CN112760575A - Aviation fastener and preparation method thereof - Google Patents
Aviation fastener and preparation 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
- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
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- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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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- 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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- 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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- 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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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Abstract
The invention provides an aviation fastener and a preparation method thereof, wherein the aviation fastener comprises the following raw materials in percentage by weight: less than or equal to 0.08 percent of C, less than or equal to 2.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.02 percent of S, less than or equal to 1.0 percent of Si, 24.0 to 27.0 percent of Ni, 13.5 to 16.0 percent of Cr, 1.0 to 1.5 percent of Mo, 1.75 to 2.3 percent of Ti, less than or equal to 0.4 percent of Al, 0.1 to 0.5 percent of V, 0.001 to 0.010 percent of B, less than or equal to 0.25 percent of Cu, and the balance of Fe. The fastener of the invention not only has good strength and hardness, but also has good high-temperature corrosion resistance, good process performance and high thermal strength, and can completely meet the requirements of the aviation force-bearing member fastener on materials.
Description
Technical Field
The invention relates to the field of alloys, in particular to an aviation fastener and a preparation method thereof.
Background
The fastener is a basic mechanical part which is used for fastening connection and has wide application range, and the fastener is a product with wide application range. In use of the fastener, the fastener is often exposed to harsh working environments, such as high temperatures, corrosion, and the like. In particular, fasteners used in the aerospace field require materials that have high strength and that also have oxidation resistance, corrosion resistance, and the like. However, in the actual production process, the alloy produced by the existing process often cannot meet the requirement of the design index of the fastener. The existing fastener product needs to be replaced due to insufficient corrosion resistance after being used for a period of time, and has poor oxidation resistance, poor stability, poor plasticity and low strength, and also has serious potential safety hazard.
Disclosure of Invention
Aiming at the technical problems, the invention provides an aviation fastener and a preparation method thereof, which aim to solve the problems in the prior art.
In order to achieve the above purpose, the present invention provides a method for preparing an aviation fastener, which comprises the following steps:
(1) preparing raw materials: the raw materials are prepared according to the designed components, and all the raw materials need to be baked and degassed, wherein the designed components of the raw materials are as follows according to the weight percentage: less than or equal to 0.08 percent of C, less than or equal to 2.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.02 percent of S, less than or equal to 1.0 percent of Si, 24.0 to 27.0 percent of Ni, 13.5 to 16.0 percent of Cr, 1.0 to 1.5 percent of Mo, 1.75 to 2.3 percent of Ti, less than or equal to 0.4 percent of Al, 0.1 to 0.5 percent of V, 0.001 to 0.010 percent of B, less than or equal to 0.25 percent of Cu, and the balance of Fe;
(2) intermediate frequency induction smelting: smelting the raw materials by using a medium frequency induction furnace to form electrode rods, and inspecting and cleaning the electrode rods, and grinding and cleaning the surfaces of the electrode rods;
(3) electroslag remelting: performing an electroslag remelting process on the electrode bar to obtain an electroslag steel ingot, wherein the electroslag current is 4000-5000A, and the electroslag voltage is 50-55V;
(4) forging: heating the electroslag steel ingot to 1100-1120 ℃, preserving heat for more than 2 hours, and forging the electroslag steel ingot into a forged rod, wherein the forging starting temperature is more than 1020 ℃, and the forging stopping temperature is more than 950 ℃;
(5) and (3) heat treatment: carrying out solution treatment on the forged rod, preserving heat for 1-2 hours at the temperature of 980-1000 ℃, and carrying out oil cooling; and hardening and heat-treating the forged rod after the solution treatment, preserving the heat for 12-16 h at the temperature of 700-720 ℃, and performing air cooling to obtain the aviation fastener.
Preferably, in the step (2), the melting temperature is 1393-1427 ℃, the refining temperature is 1520-1540 ℃, the refining time is more than 35 minutes, and the tapping temperature is 1540-1560 ℃.
