CN115874108A - Method for refining dendritic crystal structure in steel - Google Patents
Method for refining dendritic crystal structure in steel Download PDFInfo
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- CN115874108A CN115874108A CN202211650482.6A CN202211650482A CN115874108A CN 115874108 A CN115874108 A CN 115874108A CN 202211650482 A CN202211650482 A CN 202211650482A CN 115874108 A CN115874108 A CN 115874108A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 119
- 239000010959 steel Substances 0.000 title claims abstract description 119
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000007670 refining Methods 0.000 title claims abstract description 24
- 239000013078 crystal Substances 0.000 title abstract description 10
- 239000011777 magnesium Substances 0.000 claims abstract description 39
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 37
- 238000003723 Smelting Methods 0.000 claims abstract description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000000137 annealing Methods 0.000 claims abstract description 16
- 229910000861 Mg alloy Inorganic materials 0.000 claims abstract description 15
- ATTFYOXEMHAYAX-UHFFFAOYSA-N magnesium nickel Chemical compound [Mg].[Ni] ATTFYOXEMHAYAX-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000005096 rolling process Methods 0.000 claims abstract description 14
- 239000011651 chromium Substances 0.000 claims abstract description 12
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 238000005266 casting Methods 0.000 claims abstract description 11
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 11
- 239000010703 silicon Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 10
- 229910052742 iron Inorganic materials 0.000 claims abstract description 10
- 238000010791 quenching Methods 0.000 claims abstract description 10
- 230000000171 quenching effect Effects 0.000 claims abstract description 10
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 7
- 239000010439 graphite Substances 0.000 claims abstract description 7
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 210000001787 dendrite Anatomy 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 10
- 229910052751 metal Inorganic materials 0.000 abstract description 2
- 239000002184 metal Substances 0.000 abstract description 2
- 150000001875 compounds Chemical class 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 13
- 238000001816 cooling Methods 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 7
- 238000005275 alloying Methods 0.000 description 6
- 229910052748 manganese Inorganic materials 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910001315 Tool steel Inorganic materials 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000001887 electron backscatter diffraction Methods 0.000 description 2
- 238000000921 elemental analysis Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- XYVDNBKDAAXMPG-UHFFFAOYSA-M decyl 2-(1-heptylazepan-1-ium-1-yl)acetate;hydroxide Chemical compound [OH-].CCCCCCCCCCOC(=O)C[N+]1(CCCCCCC)CCCCCC1 XYVDNBKDAAXMPG-UHFFFAOYSA-M 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000013100 final test Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
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- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
Images
Classifications
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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
Abstract
The invention discloses a method for refining dendritic crystal structure in steel, belonging to the technical field of metal smelting. The method comprises the following steps: s1, smelting an iron source, a chromium source and a nickel source to obtain a furnace burden; s2, adding an aluminum source, graphite and a silicon source into the furnace burden to prepare a deoxidizing furnace burden; s3, after pressurizing to 2-4 MPa, adding a nickel-magnesium alloy into the deoxidizing furnace burden, and preserving heat to obtain a magnesium treatment furnace burden; s4, casting the magnesium treatment furnace burden to prepare a steel ingot; s5, rolling, completely annealing, quenching and carrying out secondary annealing on the steel ingot to obtain steel; the average dendritic spacing of the steel is less than 75 mu m. The method of the invention reasonably utilizes the pinning effect of the Mg-containing compound and combines with pressurized smelting, thereby greatly refining the dendritic crystal structure of the steel, reducing the secondary dendritic crystal spacing and further improving the performance of the steel.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a method for refining dendritic crystal structure in steel.
Background
The eutectoid steel, hypereutectoid steel and alloy tool steel have good strength, hardness, plasticity, toughness and processing performance, so that the application range is wide. Magnesium can purify molten steel, denaturalized inclusions, refine tissues, spheroidize carbides, improve steel properties and other metallurgical functions.
In order to improve the properties of steel, a common solution is to add more expensive alloying elements, such as Cr, W, mo, V, ni, nb, etc., to the steel. Although these elements may improve the properties of the steel, it is clear that this will lead to an increase in the mass fraction of alloy in the steel, with a consequent increase in the cost of the steel. Namely, a certain amount of magnesium or rare earth elements are added into the steel, so that the steel performance is improved, and meanwhile, the steel cost is not improved.
