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WO2021057954A9 - Steel for alloy structure and manufacturing method therefor - Google Patents

Steel for alloy structure and manufacturing method therefor Download PDF

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Publication number
WO2021057954A9
WO2021057954A9 PCT/CN2020/118043 CN2020118043W WO2021057954A9 WO 2021057954 A9 WO2021057954 A9 WO 2021057954A9 CN 2020118043 W CN2020118043 W CN 2020118043W WO 2021057954 A9 WO2021057954 A9 WO 2021057954A9
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WIPO (PCT)
Prior art keywords
steel
alloy
particles
structural steel
alloy structure
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PCT/CN2020/118043
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French (fr)
Chinese (zh)
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WO2021057954A1 (en
Inventor
郑宏光
柳向椿
刘俊江
翟瑞银
万根节
夏杨青
孟庆玉
Original Assignee
宝山钢铁股份有限公司
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Priority to KR1020227010806A priority Critical patent/KR102713980B1/en
Priority to EP20869967.8A priority patent/EP4036266A4/en
Priority to US17/763,348 priority patent/US20220349035A1/en
Priority to JP2022519356A priority patent/JP7443502B2/en
Publication of WO2021057954A1 publication Critical patent/WO2021057954A1/en
Publication of WO2021057954A9 publication Critical patent/WO2021057954A9/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/58—Oils
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/60—Aqueous agents
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • 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
    • 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
    • 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
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D2211/004—Dispersions; Precipitations
    • 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
    • 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
    • C21D2211/009—Pearlite

Definitions

  • the invention relates to a steel grade and a manufacturing method thereof, in particular to a steel for alloy structure and a manufacturing method thereof.
  • 40CrV can be used to manufacture various important parts with variable load and high load, such as locomotive connecting rods, crankshafts, push rods, propellers, beams, bushing brackets, studs, screws, non-carburized gears, nitriding treatment Various gears and pins, high-pressure boiler water pump shaft (diameter less than 30mm), high-pressure cylinder, steel pipe and bolts (the working temperature is less than 420 °C, the strength is 30MPa), etc.
  • the existing 40CrV composition range is as follows: C 0.37-0.44wt%; Si 0.17-0.37wt%; Mn 0.5-0.8wt%; S ⁇ 0.015wt%; P ⁇ 0.025wt%; Cr 0.8-1.1wt%; V 0.1-0.2wt%; Al ⁇ 0.015wl.
  • the mechanical properties of this steel are as follows: yield strength (Rel) ⁇ 735MPa; tensile strength (Rm) ⁇ 885MPa; elongation ⁇ 10%; hardness ⁇ 241HB; impact toughness ⁇ 71J.
  • One of the objectives of the present invention is to provide a steel for alloy structure, which adopts the design of adding trace alloying elements, and controls the total oxygen with a lower content by adding an appropriate amount of Zr and Mg. It further strengthens and toughens the alloy structural steel, so that the alloy structural steel has higher strength and lower material cost.
  • the present invention proposes a kind of steel for alloy structure, and its chemical element mass percentage is:
  • C In the alloy structural steel according to the present invention, C mainly affects the precipitation amount and precipitation temperature range of carbides. Controlling the lower mass percentage of C is beneficial to improve the mechanical properties of the alloy structural steel of the present invention. In addition, C has a certain strengthening effect, but too high mass percentage of C will reduce the corrosion resistance of the material. Considering the production capacity of the smelting equipment and taking into account the mechanical properties and impact toughness of the material, the mass percentage of C in the alloy structural steel of the present invention is controlled to be 0.35-0.45%.
  • Si can increase the strength of the steel in the steel, but it is not good for the formability and toughness of the steel. In addition, Si often remains in the smelting process, so it is important to properly select the content of Si. Based on this, the mass percentage of Si in the alloy structural steel of the present invention is controlled to be 0.27-0.35%.
  • Mn is a weak austenitic element that can suppress the harmful effects of sulfur in alloy structural steels and improve thermoplasticity.
  • too high mass percentage of Mn is not conducive to ensuring its corrosion resistance.
  • the mass percentage of Mn is controlled to be 0.6-0.8% in the technical solution of the present invention.
  • Al In the alloy structural steel according to the present invention, Al mainly controls the oxygen content in the steel and affects the dislocation behavior to strengthen the alloy. Increasing the total amount of Al can significantly improve the solution temperature and mechanical properties, but it will reduce the plasticity. In addition, the addition of Al is beneficial to the elongation deformation properties of the steel and improves the processing properties of the steel. Too high Al content will reduce the impact toughness of steel. Based on this, the mass percentage of Al in the alloy structural steel of the present invention is controlled to be 0.015-0.05%.
  • V has a very strong affinity with carbon and oxygen, and can form a corresponding stable compound.
  • V mainly exists in the form of carbides in steel.
  • the main function of V is to refine the structure and grain of the steel and reduce the strength and toughness of the steel.
  • V dissolves into solid solution at high temperature, it increases the hardenability; on the contrary, if it exists in the form of carbide, it reduces the hardenability.
  • V can increase the tempering stability of quenched steel and produce a secondary hardening effect.
  • Vanadium in alloy structural steel is often used in combination with manganese and chromium elements because it will reduce the hardenability under general heat treatment conditions. Vanadium is mainly used in quenched and tempered steel to improve the strength and yield ratio of steel, refine grains and reduce overheating sensitivity. Based on this, the mass percentage of V in the alloy structural steel of the present invention is controlled to be 0.06-0.1%.
  • Zr is a strong carbide forming element, and its function in steel is similar to that of niobium, tantalum and vanadium. Adding a small amount of Zr can play the role of degassing, purification and grain refinement, which is beneficial to the low temperature performance of steel and improves the stamping performance. In addition, a small amount of Zr is added, and part of the Zr is dissolved in the steel to form an appropriate amount of ZrC and ZrN, which is beneficial to refine the grains and improve the stamping performance. Based on this, the mass percentage of Zr in the alloy structural steel of the present invention is controlled to be 0.2-1.0%.
  • Mg is a very active metal element, which has a strong affinity with O, N, and S. Therefore, Mg is a good deoxidizer and desulfurizer in iron and steel smelting, and is also a good nodularizer for cast iron. However, Mg is hardly dissolved in the matrix of cast iron, and exists in the state of compounds MgS, MgO, Mg 3 N 2 and Mg 2 Si. In addition, Mg and C can also form a series of compounds, such as MgC 2 , Mg 2 C 3 . Based on this, the mass percentage of Mg in the alloy structural steel of the present invention is controlled to be 0.001-0.005%.
  • N is a stable austenite element. Controlling a relatively low mass percentage of N is beneficial to improve the impact toughness of the alloy structural steel of the present invention. In addition, higher mass percentages of nitrogen result in reduced toughness and ductility of the steel, and also reduce hot workability. Based on this, the mass percentage of N in the alloy structural steel of the present invention is controlled to be N ⁇ 0.005%.
  • O In the alloy structural steel of the present invention, O mainly exists as oxide inclusions, and a high total oxygen content indicates that there are many inclusions. Reducing the total oxygen content is beneficial to improve the comprehensive properties of the material. In order to ensure good mechanical and corrosion resistance properties of the material, in the technical solution of the present invention, the mass percentage of O is controlled to be O ⁇ 0.001%.
