CN115637311B - Steel belt for high-carbon needle making and preparation method thereof - Google Patents
Steel belt for high-carbon needle making and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 105
- 239000010959 steel Substances 0.000 title claims abstract description 105
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- 238000005096 rolling process Methods 0.000 claims abstract description 46
- 238000000137 annealing Methods 0.000 claims abstract description 42
- 238000005097 cold rolling Methods 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 38
- 238000005266 casting Methods 0.000 claims abstract description 24
- 238000007670 refining Methods 0.000 claims abstract description 18
- 238000009749 continuous casting Methods 0.000 claims abstract description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910000677 High-carbon steel Inorganic materials 0.000 claims abstract description 14
- 239000002893 slag Substances 0.000 claims abstract description 13
- 239000002253 acid Substances 0.000 claims abstract description 10
- 238000005406 washing Methods 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910052742 iron Inorganic materials 0.000 claims abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 5
- 238000004321 preservation Methods 0.000 claims abstract description 5
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 5
- 239000000126 substance Substances 0.000 claims abstract description 4
- 230000009467 reduction Effects 0.000 claims description 25
- 238000005204 segregation Methods 0.000 claims description 18
- 150000001247 metal acetylides Chemical class 0.000 claims description 17
- 238000004519 manufacturing process Methods 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- 238000007789 sealing Methods 0.000 claims description 3
- 238000007654 immersion Methods 0.000 claims 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052760 oxygen Inorganic materials 0.000 abstract description 10
- 239000001301 oxygen Substances 0.000 abstract description 10
- 238000004080 punching Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 abstract description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 30
- 230000008092 positive effect Effects 0.000 description 19
- 230000000694 effects Effects 0.000 description 18
- 238000010438 heat treatment Methods 0.000 description 17
- 230000008569 process Effects 0.000 description 15
- 238000005261 decarburization Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 230000002411 adverse Effects 0.000 description 8
- 239000004753 textile Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 6
- 230000002829 reductive effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000000670 limiting effect Effects 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910001562 pearlite Inorganic materials 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- 238000009827 uniform distribution Methods 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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- 238000003825 pressing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
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- 239000002994 raw material Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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
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Abstract
The application relates to the field of high-carbon steel punching materials, in particular to a steel belt for high-carbon needle making and a preparation method thereof; the method comprises the following steps: refining the smelted molten iron, and then carrying out continuous casting to obtain a casting blank; carrying out hot feeding, hot charging, rolling, laminar cooling, coiling, heat preservation, leveling and acid washing on a casting blank to obtain an acid washing plate; carrying out cold rolling annealing on the acid-washed plate, and then leveling to obtain a high-carbon steel belt for needle making, which has excellent mechanical properties; wherein the cold rolling annealing comprises a first cold rolling, a first annealing, a second cold rolling and a second annealing; the refined ladle slag meets the following conditions: [ FeO ] + [ MnO ] < 1%; refining is carried out by taking the grade of nonmetallic inclusion in molten steel as a target, wherein the grade of nonmetallic inclusion in molten steel is less than or equal to 1.5 grade; the chemical components of the steel belt comprise: c, si, mn, P, S, alt, cr, and the balance of Fe and unavoidable impurity elements; the oxygen content of the refined ladle slag is controlled, the grade of nonmetallic inclusion in molten steel is controlled, and the mechanical property of steel is comprehensively improved.
Description
Technical Field
The application relates to the field of high-carbon steel punching materials, in particular to a steel belt for high-carbon needle making and a preparation method thereof.
Background
The high-carbon steel for needle making belongs to a high-precision punching steel with a relatively high threshold, is generally used for producing industrial spinning needles, but because the industrial spinning needles have long-time and long-distance relative motion with cloth during working, the high-carbon steel for needle making is required to have high wear resistance, and the produced steel plate is required to be subjected to processes such as blanking, heat treatment and the like in a needle mill, wherein the heat treatment is a quenching and tempering process, and a structure taking martensite as a matrix can be obtained, so that the wear resistance can be ensured; the metallurgical structure of the steel used in the current needle mill is required to be mainly composed of spherical carbides which are dispersed and distributed on a ferrite matrix, and the uniform distribution of the carbides is beneficial to the uniformity of blanking, so that the dimensional accuracy of parts is ensured, in addition, the uniform structure can ensure that the steel is small in deformation during heat treatment, and further, the high dimensional accuracy can be ensured.
