218 results about "Non-metallic inclusions" patented technology

The invention belongs to the technical field of metal material preparation, and particularly relates to a high-purity platinum-molybdenum thermocouple wire and a preparation method and application thereof. The preparation method of the high-purity platinum-molybdenum thermocouple wire comprises the following steps: (1) purifying crude platinum step by step to obtain high-purity sponge platinum with the purity not lower than 99.999%; (2) mixing the high-purity platinum powder and the high-purity molybdenum powder according to a formula proportion, and performing cold isostatic pressing to obtain an alloy ingot; (3) the alloy ingot is subjected to vacuum suspension smelting, gas and non-metallic inclusions are removed, and a high-purity, uniform and compact platinum-molybdenum alloy cast ingot is obtained; (4) carrying out sheathing, hot forging and surface milling on the cast ingot to obtain a thermo wire bar; and (5) the bar is subjected to cold rolling, cold drawing and argon shield annealing, and the high-purity platinum-molybdenum thermocouple wire is prepared. The platinum-molybdenum thermocouple wire prepared by the method has the characteristics of high purity, accurate content, stable thermoelectric force, irradiation resistance, long service life and the like, and can meet the performance requirement of accurate temperature measurement in a core irradiation environment in the nuclear power engineering field.

An embodiment of the present invention provides a steel material, for a pressure vessel, comprising, in weight %, 0.06-0.25% of carbon (C), 0.05-0.50% of silicon (Si), 1.0-2.0% of manganese (Mn), 0.005-0.40% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0010% or less of sulfur (S), 0.001-0.03% of niobium (Nb), 0.001-0.03% of vanadium (V), 0.001-0.03% of titanium (Ti), 0.01-0.20% of chromium (Cr), 0.05-0.15% of molybdenum (Mo), 0.01-0.50% of copper (Cu), 0.05-0.50% of nickel (Ni), 0.0005-0.0050% of magnesium (Mg), 0.0005-0.0050% of calcium (Ca), 0.0020% or less of oxygen (O), and the remainder being Fe and other unavoidable impurities. A microstructure comprises in terms of area fraction 30% or less of pearlite and the remainder being ferrite. A non-metallic inclusion contains Mg—Al—Ca—O composite oxide.

The invention relates to a smelting method of ultra-low carbon automobile steel capable of reducing carbon emission, which comprises the following steps of: carrying out converter blowing on semi-steel obtained by mixing electric furnace molten steel accounting for 30wt%-70wt% of the total amount and blast furnace molten iron accounting for 70wt%-30wt% of the total amount, and the converter blowing comprises the steps of molten iron pretreatment, converter smelting, LF (ladle furnace) refining, RH (relative humidity) operation and continuous casting. The method has the beneficial effects that (1) the mixed semisteel of the electric furnace molten steel and the blast furnace molten iron is adopted for converter blowing, so that a heat source required by converter smelting is ensured, and carbon emission generated in the blowing process can be effectively reduced; 2) the semisteel process reduces the carbon content of the material entering the converter, and effectively reduces the discharge amount of oxycarbide; and (3) the non-metallic inclusions and the performance of the finished product meet the requirements of ultra-low carbon automobile steel products.

The invention provides a method for detecting nonmetallic inclusions in steel, which comprises the following steps: placing a steel material in ethanol, cleaning with an ultrasonic cleaner, and drying to obtain steel to be detected; acquiring a detection surface of the steel to be detected; according to the method, the SEM is adopted to observe the morphology of the non-metallic inclusions on the detection surface, the sizes of the non-metallic inclusions are measured and counted, and the EDS is adopted to detect the components of the non-metallic inclusions, so that accurate positioning and qualitative analysis of the non-metallic inclusions can be realized, and the accuracy of the detection result is improved.

