CA2941276C - High-strength bolting steel and preparation method therefor - Google Patents
High-strength bolting steel and preparation method therefor Download PDFInfo
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0093—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for screws; for bolts
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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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
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Abstract
A high-strength bolting steel and a preparation method therefor. The components of the steel are: 0.05 wt% to 0.5 wt% of rare earth elements, 0.35 wt% to 0.45 wt% of carbon, 1.2 wt% to 1.8 wt% of chromium, 0.17 wt% to 0.37 wt% of silicon, 0.4 wt% to 0.8wt % of molybdenum, 0.2 wt% to 0.4 wt% of vanadium, 0 to 0.005 wt% of niobium and the balance of ferrum. The preparation method comprises: hot forging for the bolting steel with the above components is carried out, then quenching and tempering are carried out.
Description
HIGH-STRENGTH BOLTING STEEL AND PREPARATION METHOD THEREFOR
100011 This application claims the benefit of priority to Chinese Patent Application No.
201410091577.8, titled "HIGH STRENGTH BOLTING STEEL AND PREPARING
.. METHOD THEREOF", filed with the Chinese State Intellectual Property Office on March 13, 2014.
FIELD
100011 This application claims the benefit of priority to Chinese Patent Application No.
201410091577.8, titled "HIGH STRENGTH BOLTING STEEL AND PREPARING
.. METHOD THEREOF", filed with the Chinese State Intellectual Property Office on March 13, 2014.
FIELD
[0002] The present application relates to the field of metal, and in particular to a high strength bolting steel and a preparing method for the high strength bolting steel.
BACKGROUND
BACKGROUND
[0003] In recent years, strong wind disasters, such as typhoon, frequently attack the southeast costal areas of China, causing damage to a number of electric transmission and transformation equipments and severely affecting a safe operation of a power grid. Since the southeast costal areas are developed areas of China and an electric load is concentrated there, the strong wind disasters often cause inestimable social damage and economical loss for the local areas. A high voltage power arrester in a substation is an important device for power supplying of a power system, which has a relatively low inherent frequency, and a part of the .. inherent frequency at low level is close to a main frequency range of a strong fluctuating wind, such as typhoon. The device will vibrate due to the strong fluctuating wind, causing stress concentration in different positions. In the case that the device resonates due to the motivation, the stress concentration areas of the device will rupture and fail.
[0004] Bolts of the power arrester device are generally arranged in the stress concentration areas of the device for supporting, fixing and connecting. In the case that the vibrations caused by wind causes stress concentration in the device, the bolts are apt to distort when suffering pulling stress and bending stress. Further, due to the supporting by the bolts, upper porcelain knobs will distort due to the distortion of the bolts, thereby causing failure of the whole device in the strong wind.
- -, English translation of PCT/CN2014/081896
- -, English translation of PCT/CN2014/081896
[0005] In recent years, it is found by practice that adding RE (rare earth) elements to an alloy steel can efficiently improve a mechanical property of the alloy steel and improve various performance indexes of the material in different degrees. The performances of the material can be optimized by separately preparing the RE elements and the alloy steel, and mixing the RE elements with the alloy steel. Thus, currently, it is of great importance to optimize the components and improve performances of the bolting alloy steel dedicated for the arrester device in the wind resistance field of the power arrester.
SUMMARY
SUMMARY
[0006] An object of the present application is to provide a high strength and plastic bolting steel and a preparation method for making the high strength and plastic bolting steel.
[0007] In view of the above, a high strength belting steel is provided according to the present application, which includes:
RE 0.05w0/0-0.5wt%;
C 0.3510%-0.45wt%;
Cr 1.2wtcY0-1.8wt%;
Si 0.17wt%-0.37wt%;
Mo 0.4wt%-0.8wt%;
V 0.2wt%-0.4wt%;
Nb 0-0.005wt%;
with remainder being Fe, where the RE is at least one of La and Ce.
RE 0.05w0/0-0.5wt%;
C 0.3510%-0.45wt%;
Cr 1.2wtcY0-1.8wt%;
Si 0.17wt%-0.37wt%;
Mo 0.4wt%-0.8wt%;
V 0.2wt%-0.4wt%;
Nb 0-0.005wt%;
with remainder being Fe, where the RE is at least one of La and Ce.
[0008] Preferably, a content of the RE is 0.10wt%-0.48wt%.
[0009] Preferably, a content of the Mo is 0.48wt%-0.72wt%.
[0010] Preferably, a content of the Si is 0.20wt%-0.32wt%.
[0011] Preferably, a content of the Nb is 0.002wt%-0.0048wt%.
[0012] A method for preparing the high strength bolting steel is further provided according to the present application, which includes:
step 1) casting a bolting steel ingot containing: rare earth 0.05wt%-0.5wt%, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8wt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, where the rare earth is at least one of lanthanum and cerium;
step 2) forging the bolting steel ingot and annealing the forged bolting steel ingot;
step 3) quenching the bolting steel ingot obtained in step 2) and tempering the quenched bolting steel to obtain a high strength bolting steel.
100131 Preferably, step 1) may include:
preparing a raw material containing: the rare earth 0.05wt%-0.5wt%, the carbon 0.35wt%-0.45wt%, the chromium 1.2wt%-1.8wt%, the silicon 0.17wt%-0.37wt%, the molybdenum 0.4wt%-0.8wt%. the vanadium 0.2wt%-0.4wt%, the niobium 0-0.005wt%
with remainder being the Fe, where the rare earth is at least one of the lanthanum and the cerium;
smelting, based on contents of the raw material, the carbon, the chromium, the silicon, the molybdenum, the vanadium, the niobium and the Fe for 40mins-45mins at 1500 C to 1600 C, and preserving heat for 15mins-25mins to obtain an initial bolting steel ingot:
re-smelting the initial bolting steel ingot, adding at least one of the lanthanum and the cerium, and casting into a bolting steel ingot.
[0014] Preferably, a temperature of the annealing is 650 C to 700 C, and the duration of heat preservation for the annealing is 2-3 hours.
[0015] Preferably, a temperature of the quenching is 800 C to 900 C, and the duration of heat preservation for the quenching is 1 2 hours.
[0016] Preferably, a temperature of the tempering is 500 C to 600 C, and the duration of heat preservation for the tempering is 1-2 hours.