However, the existing process used in the needle making factory can lead to the conditions of more component segregation, low tissue uniformity and uncontrollable decarburization degree of the steel for making the needle, so that the mechanical properties of the prepared textile needle can not be ensured to be good; therefore, how to improve the mechanical properties of the spinning needles is a technical problem to be solved at present.
Disclosure of Invention
The application provides a high-carbon steel belt for needle making and a preparation method thereof, which are used for solving the technical problem of lower mechanical property of textile needles in the prior art.
In a first aspect, the present application provides a method for preparing a steel strip for high-carbon needle making, the method comprising:
refining the smelted molten iron, and then carrying out continuous casting to obtain a casting blank;
carrying out hot feeding, hot charging, rolling, laminar cooling, coiling, heat preservation, leveling and acid washing on the casting blank to obtain an acid washing plate;
performing cold rolling annealing on the acid-washed plate, and then flattening to obtain a high-carbon steel belt for needle making, which has excellent mechanical properties;
wherein the cold rolling annealing comprises a first cold rolling, a first annealing, a second cold rolling and a second annealing;
the components of the refined ladle slag comprise FeO and MnO, and the FeO and the MnO satisfy the following conditions:
wherein [ FeO ] + [ MnO ] < 1%, wherein [ FeO ] is mass fraction of FeO, and [ MnO ] is mass fraction of MnO;
the refining is carried out by taking the grade of nonmetallic inclusion in molten steel as the target of less than or equal to 1.5 grade.
Optionally, the center segregation of the casting blank is less than or equal to 1.5 level.
Optionally, the time of the hot feeding and hot charging is less than or equal to 8 hours, and the temperature of the hot feeding and hot charging is more than or equal to 400 ℃.
Optionally, the rolling comprises descaling before rough rolling, descaling before rough rolling and finish rolling;
the pressure of the descaling before rough rolling is more than or equal to 20MPa, and the pressure of the descaling before finish rolling is more than or equal to 25MPa.
Optionally, the reduction rate of the first cold rolling is 30% -70%, and the reduction rate of the second cold rolling is 10% -40%.
Optionally, the first annealing and the second annealing are both performed in a perhydro annealing mode.
Optionally, the peak temperature of the first annealing is 650 ℃ to 750 ℃.
Optionally, the peak temperature of the second annealing is 400 ℃ to 550 ℃.
In a second aspect, the present application provides a steel strip for high-carbon needle making, the steel strip being prepared by the method according to the first aspect, and the steel strip comprising, in mass fraction: 0.75 to 1.00 percent of C, 0.2 to 0.6 percent of Si, 0.2 to 0.7 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.02 percent of S, less than or equal to 0.012 percent of Alt, 0.15 to 0.35 percent of Cr, and the balance of Fe and unavoidable impurity elements.
Optionally, the metallographic structure of the steel strip comprises carbide, the carbide comprises spherical carbide, the spheroidization rate of the spherical carbide is more than or equal to 95%, and the average diameter of the spherical carbide is 0.8-1.1 mu m.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
according to the preparation method of the steel strip for the high-carbon needle making, provided by the embodiment of the application, the oxygen content of ladle slag in a refining process is controlled, and meanwhile, the grade of nonmetallic inclusion in molten steel in a refining stage is controlled, so that the oxygen content of the whole refining process is controlled, excessive metallic inclusion and nonmetallic inclusion are avoided, the diameters of the metallic inclusion and nonmetallic inclusion are avoided from being too large, the problems that segregation of steel is excessive, the structure is uneven and the decarburization degree cannot be controlled are solved, fewer biased inclusion in a metallographic structure of the steel can be ensured, the uniformity degree of the structure is increased, the stability of the carbon content is controlled, and further the control of the decarburization degree is facilitated, so that the mechanical property of the steel can be comprehensively improved, and the steel strip for the high-carbon needle making with excellent mechanical property is obtained.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic flow chart of a method according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of the temperature change of the cold rolling annealing process according to the embodiment of the present application;
FIG. 3 is a diagram showing the metallographic structure of the steel strip for high-carbon needle making according to the embodiment of the present application;
fig. 4 is a diagram of a metallographic structure of high carbon steel SK85 according to an embodiment of the present application.
