808results about How to "Grain refinement" patented technology

The invention relates to an annealing-free alloy cold heading steel wire rod for a 12.9-grade bolt and a production method of the annealing-free alloy cold heading steel wire rod. The production process comprises the steps of molten iron pre-removal of P / S, electric furnace or converter smelting, external refining, bloom continuous casting, rolling into an intermediate billet and steel billet finishing, intermediate billet heating, high-pressure water descaling, rough rolling, intermediate rolling, pre-finish rolling, finish rolling, spinning, coil collecting and cooling. The annealing-free alloy cold forging steel wire for the 12.9-grade bolt comprises the following components in percentage by mass: 0.30%-0.35% of C, 0.10%-0.30% of Si, 0.70%-1.20% of Mn, 1.0%-1.5% of Cr, 0.15%-0.30% of Mo, 0.015%-0.030% of Al, 0.0030%-0.0080% of N, 0.01%-0.04% of Nb, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Cu, less than or equal to 0.015% of P, less than or equal to 0.010% of S, less than or equal to 0.012% of (As + Sb + Bi), less than or equal to 0.0010% of O and the balance of Fe and inevitable impurity elements, the niobium-nitrogen product (Nb * N) is greater than On the premise that main alloy components are not reduced, a fine grain structure can be obtained under a certain condition by adding grain refining elements, and the delayed phase change effect the same as that of a low-temperature finish rolling process is achieved by utilizing the delayed phase change characteristic of the fine grain structure.

The invention discloses a laser-TIG (Tungsten Inert Gas) hybrid welding and method based on ultrasonic-assisted wire powder coaxial conveying, after entering, a laser beam forms a semicircular Bessel beam through a lens, a metal wire passes through an ultrasonic-assisted device and then introduces vibration into a welding pool, and six powder conveying guide pipes are uniformly distributed around the metal wire; according to the wire core six-way powder channel coaxial device, a semi-circular light beam passes through the wire core six-way powder channel coaxial device and enters a laser head, and finally the effect of coaxially melting a wire powder material through laser is achieved. A TIG welding auxiliary device is added to one side of a molten pool, metallurgical reaction is promoted, and compactness of a welding seam is improved. The device mainly comprises an annular laser beam wire core six-way powder channel simultaneous melting system, an automatic wire feeding system, a powder feeding system, an ultrasonic vibration system, a TIG auxiliary welding system and the like. The welding efficiency can be improved through the wire core six-way powder channel coaxial melting technology, the flowing stability of a molten pool can be promoted through the ultrasonic-assisted technology, and the welding seam forming quality can be improved through laser-TIG composite welding.

The invention discloses active brazing filler metal for sealing sapphire and kovar alloy and a preparation method of the active brazing filler metal. The active brazing filler metal comprises 25.0 wt%-27.5 wt% of Cu, 1.0 wt%-6.0 wt% of Ti, 1.0 wt%-5.0 wt% of Al, 0.1 wt%-1.0 wt% of B, 0.1 wt%-0.5 wt% of rare earth element RE, RE is one or more of La, Ce, Sc, Pr, Nd and Er, and the balance is Ag. The preparation method comprises the following steps: preparing silver-based pre-alloying powder by adopting a gas atomization method, mixing the alloy powder with additive element powder in a ball milling manner, sintering by utilizing vacuum pressure to obtain an alloy ingot blank, and carrying out rough rolling, intermediate annealing and finish rolling to obtain an active brazing filler metal strip with the thickness of 0.05-0.2 mm. The active brazing filler metal is well matched with the thermal expansion coefficient of sapphire, direct brazing of sapphire and Kovar alloy can be achieved, the brazing temperature is moderate, and a brazed joint is uniform in structure and free of defects such as air holes and cracks.