Magnesium has a lower boiling point and a higher vapor pressure at 1873K than other elements. This makes the use of magnesium in steel very difficult under conventional smelting conditions. In the related art, the research on the metallurgical effect of magnesium is mostly the research on trace magnesium, namely the mass fraction of the researched magnesium is not more than 0.03%, and the mass fraction of magnesium in an application scene is even lower than the range.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method for refining a dendritic structure in steel.
Disclosure of Invention
An object of the present invention is to provide a method of refining a dendrite structure in steel to solve at least one aspect of the problems and disadvantages set forth in the background art as described above.
Specifically, the invention provides a method for refining dendritic structures in steel, which comprises the following steps:
s1, smelting an iron source, a chromium source and a nickel source to obtain a furnace burden;
s2, adding an aluminum source, graphite and a silicon source into a furnace charge to prepare a deoxidizing furnace charge;
s3, after pressurizing to 2-4 MPa, adding nickel-magnesium alloy into the deoxidizing furnace burden, and keeping the temperature to obtain a magnesium treatment furnace burden;
s4, casting the magnesium treatment furnace burden to prepare a steel ingot;
s5, rolling, completely annealing, quenching and carrying out secondary annealing on the steel ingot to obtain steel;
the average dendritic spacing of the steel is less than 75 μm.
According to one of the technical schemes of the method, the method at least has the following beneficial effects:
under the condition of high pressure, the nickel-magnesium alloy is added for alloying, so that the magnesium content in the steel is greatly improved, and the magnesium pinning effect is fully utilized, thereby realizing the control of the average dendritic crystal spacing of the steel.
According to some embodiments of the invention, the steel has an average dendrite spacing of 30 to 75 μm.
According to some embodiments of the invention, the steel has a tensile strength of 1500 to 1600MPa.
According to some embodiments of the invention, the steel has a tensile strength of 1520MPa to 1600MPa.
According to some embodiments of the invention, the steel has a tensile strength of 1550MPa to 1560MPa.
According to some embodiments of the invention, the steel has a yield strength of 1350MPa to 1450MPa.
According to some embodiments of the invention, the steel has a yield strength of 1370MPa to 1450MPa.
According to some embodiments of the invention, the steel has a yield strength of 1420MPa to 1430MPa.
According to some embodiments of the invention, the steel has an elongation at break of 10% to 13%.
According to some embodiments of the invention, the steel has an elongation at break of 10% to 12%.
According to some embodiments of the invention, the steel has an elongation at break of 10% to 11%.
According to some embodiments of the invention, the steel has a reduction of area of 20% to 35%.
According to some embodiments of the invention, the steel has a reduction of area of 23% to 34%.
According to some embodiments of the invention, the steel has a reduction of area of 28% to 29%.
According to some embodiments of the invention, the steel comprises magnesium in an amount of 0.03 to 0.2% by weight.
According to some embodiments of the invention, the mass fraction of carbon in the steel is between 0.77% and 1.00%.
According to some embodiments of the invention, the mass fraction of carbon in the steel is between 0.8% and 0.9%.
According to some embodiments of the invention, the silicon source has a mass fraction of silicon above 99%.
According to some embodiments of the invention, the mass fraction of chromium in the chromium source is 99% or more.
According to some embodiments of the invention, the mass fraction of manganese in the manganese source is above 99%.
According to some embodiments of the invention, the mass fraction of iron in the iron source is above 99%.
According to some embodiments of the invention, the nickel-magnesium alloy consists of nickel and magnesium.
According to some embodiments of the invention, the nickel in the nickel magnesium alloy is 65% to 75% by weight.
According to some embodiments of the invention, the aluminum source has a mass fraction of aluminum above 99%.
According to some embodiments of the invention, the pressure during the smelting is below 10 Pa.
The burning loss of easily oxidized elements (silicon element, manganese element and the like) in the smelting process can be avoided under 10Pa, and the yield is stable. Meanwhile, the oxygen content in steel is reduced, namely, the reaction of magnesium added and oxygen is reduced, so that excessive magnesium oxide inclusions are formed, and the yield and the effect of magnesium are influenced.