Preferably, the step (2) further comprises sampling the electrode rod and performing smelting analysis to control the chemical composition of the electroslag steel ingot to be consistent with that of the aviation fastener.
Preferably, the step (3) further comprises feeding at the later stage of the electroslag remelting process, wherein the feeding time is longer than 20 minutes, and the electroslag steel ingot is air-cooled.
Preferably, in the step (3), electroslag is performed on one steel ingot after argon arc welding of two electrode bars, the weight of each electrode bar is 260Kg, and the weight of each electroslag steel ingot is 400-480 Kg.
Preferably, the step (3) further comprises cutting off two end parts of the electroslag steel ingot, wherein the cutting-off rate of the head part is greater than or equal to 2%, and the cutting-off rate of the tail part is greater than or equal to 1.5%.
Preferably, the step (4) further comprises the step of grinding the surface of the electroslag steel ingot after the first fire is started to remove crack defects; and performing ultrasonic flaw detection on 100% of the forged rods.
Preferably, the aerospace fastener comprises a bolt, a nut, a stud and/or a shim.
Preferably, the raw materials comprise the following design components in percentage by weight: 0.05-0.07% of C, 1.45% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 0.3-0.5% of Si, 25.5-26.0% of Ni, 14.9-15.5% of Cr, 1.1-1.4% of Mo, 1.95-2.25% of Ti, 0.15% of Al, 0.35% of V, 0.001-0.010% of B, 0.05-0.15% of Cu and the balance of Fe.
The invention also provides an aviation fastener which is prepared by the preparation method.
Compared with the prior art, the nickel can increase the stability of the product, the higher chromium can enhance the oxidation resistance of the product so as to meet the corrosion resistance requirement of the stainless steel bar, and the electroplating process is not needed, so that the problem of hydrogen embrittlement in the electroplating process is solved, and the hydrogen embrittlement resistance of the stainless steel is improved; molybdenum can play a role in solid solution strengthening, titanium and aluminum can play a role in strengthening, vanadium can play a role in precipitation strengthening, and the high-temperature strength of the steel is improved. The invention enables the added elements to have synergistic effect by optimizing the component ratios, and is matched with the perfect preparation process of the fastener (comprising step setting, parameter design and the like, and the superposition effect of solid solution treatment and thermal hardening treatment), so that the prepared fastener has uniform component structure, good strength and hardness, good high-temperature corrosion resistance, good technological performance and high thermal strength. The high-temperature-resistant high-strength fastening piece can work normally for 100 hours at the high temperature of 650 ℃, has good mechanical property and structural stability, can bear certain working pressure, and well meets the requirements of the aviation force-bearing piece fastening piece on materials.
Detailed Description
In order to further understand the objects, structures, features and functions of the present invention, the following embodiments are described in detail.
The invention provides a preparation method of an aviation fastener, which comprises the following steps:
step (1), preparing raw materials: the raw materials are prepared according to the designed components, and all the raw materials need to be baked and degassed, wherein the designed components of the raw materials are as follows according to the weight percentage: less than or equal to 0.08 percent of C, less than or equal to 2.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.02 percent of S, less than or equal to 1.0 percent of Si, 24.0 to 27.0 percent of Ni, 13.5 to 16.0 percent of Cr, 1.0 to 1.5 percent of Mo, 1.75 to 2.3 percent of Ti, less than or equal to 0.4 percent of Al, 0.1 to 0.5 percent of V, 0.001 to 0.010 percent of B, less than or equal to 0.25 percent of Cu, and the balance of Fe. Specifically, for example, according to the procurement technical requirements and procurement plans, the required smelting raw materials are purchased from qualified suppliers, and the product quality certificate of the raw materials is provided. The acceptance of the raw materials is carried out according to the regulations of the technical Specifications of Enterprise products, and the raw materials must meet the technical requirements of smelting quality. Wherein the alloying metal is added in the form of a pure metal or an intermediate alloy.
