167 results about "Internal oxidation" patented technology

The present invention addresses the problem of providing a steel sheet and galvannealed steel sheet both having good liquid metal embrittlement (LME) resistance.　This steel sheet has a tensile strength of 780 MPa or more and has specified chemical components. A GDS measurement performed in the thickness direction of the steel sheet finds that the depth at which Bx / B150 ≥ 5.0 is satisfied, where Bx is the light emission intensity at a depth x (μm) and B150 is the light emission intensity at a depth of 150 μm, is 0.5 μm or more from the surface of the steel sheet. The thickness of an oxide formed on the surface of the steel sheet is 0.5 μm or less. An internal oxide layer having a thickness of 1.0 μm or more exists in the thickness direction of the steel sheet from the surface of the steel sheet. Also, this galvannealed steel sheet comprises a galvannealed layer on at least a part of the surface of the steel sheet and the thickness of the oxide formed on the surface of the galvannealed layer is 0.5 μm or less.

The invention discloses 780MPa-grade hot-dip galvanized DH steel and a manufacturing method thereof, the alloy components of DH780 steel grade are optimized, the contents of Si and Mn elements are reduced, and the generation of external oxides is reduced, so that the risk of plating leakage defects is reduced; besides, by improving the dew point in the annealing process and increasing the oxygen partial pressure in the annealing atmosphere, internal oxidation of Si and Mn elements on the surface layer of the DH780 steel grade is promoted, so that the plating leakage defect is effectively reduced, and the surface quality of the steel plate is remarkably improved; according to the method, the production cost is reduced, the weldability and machinability of a product are improved, the integrity and uniformity of a plating layer are effectively improved, the corrosion resistance of the product is improved, the service life of the product is prolonged, and the application range of the DH780 steel grade hot-dip galvanized steel plate is widened.

A non-oriented electrical steel sheet has a chemical composition containing, in terms of % by mass, C: 0.0015% or less and Si: 2.5 to 4.0% and having an average crystal grain size of 10 to 40 μm, and an internal oxidation layer having a thickness of 0.5 to 3.0 μm present in a sheet thickness direction of a surface thereof.

The invention discloses a method for separating and recycling a silver-copper composite material through selective interface oxidation. The method comprises the following steps that the material is crushed and sheared, and a crushed material is obtained; the crushed material is pretreated and then fed into an oxidation fluidized bed, an internal oxidation reaction is conducted in a gas phase at the temperature of 400-700 DEG C and the oxygen pressure of 0.2-0.6 MPa, the reaction time is 20-60 h, and a high-temperature material is obtained; quenching the high-temperature material to generate stress cracks on an oxidation interface to obtain a cooled material; and stripping the cooled material under the mechanical action to obtain a recycled copper material and a recycled silver material, oxidizing the electrical contact material or leftover materials of the electrical contact material in the oxygen atmosphere to oxidize an interface between the silver-copper composite materials to form an oxidation film, separating the two materials of the silver-copper composite materials under the quenching and mechanical actions, and then, obtaining the recycled copper material and the recycled silver material. The method is high in recovery rate, high in recovery purity and environment-friendly.

The invention provides an integral forming method and device for a pressure accumulator diaphragm capsule, and the method comprises the following steps: sleeving a movable female die into a pipe blank part, and adjusting the distance between the movable female die and a fixed female die; a high-pressure fluid medium is introduced through an internal flow channel of the connecting rod, and the pressure and loading time of the high-pressure medium are regulated by a pressure regulating device; the positions of the movable core head, the fixed sealing head, the pre-expansion limiting die and the movable female die are kept immovable, and the pressure regulation and control device is adjusted to unload the pressure of the high-pressure medium; the pre-expansion limiting die is separated in the radial direction and rotates to be separated from the pipe blank part; the movable female die moves in the axial direction to form a single waveform; the movable female die moves progressively in the axial direction, and the movable core head moves in the axial direction as well; and forming of a second waveform and a subsequent waveform is completed. According to the method, the defects of welding deformation, weld joint gouges, weld joint surface oxidation color, weld joint black spots and joint internal oxide inclusion caused by a traditional welding method are overcome, the quality control difficulty in the production process is reduced, and the production efficiency and the production quality of the diaphragm capsule are remarkably improved.