[001-1 The high strength bolting steel is provided according to the present application, which includes: rare earth 0.05wt%-0.5wt%, carbon 0.35%-0.45wt%, chromium 1.2w0/0-1.8wt%, silicon 0.17w0/0-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being the Fe. In the present application, the lanthanum or the cerium added into the bolting steel can efficiently refine grain structures of the bolting steel, reduce the content of hydrogen and diffusion and permeation of hydrogen in the steel, reduce grain boundary segregation of the harmful elements. and improve strength of the steel: the added chromium can efficiently improve the antioxidation and anticorrosion capability of the material, and improve the hardenability of the material to increase the strength; and the added molybdenum can strengthen the grain boundary of the material, improve the hardenability of the material, increase the tempering stability and improve the toughness of the material. The carbon, vanadium, niobium and Fe are further added into the bolting steel according to the present application, which interact and cooperate with each other, such that the bolting steel has high strength and plasticity, thereby providing strong supporting, fixing and connecting for the power arrester device, efficiently resisting stress concentration and deviation behavior of the arrester device due to a strong wind, and protecting a safe operation of the device.
[0018] A method for preparing the high strength bolting steel is further provided according to the present application. During a process of preparing the bolting steel, in the present application, the bolting steel ingot is prepared firstly, and then the prepared bolting steel ingot is forged, such that grains of the bolting steel ingot are broken sufficiently to obtain structures with fine and uniform grains; the forged bolting steel ingot is annealed to eliminate stress generated during the forging process; and lastly the annealed bolting steel ingot is quenched and tempered, thereby obtaining martensite structures and a part of austenite structures having fine and uniform internal grains, and efficiently improving the strength and plasticity of the material.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] Hereinafter technical solutions of embodiments of the present application are described in detail. Apparently, the descried embodiments are only some rather than all of the embodiments of the present application. Any other embodiments obtained based on the embodiments of the present application by those skilled in the art without any creative work fall within the scope of protection of the present application.
[0020] According to an embodiment of the present application, a high strength bolting steel English translation of PCT/CN2014/081896 is provided, which includes:
RE 0.05w0/0-0.5wt%;
0.35wt%-0.45wt%;
Cr 1.2wt%-1.8wt%;
Si 0.17wt%-0.37wt%;
Mo 0.4wV/0-0.8wt%;
V 0.2wt%-0.4wt%;
Nb 0-0.005wt%;
with remainder being Fe, where the RE is at least one of La and Ce.
[0021] Lanthanum (La) and Cerium (Ce) each are RE elements. In the present application, La, Ce or a mixture of La and Ce is added into the bolting steel, and La or Ce, which, as an active element, can refine grain structures of the bolting steel efficiently, thereby reducing a content of hydrogen and diffusion and permeation of hydrogen in the steel, decreasing grain boundary segregation of hydrogen, sulphur and other harmful elements, and improving the strength, stiffness and plasticity of the steel. In the present application, a content of La, Ce or the mixture of La and Ce is 0.05wt%-0.5wt%. In this range, martensite and austenite structures increase obviously in the steel, and mechanical properties of the steel are optimized.
In the case that the content of La, Ce or the mixutre of La and Ce is less than 0.05wt%, the generated effect is limited due to a less content, thereby influencing wind resistance performance of the material. In the case that the content of La, Ce and the mixture of La and Ce exceeds 0.5%, metal inclusions containing La, Ce or the mixture of La and Ce enlarge and increase in the material structure, and the material performance is influenced, thereby causing that a wind resistance requirement of the power arrester can not be met gradually. The content of La, Ce or the mixture of La and Ce is preferably in a range of 0.08wt%-0.5wt%, more preferably in a range of 0.10wV/0-0.48wt%, most preferably in a range of 0.12wt%-0.40wt%, and most preferably in a range of 0.25wt%-0.35wt%.
[0022] Carbon (C), as an added element in the present application, can improve the strength, hardness and hardenability of the material. In the case that a content of C is less than 0.35wt%, English translation of PCT/CN2014/081896 the bolting steel has good toughness and plasticity, but the strength, hardness and hardenability of the steel will be limited to a certain degree. In the case that the content of C is greater than 0.45w1%, the toughness and plasticity of the material is reduced significantly, and brittle fracture will occur easily. Thus, the content of C should be in a range of 0.35wt%-0.45wt%. The content of C is preferably in a range of 0.37wt%-0.42wV/o, and more preferably in a range of 0.35wt%-0.40wt%.
[0023] Chromium (Cr) is added to the bolting steel, thereby efficiently improving antioxidation and anticorrosion capability of the material, and improving the hardenability of the material to increase the strength of the material. In the case that a content of Cr is less than 1.2wt%, the above effect is difficult to be achieved; or in the case that the content of Cr is higher than I .8wt%, the toughness of the material will be reduced, thus the content of Cr should be in a range of 1.2wV/0-1.8wt%. The content of Cr is preferably in a range of 1.3wt%-1.6wt%, and more preferably in a range of 1.4wt%-1.55wt%.
[0024] Silicon (Si) is a good deoxidizer for the material, and Si is added into the bolting steel, thereby improving strength of a solid solution of the bolting steel, which is beneficial to increase tempering stability of the material. In the case that a content of silicon is higher than 0.37wt%, plasticity of the material will be reduced, or in the case that the content of silicon is less than 0.17wt%, the function of the deoxidizer and solid solution strengthening of silicon will be weakened. Thus, the best effect can be achieved only when the content of silicon is in a range of 0.17wt%-0.37wt%. The content of silicon is preferably in a range of 0.20wt%-0.32wt%, more preferably in a range of 0.23w0/0-0.30wt%, and most preferably in a range of 0.25wt%-0.28wt%.
[0025] Molybdenum (Mo) can strengthen grain boundary of the material, improve hardenability of the material, increase temping stability and improve toughness of the material.
In the case that a content of molybdenum is less than 0.4wt%, the above effect is difficult to be achieved; or in the case that the content of Mo is higher than 0.8wt%, a cost of the bolting steel is increased and the optimal economy can not be realized. Thus, a good effect can be achieved only when the content of molybdenum in the bolting steel is in a range of 0.4wt%-0.8wt%. The content of Mo is preferably in a range of 0.48wt%-0.72wt%, more preferably in a range of 0.54wt%-0.68wt%, and most preferably in a range of 0.60wt%-0.65wt%.
[0026] Vanadium (V) can efficiently restrain diffusion of hydrogen, refine grains, and improve a mechanical property of the material. In the case that a content of V
is less than 0.2wt%, the above effect is difficult to be achieved; or in the case that the content of V is higher than 0.4wt%, the beneficial effect to the material structure will not be improved but the mechanical property of the material will be influenced as the content increases. Thus, the content of vanadium should be in a range of 0.2wt%-0.4wt%. The content of vanadium is preferably in a range of 0.25wt%-0.38vvt%, more preferably in a range of 0.28wt%-0.35wt%, and most preferably in a range of 0.30wt /0-0.32wt%.
[0027] Niobium (Nb) can improve toughness of the material and refine grain structures efficiently. Niobium is a trace element contained in the material. In the case that a content of niobium is too high, the above effect can not be achieved, and the economy will be influenced greatly. Thus, the content of niobium should be in a range of 0-0.005wt%. The content of niobium is preferably in a range of 0.002wt%-0.0048wt%, and more preferably in a range of 0.0035wt%-0.0040wt%.