  • the alloy structural steel of the present invention also has at least one of the following chemical elements: Ce, Hf, La, Re, Sc and Y, and the total addition amount of these elements is ⁇ 1% .
  • a small amount of the above-mentioned rare earth elements can be added to combine oxygen and sulfur elements in steel to form rare earth oxides and sulfides, purify molten steel and reduce the size of inclusions.
  • the formed rare earth oxides and sulfides can be used as nucleation particles in the solidification process to refine the initial solidified grains, and also help to improve the properties of steel.
  • the mass percentage content of each element satisfies at least one of the following items:
  • the mass percentage content ratio of each element also satisfies at least one of the following items:
  • controlling the mass percentage of Zr to N, V, and C is beneficial to control the amount of ZrC and ZrN formed, and the formation of ZrC and ZrN can play a role in refining grains, improving steel mechanical properties and stamping properties. At the same time, it can also play a role in solidifying part of the N in the steel and reducing the mass percentage of the solid solution N.
  • the mass percentage content ratio of each element also satisfies at least one of the following items:
  • controlling the mass percentage of Mg to O and S can be beneficial to the formation of MgO and MgS in the alloy during the cooling and solidification process, and the formation of MgS and MgO can further refine the grains and stabilize the alloy. On the other hand, it can also reduce the damage of O and S in the alloy to the grain boundary, thereby improving the impact toughness of the alloy structural steel in this case.
  • the matrix of its microstructure is ferrite+pearlite, which has ZrC, ZrN, MgO, MgS particles.
  • the above-mentioned particles of ZrC, ZrN, MgO, and MgS mean that ZrC, ZrN, MgO, and MgS exist in the form of fine particles in the steel for alloy structure.
  • the above-mentioned particles can further refine and stabilize the austenite grain size during the continuous casting cooling and solidification process and the hot rolling process, thereby avoiding the formation of defects on the surface of the billet or the final product, and can also improve the mechanical properties of the product.
  • the sum of the number of ZrC and ZrN particles is 3-15 particles/mm 2 .
  • controlling the sum of the number of ZrC and ZrN particles to 3-15 particles/mm 2 can reduce the amount of solidified grains, improve the mechanical properties and stamping properties of steel, and reduce the amount of N in the solidified steel.
  • the effect of the mass percentage of dissolved N is better.
  • the sum of the numbers of MgO and MgS particles is 5-20 particles/mm 2 .
  • controlling the sum of the number of MgO and MgS particles to be 5-20 particles/mm 2 can further refine the grains, stabilize the austenite grains and reduce the effect of O and S on the grain boundaries in the alloy. Therefore, the effect of improving the impact toughness of the alloy structural steel in this case is better.
  • the diameters of the particles of ZrC, ZrN, MgO and MgS are 0.2-7 ⁇ m.
  • the yield strength is greater than or equal to 755MPa
  • the tensile strength is greater than or equal to 900MPa
  • the elongation is greater than or equal to 12%
  • the impact toughness is greater than or equal to 100J.
  • another object of the present invention is to provide the above-mentioned manufacturing method of alloy structural steel, through which alloy structural steel with higher mechanical properties, better impact toughness and more reasonable cost can be obtained.
  • the present invention proposes a method for manufacturing the above-mentioned alloy structural steel, which comprises the steps:
  • step (1) electric furnace smelting, LF and VD (or RH) refining can be used in step (1), and a small amount of zirconium iron, and magnesium-aluminum alloys, after the mass percentage of each chemical element in the steel meets the range limited in this case, soft stirring with argon blowing is performed, and the argon gas flow is controlled at 5-8 liters/min.
  • step (1) bloom continuous casting can be used for casting, and the pulling speed is controlled to be 0.45-0.65m/min; mold powder is used, and mold electromagnetic stirring is used, and the current is 500A , the frequency is 2.5-3.5Hz, and the equiaxed crystal proportion of the bloom after continuous casting is ⁇ 20%.
  • the blank in step (2), can be pretreated before blooming, for example, surface finishing and grinding can be performed to remove visible surface defects and ensure good surface quality.
  • the heating temperature during preliminary rolling is 1150-1250°C; the heating temperature during secondary hot rolling is 1150-1250°C .
  • step (4) the quenching heating temperature is controlled at 855-890° C., the quenching cooling rate is controlled at 50-90° C./s; the tempering heating temperature is controlled at 645-670° C. °C, the tempering cooling rate is controlled at 50-90°C/s.
  • the coolant used for quenching may be mineral oil, and the coolant used for tempering may be mineral oil or water.
  • the steel for alloy structure and the manufacturing method thereof of the present invention have the following advantages and beneficial effects:
  • the steel for alloy structure of the present invention adopts the design of adding trace alloy elements. By adding an appropriate amount of Zr and Mg, the total oxygen content is controlled at a lower content, and the characteristics of the added trace alloy elements are used to further strengthen and toughen the alloy structure. steel, so that the alloy structural steel has higher strength and lower material cost.
  • the alloy structural steel of embodiment 1-6 adopts the following steps to make:
  • RH refining can also be used for refining, and at the end of VD (or RH) refining, a small amount of zirconium-iron and magnesium-aluminum alloys can be added successively to prepare the chemical elements in the steel. After the mass percentage satisfies the range defined in this case, soft stirring is performed by blowing argon gas, and the argon gas flow rate is controlled at 5-8 liters/min.
  • step (1) bloom continuous casting can be used for casting, and the pulling speed is controlled to be 0.45-0.65m/min; mold powder is used, and mold electromagnetic stirring is used, and the current is 500A , the frequency is 2.5-3.5Hz, and the equiaxed crystal proportion of the bloom after continuous casting is ⁇ 20%.
  • the blank in step (2), can be pretreated before blooming, for example, surface finishing and grinding can be performed to remove visible surface defects and ensure good surface quality.
  • Comparative Examples 1-3 were obtained by using the components and manufacturing processes of the prior art.
  • Table 1 lists the mass percentage ratio of each chemical element of the alloy structural steels of Examples 1-6 and the existing structural steels of Comparative Examples 1-3.
  • Table 2 lists the microstructures in the obtained alloy structural steels of Examples 1-6 and the existing structural steels of Comparative Examples 1-3.
  • Table 3 lists the specific process parameters of the alloy structural steels of Examples 1-6 and the existing alloy structural steels of Comparative Examples 1-3.
  • the tensile test (yield strength R el , tensile strength R m , elongation test) of the present invention is tested by using a zwick/roell Z330 tensile testing machine, and the test standard is in accordance with the national standard GB/T 228.1-2010. Among them, the tests of yield strength R el , tensile strength R m and elongation are carried out according to the standards defined in 3.10.1, 3.10.2 and 3.6.1 of this standard, respectively.
  • the impact toughness was tested by Zwick/Roell PSW 750 impact testing machine.
  • the test standard was in accordance with the national standard GB/T 229-2007.
  • the value of impact toughness was obtained by measuring the energy absorbed by the alloy structural steel in the Charpy impact test.
  • the number of ZrC and ZrN particles, the number of MgO and MgS particles, the statistics and determination methods of ZrC, ZrN, MgO, MgS particle diameters were carried out by scanning electron microscope (SEM). oxford X-max 20, the determination standard is carried out according to GB/T 30834-2014.
  • Table 4 lists the test results of various examples and comparative examples.