Detailed Description
The advantages and various effects of the present invention will be more clearly apparent from the following detailed description and examples. It will be understood by those skilled in the art that these specific embodiments and examples are intended to illustrate the invention, not to limit the invention.
Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification will control.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or may be prepared by existing methods.
The technical scheme provided by the embodiment of the invention aims to solve the technical problems, and the overall thought is as follows:
in one embodiment of the present application, as shown in fig. 1, there is provided a method for manufacturing a steel strip for high-carbon needle manufacture, the method comprising:
s1, refining molten iron after smelting, and then carrying out continuous casting to obtain a casting blank;
s2, carrying out hot feeding, hot charging, rolling, laminar cooling, coiling, heat preservation, leveling and acid washing on the casting blank to obtain an acid washing plate;
s3, performing cold rolling annealing on the pickling plate, and then flattening to obtain a high-carbon steel belt for needle making, which has excellent mechanical properties;
wherein, as shown in fig. 2, the cold rolling annealing includes a first cold rolling, a first annealing, a second cold rolling, and a second annealing;
the components of the refined ladle slag comprise FeO and MnO, and the FeO and the MnO satisfy the following conditions:
wherein [ FeO ] + [ MnO ] < 1%, wherein [ FeO ] is mass fraction of FeO, and [ MnO ] is mass fraction of MnO;
the refining is carried out by taking the grade of nonmetallic inclusion in molten steel as the target of less than or equal to 1.5 grade.
In the embodiment of the application, the positive effect that [ FeO ] + [ MnO ] < 1% is in the range, the secondary oxidation of steel slag to molten steel is prevented by limiting the oxygen content in ladle slag, the excessive oxygen content of the molten steel is avoided, and meanwhile, the diameter and the shape of inclusions in the molten steel are ensured, so that the problems of excessive segregation and uneven structure of steel can be avoided, and the mechanical property of the steel is effectively improved; when the mass fraction sum is larger than the end value of the range, the excessive oxygen content in ladle slag is caused, and the secondary oxidation of steel slag to molten steel is caused, so that the excessive diameter of inclusions in the molten steel is promoted, the excessive segregation of steel is caused, and the structure is uneven.
The positive effect of limiting refining to the level less than or equal to 1.5 of nonmetallic inclusion in molten steel is that the level of nonmetallic inclusion is limited, so that the content of nonmetallic inclusion and the composition of carbon content can be further limited, the decarburization process can be effectively controlled, and the mechanical property of steel is ensured.
In some alternative embodiments, the continuous casting includes continuous casting in a submerged casting and tundish sealing manner.
In the embodiment of the application, continuous casting is carried out by submerged casting and tundish sealing, so that secondary oxidation of continuous casting is reduced, total oxygen of the tundish is improved, and further control of oxygen content is realized.
In some alternative embodiments, the casting blank has a center segregation less than or equal to 1.5 grade, wherein the grade of center segregation is evaluated according to national standard GB/T10561-2005.
In the embodiment of the application, the central segregation of the casting blank is less than or equal to 1.5 level, and the positive effect is that the composition segregation of the steel can be ensured to be less in the range of the segregation class, so that the tissue uniformity degree of the steel is ensured, and the mechanical property of the steel is further ensured.
In some alternative embodiments, the hot pack is provided for less than or equal to 8 hours and the hot pack is provided at a temperature of greater than or equal to 400 ℃.
In the embodiment of the application, the time of hot feeding and hot charging is less than or equal to 8 hours, and the positive effects of ensuring that a casting blank enters a heating furnace as soon as possible after being offline and avoiding cracks caused by cold of the casting blank are achieved; when the time is longer than the end value of the range, the adverse effect is that the hot charging time is too long, and the risk of cracking of the casting blank is increased.