[0028] "I he high strength bolting steel provided according to the present application includes: rare earth 0.05wV/0-0.5wV/0, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8wt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, wherein the rare earth is at least one of lanthanum and cerium. In the bolting steel according to the present application, the added active element lanthanum and cerium can efficiently refine grain structures of the bolting steel, reduce the content of hydrogen and diffusion and permeation of hydrogen in the steel, reduce grain boundary segregation of the harmful elements, and improve strength of the steel. The added chromium can efficiently improve the antioxidation and anticorrosion capability of the material, arid improve the hardenability of the material to increase the strength. The added Mo can strengthen the grain boundary of the material, improve the hardenability of the material, increase the tempering stability and improve the toughness of the material. Carbon, vanadium, niobium and Fe are further added into the bolting steel according to the present application, which interact and cooperate with each other, such that the bolting steel has high strength and plasticity.
[0029] According to the present application, a method for preparing the bolting steel is further provided, which includes:
step 1) casting a bolting steel ingot containing: rare earth 0.05wt%-0.5wt%, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8wt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt /0-0.8wt%, vanadium 0.2w0/0-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, where rare earth is at least one of lanthanum and cerium;
step 2) forging the bolting steel ingot and annealing the forged bolting steel ingot;
step 3) quenching the bolting steel ingot obtained in step 2) and tempering the quenched bolting steel to obtain a high strength bolting steel.
[0030] During a process of preparing the bolting steel, in the present application, the bolting steel ingot is cast firstly, and then the prepared bolting steel ingot is forged, such that internal structures of the bolting steel ingot are broken sufficiently; the annealing is performed to eliminate residual stress generated during the forging process, so as to obtain uniform and fine internal grains; and finally the annealed bolting steel is quenched and tempered, which obtains martensite structures and a part of austenite structures having uniform and fine internal grains, thereby improving the strength and plasticity of the bolting steel.
[0031] According to the present application, during the process of preparing the bolting steel, firstly the bolting steel ingot is prepared, and rare earth elements lanthanum, cerium or a mixture of lanthanum and cerium is added into the bolting steel. Lanthanum and cerium are active elements, and lanthanum and cerium may be consumed in the case that lanthanum and cerium are added earlier during the forging process, Thus in the present application, preferably the active elements lanthanum and cerium are added later.
Preferably, the bolting steel ingot is prepared as follows:
preparing a raw material containing: rare earth 0.05wt%-0.5wt%, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8vvt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, where rare earth is at least one of lanthanum and cerium;
smelting, based on contents of the raw material, carbon, chromium, silicon, molybdenum, vanadium, niobium and Fe for 40mins-45mins at 1500 C to 1600 C, and preserving heat for 15mins-25mins to obtain an initial bolting steel ingot;
re-smelting the initial bolting steel ingot, adding lanthanum, cerium or a mixture of lanthanum and cerium and casting into a bolting steel ingot.
100321 During the process of preparing the bolting steel ingot, the smelting is performed by ways well-known for those skilled in the art, and preferably the smelting is performed in a vacuum induction furnace.
[0033] After the bolting steel ingot is prepared, in the present application, the bolting steel ingot is forged, so as to eliminate structure defect generated during the casting process and break big grains in the bolting steel ingot sufficiently, thereby obtaining fine internal grains. The forging is performed by ways well-known for those skilled in the art. The steel ingot is hot-rolled at 1150 C to obtain a hot-rolled bar, then the hot-rolled bar is forged within a range of 900 C to 1030 C. That is, the bolting steel is hot formed on a horizontal forging machine, such that a metal flow line is continuous along components, and a fiber flow line is complete. The forged bolting steel is cooled slowly and then annealed. The annealing can eliminate residual stress generated in the forging process, which prepares for the subsequent heat processing. The annealing is preferably performed at a temperature of 650 C to 700 C, and the duration of heat preservation for the annealing is preferably 2-3 hours.
[0034] According to the present application, after the bolting steel is annealed, the bolting steel is quenched. The quenching is preferably performed at a temperature of 800 C
to 900 C, and the duration of heat preservation for the quenching is preferably 1-2 hours.
Finally the quenched bolting steel ingot is tempered, the tempering is preferably performed at a temperature of 500 C to 600 C, and the duration of the tempering is preferably 1-2 hours.
In the present application, after the quenching and tempering, the bolting steel ingot obtains internal structures with uniform and fine grains. After the tempering, the bolting steel obtains martensite structures and a parc cf austenite sEtuctures.
100351 According to the present application, a method for preparing the high strength bolting steel is further provided. During the process of preparing the bolting steel, in the present application, firstly the bolting steel ingot is prepared, and then the bolting steel ingot is forged, such that grains in the bolting steel ingot are broken sufficiently to obtain structures with fine and uniform grains; the forged bolting steel ingot is annealed, which eliminates stress generated in the forging process; and finally the annealed bolting steel ingot is quenched and tempered, thereby obtaining martensite structures and a part of austenite structures having fine and uniform grains, which improves the strength and plasticity of the material efficiently.
.9.
[0036] According to the elements of the bolting steel, element contents and the preparing method, the bolting material in the present application has high tensile strength and plasticity, thereby providing strong supporting, fixing and connecting for a power arrester device, efficiently resisting stress concentration and deviation behavior of the arrester device in a strong wind, and protecting a safe operation of the device. For the material components of the bolting steel provided by the present application, little precious metal is contained, the mechanical property is good, and cost-effectiveness is high. In addition, the preparing process for the material is simple and is convenient to apply, which may be promoted in a large scale.
According to the present application, the strength and stiffness of the material are improved, thereby changing a natural frequency of the arrester device at a certain degree, avoiding resonance of structures due to the motivation of a strong wind, reducing vibration amplitudes of structures of the device, and guaranteeing a normal operation of the power arrester device.
[0037] Hereinafter the high strength bolting steel and the preparing method for the high strength bolting steel are described in detail in conjunction with embodiments, and the scope .. of the present application is not limited by the following embodiments.
[00381 First embodiment [0039] In the embodiment, the bolting steel contains: Ce 0.12%, C 0.37%, Cr 1.2%, Si 0.25%, Mo 0.5%, V 0.3%, Nb 0.0048%, with remainder being Fe.
[0040 The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentages; step 2), smelting the raw material for 40mins at 1560 C by a vacuum indiction tia-nace, presrving heat for 25m1ns, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Ce and casting into a steel ingot; step 4), perfo:ming hot-rolling on the steel ingot obtained in step 3) at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 900 C, cooling the forged steel ingot slowly and then annealing, wherein the annealing temperature is 650 C and the duration of heat preservation is 2 hours; and step 5), quenching the material obtained in step 4) for lb at 320 'C, tempering the material at 500 'C for 60mins at 500 C, air-cooling the material to a room temperature to obtain a bolting steel. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 1.