Step (2), medium-frequency induction smelting: smelting the raw materials in the step (1) by using a medium-frequency induction furnace to obtain 260Kg of electrode bar, and inspecting and cleaning the electrode bar, and grinding and cleaning the surface of the electrode bar; wherein, the medium frequency induction furnace is 2 tons, for example, and the melting temperature is 1393-1427 ℃, the refining temperature is 1520-1540 ℃, the refining time is more than 35 minutes, and the tapping temperature is 1540-1560 ℃ during smelting. And sampling the electrode rod and performing smelting analysis to control the chemical composition of the electrode rod to be consistent with that of the aviation fastener. Specifically, the smelting analysis method is carried out according to GB/T223, and the content of each element can be adjusted according to the analysis result by carrying out smelting analysis in the smelting stage, so that the weight ratio design of each element meets the requirement. Moreover, the melting analysis is performed for each furnace of molten steel, and each furnace of molten steel should be sampled and analyzed when the electrode rod is poured. That is, the smelt analysis includes: sampling and analyzing molten steel of each furnace before remelting, analyzing the element content of the electrode rod, comparing the element content with the chemical composition of the aviation fastener, and finely adjusting the element content of the electrode rod in the remelting process to be in accordance with the chemical composition of the aviation fastener.
Step (3), electroslag remelting: and performing an electroslag remelting process on the electrode bar to obtain an electroslag steel ingot, wherein the electroslag current is 4000-5000A, and the electroslag voltage is 50-55V. Specifically, 500kg of an electroslag furnace is adopted for electroslag remelting, and the slag system refers to GH2132 in electroslag remelting operation specification. The alloy material can effectively improve the purity and the structure uniformity of the alloy through electroslag remelting, and further improve the performance of the alloy. And in addition, after the electroslag remelting process, feeding operation is required, the feeding time is more than 20 minutes, and the electroslag steel ingot is cooled in air. In addition, electroslag is carried out on one steel ingot after every two electrode bars are welded in an argon arc mode, the weight of each electrode bar is 260Kg, and the weight of each electroslag steel ingot is 400-480 Kg. In addition, the step also comprises the step of cutting off the two end parts of the electroslag steel ingot, wherein the cutting-off rate of the head part is not less than 2%, and the cutting-off rate of the tail part is not less than 1.5%, so that the shrinkage cavity and the excessive segregation part can be removed. And preferably, the head and the tail of the electroslag steel ingot are sampled to analyze whether the chemical components are qualified or not.
Step (4), forging: heating the electroslag steel ingot to 1100-1120 ℃, preserving heat for more than 2 hours, and forging into a forged rod, wherein the forging starting temperature is more than 1020 ℃, and the forging stopping temperature is more than 950 ℃. Moreover, the step also comprises the step of carrying out surface grinding on the electroslag steel ingot after the first fire is started to remove crack defects; and performing ultrasonic flaw detection on 100% of the forged rods.
And (5) heat treatment: carrying out solution treatment on the forged rod, preserving heat for 1-2 hours at the temperature of 980-1000 ℃, and carrying out oil cooling; and hardening and heat-treating the forged rod after the solution treatment, preserving the heat for 12-16 h at the temperature of 700-720 ℃, and performing air cooling to obtain the fastener. In practice, the above-mentioned heat treatment protocol specifies the number of thermocouples and the measurement locations. All heat treatments of the fasteners were recorded on a meter and documented for material quality. The heat treatment records comprise heat treatment heat preservation temperature and deviation thereof, heating rate, heat preservation time, cooling method, cooling rate, furnace entering and furnace exiting temperatures and the like.
In the step (5), the annealing temperature of the solution annealing treatment is set to be 980-1000 ℃, the time is set to be 1-2 hours, and the higher annealing temperature can recrystallize the forged rod, reduce the hardness and improve the processing performance; the temperature of the subsequent hardening heat treatment is set to be 700-720 ℃, the time is 12-16 h, the grain refinement is facilitated, the stress generated by rolling is eliminated, and the toughness and the strength are increased.