The positive effect of the hot charging temperature of more than or equal to 400 ℃ is that cracks of the high-carbon steel casting blank can be effectively avoided within the temperature range; when the temperature is less than the end of the range, the adverse effect is that the cast slab will crack or even break in the furnace.
In some alternative embodiments, the rolling includes pre-rough descaling, rough rolling, pre-finish descaling, and finish rolling;
the pressure of the descaling before rough rolling is more than or equal to 20MPa, and the pressure of the descaling before finish rolling is more than or equal to 25MPa.
In the embodiment of the application, the pressure of rough rolling descaling is more than or equal to 20MPa, and the positive effects are that in the pressure range, the descaling of the surface of the casting blank can be ensured to be sufficient, and meanwhile, the surface quality of the casting blank is ensured; when the pressure value is smaller than the end value of the range, the adverse effect caused by the pressure is that the pressure is too small, so that the surface of the hot coil is provided with iron oxide scale residues after pickling, and the surface quality of the final finished product is affected.
The positive effect of the descaling pressure before finish rolling is that the descaling pressure is more than or equal to 25MPa, and the descaling pressure has the effect of removing the oxide skin on the surface of the steel strip in the pressure range; when the pressure value is smaller than the end value of the range, the adverse effect is that the oxide scale on the surface of the steel belt is not removed cleanly, so that the defects of pressing in the oxide scale and the like are caused.
In some alternative embodiments, the rough rolling is performed in a "3+3" mode.
In the embodiment of the present application, by limiting the rolling mode of rough rolling, the strip-like structure due to segregation and segregation can be reduced by using fast-paced rolling and simultaneously matching with the heating mode of low air-fuel ratio.
In some alternative embodiments, the temperature of the coiling is 500 ℃ to 650 ℃ and the tension of the coiling is 30MPa to 55MPa.
In the embodiment of the application, the coiling temperature is 500-650 ℃, and the positive effect is that in the coiling temperature range, the temperature difference from finish rolling to coiling can be increased by adopting lower coiling temperature, so that the occurrence probability of segregation is reduced, and the occurrence probability of a strip-shaped tissue is further reduced.
The coiling tension is 30 kPa-55 kPa, and the positive effects are that in the tension range, the larger coiling tension is adopted, so that the air entering in the coiling process can be reduced, the degree of inter-crystal oxidation is further reduced, the uniform distribution of metallographic structures is ensured, and the mechanical property of the steel is further improved.
In some alternative embodiments, the first cold rolling has a reduction of 30% to 70% and the second cold rolling has a reduction of 10% to 40%.
In the embodiment of the application, the positive effect of limiting the reduction rate of the first cold rolling to 30% -70% is that the first cold rolling has enough mechanical energy storage, and the spheroidizing effect of carbide in a metallographic structure is ensured, so that the structural uniformity of steel is ensured, and the mechanical property of the steel is improved; when the reduction is greater than or less than the end value of the range, an adverse effect will be caused in that an excessively large reduction will increase the load of the cold rolling mill and an excessively small reduction will affect the spheroidization effect.
The rolling reduction of the second cold rolling is 10% -40%, and in the range of the rolling reduction, the rolling reduction can ensure that the steel is rolled to the expected thickness, the tissue uniformity degree of the steel can be ensured, and the mechanical property of the steel is improved; when the depression is greater than or less than the end of the range, the adverse effect is uneven tissue.
In some alternative embodiments, both the first anneal and the second anneal are annealed using a perhydro anneal mode.
In the embodiment of the application, the first annealing mode and the second annealing mode are limited to be all-hydrogen annealing modes, so that the decarburization can be improved, the thickness of the decarburized layer is controlled, and the smooth proceeding of the decarburization is ensured.
In some alternative embodiments, the peak temperature of the first anneal is 650 ℃ to 750 ℃.