Table i data table of performances of the bolting steel prepared according to the first embodiment Performance index Tensile strength (Mpa) Elongation ( /0) Performance value 1210 13.5 [0041] Second embodiment 100421 In the embodiment, the bolting steel contains: La 0.06%, Ce 0.08%, C
0.42%, Cr 1.6%, Si 0.32%, Mo 0.72%, V 0.28%, Nb 0.0045%, with remainder being Fe.
[0043] The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentages; step 2), smelting the material for 40mins at 1540 C by a vacuum induction furnace, preserving heat for 20mins, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Y and casting into a steel ingot; step 4), performing hot-rolling on the steel ingot obtained in step 3) at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 1030 C, cooling the forged steel ingot slowly to a room temperature and then annealing, where the annealing temperature is 680 C and the duration of heat preservation is 2.5 hours; and step 5), quenching the material obtained in step 4) at 830 `C., tempering the material for 70mins at 520 C, air-cooling the material to a room temperature to obtain a bolting steel, where the duration of heat preservation for the quenching is 70mins. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 2.
Table 2 data table of performances of the bolting steel prepared according to the second embodiment Performance index Tensile strength (Nina) Elongation (%) Performance value 1260 12.7 L_ _______________ [0044] Third embodiment 100451 In the embodiment, the bolting steel contains: La 0.05%, C 0.35%, Cr 1.8%, Si 0.17%, Mo 0.40%, V 0.20%, Nb 0.005%, with remainder being Fe.
- -[0046] The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentages; step 2), smelting the material for 45mins at 1550 C by a vacuum induction furnace, preserving heat for 25mins, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Y and casting into a steel ingot; step 4), performing hot-rolling on the obtained steel ingot at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 1000 Cr cooling the forged steel ingot slowly to a room temperature and then annealing, wherein the annealing temperature is 700 C ani the duration of heat preservation is 3 hours; and step 5), quenching the material obtained in step 4) at 800 'C, tempering the material for 80mins at 550 C, air-cooling the material to a room temperature to obtain a bolting steel. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 3.
Table 3 data table of performances of the bolting steel prepared according to the third embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1300 13.0 [0047] Fourth embodiment [00481 In the embodiment, the bolting steel contains: La 0.25%, Ce 0.25%, C 0.45%, Cr 1.4%, Si 0.20%, Mo 0.65%, V 0.4%, Nb 0.0012%, with remainder being Fe.
[0049] The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentage; step 2), smelting the material for 40mins at 1540 C by a vacuum induction furnace, preserving heat for 20mins, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Y and casting into a steel ingot; step 4), performing hot-rolling on the obtained steel ingot at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 1030 C, cooling the forged steel ingot slowly to a room temperature and then annealing, wherein a temperature of annealing is 680 C and the duration of heat preservation is 2.5 hours; and step 5), quenching the material obtained in step 4) at 830 C. tempering the material for 70mins at 520 C, air-cooling the material to a room temperature to obtain a bolting steel. Performances of the bolting steel prepared according to the embodiment are tested, and a test result is shown in table 4.
õ .õ---Table 4 data table of performances of the bolting steel prepared according to the fourth embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1280 13.2 100501 Fifth embodiment [00511 A process of preparing a bolting steel in the embodiment is the same as the process in the first embodiment. However, in the embodiment, the bolting steel contains: La 0.15%, Ce 0.23%. C 0.39%. Cr 1.5%. Si 0.28%, Mo 0.47%, V 0.38%, Nb 0.0014%, with remainder being Fe. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 5.
Table 5 data table of performances of the bolting steel prepared according to the fifth embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1310 13.5 100521 Sixth embodiment 100531 A process of preparing a bolting steel in the embodiment is the same as that in the first embodiment. However, in the embodiment, the bolting steel contains:
Ce 0.28%, C
0.43%, Cr 1.7%, Si 0.27%, Nlo 0.77%, V 0.33%, Nb 0.0041%, with remainder being Fe.
Performances of the bolting steel prepared according to the embodiment are tested, and a test result is shows as table 6.
step 1) casting a bolting steel ingot containing: rare earth 0.05wt%-0.5wt%, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8wt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, where the rare earth is at least one of lanthanum and cerium;
step 2) forging the bolting steel ingot and annealing the forged bolting steel ingot;
step 3) quenching the bolting steel ingot obtained in step 2) and tempering the quenched bolting steel to obtain a high strength bolting steel.
100131 Preferably, step 1) may include:
preparing a raw material containing: the rare earth 0.05wt%-0.5wt%, the carbon 0.35wt%-0.45wt%, the chromium 1.2wt%-1.8wt%, the silicon 0.17wt%-0.37wt%, the molybdenum 0.4wt%-0.8wt%. the vanadium 0.2wt%-0.4wt%, the niobium 0-0.005wt%
with remainder being the Fe, where the rare earth is at least one of the lanthanum and the cerium;
smelting, based on contents of the raw material, the carbon, the chromium, the silicon, the molybdenum, the vanadium, the niobium and the Fe for 40mins-45mins at 1500 C to 1600 C, and preserving heat for 15mins-25mins to obtain an initial bolting steel ingot:
re-smelting the initial bolting steel ingot, adding at least one of the lanthanum and the cerium, and casting into a bolting steel ingot.
[0014] Preferably, a temperature of the annealing is 650 C to 700 C, and the duration of heat preservation for the annealing is 2-3 hours.
[0015] Preferably, a temperature of the quenching is 800 C to 900 C, and the duration of heat preservation for the quenching is 1 2 hours.
[0016] Preferably, a temperature of the tempering is 500 C to 600 C, and the duration of heat preservation for the tempering is 1-2 hours.
[001-1 The high strength bolting steel is provided according to the present application, which includes: rare earth 0.05wt%-0.5wt%, carbon 0.35%-0.45wt%, chromium 1.2w0/0-1.8wt%, silicon 0.17w0/0-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being the Fe. In the present application, the lanthanum or the cerium added into the bolting steel can efficiently refine grain structures of the bolting steel, reduce the content of hydrogen and diffusion and permeation of hydrogen in the steel, reduce grain boundary segregation of the harmful elements. and improve strength of the steel: the added chromium can efficiently improve the antioxidation and anticorrosion capability of the material, and improve the hardenability of the material to increase the strength; and the added molybdenum can strengthen the grain boundary of the material, improve the hardenability of the material, increase the tempering stability and improve the toughness of the material. The carbon, vanadium, niobium and Fe are further added into the bolting steel according to the present application, which interact and cooperate with each other, such that the bolting steel has high strength and plasticity, thereby providing strong supporting, fixing and connecting for the power arrester device, efficiently resisting stress concentration and deviation behavior of the arrester device due to a strong wind, and protecting a safe operation of the device.