The invention provides a production method of an invar alloy 4J36 hot-rolled coil, belongs to the technical field of invar alloy 4J36 hot rolling, and solves the problem that the invar alloy 4J36 hot-rolled coil needs to be efficiently produced. The plate blank is preheated and then heated after being ground, and the heated plate blank is subjected to high-pressure water descaling; and the descaled plate blank is rolled into an intermediate blank through seven-pass rough rolling, the intermediate blank is rolled into a black coil through five-pass steckel mill finish rolling, and the black coil is rolled into an invar alloy 4J36 hot-rolled black coil finished product. The method comprises the steps of slab component control, slab preheating and heating, rough rolling to obtain an intermediate slab, steekle mill rolling, coiling and the like, and surface oxidation generated in the heating process is reduced by adjusting the heating process; and through rolling of the steekle mill, dynamic recrystallization is fully carried out, the surface quality of the produced invar alloy 4J36 hot-rolled coil meets the product requirement, and the yield and the production efficiency are both remarkably improved.

The invention discloses a method for improving the high-cycle fatigue performance of a Ti6Al4V titanium alloy, and belongs to the technical field of metal material processing, and the method comprises the following steps: S1, determining shot peening strengthening parameters based on material performance parameters and related standards; according to the method, high-amplitude residual compressive stress is introduced through shot peening strengthening, the stress state of the surface and the depth direction of the material is changed, accordingly, crack extension can be restrained, the fatigue life is prolonged, in addition, a plastic deformation layer is induced to be generated under the surface depth in the shot peening process, the microstructure of the material is improved, and the anti-fatigue performance of the material is improved; through femtosecond laser shock, surface defects can be effectively removed, the surface compactness can be improved, microcracks can be reduced, and a refined grain structure can be generated, so that the strength and toughness of the material are further enhanced, the high-cycle fatigue performance of the material is further improved, the two are combined, the residual stress state is optimized, and the surface integrity is improved. The fatigue performance of the Ti6Al4V titanium alloy is remarkably improved.

The invention discloses a graphene composite perovskite manganese oxide polycrystalline ceramic and a preparation method and application thereof, and belongs to the technical field of non-refrigeration high-sensitivity infrared detection. The chemical expression of the graphene composite perovskite manganese oxide polycrystalline ceramic is La < 0.81 > (Ca < 0.03 > Sr < 0.16 >) MnO3: Gy, G is graphene, y is the mass fraction of graphene in perovskite manganese oxide composite powder, and y is equal to 0.1-0.2%. The TCR value of the prepared polycrystalline ceramic can reach 30% or above, the Tk value is close to 300K, the polycrystalline ceramic has excellent adaptability to room temperature work and excellent sensitivity to temperature change, and when the polycrystalline ceramic is applied to an uncooled infrared detector, the detection precision of the uncooled infrared detector can be effectively improved.

The invention discloses a ZnFeP-particle gradient abrasion-resistant chemical composite coating and a preparation method of the ZnFeP-particle gradient abrasion-resistant chemical composite coating. The ZnFeP-particle gradient abrasion-resistant chemical composite coating is divided into a passivation layer, a low-iron ZnFeP-particle chemical composite coating and a high-iron ZnFeP-particle chemical composite coating from outside to inside, and a gradient coating with the corrosion potential from low to high is formed; the content of iron in the low-iron ZnFeP-particle chemical composite coating ranges from 0.03 wt% to 1.0 wt%, the thickness of the low-iron ZnFeP-particle chemical composite coating ranges from 8 micrometers to 18 micrometers, and the hardness of the low-iron ZnFeP-particle chemical composite coating ranges from 150 HV to 300 HV. The content of iron in the high-iron ZnFeP-particle chemical composite coating ranges from 5 wt% to 30 wt%, the thickness ranges from 8 micrometers to 18 micrometers, and the hardness ranges from 500 HV to 650 HV. By means of the ZnFeP-particle gradient abrasion-resistant chemical composite coating, a metal component can be resistant to abrasion and corrosion, and therefore the service capacity of the metal component such as electric power fittings in the abrasion working condition is obviously improved.