According to some embodiments of the invention, the temperature of the melting is between 100 ℃ and 120 ℃ liquidus.
The liquidus temperature is determined by the empirical formula: t is t 1 ＝1538-90w[C]-6.2w[Si]-1.7w[Mn]-1.3w[V]-1.0w[W]-1.8w[Cr]-33w[Mo]-28w[P]-40w[S]-90w[N]-65w[O]And (wherein w represents the mass fraction of each element) to avoid the phenomenon that the molten steel is viscous and the cast steel is not smooth due to low temperature.
According to some embodiments of the invention, the temperature during the smelting is from 1500 ℃ to 1700 ℃.
The smelting temperature is too low, the raw materials for preparation are difficult to melt, and the magnesium vapor pressure is higher due to too high temperature, so that the magnesium yield is influenced; meanwhile, the smelting safety is reduced, so that the temperature is controlled within a certain range.
According to some embodiments of the invention, the end of the smelting process is marked by complete melting of the iron, chromium and manganese sources.
According to some embodiments of the invention, the aluminum source is added in step S2 and then the temperature is maintained for 2 to 4min.
According to some embodiments of the invention, the silicon source is added in step S2 and then the temperature is maintained for 2min to 3min.
According to some embodiments of the invention, the pressurization in step S3 is at a pressure of 2.98MPa to 3.02MPa.
According to some embodiments of the invention, the incubation time in step S3 is 3min to 7min.
By controlling the heat preservation time, the complete melting of furnace burden is ensured, and the uniformity of each component in molten steel is improved.
According to some embodiments of the invention, the casting temperature is 1560 ℃ to 1570 ℃.
According to some embodiments of the invention, the post-casting dwell time is between 20min and 30min.
According to some embodiments of the invention, the temperature maintained during the rolling is between 1400K and 1500K.
According to some embodiments of the invention, the holding time during the rolling process is 90min to 100min.
According to some embodiments of the invention, the rolling produces a steel sheet.
According to some embodiments of the invention, the post-rolling is air cooled to 290K to 300K.
According to some embodiments of the invention, the steel plate has a thickness of 3mm to 5mm.
According to some embodiments of the invention, the temperature of the holding during the complete annealing process is between 1000K and 1090K.
According to some embodiments of the invention, the holding time during the complete annealing process is 5min to 10min.
According to some embodiments of the invention, the full anneal is air cooled to 290K to 300K.
According to some embodiments of the invention, the holding temperature during the quenching process is 1100K to 1200K.
According to some embodiments of the invention, the holding time during the quenching process is 5min to 10min.
According to some embodiments of the invention, the oil is cooled to 290K to 300K during the quenching.
According to some embodiments of the invention, the temperature maintained during the second annealing is 650K to 750K.
According to some embodiments of the invention, the holding time in the second annealing process is 20min to 30min.
According to some embodiments of the invention, the second annealing process is air cooled to 290K to 300K.
According to some embodiments of the present invention, the method of refining a dendritic structure in steel comprises the steps of:
s01, smelting:
heating an iron source, a chromium source and a manganese source to 1600-1700 ℃ to prepare a furnace charge;
s02, pre-deoxidation and alloying:
adding an aluminum source into the furnace charge in the step S01, and then preserving heat; sequentially adding graphite and a silicon source to prepare deoxidized furnace burden;
s03, pressurization:
pressurizing the deoxidized furnace charge to 2-4 MPa, and adding nickel-magnesium alloy to prepare a microalloyed furnace charge;
s04, casting:
casting the microalloyed furnace burden; maintaining the pressure and cooling after the casting is finished to prepare a steel ingot;
s04, rolling:
keeping the temperature of the steel ingot at 1400-1500K for 90-100 min, rolling the steel ingot into a steel plate through 6 passes of rolling, and then cooling the steel plate to 290-300K in air;
s05, complete annealing:
heating the steel plate rolled in the step S7 to 1000-1090K along with a furnace, preserving the heat for 8-10 min, and then air-cooling to 290-300K;
s06, quenching:
heating the steel plate processed in the step S05 to 1100-1200K along with the furnace, preserving the heat for 8-10 min, and then cooling the steel plate to 290-300K;
and S07, heating the steel plate treated by the S06 to 650-750K along with a furnace, preserving heat for 20-30 min, and then air-cooling to 290-300K.