The invention relates to the technical field of copper-iron alloys, and discloses a preparation method of a high-strength, high-conductivity and high-temperature-resistant powder metallurgy copper-iron alloy, which comprises the following steps: S1, preparing copper-aluminum alloy powder through an atomization method, and then preparing dispersion-strengthened copper alloy powder through internal oxidation and reduction treatment; s2, mechanical alloying composite powder is prepared through ball milling; s3, the prepared powder is pressed and formed; s4, sintering and densifying the pressed and formed powder; and S5, finally carrying out thermomechanical treatment. The invention aims to provide the high-strength, high-conductivity and high-temperature-resistant powder metallurgy copper-iron alloy which is uniform and fine in iron phase distribution, fine in crystal grain, excellent in high-temperature performance and good in processability, so as to solve the problems that the copper-iron alloy prepared by the traditional casting method is segregated in component, coarse in crystal grain, poor in high-temperature performance and processability, low in cost and the like. And the problem of poor high-temperature performance caused by growth and coarsening of the initial iron particles and the deformed iron fibers at high temperature is solved, and the method has important application prospects under the high-temperature service condition in the fields of electricity and rail transit.

The invention discloses a high-strength and high-plasticity copper alloy and a preparation method thereof. The high-strength and high-plasticity copper alloy is prepared by mixing Cu-Al pre-alloyed spherical powder and CuO powder according to the mass ratio of (100-150): 1, wherein the Cu-Al pre-alloyed spherical powder and the CuO powder are different in particle size range. The solid solution state Al element part in the high-strength plastic copper alloy is oxidized into Al2O3 through CuO, and the Al2O3 exists in a Cu matrix. The preparation method comprises the following steps: (1) mixing Cu-Al pre-alloyed spherical powder with CuO powder, and drying; (2) cold isostatic pressing treatment; (3) vacuumizing, sintering at a high temperature in a protective atmosphere, and cooling; (4) vacuumizing, reducing in a reducing atmosphere, and cooling; and (5) after preheating, the copper alloy reduction blank is placed in a rotary forging die, rotary forging and air cooling are conducted, and the copper alloy is obtained. The high-strength plastic copper alloy is good in conductivity and mechanical property and high in plasticity. The method is simple in process, environmentally friendly, low in cost and suitable for industrial production.

The invention relates to the technical field of metal composite material preparation, in particular to a preparation method of an Al2O3 dispersion strengthened copper composite material ingot blank, which comprises the following specific steps: S1, preparing gas atomized Cu powder; s2, oxygen distribution; s3, carrying out internal oxidation to obtain Cu / gamma-Al2O3 dispersed copper powder; s4, carrying out CIP processing; s5, reduction is conducted, specifically, the ingot blank is placed in high-purity hydrogen to be reduced; and S6, hot pressed sintering. The high-purity oxygen-free electrolytic copper and the copper-aluminum intermediate alloy are smelted, oxygen is added to obtain oxygen-added powder, then the oxygen-added powder is subjected to internal oxidation to obtain Cu / gamma-Al2O3 powder, the fluidity and the filling property are good, the density and the structural uniformity of a green body are improved, meanwhile, treatment is conducted under the high CIP pressure, the density of the green body is further improved, and after hot pressing sintering, the quality of the green body is improved. And the process is simple, and the cost is low.

The invention belongs to the technical field of semiconductor wafer manufacturing, and particularly relates to a method for growing a gallium oxide single crystal by a cold crucible method and a czochralski method, which comprises the following steps of: heating a gallium oxide raw material in a crucible at high frequency for the first time, keeping the temperature for a certain time, increasing the heating frequency to completely melt gallium oxide, and adjusting the pressure of cooling water to obtain the gallium oxide single crystal. The molten gallium oxide forms a gallium oxide solid layer on the inner wall of the crucible to isolate the contact between the gallium oxide at the center and the inner wall of the crucible, then crystal pulling is carried out, and the heating frequency is gradually reduced while crystal pulling is carried out. According to the technical scheme, through the design of the crucible structure and the adjustment of the heating frequency of the high-frequency heating device, a solid gallium oxide layer is formed between gallium oxide melt and the inner surface of the crucible in the crystal pulling process, the gallium oxide solid layer can completely isolate the contact between internal gallium oxide and a crucible body material, and the crystal pulling quality is improved. And the produced gallium oxide crystal is prevented from being polluted.

