CN112813346A - Cold heading steel suitable for 6.8 and 8.8-grade weather-resistant fasteners and production method thereof - Google Patents
Cold heading steel suitable for 6.8 and 8.8-grade weather-resistant fasteners and production method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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Abstract
The invention discloses cold heading steel suitable for 6.8 and 8.8-grade weather-resistant fasteners and a production method thereof, wherein the cold heading steel comprises the following components in percentage by weight: 0.09-0.13 percent of C, 0.32-0.5 percent of Si, 0.7-1.2 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.50-0.75 percent of Cr, 0.15-0.3 percent of Ni, 0.25-0.4 percent of Cu, 0.06-0.11 percent of V, more than or equal to 0.010 percent of Al, 0.009-0.013 percent of N, and the balance of Fe and inevitable impurity elements. The potential difference between the fastener prepared by the cold heading steel and the weather-resistant angle steel is lower than 50mv, galvanic corrosion does not exist, and the safety of the power transmission weather-resistant iron tower in long-term use in the atmosphere can be effectively ensured; the cold heading steel adopts a low-carbon design, has good processability, and the completeness rate of 1/3 cold upsetting test samples is 100%. The cold heading steel has good mechanical property, can be used for producing fasteners with two strength levels of 6.8 and 8.8, has very low potential difference with weather-resistant angle steel, and effectively avoids potential safety hazards caused by galvanic corrosion.
Description
Technical Field
The invention relates to cold heading steel, in particular to cold heading steel suitable for 6.8 and 8.8-grade weather-resistant fasteners and a production method thereof.
Background
The steel towers for power transmission in China mainly comprise angle steel towers, and the processing of the angle steel towers adopts an acid pickling and hot galvanizing process, which has serious environmental pollution; under the conditions that the process is gradually limited and the environment demands are met, the weather-resistant angle steel is already applied to engineering; however, the development of the steel for the weather-resistant bolt matched with the angle steel tower is totally lagged, wherein the steel is above 6.8 grade and above 8.8 grade and below phi 20. At present, the research on weather-resistant bolt steel based on bridge buildings is more, large-specification bolts with the diameter of more than 10.9 grade and more than 30 grade are mostly considered, and the C content and alloy elements are increased when the high strength is considered in the large-specification high-strength bolts; and the weather-resistant angle steel of the iron tower is low-carbon steel below Q420, and has potential safety hazards caused by galvanic corrosion if connected with an angle steel tower, and the cost is higher.
The Chinese patent application with the application number of 201610129356.4 discloses an atmospheric corrosion resistant cold heading steel hot rolled wire rod and a production method thereof, and the components of the atmospheric corrosion resistant cold heading steel hot rolled wire rod are as follows by weight percent: 0.12-0.18% of C, 0.15-0.35% of Si, 0.60-0.90% of Mn, less than or equal to 0.030% of P, less than or equal to 0.030% of S, 0.70-0.90% of Cr, 0.20-0.50% of Ni, 0.20-0.50% of Cu, and the balance of iron and trace impurities. In the composition range of the technology, the weather resistance of steel is improved, the content of C, Mn element in the common 8.8-grade cold heading steel wire rod is reduced, but elements for improving hardenability such as B, Mo and V are not added, so that the requirement of 8.8-grade fasteners on strength is difficult to meet, and particularly, the requirement on phi 20 and above specifications is low.