According to some embodiments of the invention, the steel material is one of a eutectoid steel, a hypereutectoid steel or an alloy tool steel.
According to some embodiments of the invention, in step S2, the amount of added aluminium source is between 0.5kg and 0.6kg per ton of target steel grade.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a metallographic picture of a dendritic structure of an ingot produced in example 1 of the present invention.
FIG. 2 is a metallographic image showing the dendritic structure of an ingot produced in example 2 of the present invention.
FIG. 3 is a metallographic image showing the dendritic structure of an ingot produced in example 3 of the present invention.
FIG. 4 is a metallographic image showing the dendritic structure of an ingot produced according to a comparative example of the present invention.
FIG. 5 is a graph comparing the secondary dendrite spacing of the as-cast dendritic structures of comparative example and examples 1-3.
FIG. 6 is a macroscopic picture taken using a metallographic microscope of inclusions pinned between dendrite arms found in the as-cast dendrite structure of example 2.
FIG. 7 is an EBSD map of a steel product finally obtained in example 2 of the present invention.
Fig. 8 is the result of elemental analysis at position a in fig. 7.
FIG. 9 is an EBSD map of a steel product finally obtained in a comparative example of the present invention.
Fig. 10 is the result of elemental analysis at position B in fig. 9.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
For a better understanding of the present disclosure, the present invention is described in more detail by way of specific embodiments.
In the following embodiments of the present invention, the smelting equipment is 25kg pressure induction furnace, the charging is 20kg, the smelting steel type is SKS51 steel, the main components of the smelting raw materials used are shown in table 1, and the component control ranges and targets are shown in table 2.
TABLE 1 Main Components of raw materials for smelting TABLE (% by weight)
TABLE 2 SKS51 Steel composition control Range and target composition (wt%) of the experimental steel grade
| Element(s) | C | Si | Mn | Cr | Ni | Al | P | S | O | N |
| Composition (I) | 0.85 | 0.22 | 0.38 | 0.33 | 1.75 | 0.05 | ≤0.02 | ≤0.02 | 0.0020 | 0.010 |
Example 1
The embodiment is a method for refining dendritic structures in steel, which comprises the following steps:
s1, preparing materials:
0.04kg of industrial silicon, 0.7kg of metallic chromium, 0.12kg of nickel-magnesium alloy, 0.164kg of graphite block, 0.08kg of electrolytic manganese, 0.01kg of aluminum particles and 18.5kg of industrial pure iron.
Placing industrial pure iron, metal chromium and electrolytic manganese in a crucible; the graphite block, the industrial silicon and the nickel-magnesium alloy are sequentially arranged in the built-in sealed bin;
s2, smelting:
placing furnace burden (industrial pure iron, chromium metal and electrolytic manganese) in a pressurized induction furnace, vacuumizing to below 10Pa, heating to 1600 ℃, and waiting for the furnace burden to be molten down;
s3, deoxidizing and alloying:
adding aluminum particles into the furnace burden smelted in the step S2, and then preserving heat for 3min; sequentially adding graphite blocks and industrial silicon, and keeping the temperature for 2min;
s4, magnesium treatment under pressure:
filling 2.98 MPa-3.02 MPa of argon, adding nickel-magnesium alloy after the pressure is stable, and keeping the temperature for 5min after reaching the stable pressure (namely the pressure is 2.98 MPa-3.02 MPa);
s5, casting:
the casting temperature is controlled between 1560 ℃ and 1570 ℃; maintaining the pressure for 20min (the pressure is 2.98 MPa-3.02 MPa) after the magnesium treated in the step S4 is cast, discharging gas to normal pressure (101.325 kPa), and taking out a steel ingot after cooling;
s6, rolling:
keeping the temperature of the steel ingot at 1423K for 90min, rolling the steel ingot into a 4mm thin plate through 6 times of rolling, and then cooling the steel ingot to room temperature (298K) in air to obtain a steel plate;
s7, complete annealing:
and (4) heating the steel plate rolled according to the step S6 to 1053K along with the furnace, preserving the heat for 8min, discharging the steel plate from the furnace, and air-cooling to 298K.