[0018] A method for preparing the high strength bolting steel is further provided according to the present application. During a process of preparing the bolting steel, in the present application, the bolting steel ingot is prepared firstly, and then the prepared bolting steel ingot is forged, such that grains of the bolting steel ingot are broken sufficiently to obtain structures with fine and uniform grains; the forged bolting steel ingot is annealed to eliminate stress generated during the forging process; and lastly the annealed bolting steel ingot is quenched and tempered, thereby obtaining martensite structures and a part of austenite structures having fine and uniform internal grains, and efficiently improving the strength and plasticity of the material.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] Hereinafter technical solutions of embodiments of the present application are described in detail. Apparently, the descried embodiments are only some rather than all of the embodiments of the present application. Any other embodiments obtained based on the embodiments of the present application by those skilled in the art without any creative work fall within the scope of protection of the present application.
[0020] According to an embodiment of the present application, a high strength bolting steel English translation of PCT/CN2014/081896 is provided, which includes:
RE 0.05w0/0-0.5wt%;
0.35wt%-0.45wt%;
Cr 1.2wt%-1.8wt%;
Si 0.17wt%-0.37wt%;
Mo 0.4wV/0-0.8wt%;
V 0.2wt%-0.4wt%;
Nb 0-0.005wt%;
with remainder being Fe, where the RE is at least one of La and Ce.
[0021] Lanthanum (La) and Cerium (Ce) each are RE elements. In the present application, La, Ce or a mixture of La and Ce is added into the bolting steel, and La or Ce, which, as an active element, can refine grain structures of the bolting steel efficiently, thereby reducing a content of hydrogen and diffusion and permeation of hydrogen in the steel, decreasing grain boundary segregation of hydrogen, sulphur and other harmful elements, and improving the strength, stiffness and plasticity of the steel. In the present application, a content of La, Ce or the mixture of La and Ce is 0.05wt%-0.5wt%. In this range, martensite and austenite structures increase obviously in the steel, and mechanical properties of the steel are optimized.
In the case that the content of La, Ce or the mixutre of La and Ce is less than 0.05wt%, the generated effect is limited due to a less content, thereby influencing wind resistance performance of the material. In the case that the content of La, Ce and the mixture of La and Ce exceeds 0.5%, metal inclusions containing La, Ce or the mixture of La and Ce enlarge and increase in the material structure, and the material performance is influenced, thereby causing that a wind resistance requirement of the power arrester can not be met gradually. The content of La, Ce or the mixture of La and Ce is preferably in a range of 0.08wt%-0.5wt%, more preferably in a range of 0.10wV/0-0.48wt%, most preferably in a range of 0.12wt%-0.40wt%, and most preferably in a range of 0.25wt%-0.35wt%.
[0022] Carbon (C), as an added element in the present application, can improve the strength, hardness and hardenability of the material. In the case that a content of C is less than 0.35wt%, English translation of PCT/CN2014/081896 the bolting steel has good toughness and plasticity, but the strength, hardness and hardenability of the steel will be limited to a certain degree. In the case that the content of C is greater than 0.45w1%, the toughness and plasticity of the material is reduced significantly, and brittle fracture will occur easily. Thus, the content of C should be in a range of 0.35wt%-0.45wt%. The content of C is preferably in a range of 0.37wt%-0.42wV/o, and more preferably in a range of 0.35wt%-0.40wt%.
[0023] Chromium (Cr) is added to the bolting steel, thereby efficiently improving antioxidation and anticorrosion capability of the material, and improving the hardenability of the material to increase the strength of the material. In the case that a content of Cr is less than 1.2wt%, the above effect is difficult to be achieved; or in the case that the content of Cr is higher than I .8wt%, the toughness of the material will be reduced, thus the content of Cr should be in a range of 1.2wV/0-1.8wt%. The content of Cr is preferably in a range of 1.3wt%-1.6wt%, and more preferably in a range of 1.4wt%-1.55wt%.
[0024] Silicon (Si) is a good deoxidizer for the material, and Si is added into the bolting steel, thereby improving strength of a solid solution of the bolting steel, which is beneficial to increase tempering stability of the material. In the case that a content of silicon is higher than 0.37wt%, plasticity of the material will be reduced, or in the case that the content of silicon is less than 0.17wt%, the function of the deoxidizer and solid solution strengthening of silicon will be weakened. Thus, the best effect can be achieved only when the content of silicon is in a range of 0.17wt%-0.37wt%. The content of silicon is preferably in a range of 0.20wt%-0.32wt%, more preferably in a range of 0.23w0/0-0.30wt%, and most preferably in a range of 0.25wt%-0.28wt%.
[0025] Molybdenum (Mo) can strengthen grain boundary of the material, improve hardenability of the material, increase temping stability and improve toughness of the material.
In the case that a content of molybdenum is less than 0.4wt%, the above effect is difficult to be achieved; or in the case that the content of Mo is higher than 0.8wt%, a cost of the bolting steel is increased and the optimal economy can not be realized. Thus, a good effect can be achieved only when the content of molybdenum in the bolting steel is in a range of 0.4wt%-0.8wt%. The content of Mo is preferably in a range of 0.48wt%-0.72wt%, more preferably in a range of 0.54wt%-0.68wt%, and most preferably in a range of 0.60wt%-0.65wt%.
[0026] Vanadium (V) can efficiently restrain diffusion of hydrogen, refine grains, and improve a mechanical property of the material. In the case that a content of V
is less than 0.2wt%, the above effect is difficult to be achieved; or in the case that the content of V is higher than 0.4wt%, the beneficial effect to the material structure will not be improved but the mechanical property of the material will be influenced as the content increases. Thus, the content of vanadium should be in a range of 0.2wt%-0.4wt%. The content of vanadium is preferably in a range of 0.25wt%-0.38vvt%, more preferably in a range of 0.28wt%-0.35wt%, and most preferably in a range of 0.30wt /0-0.32wt%.
[0027] Niobium (Nb) can improve toughness of the material and refine grain structures efficiently. Niobium is a trace element contained in the material. In the case that a content of niobium is too high, the above effect can not be achieved, and the economy will be influenced greatly. Thus, the content of niobium should be in a range of 0-0.005wt%. The content of niobium is preferably in a range of 0.002wt%-0.0048wt%, and more preferably in a range of 0.0035wt%-0.0040wt%.
