CN111218616B - Low-temperature-resistant high-toughness high-strength low-alloy round steel and preparation method thereof - Google Patents
Low-temperature-resistant high-toughness high-strength low-alloy round steel and preparation method thereof Download PDFInfo
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- CN111218616B CN111218616B CN202010104304.8A CN202010104304A CN111218616B CN 111218616 B CN111218616 B CN 111218616B CN 202010104304 A CN202010104304 A CN 202010104304A CN 111218616 B CN111218616 B CN 111218616B
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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
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
Abstract
The invention discloses a low-temperature-resistant high-toughness high-strength low-alloy round steel and a preparation method thereof, wherein the round steel comprises the following chemical components in percentage by mass: c: 0.11 to 0.12%, Si: 0.26 to 0.38%, Mn: 1.34-1.45%, Cr: 0.10 to 0.15%, Ni: 0.20 to 0.30%, Cu: 0.02 to 0.04%, Al: 0.033-0.058%, V: 0.079-0.086%, Nb: 0.021-0.025%, P is less than or equal to 0.020%, S is less than or equal to 0.008%, N is less than or equal to 80ppm, O is less than or equal to 18ppm, H is less than or equal to 1.5ppm, and the balance of Fe and other inevitable impurity elements. The method adopts a controlled rolling and controlled cooling process for rolling, a continuous casting slab is heated to 1150-1250 ℃, the heating time is 2.7-4 h, the rough rolling temperature is 1120-1180 ℃, the medium rolling temperature is 1070-1140 ℃, the finish rolling temperature is 920-1020 ℃, the temperature is controlled to be about 650 ℃, and then the continuous casting slab is put into a slow cooling pit and is naturally cooled to the temperature of less than or equal to 150 ℃. The yield strength of the produced product is more than or equal to 450MPa, the tensile strength is more than or equal to 600MPa, the elongation is more than or equal to 21 percent, the longitudinal impact energy at the temperature of-60 ℃ is more than or equal to 70J, the weldability is good, and the cold cracking tendency is small.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a high-strength low-alloy round steel with low temperature resistance and high toughness and a preparation method thereof.
Background
Mining and energy resource development in severe cold areas are more and more, and parts on engineering machinery also adapt to low-temperature environment, so that the requirement on low-temperature toughness of steel is more and more strict, and the steel has excellent performances such as high strength, good weldability and the like while having the low-temperature toughness.
The Chinese patent CN 104471098B application discloses a low-alloy high-strength structural steel, the Chinese patent CN 108342656A application discloses an ultra-high-strength automobile structural steel and a production method thereof, the low-temperature toughness temperatures of the disclosed low-alloy structural steel are respectively-40 ℃ and 0 ℃ which are not lower than the temperature of-60 ℃ in the invention, and Mo and Ti alloys with higher cost are added in the aspect of chemical components compared with the steel of the invention. The chinese patent CN 107236909B application discloses "high strength, high toughness corrosion resistant steel for-60 ℃ low temperature environment and its production method", the cost of the disclosed steel is much higher than that of the steel of the present invention, and it contains rare metals Zr and Ta. The Chinese patent CN 104451379A application discloses 'a high-strength low-alloy niobium vanadium structural steel and a preparation method thereof', which is different from the steel chemical composition of the invention and does not disclose various physical properties of the steel.
Disclosure of Invention
Based on the defects, the invention aims to provide the high-strength low-alloy round steel with low temperature resistance and high toughness and the preparation method thereof, and the steel has the advantages of relatively low cost, high toughness at low temperature, good weldability and good comprehensive mechanical properties.
In order to achieve the purpose, the invention adopts the following technical scheme:
the low-temperature-resistant high-toughness high-strength low-alloy round steel comprises the following chemical components in percentage by mass: c: 0.11 to 0.12%, Si: 0.26 to 0.38%, Mn: 1.34-1.45%, Cr: 0.10 to 0.15%, Ni: 0.20 to 0.30%, Cu: 0.02 to 0.04%, Al: 0.033-0.058%, V: 0.079-0.086%, Nb: 0.021-0.025%, P is less than or equal to 0.020%, S is less than or equal to 0.008%, N is less than or equal to 80ppm, O is less than or equal to 18ppm, H is less than or equal to 1.5ppm, and the balance of Fe and other inevitable impurity elements.
