure, though the plasticity was improved but the strength was too low. Comparative example 3 has substantially the same composition as example 1, but the matrix structure is a single martensite structure by direct air cooling after rolling, and the plasticity is remarkably reduced though the strength is improved. Table 4 shows the metallographic structure of some of the examples and comparative steels of the steel of the present invention, and it can be seen that corrosion resistant steel with ferrite + tempered martensite as the microstructure, excellent mechanical properties, and good corrosion resistance in various environments can be obtained by using the components and method of the present invention.
Since the Cr content of example 1 was the lowest in all the examples and the corrosion resistance of the remaining examples was higher than that of example 1, only example 1 was selected to illustrate the corrosion resistance of the steel of the present invention and compared with the conventional weathering steel 09 CuPCrNi. The corrosion resistance of the invention in different corrosion environments is evaluated by measuring the indoor accelerated corrosion results under 3 different conditions and comparing with the comparative example 1 under the same test conditions. The results of the 3 indoor accelerated corrosion tests are shown in table 5, and the corresponding test conditions are as follows:
the first one is simulated marine atmospheric corrosion, and the corresponding cycle immersion corrosion conditions are as follows, and the solution is: 2% NaCl solution; RH: 70 +/-5%; test temperature: 45 +/-2 ℃; each cycle period: 60 plus or minus 3min, and the infiltration time is 12 plus or minus 1.5 min; and (3) test period: and 72 h.
The second one is simulating industrial atmospheric corrosion, and the corresponding cycle immersion corrosion conditions are as follows, namely solution: (1.0. + -. 0.05). times.10-2mol/lNaHSO3A solution; RH: 70 +/-5%; test temperature: 45 +/-2 ℃; each cycle period: 60 plus or minus min, and the infiltration time is 12 plus or minus 1.5 min; and (3) test period: and 72 h.
The third one is simulated seawater corrosion, and the corresponding full immersion corrosion conditions are as follows: 3.5% NaCl solution; test temperature: 35 ℃ is carried out. And (3) test period: and 72 h.
Each set of experiments was set up with 3 parallel samples.
As can be seen from Table 5, the corrosion resistance of example 1 is better than 09CuPCrNi under 3 accelerated corrosion conditions, wherein: the marine atmospheric corrosion resistance of the embodiment 1 is 1.4 times of that of 09 CuPCrNi; the industrial atmospheric corrosion resistance of the embodiment 1 is 1.2 times of that of 09 CuPCrNi; example 1 has 1.5 times the seawater corrosion resistance of 09 CuPCrNi.
TABLE 5 indoor Corrosion acceleration test data for examples and comparative examples
It should be noted that the cost of examples 2 to 4 is reduced by 500 yuan/ton, 400 yuan/ton, and 620 yuan/ton, respectively, compared to the conventional technique of completely using conventional raw materials such as blast furnace molten iron, scrap steel, master alloy, and pure metal. Therefore, the method has the advantages that the Cr low-Ni Mn-containing molten iron in the laterite-nickel ore and the alloy melted in the intermediate frequency furnace are injected into the AOD furnace through the ladle, nitrogen-blown smelting, LF refining and continuous casting are carried out, the cost is reduced, and the economical efficiency is good.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (8)
1. A low-carbon Cr-Ni series high-strength corrosion-resistant steel is characterized in that the alloy components of the low-carbon Cr-Ni series high-strength corrosion-resistant steel are as follows by mass percent: c: 0.01% -0.03%, Cr: 3.0% -10.0%, Ni: 1.5% -2.0%, Si: 0.1% -0.5%, Mn: 0.5% -1.0%, P: 0.04% -0.10%, S: less than or equal to 0.005 percent, N: 0.02% -0.06%, Cu: 0.2 to 0.5 percent of the total weight of the alloy, and the balance of Fe and inevitable impurities;
wherein, the alloying of Cr and Ni is realized by adopting molten iron with middle Cr, low Ni and Mn which is smelted by laterite-nickel ore, and the N content is realized by combining a nitrogen-blowing smelting process;
the microstructure of the steel is ferrite and tempered martensite, and the volume fraction of the ferrite is 15-40%.
2. The low-carbon Cr-Ni-based high-strength corrosion-resistant steel according to claim 1, wherein the low-carbon Cr-Ni-based high-strength corrosion-resistant steel has alloy components in mass percent: c: 0.015% -0.027%, Cr: 3.3% -9.8%, Ni: 1.5% -1.9%, Si: 0.1% -0.40%, Mn: 0.5% -1.0%, P: 0.04% -0.09%, S: less than or equal to 0.005 percent, N: 0.025% -0.058%, Cu: 0.25 to 0.48 percent, and the balance of Fe and inevitable impurities.