[0028] "I he high strength bolting steel provided according to the present application includes: rare earth 0.05wV/0-0.5wV/0, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8wt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, wherein the rare earth is at least one of lanthanum and cerium. In the bolting steel according to the present application, the added active element lanthanum and cerium can efficiently refine grain structures of the bolting steel, reduce the content of hydrogen and diffusion and permeation of hydrogen in the steel, reduce grain boundary segregation of the harmful elements, and improve strength of the steel. The added chromium can efficiently improve the antioxidation and anticorrosion capability of the material, arid improve the hardenability of the material to increase the strength. The added Mo can strengthen the grain boundary of the material, improve the hardenability of the material, increase the tempering stability and improve the toughness of the material. Carbon, vanadium, niobium and Fe are further added into the bolting steel according to the present application, which interact and cooperate with each other, such that the bolting steel has high strength and plasticity.
[0029] According to the present application, a method for preparing the bolting steel is further provided, which includes:
step 1) casting a bolting steel ingot containing: rare earth 0.05wt%-0.5wt%, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8wt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt /0-0.8wt%, vanadium 0.2w0/0-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, where rare earth is at least one of lanthanum and cerium;
step 2) forging the bolting steel ingot and annealing the forged bolting steel ingot;
step 3) quenching the bolting steel ingot obtained in step 2) and tempering the quenched bolting steel to obtain a high strength bolting steel.
[0030] During a process of preparing the bolting steel, in the present application, the bolting steel ingot is cast firstly, and then the prepared bolting steel ingot is forged, such that internal structures of the bolting steel ingot are broken sufficiently; the annealing is performed to eliminate residual stress generated during the forging process, so as to obtain uniform and fine internal grains; and finally the annealed bolting steel is quenched and tempered, which obtains martensite structures and a part of austenite structures having uniform and fine internal grains, thereby improving the strength and plasticity of the bolting steel.
[0031] According to the present application, during the process of preparing the bolting steel, firstly the bolting steel ingot is prepared, and rare earth elements lanthanum, cerium or a mixture of lanthanum and cerium is added into the bolting steel. Lanthanum and cerium are active elements, and lanthanum and cerium may be consumed in the case that lanthanum and cerium are added earlier during the forging process, Thus in the present application, preferably the active elements lanthanum and cerium are added later.
Preferably, the bolting steel ingot is prepared as follows:
preparing a raw material containing: rare earth 0.05wt%-0.5wt%, carbon 0.35wt%-0.45wt%, chromium 1.2wt%-1.8vvt%, silicon 0.17wt%-0.37wt%, molybdenum 0.4wt%-0.8wt%, vanadium 0.2wt%-0.4wt%, niobium 0-0.005wt%, with remainder being Fe, where rare earth is at least one of lanthanum and cerium;
smelting, based on contents of the raw material, carbon, chromium, silicon, molybdenum, vanadium, niobium and Fe for 40mins-45mins at 1500 C to 1600 C, and preserving heat for 15mins-25mins to obtain an initial bolting steel ingot;
re-smelting the initial bolting steel ingot, adding lanthanum, cerium or a mixture of lanthanum and cerium and casting into a bolting steel ingot.
100321 During the process of preparing the bolting steel ingot, the smelting is performed by ways well-known for those skilled in the art, and preferably the smelting is performed in a vacuum induction furnace.
[0033] After the bolting steel ingot is prepared, in the present application, the bolting steel ingot is forged, so as to eliminate structure defect generated during the casting process and break big grains in the bolting steel ingot sufficiently, thereby obtaining fine internal grains. The forging is performed by ways well-known for those skilled in the art. The steel ingot is hot-rolled at 1150 C to obtain a hot-rolled bar, then the hot-rolled bar is forged within a range of 900 C to 1030 C. That is, the bolting steel is hot formed on a horizontal forging machine, such that a metal flow line is continuous along components, and a fiber flow line is complete. The forged bolting steel is cooled slowly and then annealed. The annealing can eliminate residual stress generated in the forging process, which prepares for the subsequent heat processing. The annealing is preferably performed at a temperature of 650 C to 700 C, and the duration of heat preservation for the annealing is preferably 2-3 hours.
[0034] According to the present application, after the bolting steel is annealed, the bolting steel is quenched. The quenching is preferably performed at a temperature of 800 C
to 900 C, and the duration of heat preservation for the quenching is preferably 1-2 hours.
Finally the quenched bolting steel ingot is tempered, the tempering is preferably performed at a temperature of 500 C to 600 C, and the duration of the tempering is preferably 1-2 hours.
In the present application, after the quenching and tempering, the bolting steel ingot obtains internal structures with uniform and fine grains. After the tempering, the bolting steel obtains martensite structures and a parc cf austenite sEtuctures.
100351 According to the present application, a method for preparing the high strength bolting steel is further provided. During the process of preparing the bolting steel, in the present application, firstly the bolting steel ingot is prepared, and then the bolting steel ingot is forged, such that grains in the bolting steel ingot are broken sufficiently to obtain structures with fine and uniform grains; the forged bolting steel ingot is annealed, which eliminates stress generated in the forging process; and finally the annealed bolting steel ingot is quenched and tempered, thereby obtaining martensite structures and a part of austenite structures having fine and uniform grains, which improves the strength and plasticity of the material efficiently.
.9.
[0036] According to the elements of the bolting steel, element contents and the preparing method, the bolting material in the present application has high tensile strength and plasticity, thereby providing strong supporting, fixing and connecting for a power arrester device, efficiently resisting stress concentration and deviation behavior of the arrester device in a strong wind, and protecting a safe operation of the device. For the material components of the bolting steel provided by the present application, little precious metal is contained, the mechanical property is good, and cost-effectiveness is high. In addition, the preparing process for the material is simple and is convenient to apply, which may be promoted in a large scale.
According to the present application, the strength and stiffness of the material are improved, thereby changing a natural frequency of the arrester device at a certain degree, avoiding resonance of structures due to the motivation of a strong wind, reducing vibration amplitudes of structures of the device, and guaranteeing a normal operation of the power arrester device.
[0037] Hereinafter the high strength bolting steel and the preparing method for the high strength bolting steel are described in detail in conjunction with embodiments, and the scope .. of the present application is not limited by the following embodiments.
[00381 First embodiment [0039] In the embodiment, the bolting steel contains: Ce 0.12%, C 0.37%, Cr 1.2%, Si 0.25%, Mo 0.5%, V 0.3%, Nb 0.0048%, with remainder being Fe.
[0040 The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentages; step 2), smelting the raw material for 40mins at 1560 C by a vacuum indiction tia-nace, presrving heat for 25m1ns, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Ce and casting into a steel ingot; step 4), perfo:ming hot-rolling on the steel ingot obtained in step 3) at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 900 C, cooling the forged steel ingot slowly and then annealing, wherein the annealing temperature is 650 C and the duration of heat preservation is 2 hours; and step 5), quenching the material obtained in step 4) for lb at 320 'C, tempering the material at 500 'C for 60mins at 500 C, air-cooling the material to a room temperature to obtain a bolting steel. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 1.