  • Example 1 755 900 12 123 Example 2 765 905 13 125 Example 3 763 910 12 108 Example 4 770 908 14 137 Example 5 767 912 13 117 Example 6 758 907 12 100 Comparative Example 1 735 885 10 78 Comparative Example 2 730 890 11 85 Comparative Example 3 732 893 10 73
  • the steel for alloy structure in each embodiment of this case has ZrC, ZrN, MgO, MgS particles because of its microstructure of ferrite + pearlite, and these particles play a role in refining,
  • the effect of stabilizing the austenite grains is conducive to improving the mechanical properties of the material. Therefore, the alloy structural steels of the examples in this case have better mechanical properties than the existing structural steels in Comparative Examples 1-3 using the prior art.
  • the yield strength of the alloy structural steel of each embodiment is ⁇ 755 MPa
  • the tensile strength is ⁇ 900 MPa
  • the elongation is ⁇ 12%
  • the impact toughness is ⁇ 100J.
  • the steel for alloy structure of the present invention adopts the design of adding trace alloying elements.
  • the total oxygen content is controlled at a lower content, and the characteristics of the added trace alloying elements are used to further strengthen and toughen the steel.
  • the alloy structural steel can be melted, so that the alloy structural steel has higher strength and lower material cost.

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  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
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  • Heat Treatment Of Steel (AREA)

Abstract

Disclosed is a steel for an alloy structure, the chemical elements of the steel being, in percentage by mass: 0.35-0.45% of C, 0.27-0.35% of Si, 0.6-0.8% of Mn, 0.015-0.05% of Al, 0.06-0.1% of V, 0.2-1.0% of Zr, 0.001-0.005% of Mg, P ≤ 0.025%, S ≤ 0.015%, N ≤ 0.005%, O ≤ 0.001%, the balance being Fe and other inevitable impurities. In addition, also disclosed is a method for manufacturing the steel for an alloy structure, the method comprising the steps of: (1) smelting, refining and casting; (2) blooming and cogging; (3) secondary hot rolling to form a product; and (4) heat treatment, involving quenching + tempering. The steel for an alloy structure is designed by adding trace alloy elements, the steel for an alloy structure is further strengthened and toughened, and the manufacturing cost is low.

Description

一种合金结构用钢及其制造方法A kind of steel for alloy structure and its manufacturing method 技术领域technical field
本发明涉及一种钢种及其制造方法，尤其涉及一种合金结构用钢及其制造方法。The invention relates to a steel grade and a manufacturing method thereof, in particular to a steel for alloy structure and a manufacturing method thereof.
背景技术Background technique
40CrV可以用于制造变载、高负荷的各种重要零件，如机车连杆、曲轴、推杆、螺旋桨、横梁、轴套支架、双头螺柱、螺钉、不渗碳齿轮、经渗氮处理的各种齿轮和销子、高压锅炉水泵轴(直径小于30mm)、高压气缸、钢管以及螺栓(其工作温度小于420℃，强度为30MPa)等。40CrV can be used to manufacture various important parts with variable load and high load, such as locomotive connecting rods, crankshafts, push rods, propellers, beams, bushing brackets, studs, screws, non-carburized gears, nitriding treatment Various gears and pins, high-pressure boiler water pump shaft (diameter less than 30mm), high-pressure cylinder, steel pipe and bolts (the working temperature is less than 420 ℃, the strength is 30MPa), etc.
按照合金结构钢标准(GB/T 3077-2015)，现有的40CrV成份范围如下：C 0.37-0.44wt％；Si 0.17-0.37wt％；Mn 0.5-0.8wt％；S≤0.015wt％；P≤0.025wt％；Cr 0.8-1.1wt％；V 0.1-0.2wt％；Al≥0.015wl。该钢种力学性能如下：屈服强度(Rel)≥735MPa；抗拉强度(Rm)≥885MPa；延伸率≥10％；硬度≥241HB；冲击韧性≥71J。According to the alloy structural steel standard (GB/T 3077-2015), the existing 40CrV composition range is as follows: C 0.37-0.44wt%; Si 0.17-0.37wt%; Mn 0.5-0.8wt%; S≤0.015wt%; P ≤0.025wt%; Cr 0.8-1.1wt%; V 0.1-0.2wt%; Al≥0.015wl. The mechanical properties of this steel are as follows: yield strength (Rel) ≥ 735MPa; tensile strength (Rm) ≥ 885MPa; elongation ≥ 10%; hardness ≥ 241HB; impact toughness ≥ 71J.
随着技术的发展，该钢种的力学性能不能够完全满足目前实际应用和制造的要求，基于此，期望获得一种力学性能更高、冲击韧性更好、成本更合理的合金结构用钢，以满足实际应用的需要。With the development of technology, the mechanical properties of this steel cannot fully meet the requirements of current practical application and manufacturing. Based on this, it is expected to obtain an alloy structural steel with higher mechanical properties, better impact toughness and more reasonable cost. to meet the needs of practical applications.
发明内容SUMMARY OF THE INVENTION
本发明的目的之一在于提供一种合金结构用钢，该合金结构用钢采用微量合金元素添加设计，通过添加适量的Zr、Mg，控制较低含量的总氧，利用所添加微量合金元素的特点，进一步强化、韧化该合金结构用钢，使得该合金结构用钢具有较高的强度，且材料成本较低。One of the objectives of the present invention is to provide a steel for alloy structure, which adopts the design of adding trace alloying elements, and controls the total oxygen with a lower content by adding an appropriate amount of Zr and Mg. It further strengthens and toughens the alloy structural steel, so that the alloy structural steel has higher strength and lower material cost.
为了实现上述目的，本发明提出了一种合金结构用钢，其化学元素质量百分比为：In order to achieve the above-mentioned purpose, the present invention proposes a kind of steel for alloy structure, and its chemical element mass percentage is:
C：0.35-0.45％、Si：0.27-0.35％、Mn：0.6-0.8％、Al：0.015-0.05％、V： 0.06-0.1％、Zr：0.2-1.0％、Mg：0.001-0.005％、P≤0.025％、S≤0.015％、N≤0.005％、O≤0.001％，余量为Fe和其他不可避免的杂质。C: 0.35-0.45%, Si: 0.27-0.35%, Mn: 0.6-0.8%, Al: 0.015-0.05%, V: 0.06-0.1%, Zr: 0.2-1.0%, Mg: 0.001-0.005%, P ≤0.025%, S≤0.015%, N≤0.005%, O≤0.001%, and the balance is Fe and other inevitable impurities.
在本发明所述的合金结构用钢中，各化学元素的设计原理如下所述：In the alloy structural steel of the present invention, the design principles of each chemical element are as follows:
C：在本发明所述的合金结构用钢中，C主要影响碳化物的析出量和析出温度范围。控制较低的C的质量百分比有利于改善本发明所述的合金结构用钢的力学性能。此外，C具有一定的强化作用，但是，过高的C的质量百分比会降低材料的耐蚀性能。考虑到冶炼设备的生产能力以及兼顾材料的力学性能和冲击韧性，在本发明所述的合金结构用钢中控制C的质量百分比为0.35-0.45％。C: In the alloy structural steel according to the present invention, C mainly affects the precipitation amount and precipitation temperature range of carbides. Controlling the lower mass percentage of C is beneficial to improve the mechanical properties of the alloy structural steel of the present invention. In addition, C has a certain strengthening effect, but too high mass percentage of C will reduce the corrosion resistance of the material. Considering the production capacity of the smelting equipment and taking into account the mechanical properties and impact toughness of the material, the mass percentage of C in the alloy structural steel of the present invention is controlled to be 0.35-0.45%.