S8, quenching:
and (4) heating the steel plate processed in the step S7 to 1103K along with the furnace, preserving the heat for 8min, and then cooling the oil to room temperature (298K).
And S9, heating the steel plate treated in the S8 to 693K along with the furnace, preserving the heat for 20min, and then cooling the steel plate to room temperature in air (298K).
Example 2
The present example is a method for refining dendrite structure in steel, and is different from example 1 in that: the amount of the nickel-magnesium alloy used in this example was 0.24kg.
Example 3
The present example is a method for refining dendrite structure in steel, and is different from example 1 in that: the amount of the nickel-magnesium alloy used in this example was 0.48kg.
Comparative example
The comparative example is a preparation method of high-strength steel, and is different from the example 1 in that: in this comparative example, no nickel-magnesium alloy was added.
The mass fractions of the elements in the steel ingots prepared in examples 1 to 3 of the present invention and comparative example are shown in table 3.
TABLE 3 composition (wt%) of steel ingots produced according to examples 1 to 3 of the present invention and comparative example
SKS51 ingots prepared in comparative examples and examples 1 to 3 were sliced at the same positions, and the samples were polished with 240, 400, 600, 800, 1000, 1200, 1500, 2000 mesh sandpaper in this order. The samples were polished with a W1.5 polishing paste and a polishing cloth. The polished sample was etched with 4% nital. And analyzing the dendritic structure of the sample by using a metallographic microscope. As shown in FIGS. 1 to 5, it is understood from FIGS. 1 to 5 that the dendritic structures of examples 1 to 3 were significantly finer than those of comparative examples, in which the average secondary dendrite spacing was 78 μm, and the average dendrite spacings of examples 1 to 3 were 57 μm (example 1), 43 μm (example 2) and 31 μm (example 3), respectively. The secondary dendrite spacing of the steel gradually decreases with the increase of the magnesium content in the steel.
The dendrite structure of example 2 was further analyzed by a metallographic microscope and a scanning electron microscope, and the analysis results are shown in FIGS. 6 to 10. As is clear from FIGS. 6 to 10, many inclusions, mgO, mgS and MgC, were clearly pinned between the dendrite arms of the magnesium-containing steel 2 It shows that the pinning effect of the magnesium-containing inclusion hinders the growth of the dendritic crystal, promotes nucleation and refines the dendritic crystal structure.
SKS51 steels prepared in examples 1-3 and comparative example were subjected to a room temperature tensile test after sample processing in accordance with the GB/T228-2010 Metal Material Room temperature tensile test at 25 ℃ and a tensile rate of 2mm DEGmin -1 The final test results are shown in table 4.
TABLE 4 mechanical Property test results of SKS51 steels prepared in inventive examples 1 to 3 and comparative example
As can be seen from Table 4, the tensile strength and yield strength of examples 1-2 are significantly improved compared with those of comparative example, wherein the tensile strength of example 2 is improved by 63MPa and the yield strength of example 2 is improved by 71MPa. The reason for the strength improvement in examples 1 to 2 is the grain refining effect and precipitation strengthening effect of oxides and carbides generated after Mg addition. Example 3 the reason for the decrease in strength may be that excessive addition of magnesium causes excessive precipitates, resulting in grain boundary embrittlement.
The trace magnesium has various metallurgical effects in steel, such as purifying molten steel, changing the quantity, the form and the spheroidizing carbide of inclusions, improving the hardenability and the wear resistance of the steel, and the like, and the explanation of the action mechanism is that the addition of the trace magnesium causes the change of the inclusions and then causes the transformation of the structure and the performance. Based on the action of trace magnesium, the invention improves the magnesium content in the steel to a higher level by comprehensively utilizing a pressurizing means.