The invention is applicable to the technical field of titanium alloy pipe processing, and particularly relates to a preparation method of a high-plasticity TA15 titanium alloy pipe, which comprises the following steps: step S1, selecting sponge titanium, pure metal and intermediate alloy, preparing according to standard components of TA15 titanium alloy to obtain a prepared raw material, and smelting the prepared raw material for three times by adopting a vacuum consumable smelting furnace to obtain a high-plasticity TA15 titanium alloy pipe; and the TA15 titanium alloy cast ingot with the diameter being 600 mm is obtained. According to the method, the mechanical property and plasticity of the titanium alloy pipe are remarkably improved by accurately controlling the temperature and deformation of each machining step. And three-time upsetting and three-time drawing forging is carried out within the temperature range of T beta or above, coarse grains are effectively crushed, and grain structures are refined. And then, the metallographic structure of the wool rod is gradually optimized by accurately controlling the forging temperature and the deformation amount.

The invention provides low-yield-ratio super-thick maritime work steel with excellent core low-temperature toughness and a manufacturing method of the low-yield-ratio super-thick maritime work steel, and belongs to the field of steel and iron material preparation. The low-yield-ratio super-thick marine steel with the excellent core low-temperature toughness comprises the following chemical components in percentage by mass: 0.10%-0.15% of C, 0.35%-0.45% of Si, 1.20%-1.50% of Mn, 3.00%-3.50% of Ni, 0.30%-0.50% of Mo, 0.15%-0.3% of Cr, 0.01%-0.02% of Ti, 0.030%-0.040% of V, 0.050%-0.060% of Nb, 0.0016%-0.0020% of B, 0.15%-0.25% of Cu, 0.060%-0.070% of Al, less than or equal to 0.010% of P, less than or equal to 0.004% of S, less than or equal to 0.39% of CET and the balance of Fe and inevitable impurities. According to the invention, a component design thought of a low-C, Ni-Nb-Mo-Al-B system is adopted, and a three-section rolling and quenching and tempering heat treatment process is combined. Through strict control of smelting continuous casting, controlled rolling and controlled cooling processes and quenching and tempering heat treatment parameters, the super-thick marine steel with excellent comprehensive mechanical properties is successfully prepared. The steel shows good low-temperature toughness in the core part, and meanwhile, the steel has a relatively low yield ratio. According to the low-yield-ratio super-thick maritime work steel with the excellent core low-temperature toughness, the thickness range is 80-150 mm, the yield strength is larger than or equal to 690 MPa, the tensile strength is larger than or equal to 920 MPa, the percentage elongation after fracture is larger than or equal to 20%, the yield ratio is smaller than or equal to 0.77, and the impact energy KV2 at the temperature of-60 DEG C is larger than or equal to 80 J.

The invention relates to the technical field of alloy materials, in particular to a high-strength alloy material based on a rail transit vehicle and a processing technology of the high-strength alloy material. Raw materials are smelted and cast to obtain a cast ingot; the cast ingot is sequentially subjected to solution treatment and aging treatment, and an alloy material is obtained; uniformly mixing the compound, mica powder, a curing agent and an epoxy diluent, adding epoxy resin, a defoaming agent and a flatting agent, and performing ultrasonic treatment to obtain a corrosion-resistant coating; the high-strength alloy material is obtained by sequentially grinding, polishing, cleaning and drying the surface of an alloy material, coating a corrosion-resistant coating, and curing to form a corrosion-resistant coating. The prepared high-strength alloy material has excellent mechanical properties, corrosion resistance and hydrophobicity, and is suitable for application requirements of rail transit vehicles.