Si：Si在钢中可以提高钢的强度，但是，对钢的成型性和韧性不利。此外，Si在冶炼过程中常有残留，因此，适当选择Si的含量很重要。基于此，在本发明所述的合金结构用钢中控制Si的质量百分比为0.27-0.35％。Si: Si can increase the strength of the steel in the steel, but it is not good for the formability and toughness of the steel. In addition, Si often remains in the smelting process, so it is important to properly select the content of Si. Based on this, the mass percentage of Si in the alloy structural steel of the present invention is controlled to be 0.27-0.35%.
Mn：Mn是较弱的奥氏体元素，可抑制合金结构用钢中硫的有害作用，改善热塑性。但是，Mn的质量百分比过高不利于保证其耐腐蚀性。考虑到Mn冶炼过程中常有残留，因此，在本发明所述的技术方案中控制Mn的质量百分比为0.6-0.8％。Mn: Mn is a weak austenitic element that can suppress the harmful effects of sulfur in alloy structural steels and improve thermoplasticity. However, too high mass percentage of Mn is not conducive to ensuring its corrosion resistance. Considering that there is often residual Mn in the smelting process, the mass percentage of Mn is controlled to be 0.6-0.8% in the technical solution of the present invention.
Al：在本发明所述的合金结构用钢中，Al主要通过控制钢中氧含量影响位错行为来强化合金。增加Al的总量可以明显地提高固溶温度、力学性能，但会有损塑性。此外，添加Al有利于钢的延伸变形性能，改善钢的加工性能。过高的Al含量会降低钢的冲击韧性。基于此，在本发明所述的合金结构用钢中控制Al的质量百分比为0.015-0.05％。Al: In the alloy structural steel according to the present invention, Al mainly controls the oxygen content in the steel and affects the dislocation behavior to strengthen the alloy. Increasing the total amount of Al can significantly improve the solution temperature and mechanical properties, but it will reduce the plasticity. In addition, the addition of Al is beneficial to the elongation deformation properties of the steel and improves the processing properties of the steel. Too high Al content will reduce the impact toughness of steel. Based on this, the mass percentage of Al in the alloy structural steel of the present invention is controlled to be 0.015-0.05%.
V：在本发明所述的技术方案中，V与碳、氧有极强的亲和力，可形成相应的稳定化合物。V在钢中主要以碳化物形式存在，V的主要作用是细化钢的组织和晶粒，降低钢的强度和韧性。当V在高温溶入固溶体时，增加淬透性；反之，若以碳化物形式存在时，降低淬透性。此外，V可以增加淬火钢的回火稳定性，并产生二次硬化效应。钒在合金结构钢中由于在一般热处理条件下会降低淬透性，故在合金结构钢中常和锰、铬元素联合使用。钒在调质钢中主要是提高钢的强度和屈强比，细化晶粒，降低过热敏感性。基于此，在本发明所述的合金结构用钢中控制V的质量百分比为0.06-0.1％。V: In the technical solution of the present invention, V has a very strong affinity with carbon and oxygen, and can form a corresponding stable compound. V mainly exists in the form of carbides in steel. The main function of V is to refine the structure and grain of the steel and reduce the strength and toughness of the steel. When V dissolves into solid solution at high temperature, it increases the hardenability; on the contrary, if it exists in the form of carbide, it reduces the hardenability. In addition, V can increase the tempering stability of quenched steel and produce a secondary hardening effect. Vanadium in alloy structural steel is often used in combination with manganese and chromium elements because it will reduce the hardenability under general heat treatment conditions. Vanadium is mainly used in quenched and tempered steel to improve the strength and yield ratio of steel, refine grains and reduce overheating sensitivity. Based on this, the mass percentage of V in the alloy structural steel of the present invention is controlled to be 0.06-0.1%.
Zr：在本发明所述的合金结构用钢中，Zr是强碳化物形成元素，它在钢中的作用与铌、钽、钒相似。加入少量Zr可以起到脱气、净化和细化晶粒作用， 有利于钢的低温性能，改善冲压性能。并且，添加少量Zr，部分Zr固溶在钢中，形成适量的ZrC、ZrN，有利于细化晶粒，改善冲压性能。基于此，在本发明所述的合金结构用钢中控制Zr的质量百分比为0.2-1.0％。Zr: In the alloy structural steel of the present invention, Zr is a strong carbide forming element, and its function in steel is similar to that of niobium, tantalum and vanadium. Adding a small amount of Zr can play the role of degassing, purification and grain refinement, which is beneficial to the low temperature performance of steel and improves the stamping performance. In addition, a small amount of Zr is added, and part of the Zr is dissolved in the steel to form an appropriate amount of ZrC and ZrN, which is beneficial to refine the grains and improve the stamping performance. Based on this, the mass percentage of Zr in the alloy structural steel of the present invention is controlled to be 0.2-1.0%.
Mg：Mg是一种十分活泼的金属元素，其与O、N、S都有很强的亲和力。因此，Mg在钢铁冶炼中是一种良好的脱氧和脱硫剂，同时也是铸铁良好的球化剂。但Mg很难溶解于铸铁的基体中，而以化合物MgS、MgO、Mg 3N 2、Mg 2Si状态存在。此外，Mg和C还可以形成一系列的化合物，如MgC 2、Mg 2C 3。基于此，在本发明所述的合金结构用钢中控制Mg的质量百分比为0.001-0.005％。 Mg: Mg is a very active metal element, which has a strong affinity with O, N, and S. Therefore, Mg is a good deoxidizer and desulfurizer in iron and steel smelting, and is also a good nodularizer for cast iron. However, Mg is hardly dissolved in the matrix of cast iron, and exists in the state of compounds MgS, MgO, Mg 3 N 2 and Mg 2 Si. In addition, Mg and C can also form a series of compounds, such as MgC 2 , Mg 2 C 3 . Based on this, the mass percentage of Mg in the alloy structural steel of the present invention is controlled to be 0.001-0.005%.
P和S：它们均会严重影响本案的合金结构用钢的力学性能和加工性能，必须严格控制其质量百分比，因此，P≤0.025％、S≤0.015％。P and S: Both of them will seriously affect the mechanical properties and processing properties of the alloy structural steel in this case, and their mass percentages must be strictly controlled. Therefore, P≤0.025%, S≤0.015%.
N：N是稳定奥氏体元素。控制较低的N的质量百分比有利于改善本发明的合金结构用钢的冲击韧性。此外，较高的氮的质量百分比会导致钢的韧性和延展性降低，并且还会降低可热加工性。基于此，在本发明的合金结构用钢中控制N的质量百分比为N≤0.005％。N: N is a stable austenite element. Controlling a relatively low mass percentage of N is beneficial to improve the impact toughness of the alloy structural steel of the present invention. In addition, higher mass percentages of nitrogen result in reduced toughness and ductility of the steel, and also reduce hot workability. Based on this, the mass percentage of N in the alloy structural steel of the present invention is controlled to be N≤0.005%.
