CN114990441B - Weather-resistant steel used in-70 ℃ environment and production method thereof - Google Patents
Weather-resistant steel used in-70 ℃ environment and production method thereof Download PDFInfo
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- CN114990441B CN114990441B CN202210624001.8A CN202210624001A CN114990441B CN 114990441 B CN114990441 B CN 114990441B CN 202210624001 A CN202210624001 A CN 202210624001A CN 114990441 B CN114990441 B CN 114990441B
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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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- 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
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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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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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
A weathering steel for use in an environment at-70 ℃ comprises the following components in percentage by weight: c:0.05 to 0.12 percent, less than or equal to 0.05 percent of Si, and the weight ratio of Mn:0.4 to 1.0 percent, P is not more than 0.035 percent, S: less than or equal to 0.005 percent, cu:0.10 to 0.55%, cr:1.20 to 2.50%, ni:0.82 to 2.50 percent. The production method comprises the following steps: converter steelmaking, tapping alloying and continuous casting into billets; heating a casting blank; rough rolling; finish rolling; two-section laminar cooling is adopted; and (4) coiling in a conventional manner. The invention guarantees that the yield strength is more than or equal to 355MPa, and the tensile strength is as follows: 470 to 650MPa, the elongation rate is more than or equal to 22 percent, kv2 at minus 70 ℃ is not less than 60J, the corrosion resistance is 30 percent or less under the same conventional test condition as Q345B, and the cold forming performance and the welding performance are good.
Description
Technical Field
The invention relates to steel for mechanical engineering and a production method thereof, in particular to weathering resistant steel used in an environment of-70 ℃ and a production method thereof.
Background
Due to the geographical environment and climate characteristics of different cooperative countries, the technical index difference between the demand of steel and the requirement of China is large, especially in some countries with low temperature, the outdoor temperature can reach-70 ℃, even lower, in order to ensure the safety, the steel material used in the country requires the impact toughness temperature to reach-70 ℃, and the minimum demand of national standard and industrial standard of China on the low-temperature impact energy of the weathering steel is-40 ℃. In the face of the development trend, it is necessary to develop weathering steel with impact toughness at a temperature of-70 ℃ so as to meet the requirement of enterprises in China for developing weathering steel used in an extremely cold environment of 70 ℃.
The document of Chinese patent application No. 2021110487697 discloses a' low-alloy high-strength steel suitable for the environment of-70 ℃, which has low impact value although the-70 ℃ impact toughness can meet the index requirement, and cannot be applied to forming complicated engineering and mechanical parts. Meanwhile, in the production method of the document, since cooling is performed once, the final structure of the steel material is ferrite + pearlite, and the pearlite structure of the hard phase is not favorable for improving the low-temperature toughness of the steel.
The Chinese patent publications CN 106435360A, CN 102168229 and CN 101994064A respectively emphasize the component design and the production method of the weathering steel, and the impact toughness of the weathering steel can not meet the use requirement of minus 70 ℃.
The invention produces the weathering steel with good impact toughness at minus 70 ℃ mainly by an innovative production method, particularly a rolling method, which is different from the idea of 'a low-alloy high-strength steel suitable for the environment of minus 70 ℃ in the patent application No. 2021110487697', greatly improves the impact energy at minus 70 ℃, and has wider application field; meanwhile, the steel is different from other weathering steel mainly in that the steel has good impact toughness at the temperature of-70 ℃, and is suitable for severer use environments.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a method for preparing a high-strength steel plate with the following characteristics that the yield strength is ensured to be more than or equal to 355MPa, and the tensile strength is ensured to be: 470-650 MPa, elongation not less than 22%, kv2 at-70 ℃ not less than 60J, corrosion resistance of 30% or less under the same conventional test conditions as Q345B, good cold formability and welding performance, and the production method thereof.