The invention discloses high-toughness cold-rolled dual-phase steel, a preparation method thereof and an automobile part, and belongs to the technical field of alloy production. The high-toughness cold-rolled dual-phase steel comprises the following chemical components in percentage by weight: 0.15%-0.35% of C, 0.10%-0.50% of Si, 0.50%-4.00% of Mn, less than or equal to 0.5% of Mo, Nb, Ti and V, and the balance of Fe and impurity elements, the matrix structure of the dual-phase steel is long lath ferrite and martensite. The high-toughness cold-rolled dual-phase steel with the chemical components and the matrix structure has excellent toughness while having ultrahigh strength, the reaming and cold bending properties of the dual-phase steel are effectively improved, and the high-toughness cold-rolled dual-phase steel can be applied as an excellent automobile part. The preparation method of the high-strength and high-toughness cold-rolled dual-phase steel comprises the following step of preparing raw materials according to preset chemical components of the high-strength and high-toughness cold-rolled dual-phase steel. The method is simple, easy to operate and suitable for industrial production.

The invention belongs to the technical field of welding, and discloses a dissimilar metal power modulation galvanometer laser welding method which comprises the following steps: finely cleaning a 6061 aluminum alloy and a 304 stainless steel plate by using acetone, and then airing for more than 20 minutes; the aluminum steel sheet is assembled, pressed and fixed on a welding test platform in a steel-up-aluminum-down mode; the position of the welding test platform is adjusted, argon serves as welding protection gas, and a protection gas nozzle is arranged to be aligned with a welding pool area; laser welding parameters are set, a laser power modulation mode is set to be a gradient power mode, and the gradient power mode is to regulate and control phase point laser power in a circular scanning track in the advancing direction of a welding seam; a welding test is carried out in the mode that a galvanometer laser head is fixed and a welding test platform is moved, and a laser and the welding test platform are synchronously started and stopped; and the protective gas is started 5 seconds before the laser is started, and after the laser is stopped, the protective gas is stopped lagging for 10 seconds so as to continuously protect the welding seam and prevent oxidation.

The invention discloses a method for manufacturing a functionally graded composite material through wire powder composite arc additive manufacturing, which comprises the following steps: firstly, carrying out surface treatment on a base material, enabling the surface of titanium alloy to expose fresh white bright metal luster by adopting a machining mode, and removing surface oil stains by using alcohol and acetone; according to the requirement of materials for the gas atmosphere in the additive manufacturing process, the flexible inert gas cabin is filled with appropriate gas, and the gas atmosphere is kept all the time in the additive manufacturing process. On the basis of the electric arc additive manufacturing technology, electric arc additive manufacturing of the functional gradient metal-based composite material is achieved through a wire powder composite device, and the key technology is that according to different position requirements of parts, the metal-based composite materials with different ceramic particle contents are manufactured in an additive mode; a gradient transition area is manufactured between two areas with large particle content difference, and large stress generated at an interface due to component mutation is reduced.

The invention discloses preparation of a titanium-based composite material continuous core net structure wire material for fuse wire additive manufacturing. Comprising the following steps: taking a titanium belt as an external titanium shell, and taking fine net-shaped titanium-based composite material composite powder as filling powder; and the titanium shell and the filling powder are rolled in a sealed mode, drawing and diameter reducing are conducted, a continuous core net structure wire is formed, and then the in-situ synthesis reinforced titanium-based composite material is prepared through a fuse wire additive manufacturing method. According to the method, the in-situ synthesis reaction of a reinforcement body of the continuous core net structure wire in the melting process is fully played, matrix grains are refined, the organization structure and the size and distribution of the reinforcement body are accurately regulated and controlled, the comprehensive mechanical property of the additive manufacturing titanium-based composite material can be improved, and the method has the advantages of being high in design freedom degree, high in material utilization rate and the like; and a new method is provided for integrated preparation of the difficult-to-deform titanium-based composite material complex component.