O：在本发明的合金结构用钢中，O主要以氧化物夹杂存在，总氧含量高表明夹杂物较多。降低总氧含量有利于提高材料的综合性能。为了保证材料良好的力学和耐蚀性能，在本发明的技术方案中控制O的质量百分比为O≤0.001％。O: In the alloy structural steel of the present invention, O mainly exists as oxide inclusions, and a high total oxygen content indicates that there are many inclusions. Reducing the total oxygen content is beneficial to improve the comprehensive properties of the material. In order to ensure good mechanical and corrosion resistance properties of the material, in the technical solution of the present invention, the mass percentage of O is controlled to be O≤0.001%.
进一步地，在本发明所述的合金结构用钢中，其还具有下述各化学元素的至少其中之一：Ce、Hf、La、Re、Sc和Y，这些元素的总添加量≤1％。Further, in the alloy structural steel of the present invention, it also has at least one of the following chemical elements: Ce, Hf, La, Re, Sc and Y, and the total addition amount of these elements is ≤1% .
在本发明的技术方案中,优选地可以添加少量上述的稀土元素，以结合钢中氧、硫元素，形成稀土氧化物和硫化物，净化钢液并减小夹杂物尺寸。并且,所形成的稀土氧化物和硫化物可作为凝固过程形核质点，细化初始凝固晶粒，对改善钢材性能也有一定的帮助。In the technical solution of the present invention, preferably a small amount of the above-mentioned rare earth elements can be added to combine oxygen and sulfur elements in steel to form rare earth oxides and sulfides, purify molten steel and reduce the size of inclusions. In addition, the formed rare earth oxides and sulfides can be used as nucleation particles in the solidification process to refine the initial solidified grains, and also help to improve the properties of steel.
进一步地，在本发明所述的合金结构用钢中，其中各元素质量百分含量满足下列各项的至少其中之一：Further, in the alloy structural steel of the present invention, the mass percentage content of each element satisfies at least one of the following items:
V：0.08-0.1％；V: 0.08-0.1%;
Zr：0.3-0.7％；Zr: 0.3-0.7%;
Mg：0.001-0.003％。Mg: 0.001-0.003%.
进一步地，在本发明的合金结构用钢中，各元素的质量百分比含量之比还满足下列各项的至少其中之一：Further, in the alloy structural steel of the present invention, the mass percentage content ratio of each element also satisfies at least one of the following items:
Zr/N＝40-200；Zr/N=40-200;
Zr/V＝2-16.7；Zr/V=2-16.7;
Zr/C＝0.4-2.8。Zr/C=0.4-2.8.
上述方案中，控制Zr与N、V、C的质量百分比从而有利于控制ZrC、ZrN所形成的数量，而ZrC、ZrN的形成可以起到细化晶粒、改善钢力学性能以及冲压性能的作用，同时还可以起到固化钢中的部分N，减少固溶的N的质量百分比的作用。In the above scheme, controlling the mass percentage of Zr to N, V, and C is beneficial to control the amount of ZrC and ZrN formed, and the formation of ZrC and ZrN can play a role in refining grains, improving steel mechanical properties and stamping properties. At the same time, it can also play a role in solidifying part of the N in the steel and reducing the mass percentage of the solid solution N.
进一步地，在本发明的合金结构用钢中，各元素的质量百分比含量之比还满足下列各项的至少其中之一：Further, in the alloy structural steel of the present invention, the mass percentage content ratio of each element also satisfies at least one of the following items:
Mg/O＝0.5-3；Mg/O=0.5-3;
Mg/S＝0.6-5.0。Mg/S=0.6-5.0.
上述方案中，控制Mg与O、S的质量百分比可以有利于在冷却凝固过程中在合金内MgO与MgS的形成数量，而MgS与MgO的形成一方面可以起到进一步细化晶粒、稳定奥氏体晶粒的作用，另一方面还可以减小合金中O、S对于晶界的危害，从而改善本案的合金结构钢的冲击韧性。In the above scheme, controlling the mass percentage of Mg to O and S can be beneficial to the formation of MgO and MgS in the alloy during the cooling and solidification process, and the formation of MgS and MgO can further refine the grains and stabilize the alloy. On the other hand, it can also reduce the damage of O and S in the alloy to the grain boundary, thereby improving the impact toughness of the alloy structural steel in this case.
进一步地，在本发明所述的合金结构用钢中，其微观组织的基体为铁素体+珠光体，其中具有ZrC、ZrN、MgO、MgS质点。Further, in the steel for alloy structure according to the present invention, the matrix of its microstructure is ferrite+pearlite, which has ZrC, ZrN, MgO, MgS particles.
上述ZrC、ZrN、MgO、MgS质点是指ZrC、ZrN、MgO、MgS在合金结构用钢中以细微颗粒的形式存在。上述质点可在连铸冷却凝固过程和热轧过程中进一步细化、稳定奥氏体晶粒尺寸，从而避免在坯料或是最终产品的表面形成缺陷，同时也可以改善产品的力学性能。The above-mentioned particles of ZrC, ZrN, MgO, and MgS mean that ZrC, ZrN, MgO, and MgS exist in the form of fine particles in the steel for alloy structure. The above-mentioned particles can further refine and stabilize the austenite grain size during the continuous casting cooling and solidification process and the hot rolling process, thereby avoiding the formation of defects on the surface of the billet or the final product, and can also improve the mechanical properties of the product.
进一步地，在本发明所述的合金结构用钢中，ZrC和ZrN质点的数量之和为3-15个/mm 2。 Further, in the alloy structural steel according to the present invention, the sum of the number of ZrC and ZrN particles is 3-15 particles/mm 2 .
上述方案中，本案发明人发现将ZrC、ZrN质点的数量之和控制在3-15个/mm 2，对于细化晶粒、改善钢力学性能以及冲压性能以及固化钢中的部分N，减少固溶的N的质量百分比所起到的效果更佳。 In the above solution, the inventors of the present application found that controlling the sum of the number of ZrC and ZrN particles to 3-15 particles/mm 2 can reduce the amount of solidified grains, improve the mechanical properties and stamping properties of steel, and reduce the amount of N in the solidified steel. The effect of the mass percentage of dissolved N is better.
进一步地，在本发明的合金结构用钢中，MgO和MgS质点的数量之和为5-20个/mm 2。 Further, in the alloy structural steel of the present invention, the sum of the numbers of MgO and MgS particles is 5-20 particles/mm 2 .
上述方案中，本案发明人发现将MgO、MgS质点的数量之和控制为5-20个/mm 2对于进一步细化晶粒、稳定奥氏体晶粒以及减小合金中O、S对于晶界的危害，从而改善本案的合金结构钢的冲击韧性所起到的效果更佳。 In the above solution, the inventor of the present application found that controlling the sum of the number of MgO and MgS particles to be 5-20 particles/mm 2 can further refine the grains, stabilize the austenite grains and reduce the effect of O and S on the grain boundaries in the alloy. Therefore, the effect of improving the impact toughness of the alloy structural steel in this case is better.
进一步地，在本发明的合金结构用钢中，ZrC、ZrN、MgO、MgS质点的直径为0.2-7μm。Further, in the steel for alloy structure of the present invention, the diameters of the particles of ZrC, ZrN, MgO and MgS are 0.2-7 μm.
进一步地，在本发明的合金结构用钢中，其屈服强度≥755MPa、抗拉强度≥900MPa，延伸率≥12％，冲击韧性≥100J。Further, in the alloy structural steel of the present invention, the yield strength is greater than or equal to 755MPa, the tensile strength is greater than or equal to 900MPa, the elongation is greater than or equal to 12%, and the impact toughness is greater than or equal to 100J.