The measures for realizing the aim are as follows:
a weathering steel used in-70 ℃ environment comprises the following components by weight percent: c:0.05 to 0.12 percent, less than or equal to 0.05 percent of Si, mn: 0.4-1.0%, P is not more than 0.035%, S: less than or equal to 0.005%, cu:0.10 to 0.55%, cr:1.20 to 2.50%, ni:0.82 to 2.50 percent, balance iron and inevitable impurities, and the following content: cu + Cr is more than or equal to 1.50 and less than or equal to 2.42 percent, and (Cu + Cr)/Ni is more than or equal to 0.95 and less than or equal to 2.48 percent.
Preferably: the weight percentage content of C is 0.063-0.105%.
Preferably: the weight percentage content of Cr is 1.33-2.35%.
Preferably: the weight percentage content of Ni is 1.56-2.35%.
Preferably: cu + Cr is more than or equal to 1.60 percent and less than or equal to 2.35 percent; (Cu + Cr)/Ni is more than or equal to 1.15 percent and less than or equal to 1.63 percent.
A production method of weathering steel used in-70 ℃ environment comprises the following steps:
1) Converter steelmaking, alloying the steel and continuously casting into a blank;
2) Heating the casting blank, and controlling the heating temperature to be 1200-1250 ℃;
3) Rough rolling is carried out, the rolling finishing temperature is controlled to be 1020-1060 ℃, and the accumulated reduction rate is not lower than 75 percent;
4) Carrying out finish rolling, and controlling the initial rolling temperature not to exceed 940 ℃ and the final rolling temperature to be 780-820 ℃;
5) Adopting two-stage laminar cooling, wherein the first stage is cooled to 600-640 ℃ at the cooling speed of 50-60 ℃/s; after air cooling for 6-14 s, carrying out second-stage laminar cooling, wherein the laminar cooling is carried out to 450-520 ℃ at the cooling speed of 25-45 ℃/s;
6) And (4) coiling in a conventional manner.
Preferably: the heating temperature of the casting blank is 1218-1243 ℃.
Preferably: the rough rolling finishing temperature is 1032-1052 ℃ and the cumulative reduction rate is not lower than 83 percent.
Preferably: the initial rolling temperature of the finish rolling is not more than 920 ℃, and the final rolling temperature is 792-815 ℃.
Preferably: laminar flow cooling: the first section is cooled to 617-629 ℃ at a cooling speed of 54-57 ℃/s; after air cooling for 9-12 s, the second stage laminar cooling is carried out, and the second stage laminar cooling is carried out at a cooling speed of 28-35 ℃/s to 462-508 ℃.
The action and mechanism of each metal element and main process in the invention
C: in the invention, C is the most economical and effective alloy element for improving the strength of the steel, but the low-temperature impact toughness of the steel is obviously deteriorated due to the over-high content of C, the ultra-low C design is adopted, the formation of carbide structures is reduced, and the low-temperature impact toughness of the steel is improved, the content of C in the steel is 0.05-0.12%, and the content of C in percentage by weight is preferably 0.063-0.105%.
Si: si is an important element influencing the surface quality of the hot-rolled strip steel, and in order to ensure the good surface quality of the steel plate, the Si content in the steel is designed to be less than or equal to 0.04 percent.
Mn: in the invention, the strength of the steel can be improved through the solid solution strengthening of Mn, the phase transition temperature of the steel can be reduced, the crystal grains are refined, and the low-temperature toughness of the steel is improved, and the Mn content of the steel is designed to be 0.4-1.0%.
P: in the invention, P is one of impurity elements in the low-alloy steel, and the content of P is high, so that the steel has a relatively obvious cold brittleness tendency on one hand, and P is easy to generate P segregation on the other hand, and the cold forming performance and the low-temperature impact toughness are obviously deteriorated. The P content in the steel is controlled to be low, and the P content does not exceed 0.035%.
S: in the present invention, S is a harmful element in steel, and the produced sulfide inclusions seriously affect the low-temperature impact toughness of steel, so the S content in steel should be reduced as much as possible to 0.003% or less.
Cu: the element is the main weathering element in weathering steel, can effectively improve the weathering performance of the steel, and Cu is added into the steel as an alloy element and has the functions of solid solution and precipitation strengthening. Therefore, the Cu content is controlled to 0.10 to 0.55%.