After the above steps, it is also necessary to sample the finished fasteners for performance testing, and the fasteners are cut out from the test material in batches for inspection. The sample should be of sufficient size to ensure that the sample required for the entire test and possible retests is intercepted, the specification of each heat-treated batch reserving the retest L at 300 mm. Furthermore, the sampling timing should be the post-heat treatment sampling position, i.e. the bar size before machining, for example for the product. Wherein the definition of the batch: the same smelting furnace number, the same manufacturing process, the same size, the same furnace heat treatment or the same heat treatment operation in a continuous furnace.
Wherein, the specification of the fastener after forging is phi 80mm, and the total length is 290 m; phi 112mm, total length 132 m; phi 80mm, total length 215 m; phi 112mm, total length 29 m; phi is 85mm, and the total length is 5.5 m; phi 52mm, total length 3 m; phi 90mm, total length 1 m; and air cooling after forging.
It should be noted that the chemical composition of the electrode, Ti, should be controlled according to the electroslag burning loss, and the chemical composition becomes the content value of the finished fastener.
In addition, the invention also provides an aviation fastener, which is prepared by the preparation method, and comprises the following chemical components in percentage by weight: less than or equal to 0.08 percent of C, less than or equal to 2.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.02 percent of S, less than or equal to 1 percent of Si, 24.0 to 27 percent of Ni, 13.5 to 16.0 percent of Cr, 1 to 1.5 percent of Mo, 1.75 to 2.3 percent of Ti, less than or equal to 0.4 percent of Al, 0.1 to 0.5 percent of V, 0.001 to 0.010 percent of B, less than or equal to 0.25 percent of Cu, and the balance of Fe. And preferably, the aviation fastener comprises the following chemical components in percentage by weight: 0.05-0.07% of C, 1.45% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 0.3-0.5% of Si, 25.5-26.0% of Ni, 14.9-15.5% of Cr, 1.1-1.4% of Mo, 1.95-2.25% of Ti, 0.15% of Al, 0.35% of V, 0.001-0.010% of B, 0.05-0.15% of Cu and the balance of Fe. Such aircraft fasteners include, for example, bolts, nuts, studs, screws, washers, and the like.
The elements of the present invention are described in detail below, and the contents refer to the mass percentages of the respective elements in the fastener.
C: c is an austenitizing stabilizing element and can improve the hardenability of the steel, and in the invention, C can form carbide with Cr element, but does not greatly contribute to the strength, and because the strength of the alloy material is mainly strengthened by gamma 'and gamma' phases. In addition, the increase of C will damage the plasticity of the material, so the content of C in the alloy material of the invention is preferably less than 0.08%. By strictly controlling the content of C, the influence on the mechanical property, the oxidation resistance and the corrosion resistance of the welding wire due to the formation of carbide by C and Cr can be effectively avoided, and the intercrystalline corrosion can be effectively reduced due to the lower content of C.
Mn: mn can be dissolved into Ni-Cr alloy in large quantity, so that crystal grains can be refined, the processing performance is improved, and meanwhile, the Mn-Cr alloy is also a better S, O, C remover. However, when the content is too high, segregation is easily generated, the ductile-brittle transition temperature is remarkably increased, and the plasticity and toughness of the alloy are reduced, so that the content of Mn in the invention is controlled to be less than 2.0%.
S, P: s, P is a harmful element, and the content of P is preferably less than 0.03%, and the content of S is preferably less than 0.02%.
Si: si has the characteristic of strongly inhibiting carbide precipitation in the bainite transformation process, stabilizes and refines austenite, increases C, Mn segregation, improves the hardenability of alloy, and can fully improve the hardenability and impact toughness of a fastener. However, Si has an adverse effect on the plastic properties of the material, so that the content of Si in the material of the present invention should be controlled to be less than 1%.
Ni: ni improves hardenability elements of the alloy, improves the strength of the alloy without reducing the toughness of the alloy, and is added with Cu in a compounding way to avoid high-temperature Cu brittleness of a casting blank. Moreover, Ni has strong corrosion resistance to acid and alkali and also has corrosion resistance and heat resistance at high temperature.