The application relates to a method for improving a tungsten-copper connecting interface based on internal oxidation and hydrogen reduction process, and relates to the technical field of tungsten-copper composite material preparation. First, an oxide (Cu2O, CuO) or oxygen is added to the surface of a tungsten block for internal oxidation treatment, a nano-oxide porous structure is generated on the surface, the surface roughness is increased, then hydrogen reduction is performed to remove surface oxide impurities, the surface pores are reserved, finally, the tungsten block with the treated surface is combined with copper powder through discharge plasma sintering to realize effective combination between tungsten and copper. Through the internal oxidation process, the influence of a metal alloy layer formed by a heterogeneous element brazing filler on the tungsten-copper interface compatibility and stability under radiation can be effectively avoided, and through the reduction treatment of high-purity hydrogen, the high-purity of the matrix is maintained, and the combination performance of the porous structure reinforced connecting layer is generated.

The purpose of the present invention is to provide a grain-oriented electrical steel sheet which does not have a forsterite coating film (glass coating film), and which has excellent iron loss that has been subjected to heat-resistant magnetic domain control. This grain-oriented electrical steel sheet has no forsterite coating film on the surface of a base steel sheet, is provided with a tension coating film (insulating coating film), has a plurality of grooves in the surface, and has an SiO2 intermediate layer and an insulating coating film in this order on the surface of the steel sheet, and the coating film tension of the tension coating film is 10 MPa or more. Furthermore, an SiO2 internal oxide layer is provided directly below the surface of the base steel sheet, and the irregularities between the surface of the steel sheet and the internal oxide layer are 0.001 [mu] m-0. 100 [mu] m.

Provided is a zinc plated steel sheet having excellent spot weldability and a manufacturing method thereof. The zinc plated steel sheet includes a steel sheet and a zinc plated layer formed on the surface of the steel sheet, wherein the ratio (a / b) between a widthwise average value (a) of thickness of an internal oxidized layer and a widthwise standard deviation (b) of thickness of the internal oxidized layer in the steel sheet may be 1.5 or more.

The invention relates to the technical field of alloy powder preparation, discloses high-entropy alloy powder and a preparation process thereof, and aims at solving the problems that Y2O3 particles are easy to agglomerate, the process depends on experience and the batch stability is poor in a traditional ODS high-entropy alloy process, a preparation method combining multi-scale simulation with digital twinning optimization is constructed, critical ball milling impact energy is simulated through molecular dynamics, and the high-entropy alloy powder is obtained. The method comprises the following steps: judging a ball milling end point in real time by adopting an acoustic emission intelligent monitoring system, and performing internal oxidation in an Ar-(3-10)% O2 atmosphere by utilizing defect engineering to generate Y2O3 nano-phase particles of 5-10nm; monitoring an O + / Ar + spectral line intensity ratio through a fiber optic spectrometer in SPS sintering to intelligently trigger pressure loading; constructing a digital twinborn body to realize virtual iterative optimization; the yield strength of the prepared high-entropy alloy powder reaches 1200-1300 MPa, the ductility is larger than or equal to 12%, and the strength is improved by 20-30% compared with that of a traditional process.

A hot-dip galvanized steel sheet according to one aspect of the present invention comprises a base steel sheet and a hot-dip galvanized layer formed on the surface of the base steel sheet, wherein the difference between the average of the Mn / Si values of surface oxides present on a surface portion, which is the region from the interface between the hot-dip galvanized layer and the base steel sheet to a depth of 15 nm, and the average of the Mn / Si values of internal oxides, which are present in the region from the interface to a depth of 50-100 nm, can be 0.5 or more. Mn and Si of each oxide mean the amounts (wt %) of Mn and Si components in the oxide, which are measured by EDS, and the average of Mn / Si values means the averaged value of the Mn / Si values measured for each oxide.