The invention discloses a method for analyzing nonmetallic inclusions in steel based on machine learning and pattern recognition, and relates to the technical field of metal material analys.The method comprises the steps that production samples of typical steel grades in all production stages are obtained, and component data and image data of the inclusions are obtained; preprocessing the component data, and constructing an inclusion component data set; preprocessing the image data, and constructing an inclusion image data set; dividing the data set to form a training set and a test set; training the analysis model through the training set, and testing the analysis model through the test set; and inputting the image data of the inclusions of the to-be-tested sample into the analysis model to obtain the inclusion component data of the to-be-tested sample. Through the machine learning and image recognition technology, automatic recognition and classification of the non-metallic inclusions in the steel can be achieved, the automation degree is high, and the judgment error caused by manual operation is reduced.

The invention provides steel for a 120ksi steel-grade sulfur-resistant oil well pipe, a production method of the steel, the sulfur-resistant oil well pipe, a heat treatment method and application of the sulfur-resistant oil well pipe. The steel comprises the following components: 0.60-0.80% of Cr, 0.80-1.00% of Mo, 0.050-0.100% of Nb, 0.015-0.035% of Al, 0.10-0.20% of V, 0.25-0.30% of C, 0.15-0.35% of Si, 0.50-0.70% of Mn, less than or equal to 0.010% of P, less than or equal to 0.0015% of S and the balance of Fe and other inevitable impurities. Compared with the prior art, the medium-carbon micro-alloying components, the pure steel smelting technology and the heat treatment technology are matched, dispersed and refined second phase structures are distributed on a tempered sorbite matrix in the room temperature state, the total series of non-metallic inclusions is lower than 1.0 level, and the product has good obdurability and excellent hydrogen sulfide corrosion resistance.

A method for characterizing a population of non-metallic inclusions (24) in a finished or semi-finished part (10) comprising a metal alloy, such as steel. The method comprises the steps of cutting and polishing the finished or semi-finished part (10) to provide an inspection plane (20) and scanning at least one control area (22) constituting at least a portion of the inspection plane (20). The method further comprises the steps of automatically counting the non-metallic inclusions within the at least one control region (22) using an automatic optical microscope and image analysis software and measuring or determining at least one morphological parameter, such as area and / or length and / or width and / or aspect ratio, and the position of the non-metallic inclusions within the at least one control region (22), therefore, measurement data is generated. The method further comprises the step of processing the measurement data using an extreme value analysis (EVA) or generalized Pareto distribution (GPD) analysis technique to characterize the population of non-metallic inclusions (24) in the finished or semi-finished part (10).

The invention relates to a steel H12 module for a die and a manufacturing method of the steel H12 module, the steel H12 module is obtained on the basis of an H12 material in the mode that low Cr, low Si and high Mo are adopted and Ni and Co alloys are added, the material comprises the following chemical components in percentage by mass: 0.30-0.34% of C, less than or equal to 0.20% of Si, less than or equal to 0.20% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, less than or equal to 0.30% of Cr, 3.05-3.15% of Mo, 1.10-1.30% of W, 2.00-2.30% of Ni, 0.70-0.90% of Co, 0.010-0.025% of Al and the balance of Fe, and the method mainly comprises the following steps that H12 molten the molten steel is poured into an ingot in a die casting mode, demolding is carried out, heating, forging forming and annealing are carried out after cleaning and hot delivery are carried out, finally, quality inspection is carried out on an annealed forge piece, a process route of upsetting, drawing-forging to a finished product through an oil press is adopted in forging, the center porosity can reach 1.5 levels or below, and the general porosity is smaller than or equal to 2.0 levels; ingot segregation and dot segregation are avoided; and the sum of non-metallic inclusions can be less than or equal to 3.0 grade.