Cr: cr is an element for improving the hardenability of steel, a strong carbide forming element is used together with Cu to improve the corrosion resistance of the steel, and Ni and Cr are added in a composite manner, so that the corrosion resistance of the steel is better.
Mo: the role of molybdenum in steel can be summarized as improving hardenability and heat strength, preventing temper brittleness, improving remanence and coercive force, improving corrosion resistance in certain media, preventing pitting tendency, and the like. Molybdenum has a beneficial effect in improving the ductility and toughness as well as the wear resistance of the steel. Molybdenum increases the softening and recovery temperature and the recrystallization temperature after the deformation strengthening, strongly improves the creep resistance of ferrite, effectively inhibits the aggregation of cementite at 450-600 ℃, promotes the precipitation of special carbide, and thus becomes the most effective alloy element for improving the heat strength of steel. The alloy material disclosed by the invention is applied to aerospace, and the alloy material is required to have excellent obdurability and hydrogen embrittlement corrosion resistance. Therefore, the content of Mo is controlled to be 1.00-1.5 percent in the invention. And when the molybdenum is combined with chromium or manganese and the like, the molybdenum can reduce or inhibit temper brittleness caused by other elements.
Ti: ti is a good deoxidizing and degassing agent and an effective element for fixing nitrogen and carbon. Titanium is a strong nitrogen element. After Al deoxidation at the end of refining, Ti must be used to fix nitrogen to form TiN to eliminate free nitrogen in the steel so that the boron added later can be present as free boron. Titanium can also generate insoluble carbide particles with iron and carbon, and the carbide particles are enriched at austenite grain boundaries to prevent grain coarsening; titanium also dissolves into the austenite phase to form a solid solution, which strengthens the steel. Ti mainly affects several aspects: precipitation of Ni3 Ti: if Ti is not uniform, Ni3Ti is not uniformly precipitated, and too much Ni3Ti is precipitated to improve strength but reduce plasticity; ② TiCN is separated out: locally too high Ti content increases the amount of undissolved phases Ti (C, N), resulting in deterioration of plasticity and toughness without contributing to strength. The content of titanium element in the application is controlled to be 1.750-2.30%.
Al: aluminum has strong affinity with oxygen and nitrogen, and is a nitrogen deoxidizing and fixing agent in steel making. Aluminum strongly reduces the austenitic phase region in steel. Aluminum has a low affinity for carbon and aluminum carbides generally do not occur in steel. The aluminum strongly promotes the graphitization of carbon, and the graphitization of the aluminum can be inhibited by adding strong magnetizer forming elements such as chromium, titanium, vanadium, niobium and the like. Aluminum refines the essential grains of steel and raises the temperature for coarsening the steel grains, but when the content of solid solution metal aluminum in the steel exceeds a certain value, austenite grains are easy to grow and coarsen. Therefore, the present invention controls the content of Al to be in the range of less than 0.40%.
V: the trace amount of V can endow the steel with some special functions, such as tensile strength and yield point improvement, so that the content of V is controlled to be 0.1-0.50 percent in the invention.
B: a trace amount of B greatly improves the hardenability of the high alloy, and each 1 part by mass of B corresponds to 300 parts by mass of Mo. And boron is added, so that expansion of the fastener can be reduced, and strength and hardness are improved.
Cu: copper can improve strength and toughness, but is likely to cause hot shortness at the time of hot working, so the content of copper is preferably 0.25% or less in the present invention.
Fe: fe is the balance of the material, but the content of the iron element is more than a certain amount, so the purpose of improving the iron content is to adopt cheap iron to replace expensive nickel and form a solid solution matrix with Ni, which has higher strength than a pure Ni matrix, therefore, the design scheme of adopting high-iron nickel-saving can reduce the cost of the material and ensure the high-temperature strength of the material.
The present invention will be further described with reference to the following specific examples.
The following table 1 shows the specific element composition and the weight percentage content of each component of the aviation fastener of 5 embodiments of the invention.