The Cr element forms stable and hard carbide in steel, and the content of the Cr element is designed to be 0.15 percent at most in order to obviously improve the strength and the hardness and not obviously reduce the plasticity and the toughness.
The Ni element is the most effective alloy element for improving the toughness of the steel, and the toughening mechanism is to make the material matrix easy to slide in a cross way at low temperature so as to improve the toughness, so the content of the Ni element is 0.30 percent at most for improving the low-temperature toughness of the steel.
The V element is easy to combine with carbon to form carbide, and because the dissolving temperature of VC is high, part of tiny undissolved VC exists in the steel in the quenching process, crystal boundaries are effectively pinned, the migration of the crystal boundaries is hindered, further, the crystal grains are refined, the obdurability of the material is improved, and the maximum designed V element is 0.086% in consideration of cost reasons.
Nb element can refine crystal grains, prevent recrystallization and delay phase change, can play roles of preventing austenite from growing up, refining austenite and ferrite crystal grains and generating precipitation strengthening effect, thereby improving the strength of the steel, and the maximum designed Nb element is 0.025%.
The invention also provides a preparation method of the low-temperature-resistant high-toughness high-strength low-alloy round steel, which comprises the processes of electric furnace smelting, LF refining, VD vacuum degassing, continuous casting, bar rolling and the like, wherein the invention adopts a controlled rolling and controlled cooling process for rolling, a continuous casting slab is heated to 1150-1250 ℃, the heating time is 2.7-4 h, the rough rolling temperature is 1120-1180 ℃, the medium rolling temperature is 1070-1140 ℃, the finish rolling temperature is 920-1020 ℃, the controlled cooling is carried out to about 650 ℃, and then the steel is put into a slow cooling pit for natural cooling to the temperature of less than or equal to 150 ℃.
The invention provides low-temperature-resistant high-toughness high-strength low-alloy round steel, which is prepared by the preparation method.
The invention further improves the strength of the steel material by microalloying Cr, Ni, V, Nb and other elements, simultaneously gives consideration to the toughness of the steel material at low temperature, and simultaneously has good welding performance.
Compared with the prior art, the invention has the following beneficial effects:
by using the simple operation processes of reasonable component design, smelting, rolling and cooling control and the like, the yield strength of the low-temperature-resistant high-toughness high-strength low-alloy round steel is more than or equal to 400MPa, the tensile strength is more than or equal to 550MPa, the elongation is more than or equal to 21 percent, the longitudinal impact energy at 60 ℃ is more than or equal to 70J, the carbon equivalent is less than or equal to 0.431, the weldability is good, and the cold cracking tendency is small. The steel grade well meets the requirements of low temperature resistance, high toughness, high strength and good weldability of engineering machinery parts used for operation in severe cold areas, and provides technical support for developing low-alloy round steel with low cost and high performance.
Detailed Description
Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. Unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features. The description is only for the purpose of facilitating understanding of the present invention and should not be construed as specifically limiting the present invention.
The following lists three chemical component ratios of the high-strength low-alloy round steel with low temperature resistance and high toughness produced by the production process of the invention, namely, the examples 1, 2 and 3, the chemical component ratios of the high-strength low-alloy round steel with low temperature resistance and high toughness obtained by the three examples are shown in table 1, the specific production process is shown in table 2, and the physical properties are shown in table 3.