According to the invention, the pressure of 3MPa is added in the smelting and casting processes, and a proper amount of nickel-magnesium alloy is added in the smelting process to keep the mass fraction of magnesium in the steel within a reasonable range, so that magnesium alloying is realized, the dendritic structure of the steel is greatly improved, and the performance of the steel is improved.
In conclusion, the invention provides a method for refining dendritic crystal structure in steel, which mainly regulates and controls smelting time and alloy adding sequence under the condition of high pressure, adds nickel-magnesium alloy for alloying, greatly improves the magnesium content in the steel and fully utilizes the magnesium pinning effect; and meanwhile, a quality fraction interval of the thinning effect is defined.
While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (10)
1. A method for refining dendritic structures in steel is characterized by comprising the following steps:
s1, smelting an iron source, a chromium source and a nickel source to obtain a furnace burden;
s2, adding an aluminum source, graphite and a silicon source into a furnace charge to prepare a deoxidizing furnace charge;
s3, after pressurizing to 2-4 MPa, adding a nickel-magnesium alloy into the deoxidizing furnace burden, and preserving heat to obtain a magnesium treatment furnace burden;
s4, casting the magnesium treatment furnace burden to prepare a steel ingot;
s5, rolling, completely annealing, quenching and carrying out secondary annealing on the steel ingot to obtain steel;
the average dendritic spacing of the steel is less than 75 mu m.
2. The method for refining dendrite structure in steel according to claim 1, wherein the average dendrite spacing of the steel is 30 to 75 μm.
3. The method for refining dendrite structure in steel according to claim 1 wherein the mass fraction of magnesium in said steel is 0.03% to 0.2%.
4. The method for refining dendrites in steel according to claim 1 wherein the mass fraction of carbon in said steel is 0.77% to 1.00%.
5. The method for refining dendrite structure in steel according to claim 1 wherein the temperature maintained during rolling is 1400K-1500K.
6. The method for refining dendrite structure in steel according to claim 1, wherein the temperature for the complete annealing process is 1000K to 1090K.
7. The method for refining dendrite structure in steel according to claim 1, wherein the time for the heat-holding time during the complete annealing process is 5min to 10min.
8. The method for refining a dendritic structure in steel according to claim 1, wherein the holding temperature during the quenching process is 1100K to 1200K.
9. The method for refining a dendritic structure in steel according to claim 1, wherein a holding time in the quenching process is 5 to 10min.
10. The method for refining dendrite structure in steel according to claim 1 wherein the temperature for the second annealing is 650K to 750K.
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| US4477295A (en) * | 1981-09-04 | 1984-10-16 | Vereinigte Edelstahlwerke Ag (Vew) | Method for fabricating conveyor worms or the like |
| CN102925812A (en) * | 2012-11-16 | 2013-02-13 | 武汉钢铁(集团)公司 | Hot rolling diaphragm spring steel for automobile and production method of hot rolling diaphragm spring |
| CN104313472A (en) * | 2014-10-31 | 2015-01-28 | 武汉钢铁(集团)公司 | High-carbon hot-rolled automobile diaphragm spring steel and production method thereof |
| CN114058947A (en) * | 2021-10-15 | 2022-02-18 | 首钢集团有限公司 | Multi-element composite high-carbon low-alloy tool steel and preparation method and application thereof |
| CN114480796A (en) * | 2022-01-27 | 2022-05-13 | 湖南华菱涟源钢铁有限公司 | Method for obtaining uniform granular pearlite structure without spheroidizing annealing |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4477295A (en) * | 1981-09-04 | 1984-10-16 | Vereinigte Edelstahlwerke Ag (Vew) | Method for fabricating conveyor worms or the like |
| CN102925812A (en) * | 2012-11-16 | 2013-02-13 | 武汉钢铁(集团)公司 | Hot rolling diaphragm spring steel for automobile and production method of hot rolling diaphragm spring |
| CN104313472A (en) * | 2014-10-31 | 2015-01-28 | 武汉钢铁(集团)公司 | High-carbon hot-rolled automobile diaphragm spring steel and production method thereof |
| CN114058947A (en) * | 2021-10-15 | 2022-02-18 | 首钢集团有限公司 | Multi-element composite high-carbon low-alloy tool steel and preparation method and application thereof |
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