TABLE 1 elemental composition and weight percent content of each component of an aerospace fastener according to various embodiments of the invention
Unit: weight percent (%)
Remarking: the balance being Fe, not listed in Table 1.
The preparation method of the aviation fastener of each embodiment of the invention adopts the following steps:
step (1), preparing raw materials: mixing the raw materials according to the designed components, and baking and degassing all the raw materials; wherein, according to the purchasing technical requirement and the purchasing plan, the required smelting raw materials are purchased from the qualified supplier, and the product quality certificate of the raw materials is required to be provided. The acceptance of the raw materials is carried out according to the regulations of the technical Specifications of Enterprise products, and the raw materials must meet the technical requirements of smelting quality.
Step (2), medium-frequency induction smelting: smelting the raw materials in the step (1) by adopting a 2-ton intermediate frequency induction furnace, wherein the melting temperature is 1393-1427 ℃, the refining temperature is 1520-1540 ℃, the refining time is more than 35 minutes, the tapping temperature is 1540-1560 ℃, smelting into 260Kg of electrode bar, inspecting and cleaning the electrode bar, and grinding and finishing the surface. And sampling the electrode rod for smelting analysis, and the analysis result is shown in table 1.
Step (3), electroslag remelting: and (3) performing an electroslag remelting process on the electrode bar by adopting a 500kg electroslag furnace, wherein the electroslag system refers to GH2132 in electroslag remelting operation specification, the electroslag current is 4000-5000A, and the electroslag voltage is 50-55V, so that an electroslag steel ingot is obtained. Wherein, feeding operation is needed in the later stage, the feeding time is more than 20 minutes, and the electroslag steel ingot is air-cooled. Electroslag steel ingots are electroslag welded after every 2 electrode rods are subjected to argon arc welding, and the weight of each electroslag steel ingot is 400-480 Kg. And the two end parts of the electroslag steel ingot are cut off, the head part is not less than 2%, and the tail part is not less than 1.5%, so that the shrinkage cavity and the excessive segregation part can be removed.
Step (4), forging: heating the electroslag steel ingot to 1100-1120 ℃, preserving heat for more than 2 hours, and forging into a forged rod, wherein the forging starting temperature is more than 1020 ℃, and the forging stopping temperature is more than 950 ℃. After the first fire is started, carrying out surface grinding on the electroslag steel ingot to remove crack defects; and performing ultrasonic flaw detection on 100% of the forged rods.
And (5) heat treatment: carrying out solution treatment on the forged rods qualified for flaw detection, preserving heat for 1-2 hours at the temperature of 980-1000 ℃, and carrying out oil cooling; and hardening and heat-treating the forged rod after the solution treatment, preserving the heat for 12-16 h at the temperature of 700-720 ℃, and performing air cooling to obtain the fastener.
Wherein the fastener of the above embodiments 1-5 comprises a bolt, a stud and a nut. And in order to make the prepared fastener material meet the requirements, after the finished fastener is prepared, sampling is carried out on the finished fastener to check the mechanical property, wherein the fastener which is subjected to heat treatment and is not subjected to size processing is sampled and the performance test result is shown in tables 2 and 3.
TABLE 2 results of mechanical Properties measurements
TABLE 3 high temperature durability test results
As can be seen from the test results of tables 2 and 3, the fasteners (including bolts, studs, and nuts) had good tensile strength, elongation, and the like at room temperature as well as at a high temperature of 650 ℃. And at the high temperature of 650 ℃, through a high-temperature endurance test for 100h, the fastener still has good mechanical property and tissue stability, can bear certain working pressure, and can be completely applied to the field of aerospace.
The present invention has been described in relation to the above embodiments, which are only exemplary of the implementation of the present invention. Furthermore, the technical features mentioned in the different embodiments of the present invention described above may be combined with each other as long as they do not conflict with each other. It should be noted that the disclosed embodiments do not limit the scope of the invention. Rather, it is intended that all such modifications and variations be included within the spirit and scope of this invention.