In the embodiment of the application, the positive effect that the peak temperature of the first annealing is 650-750 ℃ is enough temperature to ensure the spheroidizing effect of the carbide; when the temperature is higher or lower than the end value of the range, an adverse effect will be caused in that too high a temperature will cause lamellar pearlite to possibly appear in the metallographic structure of the steel, and too low a temperature will cause a low spheroidization rate of carbide.
In some alternative embodiments, the peak temperature of the second anneal is 400 ℃ to 550 ℃.
In the embodiment of the application, the peak temperature of the second annealing is 400-550 ℃, and the positive effect is that the uniformity of the hardness of the final steel product can be ensured in the temperature range; when the temperature is greater or less than the end of this range, the adverse effect that would result is hardness out of range.
In one embodiment of the present application, there is provided a steel strip for high carbon needle making, the steel strip being prepared by the method, the chemical composition of the steel strip including, in mass percent: 0.75 to 1.00 percent of C, 0.2 to 0.6 percent of Si, 0.2 to 0.7 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.02 percent of S, less than or equal to 0.012 percent of Alt, 0.15 to 0.35 percent of Cr, and the balance of Fe and unavoidable impurity elements.
In the embodiment of the application, the positive effect that the mass fraction of C is 0.75% -1.00% is that in the mass fraction range, the solid solution carbon content can ensure the hardness of the part after heat treatment, the hardenability of steel is ensured, when the mass fraction value is smaller than the end value of the range, the hardness of the steel after heat treatment is difficult to ensure, the strength of the steel is lower, the textile needle is easy to bend, and when the mass fraction value is larger than the end value of the range, the part after heat treatment is too brittle, and the service life of the steel is shorter.
The positive effect of Si with the mass fraction of 0.2-0.6% is that the hardness of the steel can be ensured within the mass fraction range; when the mass fraction is larger than the end value of the range, the surface quality of the hot rolled plate is affected by excessive Si element, and when the mass fraction is smaller than the end value of the range, the hardness of the steel is insufficient.
The mass fraction of Mn is 0.2% -0.7%, the positive effects are that in the mass fraction range, the hardness and hardenability of the steel are guaranteed, when the mass fraction is larger than the end value of the range, excessive Mn content can aggravate segregation, and when the mass fraction is smaller than the end value of the range, the hardness and hardenability of the steel are affected.
The positive effects of P being less than or equal to 0.02 percent and S being less than or equal to 0.02 percent are that the plasticity and toughness of the parts after heat treatment are ensured, and if the content is too high, the service life of the parts is shortened, and in addition, the fatigue life is also influenced.
The positive effect of Alt less than or equal to 0.012% is that in the mass fraction range, al element is mainly added as deoxidizer, and if the Al content is too high, brittleness of the quenched part is increased.
The positive effect of the Cr with the mass fraction of 0.15-0.35% is that the guaranteed hardness and spheroidization effect of the steel can be ensured within the mass fraction range, and meanwhile, the addition of Cr element is beneficial to inhibiting the uniformity of decarburization and spheroidization; when the value of the mass fraction is larger than the end value of the range, excessive Cr element can promote the risk of casting blank cracks, and when the value of the mass fraction is smaller than the end value of the range, the hardness of the heat-treated casting blank is difficult to ensure due to the fact that the Cr element is too low.
In some alternative embodiments, the metallographic structure of the steel strip comprises carbides, the carbides comprise spherical carbides, the spheroidization rate of the spherical carbides is equal to or more than 95%, and the average diameter of the spherical carbides is 0.8-1.1 μm.
In the embodiment of the application, the spheroidization rate of the spherical carbide is more than or equal to 95%, and the spheroidization rate is within the range of the spheroidization rate, so that the metallographic structure of the steel can be guaranteed to be fully formed into spheroidization matters, the metallographic structure of the steel is guaranteed to have enough spheroidization matters, the distribution of the structure is guaranteed to be uniform, and the excellent mechanical property of the steel is further guaranteed.
The positive effect of the average diameter of the spherical carbide being 0.8-1.1 μm is that in the diameter range, the uniform distribution of the particles of the spherical carbide can be ensured, and the excellent mechanical properties of the steel can be ensured.
The chemical compositions of the steels in each example and comparative example are shown in Table 1.