The invention relates to an oxide dispersion strengthened copper alloy plate and a preparation method thereof, and belongs to the technical field of metal composite materials. The preparation method of the oxide dispersion strengthened copper alloy plate comprises the steps that alloy powder is subjected to internal oxidation to obtain powder containing a dispersion strengthening phase, the powder is reduced and then loaded into a stainless steel sheath to be subjected to hot rolling forming, and finally a pressed blank is sintered at a certain temperature to obtain the oxide dispersion strengthened copper alloy plate. And after sintering, removing the sheath to obtain the oxide dispersion strengthened copper alloy plate. According to the method, the dispersion strengthened copper plate can be directly obtained through the powder wrapping rolling forming technology, the problems that dispersion strengthened copper is poor in machining performance and prone to cracking in the deformation process are solved, the cost can be reduced, the preparation efficiency can be improved, and possibility is provided for large-scale preparation of the dispersion strengthened copper plate.

The application discloses a high-surface-quality 980MPa-grade hot-dip galvanizing DH steel and a preparation method thereof. The main chemical component mass content of the hot-dip galvanizing DH steel is as follows: C: 0.17-0.21%, Si: 0.4-0.7%, Mn: 1.8-2.2%, Nb: 0.01-0.02%, Ti: 0.01-0.02%, Cr: 0.4-0.5%, and Als: 0.14-0.9%. The method adopts low-carbon design and high-dew-point annealing process to produce the hot-dip galvanizing steel plate which meets the low-carbon environmental protection requirement and has high surface quality, so as to meet the urgent needs of the market. The high-dew-point annealing process is a new type of annealing technology, the oxygen partial pressure is increased by increasing the dew point, the Si and Mn element internal oxidation is realized, and thus the plating leakage defect is effectively improved, and the surface smoothness and flatness of the steel plate are improved.

The element welding rotary table based on the automatic directional transposition mechanism comprises a support, a rotary table is arranged on one side of the support, a rotary table is arranged on one side of the rotary table, and a jacking limiting mechanism and an air guide mechanism are arranged on one side of the rotary table; the sleeve rod is arranged on the rotary table, the sleeve rod is sleeved with a workpiece, then the workpiece is limited and fixed through the ejector block pushed out through air pressure in the sleeve rod, the workpiece can be welded, meanwhile, the air holes capable of exhausting are formed in the vertical rods, and then protective gas is guided into the workpiece, so that the workpiece can be welded. The problem of internal oxidation caused by high welding temperature is conveniently solved, and after workpiece welding is finished, the workpieces are lifted and supported out through the multiple brackets, so that the welded high-temperature workpieces can be rapidly stripped from the welding table, and the working efficiency is prevented from being affected.

The application discloses a preparation method of a multistage coating oxygen-mediated annealing based on RAFM steel / titanium nitride, and belongs to the technical field of coating preparation. The application method comprises the following steps: depositing a TiN coating on the surface of a low-activated ferrite / martensite steel base by using a magnetron sputtering, using a pure titanium target, and setting the nitrogen / argon flow ratio to 1:13-1:18, the base vacuum degree to 4-6*10 ‑5 Pa, and the deposition time to 60-90 min, and not applying additional active heating to the base during the deposition process; packaging the deposited coating sample in a quartz tube, providing a trace oxygen atmosphere in the tube by means of the gas pressure in the tube; and then performing 800-1000 DEG C annealing treatment and keeping the temperature for 90-120 min. Through oxygen-mediated element diffusion and reaction, a multistage composite structure, which comprises, from the base outward, an internal oxidation layer, an Fe internal enrichment layer, a TiN layer, an Fe external enrichment layer and an external oxidation layer, is formed in the TiN coating in situ. The application method is simple in process, does not need to deposit a transition layer additionally, the prepared multistage coating is well combined with the base, has excellent thermal shock resistance, and can withstand more than 30 times of thermal shock cycles.

The invention provides a rare earth doped Cu-Al2O3 nano dispersion strengthened alloy and a preparation method of the rare earth doped Cu-Al2O3 nano dispersion strengthened alloy. The rare earth doped Cu-Al2O3 nano dispersion strengthened alloy disclosed by the invention is prepared from the following components in percentage by weight: 0.01 wt% to 0.08 wt% of Al2O3, 0.01 wt% to 0.03 wt% of Ce, 0.01 wt% to 0.03 wt% of Sr, 0.01 wt% to 0.03 wt% of La and the balance of copper. The conductivity of the alloy is remarkably improved and reaches 100.3 IACS, and the bottleneck that the conductivity of a Cu-Al2O3 alloy material produced by an internal oxidation method reaches 100% IACS is broken through. The invention further provides a preparation method of the rare earth doped Cu-Al2O3 nano dispersion strengthened alloy.