The invention discloses a steel bar for an automobile compressor rotor and a production and preparation method of the steel bar. The steel bar is prepared from, by mass, 0.31%-0.36% of C, 0.20%-0.35% of Si, 0.42%-0.60% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.010% of S, 1.02%-1.20% of Cr, smaller than or equal to 0.25% of Ni, 0.21%-0.28% of Mo, 0.11%-0.18% of V, smaller than or equal to 0.15% of Cu and the balance iron and inevitable impurities. The process route comprises electric furnace smelting, LF furnace refining, VD refining, continuous casting, heating furnace heating, rolling and heat preservation. The steel bar for the automobile compressor rotor is produced through the electric furnace + LF + RH + continuous casting smelting process and the rolling process, the production specification is phi 120 mm, the mechanical property requirement is met, and the steel purity is guaranteed; the mechanical property and the impact property are ensured by reasonable component design and production process; the macrostructure, non-metallic inclusions and mechanical properties of the finished steel meet the requirements of high-end products.

The invention relates to the technical field of steel production, in particular to rare earth weather-proof angle steel and a manufacturing method thereof, and the manufacturing method comprises the steps of converter / electric furnace steelmaking, LF refining, non-metallic inclusion modification treatment, continuous casting and hot rolling. During steelmaking, the temperature of molten iron entering a furnace is not less than 1250 DEG C, and S is not more than The steel-making end point is controlled to be 0.04%-0.07% of C and 0.005%-0.015% of P; after refining is finished, a Si-Ca wire or a Ca wire is fed for non-metallic inclusion modification treatment, and Ca / Al in molten steel reaches 0.08-0.12; during continuous casting, 0.10-0.16 kg of rare earth elements are added into each ton of steel by adopting a method of feeding rare earth wires into a crystallizer, and the carbon content in the steel is 0.07%-0.14%; and selecting continuous casting crystallizer casting powder matched with the steel grade. By adding La or / and Ce and combining specific operation condition control, the rare earth weather-proof angle steel with a good anti-corrosion effect is obtained.

The invention belongs to the technical field of bar production, and particularly relates to a production method of a steel bar for a heavy-load automobile half axle, and the steel bar comprises the following chemical components in percentage by mass: 0.39-0.42% of C, 0.25-0.35% of Si, 1.45-1.70% of Mn, less than or equal to 0.013% of P, less than or equal to 0.006% of S, less than or equal to 0.25% of Cr, less than or equal to 0.25% of Ni, 0.15-0.20% of Mo, 0.06-0.10% of V, less than or equal to 0.15% of Cu and the balance of Fe and inevitable impurities. The method has the advantages that high-performance, high-purity and low-cost production of the steel bar for the heavy-duty automobile half shaft is realized through green short-process production of'ecological electric furnace + LF + RH + continuous casting 'in combination with low-carbon component design and a controlled rolling and controlled cooling process. And macrostructures and non-metallic inclusions of the finished steel meet the requirements of high-end products.

The invention relates to the field of high-silicon stainless steel materials, and particularly discloses UNS S32615 high-silicon stainless steel and a medium-frequency smelting preparation method thereof. The UNS S32615 high-silicon stainless steel comprises the following chemical components in percentage by mass: 0.02%-0.03% of C, 5.6%-5.8% of Si, 1.5%-1.8% of Mn, less than or equal to 0.02% of P, less than or equal to 0.005% of S, 17.0%-17.5% of Cr, 20.8%-21.8% of Ni, 0.4%-0.6% of Mo, 1.6%-1.8% of Cu and the balance of Fe and inevitable impurities, and the content of ferrite is controlled to be below 2%. The high-frequency smelting preparation method comprises the following six steps: proportioning according to a formula, charging and melting, melting down, precipitating and deoxidizing, slagging off and making new slag, alloying and diffusing and deoxidizing, and casting molten steel. By optimizing the alloy component design and reasonably controlling the smelting process, ferrite precipitation and the content of non-metallic inclusions are reduced, the purity and the corrosion resistance of the steel are remarkably improved, meanwhile, the hot working performance and the yield of the UNS S32615 high-silicon stainless steel are improved, and the UNS S32615 high-silicon stainless steel has wide application prospects.