Examples 1 to 3
The production method of the high-strength low-alloy round steel with low temperature resistance and high toughness comprises the following steps:
1) the smelting process comprises the following steps: smelting in an electric furnace;
2) LF refining and VD vacuum degassing: controlling the alkalinity of the slag to be more than 3.0, feeding 1.0-2.5 m/t steel into an aluminum wire, and feeding 1.0-2.5 m/t steel into a calcium wire; VD vacuum degree is less than 67Pa, and the holding time is more than or equal to 12 minutes;
3) continuous casting: the liquid level of the tundish is not less than 700mm, and the fluctuation of the liquid level of the crystallizer is less than or equal to +/-2 mm. The specification of the obtained casting blank is 260mm multiplied by 300 mm;
4) heating by a heating furnace: the continuous casting blank is heated to 1150-1250 ℃, the allowable temperature difference is less than or equal to 30 ℃, and the heating time is 2.7-4 hours.
5) Rolling: the rough rolling temperature is 1120-1180 ℃, the medium rolling temperature is 1070-1140 ℃, the finish rolling temperature is 920-1020 ℃, the temperature is controlled to be about 650 ℃, and then the steel is naturally cooled to the temperature of less than or equal to 150 ℃ in a slow cooling pit.
Table 1 chemical composition of examples 1-3 round steel
Table 2 examples 1-3 controlled rolling and cooling process for round steel
Table 3 mechanical properties of the round steels of examples 1-3
In Table 3, the yield strength, tensile strength and elongation of the steel materials are tested by GB/T228-2002 "tensile test at room temperature for metallic materials", and the impact energy of the steel materials is tested by GB/T229-2007 "impact test method for summer pendulum of metallic materials".
The method can be realized by upper and lower limit values and interval values of intervals of process parameters (such as temperature, time and the like), and embodiments are not listed.
Conventional technical knowledge in the art can be used for the details which are not described in the present invention.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (4)
1. The low-temperature-resistant high-toughness high-strength low-alloy round steel is characterized by comprising the following chemical components in percentage by mass: c: 0.11 to 0.12%, Si: 0.26 to 0.38%, Mn: 1.34-1.45%, Cr: 0.10 to 0.15%, Ni: 0.20 to 0.30%, Cu: 0.02 to 0.04%, Al: 0.033-0.058%, V: 0.079-0.086%, Nb: 0.021-0.025%, P is less than or equal to 0.020%, S is less than or equal to 0.008%, N is less than or equal to 80ppm, O is less than or equal to 18ppm, H is less than or equal to 1.5ppm, and the balance of Fe and other inevitable impurity elements;
the yield strength of the low-temperature-resistant high-toughness high-strength low-alloy round steel is more than or equal to 450MPa, the tensile strength of the low-temperature-resistant high-toughness low-alloy round steel is more than or equal to 600MPa, the elongation of the low-temperature-resistant high-toughness low-alloy round steel is more than or equal to 21 percent, the longitudinal impact energy at the temperature of 60 ℃ is more than or equal to.
2. The preparation method of the low-temperature-resistant high-toughness high-strength low-alloy round steel as claimed in claim 1, wherein the preparation method comprises the following steps:
and (3) rolling by adopting a controlled rolling and controlled cooling process, wherein the continuous casting blank is heated to 1150-1250 ℃, the heating time is 2.7-4 h, the rough rolling temperature is 1120-1180 ℃, the medium rolling temperature is 1070-1140 ℃, the finish rolling temperature is 920-1020 ℃, the continuous casting blank is controlled to be cooled to 650 ℃, and then the continuous casting blank is put into a slow cooling pit to be naturally cooled to the temperature of less than or equal to 150 ℃.
3. The method of claim 2, further comprising the steps of LF refining, VD vacuum degassing:
controlling the alkalinity of the slag to be more than 3.0, feeding 1.0-2.5 m/t steel into an aluminum wire, and feeding 1.0-2.5 m/t steel into a calcium wire; VD vacuum degree is less than 67Pa, and the holding time is more than or equal to 12 minutes.
4. The method of manufacturing according to claim 2, further comprising the step of continuous casting: the liquid level of the tundish is not less than 700mm, and the fluctuation of the liquid level of the crystallizer is +/-2 mm.
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