The alloyed hot-dip galvanized steel sheet of the present disclosure has a base steel sheet having a prescribed chemical composition in mass%, and a plated layer, and the existence ratio ER of a specific internal oxide is 40% or less and the interval I of the internal oxide is 300 μm or more when a cross section of the base steel sheet is observed under prescribed conditions. The alloyed hot-dip galvanized steel sheet of the present disclosure is excellent in appearance and the like.

This invention relates to a clad steel sheet and a method for manufacturing the same. The clad steel sheet comprises: a base steel sheet, which, by weight percent, contains: C: 0.10-0.25%, Mn: 1.5-5.0%, Si: 0.5-2.5%, Cr: less than 1.5%, Al: 0.005-0.100%, P: less than 0.10%, S: less than 0.020%, B: less than 0.0050%, with the balance being Fe and other unavoidable impurities; and a coating formed on at least one side of the base steel sheet, wherein, with reference to the direction from the interface between the base steel sheet and the coating toward the thickness center, the depth of the internal oxide layer composed of one or more oxides of Mn, Si, Cr and B is 3-15 μm. More specifically, the invention relates to a clad steel sheet with excellent surface quality and weld LME resistance, and a method for manufacturing the same.

High strength plated steel sheet having high hydrogen embrittlement resistance, that is, alloyed hot dip galvannealed steel sheet including steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50% and a alloyed hot dip galvannealed layer deposited on at least one surface of the steel sheet to 10 to 100 g / m2 and containing Fe: 5.0 to 15.0% and Al: 0.01 to 1.0%, having an internal oxidation layer including grain boundary oxides in a surface layer of the steel sheet, when examining a cross-section of a surface layer of the steel sheet, a Ratio A of the length of the grain boundary oxides projected an interface of the steel sheet and the alloyed hot dip galvannealed layer to the length of interface is 50% or more and 100% or less, and a surface depleted layer with a steel composition not including the grain boundary oxides which satisfies, by mass %, Si≤0.6% and Al≥0.05% is included at a depth of ½ of the average depth of the internal oxidation layer.

It is an object to provide a welded member and a method for producing the welded member. In the welded member of the invention, the total thickness of a sheet set and the minimum thickness of a resistance spot weld satisfy formula (1). At least one steel sheet in the sheet set is a steel sheet having an internally oxidized layer in a steel sheet surface layer. In a base metal zone in the steel sheet having the internally oxidized layer, the amount of oxygen per unit area in the internally oxidized layer satisfies formula (2). In a weld heat affected zone in this steel sheet, the density of Si-containing oxide in a first region satisfies formula (3), and the average Si concentrations in second and third regions satisfy formula (4). 0.5<tweld / tall<1.0 0.02<Os<1.0 0.01≤Ns Ss / St<1.0

The invention provides a directional oxidation process for a silver metal oxide electrical contact material. The process comprises the following steps: preparing raw materials, smelting and casting to form a silver alloy cast ingot, turning, extruding, carrying out hot rolling and silver compounding, carrying out cold rolling, punching, carrying out surface treatment, coating an anti-oxidation coating on a silver surface of a contact, carrying out internal oxidation, carrying out surface treatment, and carrying out spot inspection and packaging. The invention provides an antioxidant composed of silicon oxide, aluminum oxide, magnesium oxide, sodium oxide and boron oxide, the antioxidant is uniformly mixed with water and then coated on a contact silver layer surface, a compact oxide protective film is formed at high temperature, the viscosity of the protective film is reduced by adding alkali metal, the self-healing of the protective layer is improved, and the service life of the protective layer is prolonged. The coating is prevented from being cracked in the contact oxidation expansion process; the silver metal oxide obtained through the technology is of a directional oxidation structure and is uniform in structure, new equipment is not introduced, the technology is simple, the operation difficulty is low, and the technology is suitable for all internal oxidation technology sheet products.