The invention relates to the technical field of titanium strip coils, in particular to a preparation method of a high-strength cold-rolled titanium strip coil for coiled tubing, which comprises the following steps: S1, cold rolling: a hot-rolled pickled coil with the thickness of 5.5-6.5 mm is subjected to cold rolling by adopting 20 rollers, and the hot-rolled pickled coil comprises the following components in percentage by mass: 0.26-0.33% of Fe, 0.27-0.33% of O and the balance of Ti; s2, degreasing is conducted, specifically, the titanium strip coil obtained after cold rolling is subjected to degreasing treatment; s3, annealing is conducted, specifically, a vertical bell-type furnace is filled with argon for protection for annealing treatment, furnace cooling is conducted after annealing is completed, and a titanium strip coil with the thickness being 3-4.5 mm for the coiled tubing is obtained; a cold rolling mode is adopted, the thickness of the titanium strip coil is rolled to 3.0-4.5 mm, a bell-type furnace annealing mode is adopted, an oxide layer is prevented from being generated on the surface, the bending performance of the titanium strip is enhanced, cracks are prevented from being formed on the surface during pipe manufacturing, the compressive strength, the yield strength and the ductility of the product are high, and the bending angle (6T) is large.

The present invention discloses a mixed deoxidizer and its application in HDH, belonging to the technical field of inorganic deoxidizers. The components of the mixed deoxidizer are selected from at least three of borides, carbides, hydrides and titanium dichloride, and the deoxidation method is: the mixed deoxidizer and titanium hydride are mixed and kept at 400-850°C for 1-24h; the amount of the mixed deoxidizer does not exceed 0.1% of the mass of high-oxygen titanium hydride. The mixed deoxidizer of the present invention and its application method in HDH can solve the problems of high oxygen content of titanium hydride, powder agglomeration, poor mechanical properties of related molded products, etc., and improve the actual industrial application value of titanium hydride and its processed products.

The invention discloses a manufacturing method of an ultra-large seamless steel pipe with the diameter of 2000 mm, and belongs to the technical field of seamless steel pipe manufacturing in the metallurgical industry. The method comprises the following steps: heating a solid round tube blank, carrying out skew rolling by adopting a micro-expanding process to obtain a pierced billet, manufacturing the pierced billet into a hollow billet with an expanded diameter by utilizing a skew rolling expanding process, further expanding the diameter by using a flattening skew rolling process and simultaneously improving the dimensional precision and the surface quality of the hollow billet, and obtaining a semi-finished steel tube with the diameter of 2000mm by adopting a controlled rolling sizing process. And the semi-finished steel pipe is subjected to heat treatment, flaw detection and finishing procedures to directly obtain the ultra-large seamless steel pipe finished product of 2000 mm According to the method, materials are formed through one-time heating, only pipe blank heating is needed, heat treatment and reheating are not needed, energy is saved, and performance is improved; the on-line structure regulation and control method taking controlled cooling as the core thoroughly turns the passive situation that seamless steel pipes excessively depend on alloying and off-line heat treatment in the past, breaks through the bottleneck of the traditional process, and develops a new process and a new method for high-quality and high-efficiency manufacturing of the steel pipes.

The invention discloses a method for improving the grain size and component uniformity of a solidification structure in the smelting process of a titanium alloy EB furnace through ultrasonic treatment, and belongs to the technical field of titanium alloy smelting. In order to solve the problems of non-uniform cast ingot components, serious grain boundary segregation, coarse structure grains and the like in the existing EB furnace smelting process, the invention provides a method for improving the solidification structure grain size and component uniformity in the titanium alloy EB furnace smelting process through ultrasonic treatment, which comprises the following steps: high-temperature titanium alloy melt flows into a crystallizer for solidification and ingot dummy; after ingot dummy is started, an ultrasonic radiation rod is inserted into a titanium alloy melt molten pool on the upper portion of the crystallizer; and when the cast ingot is close to a solidification end point, removing the ultrasonic radiation rod to obtain the titanium alloy cast ingot. According to the method, the ultrasonic radiation rod is inserted, the insertion depth and the ultrasonic frequency are controlled, and ultrasonic vibration and cavitation are utilized, so that grains of a titanium alloy solidification structure are refined, alloy components are uniform, the machining performance of a titanium cast ingot is improved, and efficient production of the high-quality titanium alloy is achieved.