相应地，本发明的另一目的在于提供上述的合金结构用钢的制造方法，通过该制造方法可以获得力学性能更高、冲击韧性更好、成本更合理的合金结构用钢。Correspondingly, another object of the present invention is to provide the above-mentioned manufacturing method of alloy structural steel, through which alloy structural steel with higher mechanical properties, better impact toughness and more reasonable cost can be obtained.
为了实现上述目的，本发明提出了上述的合金结构用钢的制造方法，其包括步骤：In order to achieve the above purpose, the present invention proposes a method for manufacturing the above-mentioned alloy structural steel, which comprises the steps:
(1)冶炼、精炼和浇铸；(1) Smelting, refining and casting;
(2)初轧开坯；(2) Pre-rolling and billeting;
(3)二次热轧成材；(3) Secondary hot rolling into products;
(4)热处理：淬火+回火。(4) Heat treatment: quenching + tempering.
需要说明的是，在本发明的制造方法中，在步骤(1)可以采用电炉冶炼、LF和VD(或RH)精炼，并且可以在VD(或RH)精炼末期，先后加入少量的锆铁、和镁铝合金，待钢中的各化学元素质量百分比满足本案所限定的范围后，进行吹氩气的软搅拌，氩气流量控制在5-8升/min。It should be noted that, in the manufacturing method of the present invention, electric furnace smelting, LF and VD (or RH) refining can be used in step (1), and a small amount of zirconium iron, and magnesium-aluminum alloys, after the mass percentage of each chemical element in the steel meets the range limited in this case, soft stirring with argon blowing is performed, and the argon gas flow is controlled at 5-8 liters/min.
在一些优选的实施方式中，在步骤(1)中，浇铸可以采用大方坯连铸，拉速控制为0.45-0.65m/min；采用结晶器保护渣，并且采用结晶器电磁搅拌，电流为500A，频率为2.5-3.5Hz，连铸后的大方坯等轴晶比例≥20％。In some preferred embodiments, in step (1), bloom continuous casting can be used for casting, and the pulling speed is controlled to be 0.45-0.65m/min; mold powder is used, and mold electromagnetic stirring is used, and the current is 500A , the frequency is 2.5-3.5Hz, and the equiaxed crystal proportion of the bloom after continuous casting is ≥20%.
在一些优选的实施方式中，在步骤(2)中，初轧开坯前可以对坯料进行预处理，例如可以对其进行表面精整修磨，去除可见的表面缺陷，保证表面质量良好。In some preferred embodiments, in step (2), the blank can be pretreated before blooming, for example, surface finishing and grinding can be performed to remove visible surface defects and ensure good surface quality.
进一步地，在本发明所述的制造方法中，在步骤(2)和(3)中，初轧开坯时加热温度为1150～1250℃；二次热轧成材时加热温度为1150～1250℃。Further, in the manufacturing method of the present invention, in steps (2) and (3), the heating temperature during preliminary rolling is 1150-1250°C; the heating temperature during secondary hot rolling is 1150-1250°C .
进一步地，在本发明所述的制造方法，在步骤(4)中，淬火加热温度控制为855-890℃，淬火冷却速度控制在50-90℃/s；回火加热温度控制为 645-670℃，回火冷却速度控制为50-90℃/s。Further, in the manufacturing method of the present invention, in step (4), the quenching heating temperature is controlled at 855-890° C., the quenching cooling rate is controlled at 50-90° C./s; the tempering heating temperature is controlled at 645-670° C. ℃, the tempering cooling rate is controlled at 50-90℃/s.
需要说明的是，在步骤(4)中，淬火采用的冷却剂可以为矿物油，回火采用的冷却剂可以为矿物油或水。It should be noted that, in step (4), the coolant used for quenching may be mineral oil, and the coolant used for tempering may be mineral oil or water.
本发明所述的合金结构用钢及其制造方法相较于现有技术具有如下所述的优点以及有益效果：Compared with the prior art, the steel for alloy structure and the manufacturing method thereof of the present invention have the following advantages and beneficial effects:
本发明所述的合金结构用钢采用微量合金元素添加设计，通过添加适量的Zr、Mg，控制较低含量的总氧，利用所添加微量合金元素的特点，进一步强化、韧化该合金结构用钢，使得该合金结构用钢具有较高的强度，且材料成本较低。The steel for alloy structure of the present invention adopts the design of adding trace alloy elements. By adding an appropriate amount of Zr and Mg, the total oxygen content is controlled at a lower content, and the characteristics of the added trace alloy elements are used to further strengthen and toughen the alloy structure. steel, so that the alloy structural steel has higher strength and lower material cost.
此外，通过本发明所述的制造方法可以获得一种力学性能极高、冲击韧性较好且制造成本低廉的合金结构用钢。In addition, through the manufacturing method of the present invention, an alloy structural steel with extremely high mechanical properties, good impact toughness and low manufacturing cost can be obtained.
具体实施方式Detailed ways
下面将结合具体的实施例对本发明所述的合金结构用钢及其制造方法做进一步的解释和说明，然而该解释和说明并不对本发明的技术方案构成不当限定。The steel for alloy structure and the manufacturing method thereof of the present invention will be further explained and explained below with reference to specific embodiments, but the explanation and explanation do not constitute an improper limitation on the technical solution of the present invention.
实施例1-6以及对比例1-3Examples 1-6 and Comparative Examples 1-3
实施例1-6的合金结构用钢采用以下步骤制得：The alloy structural steel of embodiment 1-6 adopts the following steps to make:
(1)采用电炉冶炼、LF精炼和浇铸。(1) Using electric furnace smelting, LF refining and casting.
(2)初轧开坯：其加热温度为1150～1250℃。(2) Blooming and billeting: the heating temperature is 1150-1250°C.
(3)二次热轧成材：其加热温度为1150～1250℃。(3) Secondary hot rolling: the heating temperature is 1150-1250°C.
(4)热处理：淬火+回火，其中，淬火加热温控制度为855-890℃，淬火冷却速度控制在50-90℃/s，冷却剂采用矿物油；回火加热温度控制为645-670℃，回火冷却速度控制为50-90℃/s，冷却剂采用矿物油或水。(4) Heat treatment: quenching + tempering, in which the quenching heating temperature is controlled at 855-890 °C, the quenching cooling rate is controlled at 50-90 °C/s, and the coolant is mineral oil; the tempering heating temperature is controlled at 645-670 °C ℃, the tempering cooling rate is controlled at 50-90℃/s, and the coolant is mineral oil or water.
需要说明的是，在一些其他的实施方式中，精炼也可以采用RH精炼，并且可以在VD(或RH)精炼末期，先后加入少量的锆铁、和镁铝合金，待钢中的各化学元素质量百分比满足本案所限定的范围后，进行吹氩气的软搅拌，氩气流量控制在5-8升/min。It should be noted that, in some other embodiments, RH refining can also be used for refining, and at the end of VD (or RH) refining, a small amount of zirconium-iron and magnesium-aluminum alloys can be added successively to prepare the chemical elements in the steel. After the mass percentage satisfies the range defined in this case, soft stirring is performed by blowing argon gas, and the argon gas flow rate is controlled at 5-8 liters/min.