Cr: the element is matched with Cu and other elements in the steel for use, so that the atmospheric corrosion resistance of the steel can be obviously improved, a compact oxide film can be promoted to be formed on the surface of the steel, and the passivation capability of the steel is improved. In addition, cr element can effectively improve the hardenability of steel, so that the content of Cr is controlled to be 1.20-2.50%, and the content of Cr is preferably 1.33-2.35% by weight; and 1.50. Ltoreq. Cu + Cr. Ltoreq.2.42, preferably 1.60. Ltoreq. Cu + Cr. Ltoreq.2.35%.
Ni: the element is the most effective element for resisting atmospheric corrosion, the action of the element on the atmospheric corrosion resistance is increased along with the increase of the content of the element, in addition, the addition of Ni can also improve the low-temperature toughness of steel and effectively prevent the hot brittleness phenomenon of Cu, so the Ni content is controlled to be 0.82-2.50 percent in the consideration of improving the corrosion resistance of weather-resistant steel and the low-temperature impact toughness at-70 ℃. Wherein 0.95 ≦ (Cu + Cr)/Ni ≦ 2.48, preferably 1.15 ≦ (Cu + Cr)/Ni ≦ 1.63%.
The invention adopts two-stage laminar cooling, the first stage is cooled to 600-640 ℃ at the cooling speed of 50-60 ℃/s; after 6-14 s of air cooling, a second stage of laminar cooling is carried out, the stage is cooled to 450-520 ℃ at a cooling rate of 25-45 ℃/s, and laminar cooling is preferably carried out: the first section is cooled to 617-629 ℃ at a cooling speed of 54-57 ℃/s; and carrying out second-stage laminar cooling after air cooling for 9-12 s, wherein the cooling speed in the second stage is 28-35 ℃/s, the cooling is carried out to 462-508 ℃, the first-stage strong cooling is carried out, the rapid cooling is carried out to the design temperature, the tissue refinement is facilitated, the impact toughness is improved, sufficient time is provided in the air cooling stage to fully transform the tough tissue, the second-stage cooling is carried out at medium speed to uniformly transform the tissue, and finally, a single, uniform and fine ferrite-ferrite single-phase tissue is obtained, and the improvement of the steel-70 ℃ impact power is facilitated.
Compared with the prior art, the invention ensures that the yield strength is more than or equal to 355MPa, the tensile strength is as follows: 470-650 MPa, elongation not less than 22%, kv2 at-70 deg.C not less than 60J, corrosion resistance of 30% or less under the same conventional test condition as Q345B, and good cold-forming property and welding property.
Detailed Description
The present invention is described in detail below:
table 1 is a list of chemical compositions for each example of the invention;
table 2 is a table of the main process parameters of each embodiment of the present invention;
table 3 is a table of performance testing scenarios for various embodiments of the present invention.
The examples of the invention were produced as follows
1) Converter steelmaking, alloying the steel and continuously casting into a blank;
2) Heating the casting blank, and controlling the heating temperature to be 1200-1250 ℃;
3) Rough rolling is carried out, the rolling finishing temperature is controlled to be 1020-1060 ℃, and the accumulated reduction rate is not lower than 75 percent;
4) Carrying out finish rolling, and controlling the initial rolling temperature not to exceed 940 ℃ and the final rolling temperature to be 780-820 ℃;
5) Adopting two-stage laminar cooling, wherein the first stage is cooled to 600-640 ℃ at the cooling speed of 50-60 ℃/s; carrying out second-stage laminar cooling after air cooling for 6-14 s, wherein the second-stage laminar cooling is carried out at the cooling speed of 25-45 ℃/s to 450-520 ℃;
6) And (4) coiling in a conventional manner.