TABLE 1
The specific preparation method is as follows:
example 1
A preparation method of a steel belt for high-carbon needle manufacture comprises the following steps:
s1, refining molten iron after smelting, and then carrying out continuous casting to obtain a casting blank;
s2, carrying out hot feeding, hot charging, rolling, laminar cooling, coiling, heat preservation, leveling and acid washing on the casting blank to obtain an acid washing plate;
s3, performing cold rolling annealing on the pickled plate, and then flattening to obtain the high-carbon steel belt for needle making, which has excellent mechanical properties as shown in FIG. 3;
wherein the cold rolling annealing comprises a first cold rolling, a first annealing, a second cold rolling and a second annealing;
the refined ladle slag meets the following conditions:
wherein [ FeO ] + [ MnO ] < 1%, wherein [ FeO ] is mass fraction of FeO, and [ MnO ] is mass fraction of MnO;
refining is carried out by taking the grade of nonmetallic inclusion in molten steel as the target of grade less than or equal to 1.5;
continuous casting was carried out using 7, 8 and 9 stages of light reduction, the amount of reduction being 4.2mm.
The hot charging time is 4 hours, and the temperature of the hot charging is 504 ℃.
The pressure of rough rolling descaling is 22MPa, and the pressure of finish rolling descaling is 32MPa.
The finish rolling temperature of the finish rolling was 890 ℃.
The coiling temperature is 516 ℃, and the coiling tension is 45MPa.
The reduction of the first cold rolling was 53%, and the reduction of the second cold rolling was 20%.
The peak temperature of the first annealing was 700 ℃, and the soak time of the first annealing was 18h.
The peak temperature of the second anneal was 460℃and the soak time of the second anneal was 10 hours.
Example 2
Example 2 and example 1 were compared, and example 2 and comparative example 1 differ in that:
continuous casting was carried out using 7, 8 and 9 stages of light reduction, the amount of reduction being 4.2mm.
The hot charging time is 3 hours, and the temperature of the hot charging is 620 ℃.
The pressure of rough rolling descaling is 22MPa, and the pressure of finish rolling descaling is 33MPa.
The finish rolling temperature of the finish rolling was 893 ℃.
The temperature of the winding was 569℃and the tension of the winding was 47MPa.
The reduction of the first cold rolling was 62%, and the reduction of the second cold rolling was 18%.
The peak temperature of the first anneal was 710 c and the soak time of the first anneal was 14h.
The peak temperature of the second annealing is 450 ℃, and the holding time of the second annealing is 15h.
Example 3
Example 3 and example 1 were compared, and example 3 and comparative example 1 differ in that:
continuous casting was carried out using 7, 8 and 9 stages of light reduction, the amount of reduction being 4.2mm.
The hot charging time is 5 hours, and the temperature of the hot charging is 480 ℃.
The pressure of rough rolling descaling is 21MPa, and the pressure of finish rolling descaling is 31MPa.
The finish rolling temperature of the finish rolling was 887 ℃.
The coiling temperature was 599 ℃, and the coiling tension was 32MPa.
The reduction of the first cold rolling was 47%, and the reduction of the second cold rolling was 24%.
The peak temperature of the first annealing was 695 ℃, and the soak time of the first annealing was 13h.
The peak temperature of the second annealing is 480 ℃, and the holding time of the second annealing is 8h.
Comparative example 1
Comparative example 1 was compared with example 1, and the difference between comparative example 1 and example 1 was that:
the report SK85 of the published literature of the metal heat treatment school report 2021, 6 th month, 46 th volume, 6 th period, the original structure and the influence of an annealing process on the spheroidizing effect of high carbon steel SK85 are selected as a comparison example.
The composition is shown in Table 1. The hot rolling process flow is as follows: heating the plate blank, rough rolling, finish rolling, laminar cooling and coiling, wherein the temperature of a soaking section of a heating furnace is 1220-1270 ℃, and the furnace time is 160min. The annealing temperature is as follows: heating to 730 ℃ at 15 ℃/s, preserving heat for 13 hours, then gradually cooling to 500 ℃ along with a furnace, and discharging from the furnace for air cooling to room temperature. The microstructure is shown in fig. 4, the spheroidization rate is about 90%, and the microstructure has some pearlite in short rod package and is not completely spheroidized.