Table i data table of performances of the bolting steel prepared according to the first embodiment Performance index Tensile strength (Mpa) Elongation ( /0) Performance value 1210 13.5 [0041] Second embodiment 100421 In the embodiment, the bolting steel contains: La 0.06%, Ce 0.08%, C
0.42%, Cr 1.6%, Si 0.32%, Mo 0.72%, V 0.28%, Nb 0.0045%, with remainder being Fe.
[0043] The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentages; step 2), smelting the material for 40mins at 1540 C by a vacuum induction furnace, preserving heat for 20mins, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Y and casting into a steel ingot; step 4), performing hot-rolling on the steel ingot obtained in step 3) at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 1030 C, cooling the forged steel ingot slowly to a room temperature and then annealing, where the annealing temperature is 680 C and the duration of heat preservation is 2.5 hours; and step 5), quenching the material obtained in step 4) at 830 `C., tempering the material for 70mins at 520 C, air-cooling the material to a room temperature to obtain a bolting steel, where the duration of heat preservation for the quenching is 70mins. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 2.
Table 2 data table of performances of the bolting steel prepared according to the second embodiment Performance index Tensile strength (Nina) Elongation (%) Performance value 1260 12.7 L_ _______________ [0044] Third embodiment 100451 In the embodiment, the bolting steel contains: La 0.05%, C 0.35%, Cr 1.8%, Si 0.17%, Mo 0.40%, V 0.20%, Nb 0.005%, with remainder being Fe.
- -[0046] The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentages; step 2), smelting the material for 45mins at 1550 C by a vacuum induction furnace, preserving heat for 25mins, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Y and casting into a steel ingot; step 4), performing hot-rolling on the obtained steel ingot at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 1000 Cr cooling the forged steel ingot slowly to a room temperature and then annealing, wherein the annealing temperature is 700 C ani the duration of heat preservation is 3 hours; and step 5), quenching the material obtained in step 4) at 800 'C, tempering the material for 80mins at 550 C, air-cooling the material to a room temperature to obtain a bolting steel. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 3.
Table 3 data table of performances of the bolting steel prepared according to the third embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1300 13.0 [0047] Fourth embodiment [00481 In the embodiment, the bolting steel contains: La 0.25%, Ce 0.25%, C 0.45%, Cr 1.4%, Si 0.20%, Mo 0.65%, V 0.4%, Nb 0.0012%, with remainder being Fe.
[0049] The preparing method for the bolting steel includes: step 1), preparing a raw material based on the above weight percentage; step 2), smelting the material for 40mins at 1540 C by a vacuum induction furnace, preserving heat for 20mins, sampling and casting, and preparing an alloy steel; step 3), re-smelting the prepared alloy steel, adding Y and casting into a steel ingot; step 4), performing hot-rolling on the obtained steel ingot at 1150 C to obtain a hot-rolled bar, forging the hot-rolled bar at 1030 C, cooling the forged steel ingot slowly to a room temperature and then annealing, wherein a temperature of annealing is 680 C and the duration of heat preservation is 2.5 hours; and step 5), quenching the material obtained in step 4) at 830 C. tempering the material for 70mins at 520 C, air-cooling the material to a room temperature to obtain a bolting steel. Performances of the bolting steel prepared according to the embodiment are tested, and a test result is shown in table 4.
õ .õ---Table 4 data table of performances of the bolting steel prepared according to the fourth embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1280 13.2 100501 Fifth embodiment [00511 A process of preparing a bolting steel in the embodiment is the same as the process in the first embodiment. However, in the embodiment, the bolting steel contains: La 0.15%, Ce 0.23%. C 0.39%. Cr 1.5%. Si 0.28%, Mo 0.47%, V 0.38%, Nb 0.0014%, with remainder being Fe. Performances of the bolting steel prepared according to the embodiment are tested, and the test result is shown in table 5.
Table 5 data table of performances of the bolting steel prepared according to the fifth embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1310 13.5 100521 Sixth embodiment 100531 A process of preparing a bolting steel in the embodiment is the same as that in the first embodiment. However, in the embodiment, the bolting steel contains:
Ce 0.28%, C
0.43%, Cr 1.7%, Si 0.27%, Nlo 0.77%, V 0.33%, Nb 0.0041%, with remainder being Fe.
Performances of the bolting steel prepared according to the embodiment are tested, and a test result is shows as table 6.
-13-English translation of PCT/CN2014/081896 Table 6 data table of performances of the bolting steel prepared according to sixth the embodiment Performance index Tensile strength (Mpa) Elongation (%) Performance value 1290 13.2 [0054] It is apparent for those skilled in the art that the present application is not limited to details of the exemplary embodiments, and the present application can be implemented in other manners without departing from the spirit or basic features of the present application.
Thus, from any point, the embodiments should be regarded as exemplary and are not intended to limit. The scope of the present application is defined by the attached claims rather than the above description. Thus, all modifications within the concept and scope of the claims and equivalent thereof will fall into the scope of the present application.
[0055] In addition, it should be understood that the specification is described according to the embodiments, but each embodiment does not include only one independent technical solution. The specification is described in this way for clearance, and those skilled in the art should take the specification as a whole. Technical solutions in various embodiments may be combined appropriately to form other embodiments which can be understood by those skilled in the art.
Thus, from any point, the embodiments should be regarded as exemplary and are not intended to limit. The scope of the present application is defined by the attached claims rather than the above description. Thus, all modifications within the concept and scope of the claims and equivalent thereof will fall into the scope of the present application.
[0055] In addition, it should be understood that the specification is described according to the embodiments, but each embodiment does not include only one independent technical solution. The specification is described in this way for clearance, and those skilled in the art should take the specification as a whole. Technical solutions in various embodiments may be combined appropriately to form other embodiments which can be understood by those skilled in the art.
-14-
Claims (8)
1. A bolting steel, comprising:
rare earth 0.05wt%~0.5wt%;
C 0.35wt%~0.45wt%;
Cr 1.2wt%~1.8wt%;
Si 0.17wt%~0.37wt%;
Mo 0.4M%~0.8wt%;
V 0.2wt%~0.4wt%;
Nb 0.002wt%~0.0048wt%; and with remainder being Fe, wherein the rare earth is at least one of La and Ce.
rare earth 0.05wt%~0.5wt%;
C 0.35wt%~0.45wt%;
Cr 1.2wt%~1.8wt%;
Si 0.17wt%~0.37wt%;
Mo 0.4M%~0.8wt%;
V 0.2wt%~0.4wt%;
Nb 0.002wt%~0.0048wt%; and with remainder being Fe, wherein the rare earth is at least one of La and Ce.