Application No.: 201310290465.0, discloses a method for preparing high-strength annealing-free cold forging steel with atmospheric corrosion resistance, which comprises the steps of melting, oxidizing, detecting alloy components, adjusting, refining, casting, hot rolling and heat treatment, wherein the chemical elements comprise the following components in percentage by weight: 0.35 to 0.50 percent of C, 0.45 to 0.55 percent of Si, 0.25 to 0.356 percent of Mn, 0.005 to 0.025 percent of P, 0.005 to 0.02 percent of S, 0.35 to 0.55 percent of Cr, 0.65 to 0.80 percent of Cu, 1.0 to 1.2 percent of Zn, 0.2 to 0.3 percent of W, 0.19 to 0.22 percent of Bi, 0.01 to 0.02 percent of Yb, 0.08 to 0.12 percent of Ni, 0.01 to 0.03 percent of Sn, 0.02 to 0.04 percent of Gd, 0.12 to 0.18 percent of Dy and the balance of iron. The cold heading steel has the advantages that the surface of the material is resistant to oxidation corrosion in atmosphere and water environment, the service life is longer, annealing and heat treatment are not needed in cold heading forming, the metal consumption is low, the strength is high, and the cold heading steel can be used for processing 8.8-grade bolts and matched nuts. Compared with the common medium and high strength cold heading steel, the carbon content is reduced, and the welding performance is excellent. The method has the disadvantages that the material provided by the technology can meet the strength requirement of 8.8-grade bolts and matched nuts, but compared with the common 8.8-grade cold heading steel wire rod, the C content is greatly improved, and the iron tower has larger galvanic corrosion; in addition, a large amount of noble metals and rare earth elements are added in the technology, so that the production cost of the material is certainly greatly improved, the difficulty of material popularization is increased, and the application range of the material is limited.
The Chinese patent application with the application number of 201711333523.8 discloses a weather-resistant cold-heading steel wire rod for an 800 MPa-level fastener and a production method thereof, and the weather-resistant cold-heading steel wire rod comprises the following components: 0.15 to 0.30 percent of C, 0.10 to 0.40 percent of Si, 0.80 to 1.20 percent of Mn, less than or equal to 0.035 percent of P, less than or equal to 0.040 percent of S, 0.30 to 0.70 percent of Cr, 0.25 to 0.55 percent of Ni, 0.15 to 0.40 percent of Cu, 0.02 to 0.10 percent of V, and the balance of Fe and inevitable impurity elements. The content of C in the cold forging steel is from low carbon to medium carbon, other components also cover a larger range, and the requirement of 8.8-grade performance is difficult to meet when the lower limit of the components is reached; particularly, for the applicable phi 15-phi 24 specification mentioned in the document, the capacity of meeting hardenability is insufficient; meanwhile, the embodiment can also show that even if the carbon content is controlled to be in the middle limit, the obtained bolt performance of 821MPa \817MPa \826MPa does not meet the requirement of 830MPa-1030MPa of the 8.8-level requirement of GB/T1231, namely the requirement of corresponding tensile load cannot be met.
Disclosure of Invention
The invention aims to solve the technical problem of providing cold heading steel which has excellent performance and is suitable for 6.8 and 8.8-grade weather-resistant fasteners; the invention also provides a production method of the cold heading steel suitable for the 6.8 and 8.8-grade weather-resistant fasteners.
In order to solve the technical problems, the invention comprises the following components in percentage by weight: 0.09-0.13 percent of C, 0.32-0.5 percent of Si, 0.7-1.2 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.50-0.75 percent of Cr, 0.15-0.3 percent of Ni, 0.25-0.4 percent of Cu, 0.06-0.11 percent of V, more than or equal to 0.010 percent of Al, 0.009-0.013 percent of N, and the balance of Fe and inevitable impurity elements.
The specification of the cold heading steel wire rod is phi 13-phi 20 mm.
The cold heading steel is formed into a 6.8-grade fastener by cold heading; the cold heading steel is firstly subjected to cold heading forming and then is subjected to heat treatment to form 8.8-grade fasteners.
The invention has the following components:
c: c is the most obvious element for strengthening the solid solution in the steel and improving the strength, but the strength and the hardness of the steel are increased and the plasticity and the toughness are reduced along with the increase of the content of C. Aiming at a 6.8 cold heading forming bolt and an 8.8 quenched and tempered bolt, in order to meet the strength requirements of bolts of two different processes, the bolt is reasonably matched with other elements, and weather-resistant matching with weather-resistant angle steel is considered, so that the range of the bolt is set to be 0.09-0.13%;
si: si is a ferrite solid solution strengthening element and is an element for effectively improving the anti-elastic-reduction capability of steel, and in order to improve the yield strength and the anti-elastic-reduction performance of the bolt, the range of Si is 0.32-0.5%.