The invention relates to the technical field of high-speed tool steel, in particular to cobalt-containing high-speed tool steel and a preparation method thereof.The preparation method comprises the following steps that raw materials including, by weight, 55-60 parts of Fe, 2-5 parts of Mo, 2-4 parts of W, 0.5-0.8 part of V, 0.2-0.5 part of Co, 0.1-0.2 part of C and 0.1-0.2 part of rare earth elements are weighed; according to the cobalt-containing high-speed tool steel, through precise control over the content of alloy elements such as C, Mo, W, V and Co, ideal technical indexes of metallographic structures and machining performance are achieved, so that it is guaranteed that after heat treatment, ideal wear resistance and hardness are achieved, the wear resistance, impact resistance and hardness of a product are improved in a balanced and coordinated mode, and the effects of corrosion resistance and cold and heat resistance stability of the product are remarkable.

The invention provides a high-strength pure titanium rod wire and a preparation method thereof, and relates to the technical field of biomedical metal materials, and the preparation method comprises the following steps: preparing materials according to industrial pure titanium components, carrying out vacuum consumable smelting to obtain a titanium ingot blank, and carrying out cogging forging and continuous rolling on the titanium ingot blank to obtain a coiled rod blank; the coiled bar blank is subjected to hot drawing to obtain a pure titanium bar, and the pure titanium bar subjected to hot drawing is sequentially subjected to scaling treatment, heat treatment, cold drawing, sliding block straightening, stress relief annealing and centerless grinding to obtain a finished product of the high-strength pure titanium bar wire. According to the method, the surface reduction rate is controlled through cold drawing, the performance of the rod wire is adjusted through a reasonable heat treatment system, metastable structures in the alloy are obviously deformed and close to each other through cold drawing, the deformation amount of cold drawing is continuously increased, grain boundaries and dendritic grain boundaries are close to each other, the interface distance is gradually reduced, grains and the metastable structures are refined, and the yield of the rod wire is increased. Due to the increase of dislocation density and grain refinement, the yield strength and tensile strength of the cold-drawn pure titanium rod wire are improved.

The invention provides a neodymium iron boron sintered magnet and a preparation method and application thereof. The neodymium iron boron sintered magnet comprises the following components: R, wherein the mass content of R is 28-33wt%; r comprises Nd and Ce, and optionally comprises or does not comprise at least one of Pr, Dy, Tb, Ho and Gd; m, wherein the mass content of the M is 1.5-2.5 wt%; b, the mass content of the B is 0.95 to 1.05 wt%; the mass content of the Ti ranges from 0.1 wt% to 0.25 wt%; fe is the balance; in the neodymium iron boron sintered magnet, the mass content of Ce is 0.3-5 wt%. By accurately controlling the main alloy element components, the generation of a soft magnetic phase in main phase grains is avoided; and meanwhile, the element components of the auxiliary alloy are optimized, and the dosage ratio of the main alloy to the auxiliary alloy is adjusted, so that main phase grains are refined, a fine titanium-rich phase which is dispersed and distributed is formed in a grain boundary phase, and the magnetic performance of the product is improved.

The invention belongs to the technical field of 3-series aluminum alloys, and particularly relates to a 3xxx aluminum alloy and a preparation method and application thereof. By optimizing the content of Mn, Fe and other elements and combining the high-temperature homogenizing annealing process, the aluminum alloy material has high strength and machinability, meanwhile, the size of coarse intermetallic compounds is reduced through high-temperature rolling, distribution is more uniform, grains and textures are refined through the continuous intermediate annealing process, and the yield of the aluminum alloy material is improved. The alloy plasticity is improved, the anisotropy of the plate is reduced, and the battery shell yield is higher. Moreover, high-temperature homogenization and hot continuous rolling are integrated, so that the production time is shortened, and the production efficiency is improved. According to the method, a high-temperature short-time intermediate annealing process is adopted, the grain size in the 3xxx aluminum alloy plate strip is regulated and controlled to be 25-35 microns, the texture proportion of Cube is 2-3.5%, and the texture proportion of Goss is 3-5%, the alloy plasticity is improved, the anisotropy of the plate is reduced, and the surface quality of a battery shell can be effectively improved.