TABLE 1 list of chemical compositions (wt%) of inventive and comparative examples
Table 2 list of main process parameters of various embodiments of the present invention
TABLE 3 mechanical Properties of examples of the invention and comparative examples
Note: experimental conditions for 72 hours: test solutions: 1.0X 10 -2 mol/l NaHSO 3 And (3) supplying solution: 2.0X 10 -2 mol/l NaHSO 3 The test temperature: 45 ± 2 ℃, relative humidity: 70 +/-5 RH.
As can be seen from Table 3, the mechanical properties of the steels of the examples of the invention are: the yield strength is more than 355MPa, the tensile strength is 501-570 MPa, the elongation is more than 22%, B =20mm, d =2a is qualified in bending tests, kv2 at-70 ℃ is more than 80J, and the corrosion resistance rate relative to Q345 is less than or equal to 30%. It can completely meet the requirements of steel for engineering machinery at extremely low temperature.
The present embodiments are merely preferred examples, and are not intended to limit the scope of the present invention.
Claims (5)
1. A production method of weathering steel used in-70 ℃ environment comprises the following steps:
1) Converter steelmaking, tapping alloying and continuous casting into billets;
2) Heating the casting blank, and controlling the heating temperature to be 1200-1250 o C；
3) Rough rolling is carried out, the rolling finishing temperature is controlled to be 1020-1060 ℃, and the accumulated reduction rate is not lower than 75 percent;
4) Carrying out finish rolling, and controlling the initial rolling temperature not to exceed 940 ℃ and the final rolling temperature to be 780-820 ℃;
5) Carrying out laminar cooling by adopting two sections, wherein the first section is cooled to 600-640 ℃ at a cooling speed of 50-60 ℃/s; carrying out second-stage laminar cooling after air cooling for 6-14S, and cooling to 450-520 ℃ at a cooling speed of 25-45 ℃/s;
6) Coiling in a conventional way;
the weathering steel used in the environment of-70 ℃ comprises the following components in percentage by weight: c:0.05 to 0.12%, si not more than 0.04%, mn:0.4 to 1.0 percent, P is not more than 0.035 percent, S: less than or equal to 0.005%, cu:0.10 to 0.55%, cr:1.20 to 2.50%, ni:0.82 to 2.50 percent, balance iron and inevitable impurities, and the balance iron and the inevitable impurities meet the following requirements: cu + Cr is more than or equal to 1.50 and less than or equal to 2.42 percent, and (Cu + Cr)/Ni is more than or equal to 0.95 and less than or equal to 2.48 percent.
2. The method for producing weathering steel for use in an environment of-70 ℃ according to claim 1, wherein: the heating temperature of the casting blank is 1218-1243 ℃.
3. The method for producing weathering steel for use in an environment of-70 ℃ according to claim 1, wherein: the rough rolling finishing temperature is 1032 to 1052 ℃, and the cumulative reduction is not lower than 83 percent.
4. The method for producing weathering steel for use in an environment of-70 ℃ according to claim 1, wherein: the initial rolling temperature of the finish rolling is not more than 920 ℃, and the final rolling temperature is 792-815 ℃.
5. The method for producing weathering steel for use in an environment of-70 ℃ according to claim 1, characterized in that: laminar flow cooling: cooling the first section to 617-629 ℃ at a cooling speed of 54-57 ℃/s; and after air cooling for 9 to 12s, carrying out second-stage laminar cooling, wherein the cooling speed is 28 to 35 ℃/s, and the cooling is carried out to 462 to 508 ℃ in the stage.
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| JPH08199233A (en) * | 1995-01-30 | 1996-08-06 | Nippon Steel Corp | Production of high strength gauge h steel excellent in surface characteristic |
| CN107475624A (en) * | 2017-08-16 | 2017-12-15 | 攀钢集团攀枝花钢铁研究院有限公司 | Titaniferous think gauge weathering steel and its production method |
| CN108251746B (en) * | 2018-01-31 | 2019-03-12 | 福建三宝钢铁有限公司 | A kind of high durable, sea water corrosion-resistant steel with low cost muscle and production technology |
| MX2022003382A (en) * | 2019-09-19 | 2022-07-11 | Nucor Corp | Ultra-high strength weathering steel for hot-stamping applications. |
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