Mn: mn functions as solid solution strengthening and fine grain strengthening, and delays pearlite and ferrite transformation, and is an effective alloying element for improving hardenability, but this element tends to overheat at high temperatures. The range of Mn in the invention is 0.70-1.2%.
P, S: p, S is a segregated impurity element, in order to improve the uniformity of the structure and performance of the cold forging steel, the processing performance of S is considered, and P is less than or equal to 0.020% and S is less than or equal to 0.010%.
Cr: cr can remarkably improve the hardenability of steel, and Cr element can improve the corrosion resistance of the material. The component range of Cr is determined to be 0.50-0.75% by comprehensively considering the factors of strength, structure control, corrosion resistance and the like.
Ni: ni is an austenite forming element, and is matched with chromium to improve the high-temperature oxidation resistance and stress corrosion resistance of the steel and improve the impact toughness. Therefore, the content of Ni is 0.15-0.3%.
Cu: the Cu can obviously improve the atmospheric corrosion resistance of the steel, can improve the hardenability of the steel, can effectively improve the hardenability of the steel under the condition of low C, and the cooperation of Cr, can promote the formation of a surface passivation film, reduce the corrosion induction sensitivity of a steel matrix, and improve the corrosion resistance of steel. Therefore, the Cu content is designed to be 0.25-0.4%.
V: v can inhibit the recrystallization of austenite in the rolling process, prevent the growth of manager, refine ferrite grains by VN and improve the obdurability of steel. In addition, the V can increase the hardenability of steel after effective solid solution, improve the uniformity of the structure after quenching and tempering, and the range of the V is set to be 0.06-0.11%.
Al: when Al is added into steel as alloying element, it can be combined with N to obviously refine crystal grain, so that it can obviously raise the toughness of steel, at the same time can reduce cold-brittleness tendency and ageing tendency, and can be matched with Cu, Si and Cr elements to raise the corrosion resistance of steel. However, too high Al content affects hot workability and machinability of the steel, so that Al content is controlled to be not less than 0.010%, preferably 0.010-0.025%.
N: v needs to form VN by combining with N, effectively form solid solution at high temperature and improve hardenability and toughness of steel through cooling control, and simultaneously N and Al combine to refine crystal grains, thereby controlling N0.009% -0.013%.
The method comprises the working procedures of converter smelting, LF refining, soft blowing treatment, continuous casting and wire rod rolling;
the wire rod rolling procedure comprises heating, rolling and cooling processes; in the heating process, the heating time is 90-120 min, the temperature of a heating section is 920-1150 ℃, and the temperature of a soaking section is 1080-1130 ℃; in the rolling process, the precision rolling temperature is controlled to be 830-850 ℃, and the spinning temperature is controlled to be 820-840 ℃; in the cooling process, the speed of a roller way at the inlet of the stelmor cooling control procedure is 14-16 m/min, each section is gradually increased by 0.6m/min, the heat-insulating cover is completely opened, and the fan is completely closed.