The invention discloses a method for manufacturing a CoCrNi medium-entropy alloy by TiC ceramic powder-enhanced laser additive manufacturing. The method comprises the following steps: S1, selecting CoCrNi alloy powder and TiC ceramic powder with a particle size of (10-60) μm; S2, mixing the CoCrNi and TiC powders by mechanical ball milling, wherein the atomic ratio of the two powders is CoCrNi:TiC=(0.8-1):(0.1-0.2); S3, vacuum drying the mixed powder, and preparing a TiC ceramic powder-enhanced CoCrNi medium-entropy alloy material with fewer defects and excellent performance by using a laser selective melting (SLM) technique; the invention reduces the generation of cracks and pores in the process of additive manufacturing, and reduces the generation of defects inside the printed material; improves the density and Vickers hardness of the CoCrNi medium-entropy alloy, refines the average grain size, etc., and prepares a CoCrNi / TiC medium-entropy alloy with better performance; the invention adds a specific proportion of TiC ceramic powder, which can effectively achieve the effect of refining grains and reducing internal defects.

The invention relates to a preparation method of biphase hard nanoparticle reinforced nodular cast iron applied to lost foam casting. The preparation method comprises the following steps: (1) a synchronous chemical preparation process of TiC-TiB2 biphase hard nanoparticles; and (2) preparing the reinforced nodular cast iron containing the double-phase hard nanoparticles by using an evanescent mode casting process. The preparation method has the advantages that the preparation process is simple, casting equipment and the process are not changed, nano-particles are uniformly dispersed and the like, and the mechanical property and the wear resistance of the obtained nano-particle reinforced nodular cast iron are obviously improved; tiC-TiB2 double-phase hard nanoparticles are added into an evanescent mode model, in the casting process, the nanoparticles gradually enter molten iron along with melting of the model, the nucleation rate of a primary structure of nodular cast iron is effectively increased, grains are refined, and the obdurability of a matrix is improved; the nano-particle reinforced nodular cast iron can be widely applied to the fields of automobiles, mining equipment, ships, infrastructure construction and the like.

The invention relates to a method for forming a GH4169 alloy thin-wall ring piece, which comprises the following steps of: forging two pieces in the height direction in a combined manner, and designing a specific forging drawing, preparing a bar material, manufacturing a blank, rolling, carrying out heat treatment, turning and carrying out flaw detection, for example, designing the small allowance of the outer diameter and the inner diameter of the forging drawing, smelting the bar material in a specific specification by using a triple process, the method has the beneficial effects that the rolling stability is improved, the grain structure is refined, raw materials are saved, the production efficiency is doubled, the flaw detection requirement is met, and the method is suitable for manufacturing related parts in the aerospace field and has wide application prospects and important popularization value.

The invention discloses novel high-strength and high-toughness hot work die steel and a preparation method thereof, and belongs to the technical field of material preparation. The steel comprises the following chemical components in percentage by mass: 0.25%-0.45% of C, 0.35%-0.65% of Si, 0.34%-0.56% of Mn, 0.72%-0.96% of Ni, 2.35%-2.89% of Cr, 2.28%-2.56% of Mo, 0.95%-1.25% of Co, 0.86%-1.26% of V, 0.25%-0.48% of Nb, less than or equal to 0.015% of P, less than or equal to 0.01% of S and the balance of Fe and inevitable impurities. On the basis of the universal hot work die steel, Co is added to improve the high-temperature strength and thermal stability of the die steel, the Cr element is reduced, the tempering resistance of the die steel is improved, and the Mo, V and Nb elements are beneficial to precipitation of secondary carbides in the tempering process so as to improve the obdurability. In the preparation process, film-shaped retained austenite which is distributed in a dispersed mode and is high in mechanical stability is introduced into the structure of the die steel through the quenching partition technology, so that the die steel material has high strength and meanwhile has high toughness, and the die steel material can be used in the working environment with complex working conditions.