3. A method for producing a low-carbon Cr-Ni-based high-strength corrosion-resistant steel according to any one of claims 1 and 2, comprising:
step 1: smelting and casting to obtain a casting blank;
in the step 1, injecting Cr low-Ni Mn-containing molten iron in the laterite-nickel ore and an alloy melted on an intermediate frequency furnace into an AOD furnace through a ladle, blowing nitrogen for smelting, LF (ladle furnace) for refining, and continuously casting to form a casting blank;
step 2: homogenizing the casting blank, namely heating to an austenite homogenization temperature and preserving heat;
the austenite homogenization temperature is controlled to be 1150-1250 ℃, and when the Cr content of the low-carbon Cr-Ni series high-strength corrosion-resistant steel is 7-10%, the austenite homogenization temperature is controlled to be 1150-1200 ℃; the heat preservation time is 0.5-3 h;
and step 3: after the heat-preserved casting blank is discharged from a furnace, removing oxide skin, directly rolling, wherein the rolling process adopts two sections of rolling, namely recrystallization rough rolling and non-recrystallization finish rolling; wherein the accumulated deformation of rough rolling is more than or equal to 65 percent;
when the Cr content of the low-carbon Cr-Ni series high-strength corrosion-resistant steel is (3%, 7%), the recrystallization rough rolling temperature is controlled to be 1100-; when the Cr content is (7%, 10%), the recrystallization rough rolling temperature is controlled at 1100-;
and 4, step 4: after rolling to the target thickness in the step 3, carrying out laminar cooling to 550-750 ℃ for coiling to obtain a plate coil;
and 5: annealing the plate coil, wherein the annealing step comprises the following steps: the coiled plate coil is cooled to below 100 ℃ and then heated to 550 ℃ and 700 ℃ again, and the temperature is kept for 0.5-5 h.
4. The method as claimed in claim 3, wherein the austenite homogenization temperature is controlled to 1150-1195 ℃ when the Cr content of the low-carbon Cr-Ni based high-strength corrosion-resistant steel is 7-10% in the step 2.
5. The method for producing a low-carbon Cr-Ni-based high-strength corrosion-resistant steel according to claim 3, wherein the heat-retaining time in the step 2 is 1 to 3 hours.
6. The method for preparing low-carbon Cr-Ni based high-strength corrosion-resistant steel as claimed in claim 3, wherein in the step 3, when the Cr content of the low-carbon Cr-Ni based high-strength corrosion-resistant steel is [3%, 7% ], the recrystallization rough rolling temperature is controlled to 1100-.
7. The method for producing a low carbon Cr-Ni based high strength corrosion-resistant steel as claimed in claim 5, wherein in the step 3, when the Cr content of the low carbon Cr-Ni based high strength corrosion-resistant steel is (7%, 10%), the recrystallization roughing temperature is controlled to 1100-.
8. The method for producing a low carbon Cr-Ni based high strength corrosion-resistant steel according to any one of claims 4 to 7, wherein in the step 5, the annealing step is: the coiled plate coil is cooled to below 100 ℃, then is heated again to 600-650 ℃, and is kept warm for 3-2 h.
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| CN102127717A (en) * | 2010-01-18 | 2011-07-20 | 宝山钢铁股份有限公司 | Cr-contained weathering steel with excellent toughness and high corrosion resistance |
| JP4868917B2 (en) * | 2006-04-04 | 2012-02-01 | 株式会社神戸製鋼所 | Steel material for crude oil tank bottom plate with excellent corrosion resistance |
| JP2016514211A (en) * | 2013-03-13 | 2016-05-19 | シティー、ユニバーシティー、オブ、ホンコンＣｉｔｙ Ｕｎｉｖｅｒｓｉｔｙ Ｏｆ Ｈｏｎｇ Ｋｏｎｇ | Copper-rich nanocluster reinforced ultra high strength ferritic steel and method for producing the same |
| CN105957574A (en) * | 2016-07-17 | 2016-09-21 | 邢桂生 | Manufacturing method of nuclear waste packing device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP4868917B2 (en) * | 2006-04-04 | 2012-02-01 | 株式会社神戸製鋼所 | Steel material for crude oil tank bottom plate with excellent corrosion resistance |
| CN102127717A (en) * | 2010-01-18 | 2011-07-20 | 宝山钢铁股份有限公司 | Cr-contained weathering steel with excellent toughness and high corrosion resistance |
| JP2016514211A (en) * | 2013-03-13 | 2016-05-19 | シティー、ユニバーシティー、オブ、ホンコンＣｉｔｙ Ｕｎｉｖｅｒｓｉｔｙ Ｏｆ Ｈｏｎｇ Ｋｏｎｇ | Copper-rich nanocluster reinforced ultra high strength ferritic steel and method for producing the same |
| CN105957574A (en) * | 2016-07-17 | 2016-09-21 | 邢桂生 | Manufacturing method of nuclear waste packing device |
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