Related experiments:
the steel products obtained in the comparative examples and examples were collected, and the mechanical properties and spheroidization rate were measured, and the results are shown in Table 2.
Test method of related experiment:
yield strength (R) p0.2 ): the measurement is carried out according to national standard GB/T228.1-2010;
tensile Strength (R) m ): the measurement is carried out according to national standard GB/T228.1-2010;
total elongation: measuring according to national standard GB/T228.1-2010, and adopting a gauge length of 50 mm;
hardness (HV 5): according to national standard GB/T4340.1-2009, HV5 is adopted for measurement;
TABLE 2
Table 2 detailed analysis:
yield strength (R) p0.2 ) The tensile strength of the steel is 0.2% when the non-proportional elongation is equal to the standard, and the better the yield strength is, the better the mechanical property of the steel is.
Tensile Strength (R) m ) The tensile strength meets the standard, and the mechanical property of the steel is good.
The total elongation is the percentage of the ratio of the total deformation delta L of the gauge length after the tensile fracture of the sample to the original gauge length L, and the more the total elongation meets the standard, the better the mechanical property of the steel is.
The spheroidization rate refers to the probability of carbide forming spheroidization in the metallographic structure of the steel, and the higher the spheroidization rate is, the more spheroidization of carbide is formed.
From the data of examples 1-3, it can be seen that:
by adopting the method, the oxygen content of ladle slag in the refining process is controlled, and the grade of nonmetallic inclusion in molten steel in the refining stage is controlled at the same time, so that the problems of excessive segregation, uneven structure and uncontrollable decarburization degree of steel can be avoided, the control of decarburization degree is facilitated, and the mechanical property of the steel can be comprehensively improved.
From the data of comparative example 1, it can be seen that:
the spheroidization rate of the invention is more than or equal to 95%, the structure is uniform, although the spheroidization rate of the comparative example is about 90%, the comparative example has some short rod-shaped pearlite which is not completely spheroidized, the spheroidization effect directly influences the blanking effect, and influences the dimensional accuracy after heat treatment, the structure uniformity and the hardness uniformity after heat treatment, thereby influencing the fatigue performance of the final steel product.
One or more technical solutions in the embodiments of the present application at least further have the following technical effects or advantages:
(1) According to the method provided by the embodiment of the application, the oxygen content of ladle slag in the refining process is controlled, and the grade of nonmetallic inclusion in molten steel in the refining stage is controlled at the same time; meanwhile, each process stage of the continuous casting link and the hot rolling link is controlled, so that the problems of excessive segregation, uneven structure and uncontrollable decarburization degree of the steel can be avoided, the control of the decarburization degree can be facilitated, and the mechanical property of the steel can be comprehensively improved.
(2) The method provided by the embodiment of the application is controlled in each link of component design, steelmaking, continuous casting, hot rolling, pickling, cold rolling, annealing and the like, so that the steel for needle making with less component segregation, uniform structure and low decarburization degree is obtained.
(3) The method provided by the embodiment of the application can finally obtain the finished steel plate with the thickness of 0.2-3 mm, the yield strength of the final finished steel plate is 650-750 MPa, the tensile strength is 750-850 MPa, the elongation after fracture (A50) is 8-15%, the hardness (HV 5) is 220-260 HV, the spheroidization rate is more than or equal to 95%, and the average diameter of spheroidized objects is 0.8-1.1 mu m.
(4) The steel band that this application embodiment provided, the spheroidization rate is higher, simultaneously because the spheroidization rate influences blanking and heat treatment back textile needle dimensional accuracy, therefore the steel band of this application can make more accurate textile needle.
Explanation of the drawings:
FIG. 3 is a diagram showing the metallographic structure of the steel strip for high-carbon needle making according to the embodiment of the present application;
fig. 4 is a diagram of a metallographic structure of high carbon steel SK85 according to an embodiment of the present application;
as can be seen from fig. 3 and 4, the method and the steel strip composition provided by the present application can obtain steel for needle making with higher spheroidization rate, and since the spheroidization rate affects the dimensional accuracy of the textile needles after blanking and heat treatment, the steel strip of the present application can manufacture more accurate textile needles.