在一些优选的实施方式中，在步骤(1)中，浇铸可以采用大方坯连铸，拉速控制为0.45-0.65m/min；采用结晶器保护渣，并且采用结晶器电磁搅拌， 电流为500A，频率为2.5-3.5Hz，连铸后的大方坯等轴晶比例≥20％。In some preferred embodiments, in step (1), bloom continuous casting can be used for casting, and the pulling speed is controlled to be 0.45-0.65m/min; mold powder is used, and mold electromagnetic stirring is used, and the current is 500A , the frequency is 2.5-3.5Hz, and the equiaxed crystal proportion of the bloom after continuous casting is ≥20%.
在一些优选的实施方式中，在步骤(2)中，初轧开坯前可以对坯料进行预处理，例如可以对其进行表面精整修磨，去除可见的表面缺陷，保证表面质量良好。In some preferred embodiments, in step (2), the blank can be pretreated before blooming, for example, surface finishing and grinding can be performed to remove visible surface defects and ensure good surface quality.
对比例1-3采用现有技术的成分以及制造工艺获得。Comparative Examples 1-3 were obtained by using the components and manufacturing processes of the prior art.
表1列出了实施例1-6的合金结构用钢以及对比例1-3的现有结构用钢的各化学元素的质量百分配比。Table 1 lists the mass percentage ratio of each chemical element of the alloy structural steels of Examples 1-6 and the existing structural steels of Comparative Examples 1-3.
表1.(wt％，余量为Fe和其他不可避免的杂质)Table 1. (wt%, balance is Fe and other unavoidable impurities)
Figure PCTCN2020118043-appb-000001
Figure PCTCN2020118043-appb-000001
Figure PCTCN2020118043-appb-000002
Figure PCTCN2020118043-appb-000002
表2列出了所获得的实施例1-6的合金结构用钢以及对比例1-3的现有结构用钢中微观组织的情况。Table 2 lists the microstructures in the obtained alloy structural steels of Examples 1-6 and the existing structural steels of Comparative Examples 1-3.
表2.Table 2.
Figure PCTCN2020118043-appb-000003
Figure PCTCN2020118043-appb-000003
表3列出了实施例1-6的合金结构用钢以及对比例1-3的现有合金结构用钢的具体工艺参数。Table 3 lists the specific process parameters of the alloy structural steels of Examples 1-6 and the existing alloy structural steels of Comparative Examples 1-3.
表3.table 3.
Figure PCTCN2020118043-appb-000004
Figure PCTCN2020118043-appb-000004
Figure PCTCN2020118043-appb-000005
Figure PCTCN2020118043-appb-000005
为了验证本案的实施效果，同时证明本案较之现有技术的优异效果，将实实施例1-6的合金结构用钢以及对比例1-3的现有结构用钢进行力学测试。测试采用的是25mm厚度的钢材。In order to verify the implementation effect of this case and at the same time prove the superior effect of this case compared to the prior art, mechanical tests were performed on the alloy structural steels of Examples 1-6 and the existing structural steels of Comparative Examples 1-3. The test used 25mm thick steel.
本发明的拉伸试验(屈服强度R el、抗拉强度R m、延伸率试验)采用zwick/roell Z330拉伸试验机进行测试，试验标准按国家标准GB/T 228.1-2010。其中，屈服强度R el、抗拉强度R m、延伸率的测试分别按照该标准中3.10.1、3.10.2和3.6.1所定义的标准进行。 The tensile test (yield strength R el , tensile strength R m , elongation test) of the present invention is tested by using a zwick/roell Z330 tensile testing machine, and the test standard is in accordance with the national standard GB/T 228.1-2010. Among them, the tests of yield strength R el , tensile strength R m and elongation are carried out according to the standards defined in 3.10.1, 3.10.2 and 3.6.1 of this standard, respectively.
冲击韧性采用Zwick/Roell PSW 750冲击试验机进行测试，试验标准按国家标准GB/T 229-2007，通过测定合金结构用钢在夏比冲击试验中吸收的能量以获得冲击韧性的数值。The impact toughness was tested by Zwick/Roell PSW 750 impact testing machine. The test standard was in accordance with the national standard GB/T 229-2007. The value of impact toughness was obtained by measuring the energy absorbed by the alloy structural steel in the Charpy impact test.
ZrC和ZrN质点数量，MgO和MgS质点数量，ZrC、ZrN、MgO、MgS质点直径的统计和测定方法采用扫描电镜(SEM)进行，扫描电镜型号为蔡司扫描电镜EVO 18，同时配合牛津能谱仪oxford X-max 20，测定标准按GB/T 30834-2014进行。The number of ZrC and ZrN particles, the number of MgO and MgS particles, the statistics and determination methods of ZrC, ZrN, MgO, MgS particle diameters were carried out by scanning electron microscope (SEM). oxford X-max 20, the determination standard is carried out according to GB/T 30834-2014.
表4列出了各个实施例以及对比例的测试结果。Table 4 lists the test results of various examples and comparative examples.
表4.Table 4.
编号Numbering 屈服强度R el(MPa) Yield strength R el (MPa) 抗拉强度R m(MPa) Tensile strength R m (MPa) 延伸率(％)Elongation (%) 冲击韧性(J)Impact toughness (J)
实施例1Example 1 755755 900900 1212 123123
实施例2Example 2 765765 905905 1313 125125
实施例3Example 3 763763 910910 1212 108108
实施例4Example 4 770770 908908 1414 137137
实施例5Example 5 767767 912912 1313 117117
实施例6Example 6 758758 907907 1212 100100
对比例1Comparative Example 1 735735 885885 1010 7878
对比例2Comparative Example 2 730730 890890 1111 8585
对比例3Comparative Example 3 732732 893893 1010 7373
结合表2和表4可以看出，本案各实施例的合金结构用钢由于其微观组织为铁素体+珠光体，其中具有ZrC、ZrN、MgO、MgS质点，这些质点起到了到细化、稳定奥氏体晶粒的作用，有利于提高材料力学性能，因此本案各实施 例的合金结构用钢相较于采用现有技术的对比例1-3的现有结构用钢，力学性能表现更好，各实施例的合金结构用钢的屈服强度≥755MPa、抗拉强度≥900MPa，延伸率≥12％，冲击韧性≥100J。Combining Table 2 and Table 4, it can be seen that the steel for alloy structure in each embodiment of this case has ZrC, ZrN, MgO, MgS particles because of its microstructure of ferrite + pearlite, and these particles play a role in refining, The effect of stabilizing the austenite grains is conducive to improving the mechanical properties of the material. Therefore, the alloy structural steels of the examples in this case have better mechanical properties than the existing structural steels in Comparative Examples 1-3 using the prior art. Well, the yield strength of the alloy structural steel of each embodiment is ≥755 MPa, the tensile strength is ≥900 MPa, the elongation is ≥12%, and the impact toughness is ≥100J.
综上所述，本发明所述的合金结构用钢采用微量合金元素添加设计，通过添加适量的Zr、Mg，控制较低含量的总氧，利用所添加微量合金元素的特点，进一步强化、韧化该合金结构用钢，使得该合金结构用钢具有较高的强度，且材料成本较低。To sum up, the steel for alloy structure of the present invention adopts the design of adding trace alloying elements. By adding an appropriate amount of Zr and Mg, the total oxygen content is controlled at a lower content, and the characteristics of the added trace alloying elements are used to further strengthen and toughen the steel. The alloy structural steel can be melted, so that the alloy structural steel has higher strength and lower material cost.