According to the continuous casting process, argon is used for protection in the whole process, the superheat degree is controlled to be 15-30 ℃, the secondary cooling specific water quantity is 0.8-1.1L/kg, and the casting speed is controlled to be 1.70-2.0 m/min.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: the invention adopts low-carbon high-silicon and adds V which is effectively dissolved in solid solution and plays a role in improving hardenability under the combined action of Cr, Ni and Cu, thereby ensuring the tightness of the cold heading steelThe fastener can meet the performance of fasteners with two strength levels of 6.8 and 8.8; according to the invention, the yield strength of the bolt can be improved by increasing the content of Si, and the anti-elastic-reduction capability of the bolt is improved; the invention adopts low-carbon design and is matched with Al, Cr, Ni and Cu, so that the alloy has good weather resistance; the pitting potential of the steel is more than or equal to-0.3V, and the corrosion weight loss rate of a 72h periodic infiltration test is less than or equal to 3 g/(m)2H); the potential difference between the fastener and the weather-resistant angle steel prepared by the invention is lower than 50mv, galvanic corrosion does not exist, and the safety of the power transmission weather-resistant iron tower in long-term use in the atmosphere can be effectively ensured; the invention adopts a low-carbon design, has good processing performance, and the completeness rate of 1/3 cold upsetting test samples is 100%. The invention has good mechanical property, can be used for producing fasteners with two strength levels of 6.8 and 8.8, has low potential difference with weather-resistant angle steel, and effectively avoids potential safety hazard caused by galvanic corrosion.
The cold heading steel obtained by the method can meet the requirements of 6.8 and 8.8-grade weather-resistant bolt materials, the production cost is saved, and the quality stability of the cold heading steel is ensured to the greatest extent.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
Examples 1 to 7: the production method of the cold heading steel suitable for the 6.8 and 8.8-grade weather-resistant fasteners comprises the working procedures of converter smelting, LF refining, soft blowing treatment, continuous casting and wire rolling; the process of each procedure is as follows:
(1) a converter smelting process: v in the smelting raw material molten iron is more than or equal to 0.06 wt%, and the proportion of scrap steel (refer to GB4223 scrap steel) in the raw materials charged into the furnace is controlled to be 10-12 wt%; smelting by adopting a combined blowing converter, adopting 100 percent argon for bottom blowing in the whole process, controlling the decarburization period and slag discharge of the converter smelting, and keeping the smelting end point C to be more than or equal to 0.08wt percent. During tapping, a slag blocking cap is adopted to block early slag, and a slag blocking ball or a slag blocking plug is adopted to block later slag, so that the maintenance of a tapping hole is enhanced to improve the slag blocking effect; the tapping time is ensured to be more than or equal to 4 minutes. 1.5-2.0 kg/t ferrosilicon steel and 1.5-2.0 kg/t aluminum steel are adopted for precipitation deoxidation; when steel is tapped from 1/3-1/2, steel synthetic refining slag, 2.0-3.0 kg/t steel of a nickel plate and 3.0-4.0 kg/t steel of a copper plate are added along the steel flow, wherein the steel synthetic refining slag comprises the following components: 3.5-4.5 kg/t steel of metallurgical dust and 2.0-3.0 kg/t steel of bauxite. The process parameters of converter smelting described in the examples are shown in Table 1.
Table 1: technological parameters of converter smelting
(2) An LF refining procedure: 3.0-4.0 kg/t of steel is adopted for diffusion deoxidation, and argon is blown at the bottom in the whole LF refining process; adding 1.5-2.5 kg/t steel of active lime, 0-1.5 kg/t steel of fluorite, preferably 0.8-1.5 kg/t steel, and slagging; final slag alkalinity: 3.5 to 4.5; keeping white slag time to be more than or equal to 20min, and power transmission time to be more than or equal to 30 min; 100-150 kg of ferrovanadium nitride (FeV77N12) is added in the white slag period. The process parameters for LF refining described in the examples are shown in table 2.
Table 2: technological parameters of LF refining
(3) Soft blowing treatment process: and (3) blowing argon into the ladle position for more than or equal to 20min, and adding more than or equal to 1.5kg of ladle covering agent, preferably 1.5-2.0 kg of covering agent when the ladle is out of the station.
(4) And (3) continuous casting process: adopting a square billet with the thickness of 150mm multiplied by 150mm, carrying out argon protection in the whole process, and carrying out ladle slag tapping detection; controlling the superheat degree to be 15-30 ℃, the target superheat degree delta T to be 20 ℃, the secondary cooling specific water amount to be 0.8-1.1L/kg, the drawing speed to be 1.70-2.0 m/min and the target drawing speed to be 1.85 m/min. The process parameters for the soft blow treatment and continuous casting described in the examples are shown in Table 3.