The invention provides a method for preparing high-strength low-thermal-expansion invar alloy through laser cladding and the high-strength low-thermal-expansion invar alloy. According to the method for preparing the high-strength low-thermal-expansion invar alloy through laser cladding, in the printing process of each layer, when the invar alloy is printed, a rolling head is utilized to move along the surface of the printed invar alloy in the printing direction, and the rolling head applies certain load pressure to the invar alloy; according to the method, invar alloy grains can be remarkably refined, residual stress distribution in the printing process is improved, the size and number of defects in the printing process are controlled by introducing plastic deformation through in-situ rolling, and the density of a printed component is improved; according to the method, the yield strength of the invar alloy component is greatly improved on the premise that the low thermal expansion coefficient is guaranteed when the invar alloy component is prepared through the laser cladding technology.

The invention relates to the technical field of grinding tools, in particular to a preparation process of a grinding oilstone, silicon nitride and diamond are adopted as raw materials to prepare the grinding oilstone, the silicon nitride has high hardness, high wear resistance and good chemical stability, and the diamond as the hardest substance in the nature has extremely high cutting capacity and wear resistance; silicon nitride and diamond are effectively combined to prepare the composite grinding oilstone, the grinding efficiency of the oilstone can be remarkably improved, the service life of the oilstone can be remarkably prolonged, and compared with an existing mode, the performance during use is improved; meanwhile, by adopting one or at least two of an oil-based binder, a wax-based binder, an oil-wax-based binder and a polyaldehyde binder as the binder, the surface brightness, smoothness, strength and abrasion resistance of the grinding oilstone can be improved, and the problems that in the prior art, the grinding oilstone is poor in performance in actual use, and the grinding oilstone is prone to being damaged are solved in this way. And the surface brightness and smoothness of the oilstone are poor.

The invention discloses a 19-electron NbCoSb thermoelectric material and a preparation method and application thereof, and particularly relates to the field of thermoelectric materials. Comprising the steps that Nb elementary substance powder, Co elementary substance powder and Sb elementary substance powder are placed in a high-energy ball mill to be subjected to mechanical alloying, and nanoscale NbCoSb compound precursor powder is obtained; the ball milling time of the high-energy ball mill is 12-24 hours; the nanoscale NbCoSb compound precursor powder is screened; and putting the screened nanoscale NbCoSb compound precursor powder into a graphite mold, and putting the graphite mold into a discharge plasma sintering furnace for sintering to obtain the N-type NbCoSb thermoelectric material. A large number of multi-scale nano structures and defects are introduced into the precursor, low thermal conductivity can be obtained while the electrical transport property is maintained, and then the high-performance thermoelectric material with good high-temperature stability is obtained.

The invention relates to a die-casting forming method for improving the density of a casting, belongs to the technical field of aluminum alloy casting, and solves the problems of high porosity, low density and low mechanical property of an aluminum alloy thick-wall die casting in the prior art. A die-casting forming method for improving the density of a casting comprises the following steps that firstly, an aluminum alloy metal raw material is added into a preheated smelting furnace, melting and heating are conducted, aluminum alloy liquid is obtained, and a refining modifier is added and stirred; 2, degassing treatment is conducted on the aluminum alloy liquid, and surface scum is removed after standing; 3, a die-casting die is preheated, and a layer of release agent is sprayed on the die-casting die; 4, the molten aluminum alloy is cooled and poured into a pouring gate of the die-casting die, the thickness of the pouring gate is 8-12 mm, and the molten aluminum alloy is slowly injected into a cavity of the die-casting die through an injection punch; and 5, the aluminum alloy die casting is taken out, the die casting is placed in a water tank to be quenched, and the high-density die casting is obtained. And preparation of the high-density aluminum alloy thick-wall die casting is achieved.