此外，通过本发明所述的制造方法可以获得一种力学性能极高、冲击韧性较好且制造成本低廉的合金结构用钢。In addition, through the manufacturing method of the present invention, an alloy structural steel with extremely high mechanical properties, good impact toughness and low manufacturing cost can be obtained.
需要说明的是，本发明的保护范围中现有技术部分并不局限于本申请文件所给出的实施例，所有不与本发明的方案相矛盾的现有技术，包括但不局限于在先专利文献、在先公开出版物，在先公开使用等等，都可纳入本发明的保护范围。It should be noted that the prior art part in the protection scope of the present invention is not limited to the examples given in this application document, and all prior art that does not contradict the solution of the present invention, including but not limited to the prior art Patent documents, prior publications, prior publications, etc., can all be included in the protection scope of the present invention.
此外，本案中各技术特征的组合方式并不限本案权利要求中所记载的组合方式或是具体实施例所记载的组合方式，本案记载的所有技术特征可以以任何方式进行自由组合或结合，除非相互之间产生矛盾。In addition, the combination of the technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments, and all the technical features described in this case can be freely combined or combined in any way, unless conflict with each other.
还需要注意的是，以上所列举的实施例仅为本发明的具体实施例。显然本发明不局限于以上实施例，随之做出的类似变化或变形是本领域技术人员能从本发明公开的内容直接得出或者很容易便联想到的，均应属于本发明的保护范围。It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and the subsequent similar changes or deformations can be directly drawn or easily associated by those skilled in the art from the contents disclosed in the present invention, and should all belong to the protection scope of the present invention. .

Claims (13)

  1. 一种合金结构用钢，其特征在于，所述合金结构用钢的化学元素质量百分含量为：A steel for alloy structure, characterized in that the chemical element mass percentage content of the steel for alloy structure is:
    C：0.35-0.45％、Si：0.27-0.35％、Mn：0.6-0.8％、Al：0.015-0.05％、V：0.06-0.1％、Zr：0.2-1.0％、Mg：0.001-0.005％、P≤0.025％、S≤0.015％、N≤0.005％、O≤0.001％，余量为Fe和其他不可避免的杂质。C: 0.35-0.45%, Si: 0.27-0.35%, Mn: 0.6-0.8%, Al: 0.015-0.05%, V: 0.06-0.1%, Zr: 0.2-1.0%, Mg: 0.001-0.005%, P ≤0.025%, S≤0.015%, N≤0.005%, O≤0.001%, and the balance is Fe and other inevitable impurities.
  2. 如权利要求1所述的合金结构用钢，其特征在于，所述合金结构用钢还具有下述各化学元素的至少其中之一：Ce、Hf、La、Re、Sc和Y，这些元素的总添加量≤1％。The steel for alloy structure according to claim 1, characterized in that, the steel for alloy structure further has at least one of the following chemical elements: Ce, Hf, La, Re, Sc and Y. The total addition amount is less than or equal to 1%.
  3. 如权利要求1所述的合金结构用钢，其特征在于，所述化学元素质量百分含量满足下列各项的至少其中之一：The alloy structural steel according to claim 1, wherein the mass percentage content of the chemical elements satisfies at least one of the following items:
    V：0.08-0.1％；V: 0.08-0.1%;
    Zr：0.3-0.7％；Zr: 0.3-0.7%;
    Mg：0.001-0.003％。Mg: 0.001-0.003%.
  4. 如权利要求1所述的合金结构用钢，其特征在于，所述化学元素质量百分含量之比还满足下列各项的至少其中之一：The alloy structural steel according to claim 1, wherein the ratio of the chemical element by mass percentage also satisfies at least one of the following items:
    Zr/N＝40-200；Zr/N=40-200;
    Zr/V＝2-16.7；Zr/V=2-16.7;
    Zr/C＝0.4-2.8。Zr/C=0.4-2.8.
  5. 如权利要求1所述的合金结构用钢，其特征在于，所述化学元素质量百分含量之比还满足下列各项的至少其中之一：The alloy structural steel according to claim 1, wherein the ratio of the chemical element by mass percentage also satisfies at least one of the following items:
    Mg/O＝0.5-3；Mg/O=0.5-3;
    Mg/S＝0.6-5.0。Mg/S=0.6-5.0.
  6. 如权利要求1所述的合金结构用钢，其特征在于，所述合金结构用钢微观组织的基体为铁素体+珠光体，所述合金结构用钢具有ZrC、ZrN、MgO、MgS质点。The steel for alloy structure according to claim 1, wherein the matrix of the microstructure of the steel for alloy structure is ferrite+pearlite, and the steel for alloy structure has ZrC, ZrN, MgO, MgS particles.
  7. 如权利要求6所述的合金结构用钢，其特征在于，所述ZrC和所述ZrN质点的数量之和为3-15个/mm 2。 The alloy structural steel according to claim 6, wherein the sum of the numbers of the ZrC and the ZrN particles is 3-15 particles/mm 2 .
  8. 如权利要求6所述的合金结构用钢，其特征在于，所述MgO和所述 MgS质点的数量之和为5-20个/mm 2。 The alloy structural steel according to claim 6, wherein the sum of the numbers of the MgO particles and the MgS particles is 5-20 particles/mm 2 .
  9. 如权利要求6所述的合金结构用钢，其特征在于，所述ZrC、ZrN、MgO、MgS质点的直径为0.2-7μm。The steel for alloy structure according to claim 6, wherein the diameter of the particles of ZrC, ZrN, MgO and MgS is 0.2-7 μm.
  10. 如权利要求1-9中任意一项所述的合金结构用钢，其特征在于，所述合金结构用钢的屈服强度≥755MPa、抗拉强度≥900MPa，延伸率≥12％，冲击韧性≥100J。The alloy structural steel according to any one of claims 1-9, characterized in that, the alloy structural steel has a yield strength≥755MPa, a tensile strength≥900MPa, an elongation rate≥12%, and an impact toughness≥100J .
  11. 一种如权利要求1-10中任意一项所述的合金结构用钢的制造方法，其特征在于，包括步骤：A method for manufacturing alloy structural steel according to any one of claims 1-10, characterized in that, comprising the steps of:
    (1)冶炼、精炼和浇铸；(1) Smelting, refining and casting;
    (2)初轧开坯；(2) Pre-rolling and billeting;
    (3)二次热轧成材；(3) Secondary hot rolling into products;
    (4)热处理：淬火+回火。(4) Heat treatment: quenching + tempering.
  12. 如权利要求11所述的制造方法，其特征在于，初轧开坯时加热温度为1150～1250℃；二次热轧成材时加热温度为1150～1250℃。The manufacturing method according to claim 11, characterized in that, the heating temperature is 1150-1250°C during the preliminary rolling, and the heating temperature is 1150-1250°C during the secondary hot rolling.
  13. 如权利要求11所述的制造方法，其特征在于，在热处理中，淬火加热温度控制为855-890℃，淬火冷却速度控制在50-90℃/s；回火加热温度控制为645-670℃，回火冷却速度控制在50-90℃/s。The manufacturing method of claim 11, wherein, in the heat treatment, the quenching heating temperature is controlled to be 855-890°C, the quenching cooling rate is controlled to be 50-90°C/s; the tempering heating temperature is controlled to be 645-670°C , the tempering cooling rate is controlled at 50-90℃/s.
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