Claims (10)
1. A preparation method of an aviation fastener is characterized by comprising the following steps:
(1) preparing raw materials: the raw materials are prepared according to the designed components, and all the raw materials need to be baked and degassed, wherein the designed components of the raw materials are as follows according to the weight percentage: less than or equal to 0.08 percent of C, less than or equal to 2.0 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.02 percent of S, less than or equal to 1.0 percent of Si, 24.0 to 27.0 percent of Ni, 13.5 to 16.0 percent of Cr, 1.0 to 1.5 percent of Mo, 1.75 to 2.3 percent of Ti, less than or equal to 0.4 percent of Al, 0.1 to 0.5 percent of V, 0.001 to 0.010 percent of B, less than or equal to 0.25 percent of Cu, and the balance of Fe;
(2) intermediate frequency induction smelting: smelting the raw materials by using a medium frequency induction furnace to form electrode rods, and inspecting and cleaning the electrode rods, and grinding and cleaning the surfaces of the electrode rods;
(3) electroslag remelting: performing an electroslag remelting process on the electrode bar to obtain an electroslag steel ingot, wherein the electroslag current is 4000-5000A, and the electroslag voltage is 50-55V;
(4) forging: heating the electroslag steel ingot to 1100-1120 ℃, preserving heat for more than 2 hours, and forging the electroslag steel ingot into a forged rod, wherein the forging starting temperature is more than 1020 ℃, and the forging stopping temperature is more than 950 ℃;
(5) and (3) heat treatment: carrying out solution treatment on the forged rod, preserving heat for 1-2 hours at the temperature of 980-1000 ℃, and carrying out oil cooling; and hardening and heat-treating the forged rod after the solution treatment, preserving the heat for 12-16 h at the temperature of 700-720 ℃, and performing air cooling to obtain the aviation fastener.
2. The method for preparing an aviation fastener as claimed in claim 1, wherein in the step (2), the melting temperature is 1393-1427 ℃, the refining temperature is 1520-1540 ℃, the refining time is more than 35 minutes, and the tapping temperature is 1540-1560 ℃.
3. The method for producing an aerospace fastener according to claim 1, wherein step (2) further comprises sampling the electrode rod and performing melting analysis to control the chemical composition of the ingot to match the chemical composition of the aerospace fastener.
4. The method of claim 1, wherein step (3) further comprises performing feeding operation at a later stage of the electroslag remelting process, wherein the feeding time is longer than 20 minutes, and the electroslag ingot is air cooled.
5. The method for preparing the aviation fastener according to claim 1, wherein in the step (3), one steel ingot is electroslag-welded after argon arc welding of each two electrode rods, the weight of each electrode rod is 260Kg, and the weight of each steel ingot is 400 to 480 Kg.
6. The method for preparing an aviation fastener according to claim 1, wherein the step (3) further comprises cutting off two ends of the electroslag steel ingot, wherein the head cutting-off rate is greater than or equal to 2%, and the tail cutting-off rate is greater than or equal to 1.5%.
7. The method for preparing an aviation fastener according to claim 1, wherein in the step (4), the method further comprises the following steps of carrying out surface grinding on the electroslag steel ingot after the first fire is started to remove crack defects; and performing ultrasonic flaw detection on 100% of the forged rods.
8. The method of making an aerospace fastener according to claim 1, wherein the aerospace fastener comprises a bolt, a nut, a stud and/or a shim.
9. The method for manufacturing an aerospace fastener according to claim 1, wherein the raw materials comprise, by weight: 0.05-0.07% of C, 1.45% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 0.3-0.5% of Si, 25.5-26.0% of Ni, 14.9-15.5% of Cr, 1.1-1.4% of Mo, 1.95-2.25% of Ti, 0.15% of Al, 0.35% of V, 0.001-0.010% of B, 0.05-0.15% of Cu and the balance of Fe.
10. An aerospace fastener, characterized in that it is produced using the method of production according to any one of claims 1-9.
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