It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. The preparation method of the steel belt for the high-carbon needle manufacture is characterized by comprising the following steps of:
refining the smelted molten iron, and then carrying out continuous casting to obtain a casting blank;
carrying out hot feeding, hot charging, rolling, laminar cooling, coiling, heat preservation, leveling and acid washing on the casting blank to obtain an acid washing plate;
performing cold rolling annealing on the acid-washed plate, and then flattening to obtain a high-carbon steel belt for needle making, which has excellent mechanical properties;
wherein the cold rolling annealing comprises a first cold rolling, a first annealing, a second cold rolling and a second annealing;
the components of the refined ladle slag comprise FeO and MnO, and the FeO and the MnO satisfy the following conditions:
wherein [ FeO ] + [ MnO ] < 1%, wherein [ FeO ] is mass fraction of FeO, and [ MnO ] is mass fraction of MnO;
refining is carried out by taking the grade of nonmetallic inclusion in molten steel as a target, wherein the grade of nonmetallic inclusion in molten steel is less than or equal to 1.5 grade;
the continuous casting comprises the steps of carrying out continuous casting in a manner of immersion casting and tundish sealing;
the hot feeding and hot charging time is less than or equal to 8 hours, and the temperature of the hot feeding and hot charging is more than or equal to 400 ℃;
the rolling comprises descaling before rough rolling, descaling before rough rolling and finish rolling;
the pressure of the descaling before rough rolling is more than or equal to 20MPa, and the pressure of the descaling before finish rolling is more than or equal to 25MPa;
the coiling temperature is 500-650 ℃, and the coiling tension is 30-55 MPa;
the steel strip comprises the following chemical components in percentage by mass: 0.75 to 1.00 percent of C, 0.2 to 0.6 percent of Si, 0.2 to 0.7 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.02 percent of S, less than or equal to 0.012 percent of Alt, 0.15 to 0.35 percent of Cr, and the balance of Fe and unavoidable impurity elements, wherein the metallographic structure of the steel strip comprises carbides, the carbides comprise spherical carbides, the spheroidization rate of the spherical carbides is more than or equal to 95 percent, the average diameter of the spherical carbides is 0.8 to 1.1 mu m, the thickness of the finished steel strip is 0.2 to 3mm, the yield strength is 650 to 750MPa, the tensile strength is 750 to 850MPa, the elongation A50 after fracture is 8 to 15 percent, and the hardness HV5 is 220 to 260HV.
2. The method according to claim 1, wherein the center segregation of the cast slab is 1.5 or less.
3. The method according to claim 1, wherein the reduction of the first cold rolling is 30% to 70% and the reduction of the second cold rolling is 10% to 40%.
4. The method of claim 1, wherein the first anneal and the second anneal are both annealed using a perhydro anneal mode.
5. The method of claim 4, wherein the peak temperature of the first anneal is 650 ℃ to 750 ℃.
6. The method of claim 4, wherein the second anneal has a peak temperature of 400 ℃ to 550 ℃.
7. A steel strip for high carbon needle manufacture, characterized in that it is produced by the method according to any one of claims 1 to 6, comprising, in mass fraction: 0.75 to 1.00 percent of C, 0.2 to 0.6 percent of Si, 0.2 to 0.7 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.02 percent of S, less than or equal to 0.012 percent of Alt, 0.15 to 0.35 percent of Cr, and the balance of Fe and unavoidable impurity elements.
8. The steel strip according to claim 7, wherein the metallographic structure of the steel strip comprises carbides, the carbides comprise spherical carbides, the spheroidization rate of the spherical carbides is equal to or more than 95%, and the average diameter of the spherical carbides is 0.8-1.1 μm.
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| CN105200308A (en) * | 2014-05-28 | 2015-12-30 | 宝山钢铁股份有限公司 | Fine blanked steel and manufacturing method of adjustment mechanism fine blanked part |
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