Table 3: technological parameters of soft blowing treatment and continuous casting
(5) A wire rod rolling procedure: adopting a continuous casting billet with the diameter of 150mm multiplied by 150mm, and comprising the processes of heating, rolling and cooling; in the heating process, the heating time is 90-120 min, the temperature of a heating section is 920-1150 ℃, the temperature of a soaking section is 1080-1130 ℃, and the descaling pressure of high-pressure water is more than or equal to 18 MPa; in the rolling process, the precision rolling temperature is controlled to be 830-850 ℃, and the spinning temperature is controlled to be 820-840 ℃; in the cooling process, the speed of a roller way at the inlet of the stelmor cooling control procedure is 14-16 m/min, each section is gradually increased by 0.6m/min, the heat-insulating cover is completely opened, and the fan is completely closed. And obtaining the cold heading steel hot rolled wire rod with the specification of phi 13-phi 20mm after rolling. The process parameters for the wire rod rolling described in the examples are shown in table 4.
Table 4: technological parameters for wire rod rolling
(6) The properties of the cold heading steel hot rolled wire rod obtained in each example are as follows: the tensile strength is more than or equal to 540MPa, the yield strength is more than or equal to 425MPa, the elongation is more than or equal to 25 percent, the face shrinkage is more than or equal to 55 percent, and the completeness of 1/3 cold upset samples is 100 percent; the pitting potential is more than or equal to-0.3V, the potential difference with weather-resistant tower materials is less than 50mV, and the corrosion weight loss rate of a 72h periodic infiltration test is less than or equal to 3 g/(m)2H). The compositions of the hot rolled wire rod of cold heading steel obtained in each example are shown in Table 5; the properties of the hot rolled wire rod of cold heading steel obtained in each example are shown in Table 6.
Table 5: composition of the obtained cold heading steel hot rolled wire rod
| Examples | C | Si | Mn | P | S | Cr | Ni | Cu | Al | V | N |
| 1 | 0.130 | 0.450 | 0.70 | 0.008 | 0.004 | 0.50 | 0.24 | 0.25 | 0.015 | 0.09 | 0.0130 |
| 2 | 0.110 | 0.470 | 1.18 | 0.011 | 0.006 | 0.75 | 0.30 | 0.37 | 0.010 | 0.10 | 0.0092 |
| 3 | 0.092 | 0.495 | 1.12 | 0.008 | 0.005 | 0.52 | 0.29 | 0.40 | 0.010 | 0.10 | 0.0103 |
| 4 | 0.100 | 0.320 | 0.97 | 0.020 | 0.007 | 0.73 | 0.15 | 0.28 | 0.018 | 0.07 | 0.0095 |
| 5 | 0.126 | 0.480 | 0.77 | 0.012 | 0.010 | 0.71 | 0.24 | 0.36 | 0.020 | 0.10 | 0.0105 |
| 6 | 0.090 | 0.380 | 1.20 | 0.008 | 0.006 | 0.67 | 0.18 | 0.32 | 0.025 | 0.06 | 0.0110 |
| 7 | 0.106 | 0.50 | 0.83 | 0.008 | 0.006 | 0.62 | 0.27 | 0.30 | 0.016 | 0.11 | 0.0090 |
| Comparative example 1 | 0.32 | 0.14 | 0.74 | 0.01 | 0.003 | 0.027 | 0.005 | 0.02 | 0.03 | 0.005 | 0.045 |
| Comparative example 2 | 0.38 | 0.23 | 0.63 | 0.021 | 0.006 | 1.07 | 0.029 | 0.01 | 0.023 | 0.004 | 0.050 |
In the table 5, comparison 1 and comparison 2 are cold heading steel hot rolled wire rods produced by adopting a conventional ratio and a conventional process.
Table 6: properties of the obtained cold heading steel hot rolled wire rod
In Table 6, comparative example 3 is a Q355 weathering steel 14mm angle steel used as a tower material.