2. The bolting steel according to claim 1, wherein a content of the rare earth is 0.10wt%~0.48wt%.
3. The bolting steel according to claim 1, wherein a content of the Mo is 0.48wt%~0.72wt%.
4. The bolting steel according to claim 1, wherein a content of the Si is 0.20wt%~0.32wt%.
5. A method for preparing a bolting steel, comprising:
step 1) casting a bolting steel ingot containing: rare earth 0.05wt%~0.5wt%, carbon 0.35wt%~0.45wt%, chromium 1.2wt%~1.8wt%, silicon 0.17wt%~0.37wt%, molybdenum 0.4wt%~0.8wt%, vanadium 0.2wt%~0.4wt%, niobium 0.002wt%~0.0048wt%, with remainder being Fe, wherein rare earth is at least one of lanthanum and cerium;
~15~
step 2) forging the bolting steel ingot and annealing the forged bolting steel ingot; and step 3) quenching the bolting steel ingot obtained in step 2) and tempering the quenched bolting steel to obtain a bolting steel, wherein a temperature of the quenching is 800°C to 900°C , and the duration of heat preservation for the quenching is 1~2 hours.
step 1) casting a bolting steel ingot containing: rare earth 0.05wt%~0.5wt%, carbon 0.35wt%~0.45wt%, chromium 1.2wt%~1.8wt%, silicon 0.17wt%~0.37wt%, molybdenum 0.4wt%~0.8wt%, vanadium 0.2wt%~0.4wt%, niobium 0.002wt%~0.0048wt%, with remainder being Fe, wherein rare earth is at least one of lanthanum and cerium;
~15~
step 2) forging the bolting steel ingot and annealing the forged bolting steel ingot; and step 3) quenching the bolting steel ingot obtained in step 2) and tempering the quenched bolting steel to obtain a bolting steel, wherein a temperature of the quenching is 800°C to 900°C , and the duration of heat preservation for the quenching is 1~2 hours.
6. The preparing method according to claim 5, wherein step 1) comprises:
preparing a raw material containing: the rare earth 0.05wt%~0.5wt%, the carbon 0.35wt%~0.45wt%, the chromium 1.2wt%~1.8wt%, the silicon 0.17wt%~0.37wt%, the molybdenum 0.4wt%~0.8wt%, the vanadium 0.2wt%~0.4wt%, the niobium0.002wt%~0.0048wt%, with remainder being the Fe, wherein the rare earth is at least one of the lanthanum and the cerium;
smelting, based on contents of the raw material, the carbon, the chromium, the silicon, the molybdenum, the vanadium, the niobium and the Fe for 40mins~45mins at 1500°C to 1600°C, and preserving heat for 15mins~25mins to obtain an initial bolting steel ingot; and re~smelting the initial bolting steel ingot, adding at least one of the lanthanum and the cerium and casting into the bolting steel ingot.
preparing a raw material containing: the rare earth 0.05wt%~0.5wt%, the carbon 0.35wt%~0.45wt%, the chromium 1.2wt%~1.8wt%, the silicon 0.17wt%~0.37wt%, the molybdenum 0.4wt%~0.8wt%, the vanadium 0.2wt%~0.4wt%, the niobium0.002wt%~0.0048wt%, with remainder being the Fe, wherein the rare earth is at least one of the lanthanum and the cerium;
smelting, based on contents of the raw material, the carbon, the chromium, the silicon, the molybdenum, the vanadium, the niobium and the Fe for 40mins~45mins at 1500°C to 1600°C, and preserving heat for 15mins~25mins to obtain an initial bolting steel ingot; and re~smelting the initial bolting steel ingot, adding at least one of the lanthanum and the cerium and casting into the bolting steel ingot.
7. The preparing method according to claim 5, wherein a temperature of the annealing is 650°C to 700°C, and the duration of heat preservation for the annealing is 2~3 hours.
8. The preparing method according to claim 5, wherein a temperature of the tempering is 500°C to 600°C, and the duration of heat preservation for the tempering is 1~2 hours.
~16~
~16~
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410091577.8A CN103820712A (en) | 2014-03-13 | 2014-03-13 | High-strength bolting steel and preparation method thereof |
| CN201410091577.8 | 2014-03-13 | ||
| PCT/CN2014/081896 WO2015135268A1 (en) | 2014-03-13 | 2014-07-09 | High-strength bolting steel and preparation method therefor |
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| CA2941276A1 CA2941276A1 (en) | 2015-09-17 |
| CA2941276C true CA2941276C (en) | 2019-12-31 |
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| CN (1) | CN103820712A (en) |
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| CN103820712A (en) * | 2014-03-13 | 2014-05-28 | 国家电网公司 | High-strength bolting steel and preparation method thereof |
| CN108754303A (en) * | 2018-04-20 | 2018-11-06 | 北京交通大学 | A kind of high strength bolting steel of atmospheric corrosion resistance and excellent in resistance to delayed fracture |
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| JPS5884960A (en) * | 1981-11-13 | 1983-05-21 | Kawasaki Steel Corp | High tensile steel with superior delayed rupture resistance |
| JPS61204353A (en) * | 1985-03-07 | 1986-09-10 | Nippon Steel Corp | Steel material having superior strength and toughness in as warm forged state |
| CN1131334C (en) * | 2000-04-17 | 2003-12-17 | 冶金工业部钢铁研究总院 | High strength screw bolt steel with good delay resistant breaking performance |
| JP4502126B2 (en) * | 2005-03-07 | 2010-07-14 | 住友金属工業株式会社 | Steel for machine structure |
| JP2007031746A (en) * | 2005-07-22 | 2007-02-08 | Kobe Steel Ltd | Steel for high strength bolt having excellent delayed fracture resistance, and high strength bolt |
| JP4826542B2 (en) * | 2007-05-01 | 2011-11-30 | 住友金属工業株式会社 | Steel for bolts and bridges using the same |
| JP5251632B2 (en) * | 2008-05-13 | 2013-07-31 | 新日鐵住金株式会社 | High strength steel material with excellent delayed fracture resistance, high strength bolt and manufacturing method thereof |
| CN102094153B (en) * | 2011-03-02 | 2013-04-17 | 上海工程技术大学 | Preparation method of high-strength high-toughness alloy steel for bolts |
| CN102943210B (en) * | 2012-11-09 | 2015-02-04 | 谢亚平 | High-strength bolt and processing method thereof |
| CN103820712A (en) * | 2014-03-13 | 2014-05-28 | 国家电网公司 | High-strength bolting steel and preparation method thereof |
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- 2014-03-13 CN CN201410091577.8A patent/CN103820712A/en active Pending
- 2014-07-09 CA CA2941276A patent/CA2941276C/en active Active
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| CA2941276A1 (en) | 2015-09-17 |
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