To provide an Fe-based electroplated steel sheet that not only has excellent chemical convertibility or excellent coating appearance when subjected to hot-dip galvanizing, but also has excellent resistance to cracking in resistance welding. Disclosed is an Fe-based plated steel sheet including: a cold-rolled steel sheet having a chemical composition containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on one or both surfaces of the cold-rolled steel sheet with a coating weight per surface of 1.0 g / m2 or more, in which a thickness of an internal oxidation layer is 2.00 μm or less, and an average value of C concentration in a range of 10 μm to 20 μm in a thickness direction from the surface of the Fe-based electroplating layer is 0.10 mass % or less.

This steel sheet has a predetermined chemical composition, and includes, as a metallographic structure, ferrite, bainite, and pearlite in a total volume percentage of 0% or more and 50% or less, residual austenite in a volume percentage of 3% or more and 20% or less, and a remainder of fresh martensite and tempered martensite, in which residual austenite having an aspect ratio of 3.0 or more occupies 80% or more of a total residual austenite by area ratio, the steel sheet includes an internal oxide layer having a thickness of 4.0 μm or more from a surface of the steel sheet and a decarburized layer having a thickness of 10 μm or more and 100 μm or less from the surface of the steel sheet, and an amount of diffusible hydrogen included in the steel sheet is 1.00 ppm or less on a mass basis.

Steel sheet and plated steel sheet comprised of steel sheet with a thin thickness in which sufficient strength and plateability or chemical convertibility are both achieved, i.e., steel sheet having a chemical composition containing, by mass %,C: 0.05 to 0.30%,Si: 0.01 to 2.50%,Mn: 0.80 to 3.00%,Al: 0.010 to 2.000%, etc. and having a balance comprising Fe and impurities andhaving a thickness of 0.4 to 2.0 mm,in which steel sheet,a tensile strength is 550 to 1500 MPa,an internal oxidation layer and decarburized layer are contained,when a thickness of the decarburized layer per side of the steel sheet: A (μm), a bulk C concentration of the steel sheet: Cb (%), and a thickness of the steel sheet: t (mm),0.01≤A / t≤0.15, anda C concentration at the ½A position is Cb / 2 or more andplated steel sheet using that steel sheet.

The invention belongs to the technical field of alloy manufacturing, and particularly relates to a low-deformation ultrahigh-temperature electrothermal alloy and a preparation method thereof. Compared with a single-powder single-oxygen idea in the prior art, the scheme has the advantages that double powder-double chemical potential gradient is used for driving secondary dispersion precipitation for the first time, the side effect of'shell caused by excessive oxygen 'is converted into an'internal oxygen source', the inherent contradiction between agglomeration of an external addition method and insufficient gradient of an internal oxidation method is overcome, a continuous and controllable causal chain is formed, and the method is suitable for industrial production. And finally, the strength-service life bottleneck of the 1400 DEG C grade FeCrAl electrothermal alloy is solved.

The invention discloses a preparation method of a high-heat-resistance aluminum alloy, and belongs to the technical field of nonferrous metal manufacturing. Copper-clad aluminum composite powder, iron-clad aluminum composite powder and nickel-clad aluminum composite powder are prepared through a chemical plating method, the powder is mixed according to a certain proportion, slightly oxidized in air and then subjected to vacuum sheathing, and a sheathing powder billet is subjected to hot isostatic pressing or hot extrusion densification treatment; in the densification process, a dual process of internal oxidation and nano heat-resistant phase precipitation is further carried out, and finally two nano heat-resistant phases, namely Al2O3 and an AlFeNiCu intermetallic compound, are formed in the aluminum alloy, so that the heat resistance of the aluminum alloy is remarkably improved.

The invention discloses an oxide dispersion strengthened copper alloy stranded wire and a preparation method thereof, and belongs to the technical field of copper-based composite materials and powder metallurgy, the alloy components comprise, by mass, 0.15%-0.55% of Al, 0.03%-0.15% of Y, 0.01%-0.06% of Ti and the balance Cu, Al2O3 and Y3Al5O12 composite dispersed phases are dispersed and distributed in a matrix, and the composite dispersed phases are dispersed and distributed in the matrix. The preparation method comprises the steps of gas atomization powder preparation, gradient oxygen partial pressure internal oxidation, hydrogen reduction, cold isostatic pressing, hot extrusion, cold drawing, stranding and stable annealing, the tensile strength of the stranded wire is not lower than 500 MPa, the electric conductivity is not lower than 82% IACS, and the strength retention rate is not lower than 90% after heat preservation at 800 DEG C for 100 h.