(7) 6.8-grade fastener preparation: and after the cold heading steel hot rolled wire rod is formed by cold heading, the 6.8-grade fastener can be obtained. The performance of the grade 6.8 fastener is: the tensile strength is more than or equal to 600MPa, the elongation is more than or equal to 0.25%, and the hardness is 89-99.5 HRB. The properties of the grade 6.8 fasteners made from the hot rolled coil of cold heading steel obtained in each example are shown in Table 7.
Table 7: performance of class 6.8 fasteners
| Examples | Bolt specification | Tensile strength MPa | Percentage of face shrinkage% | Elongation percentage% | Hardness of |
| 1 | M12 | 720 | -- | 0.3 | 98HRB |
| 2 | M12 | 710 | -- | 0.3 | 97HRB |
| 3 | M16 | 705 | -- | 0.28 | 98HRB |
| 4 | M16 | 690 | -- | 0.3 | 97HRB |
| 5 | M18 | 690 | -- | 0.36 | 96HRB |
| 6 | M20 | 688 | -- | 0.35 | 95.5HRB |
| 7 | M20 | 710 | -- | 0.33 | 95HRB |
| Comparative example 1 | M20 | 720 | -- | 0.28 | 95HRB |
| Comparative example 2 | M20 | 710 | -- | 0.26 | 94HRB |
(8) 8.8-grade fastener preparation: the 8.8-grade fastener can be obtained by performing cold heading forming and reheating treatment on the cold heading steel hot rolled wire rod; the heat treatment process comprises the following steps: adopting quenching and tempering processes; the quenching temperature is 900 +/-20 ℃, and the medium is saline water; the tempering temperature is 450 +/-20 ℃, and the tempering medium is saline water. The performance of the 8.8-grade fastener is: the tensile strength is not less than 870MPa, the elongation is not less than 12%, and the hardness is 23-34 HRC. The properties of the 8.8 grade fasteners made from the hot rolled coil of cold heading steel obtained in each example are shown in Table 8.
Table 8: performance of 8.8 class fastener
Claims (5)
1. The cold heading steel suitable for 6.8 and 8.8-grade weather-resistant fasteners is characterized by comprising the following components in percentage by weight: 0.09-0.13 percent of C, 0.32-0.5 percent of Si, 0.7-1.2 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.50-0.75 percent of Cr, 0.15-0.3 percent of Ni, 0.25-0.4 percent of Cu, 0.06-0.11 percent of V, more than or equal to 0.010 percent of Al, 0.009-0.013 percent of N, and the balance of Fe and inevitable impurity elements.
2. The cold heading steel suitable for use in 6.8 and 8.8 grade weather resistant fasteners and the method of producing the same as claimed in claim 1 wherein: the specification of the cold heading steel wire rod is phi 13-phi 20 mm.
3. The cold heading steel suitable for the weather-resistant fasteners of the 6.8 and 8.8 grades and the production method thereof according to the claim 1, characterized in that the cold heading steel is formed into the fasteners of the 6.8 grades by cold heading; the cold heading steel is firstly subjected to cold heading forming and then is subjected to heat treatment to form 8.8-grade fasteners.
4. The method for producing cold heading steel suitable for use in 6.8 and 8.8 grade weather resistant fasteners as claimed in claim 1 wherein: the method comprises the working procedures of converter smelting, LF refining, soft blowing treatment, continuous casting and wire rod rolling;
the wire rod rolling procedure comprises heating, rolling and cooling processes; in the heating process, the heating time is 90-120 min, the temperature of a heating section is 920-1150 ℃, and the temperature of a soaking section is 1080-1130 ℃; in the rolling process, the precision rolling temperature is controlled to be 830-850 ℃, and the spinning temperature is controlled to be 820-840 ℃; in the cooling process, the speed of a roller way at the inlet of the stelmor cooling control procedure is 14-16 m/min, each section is gradually increased by 0.6m/min, the heat-insulating cover is completely opened, and the fan is completely closed.
5. The method of producing cold heading steel suitable for use in 6.8 and 8.8 grade weather resistant fasteners as claimed in claim 4 wherein: in the continuous casting process, argon protection is performed in the whole process, the superheat degree is controlled to be 15-30 ℃, the secondary cooling specific water quantity is 0.8-1.1L/kg, and the drawing speed is controlled to be 1.70-2.0 m/min.
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| CN202011594474.5A Pending CN112813346A (en) | 2020-12-29 | 2020-12-29 | Cold heading steel suitable for 6.8 and 8.8-grade weather-resistant fasteners and production method thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114086061A (en) * | 2021-10-28 | 2022-02-25 | 马鞍山钢铁股份有限公司 | 6.8-grade corrosion-resistant cold forging steel and production method thereof |
| CN114293099A (en) * | 2021-12-03 | 2022-04-08 | 石横特钢集团有限公司 | High-toughness weather-resistant section steel and production process method thereof |
| CN114875332A (en) * | 2022-05-30 | 2022-08-09 | 湖南华菱湘潭钢铁有限公司 | Production method of annealing-free wire rod for high-strength alloy welding wire of 80 kilograms or more |
| CN115198208A (en) * | 2022-07-05 | 2022-10-18 | 马鞍山钢铁股份有限公司 | Heat-resistant and corrosion-resistant cold forging steel and heat treatment method, production method and application thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105714195A (en) * | 2016-03-08 | 2016-06-29 | 邢台钢铁有限责任公司 | Atmospheric-corrosion-resistant cold heading steel hot rolled wire rod and production method thereof |
| CN111206190A (en) * | 2020-03-05 | 2020-05-29 | 马鞍山钢铁股份有限公司 | Non-quenched and tempered cold heading steel for weather-resistant fastener, weather-resistant fastener and production methods of non-quenched and tempered cold heading steel and weather-resistant fastener |
-
2020
- 2020-12-29 CN CN202011594474.5A patent/CN112813346A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105714195A (en) * | 2016-03-08 | 2016-06-29 | 邢台钢铁有限责任公司 | Atmospheric-corrosion-resistant cold heading steel hot rolled wire rod and production method thereof |
| CN111206190A (en) * | 2020-03-05 | 2020-05-29 | 马鞍山钢铁股份有限公司 | Non-quenched and tempered cold heading steel for weather-resistant fastener, weather-resistant fastener and production methods of non-quenched and tempered cold heading steel and weather-resistant fastener |
Non-Patent Citations (2)
| Title |
|---|
| 北京金属学会: "《第十届北京冶金青年科技优秀论文集》", 30 September 2010, 河南科学技术出版社 * |
| 杜长坤: "《冶金工程概论》", 30 April 2012, 冶金工业出版社 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114086061A (en) * | 2021-10-28 | 2022-02-25 | 马鞍山钢铁股份有限公司 | 6.8-grade corrosion-resistant cold forging steel and production method thereof |
| CN114086061B (en) * | 2021-10-28 | 2023-03-03 | 马鞍山钢铁股份有限公司 | 6.8-grade corrosion-resistant cold forging steel and production method thereof |
| CN114293099A (en) * | 2021-12-03 | 2022-04-08 | 石横特钢集团有限公司 | High-toughness weather-resistant section steel and production process method thereof |
| CN114875332A (en) * | 2022-05-30 | 2022-08-09 | 湖南华菱湘潭钢铁有限公司 | Production method of annealing-free wire rod for high-strength alloy welding wire of 80 kilograms or more |
| CN115198208A (en) * | 2022-07-05 | 2022-10-18 | 马鞍山钢铁股份有限公司 | Heat-resistant and corrosion-resistant cold forging steel and heat treatment method, production method and application thereof |
| CN115198208B (en) * | 2022-07-05 | 2023-08-11 | 马鞍山钢铁股份有限公司 | Heat-resistant and corrosion-resistant cold heading steel and heat treatment method, production method and application thereof |
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