The invention belongs to the technical field of analysis and detection of steel and iron materials, and particularly relates to a method for continuously detecting non-metallic inclusions in steel samples with different heights by utilizing OTS. Comprising the following steps: sequentially preparing a compensating plate, screening a deviation sample group, performing height compensation on a metallographic sample in the deviation sample group by using the compensating plate, and performing sample detection on the compensated deviation sample group. According to the invention, the metallographic sample with large height deviation can be continuously detected, on one hand, continuous work of the electron microscope can be realized without guarding and manpower is saved, on the other hand, an emitter of the electron microscope can be saved, continuous work of the emitter after detection of one sample is avoided, the cost is saved, and the detection efficiency is improved. Therefore, the working efficiency of detecting the non-metallic inclusions by using the OTS full-automatic analysis system for the non-metallic inclusions in the steel is improved.

The invention provides an electrolyte composition, an electrochemical in-situ etching method of non-metallic inclusions for heavy rail steel and application of the electrochemical in-situ etching method. The electrolyte composition comprises the following components in parts by weight: 1.6 to 2.3 parts of lithium chloride, 10 to 13.5 parts of acetylacetone, 45 to 84 parts of methanol and 2 to 43 parts of a reagent A, the reagent A is a mixed aqueous solution of ethylenediamine tetraacetic acid and sodium citrate. The lithium chloride, the acetylacetone, the methanol and the reagent A in specific parts are matched for use, the obtained electrolyte composition is used for in-situ electrochemical etching of the heavy rail steel, and three-dimensional in-situ etching of the non-metallic inclusions in the heavy rail steel can be successfully achieved. The in-situ information of the non-metallic inclusions in the hypereutectoid heavy rail steel is reserved, and the three-dimensional morphology of the non-metallic inclusions can be presented more comprehensively.

The invention discloses a method for evaluating the machinability of sulfur-containing free-cutting steel. The method comprises the following steps: (1) testing the hardness of a section; (2) assigning hardness test data; (3) grade evaluation of sulfide inclusions; and (4) comprehensive assignment calculation is conducted, specifically, the product of the hardness absolute value grade assignment, the hardness standard deviation grade assignment and the sulfide inclusion grade assignment serves as the comprehensive assignment, the turning performance of the materials is sequenced according to the comprehensive assignment, and the smaller the comprehensive assignment is, the easier machining is. According to the evaluation method disclosed by the invention, before the sulfur-containing free-cutting cold-drawing bar is cut, the machinability of the bar is visually evaluated by detecting the hardness, the uniformity of the hardness and the distribution pattern of non-metallic inclusions and through assignment calculation, so that bar processing enterprises can be helped to estimate the processing efficiency and calculate the cost, and the processing efficiency of the bars is improved. And a guiding effect is achieved on enterprise production and operation.

According to the smelting method, a medium-frequency induction furnace is adopted for smelting, and nitrogen control, white slag making and soft blowing processes are carried out in a heat preservation smelting step; in the nitrogen control process, nitrogen nitride ferrochrome is added to serve as a nitrogen increasing agent for first nitrogen increasing, the nitrogen adding amount is increased according to the upper limit during nitrogen increasing, bottom blowing nitrogen serves as a protective atmosphere, and the nitrogen increasing time is controlled to range from 15 min to 20 min; in the white slag making process, after nitrogen is increased for the first time, 10-25 kg of small lime and 5-15 kg of fluorite are supplemented according to the slag amount for slagging, and 1-3 kg of aluminum particles and 2-15 kg of low-aluminum silicon iron are added for diffusion deoxidation. According to the method, a medium-frequency induction furnace is adopted as smelting equipment, the nitrogen control process is operated in a temperature interval under the nitrogen bottom blowing condition, [N] in molten steel is accurately controlled through boiling nitrogen increasing and slag layer covering, [O] and non-metallic inclusions in the molten steel are adsorbed through white slag making, the alloying rate is controlled through time, and the oxygen adsorption capacity is reduced.

This invention provides a high-end vacuum argon-oxygen refining apparatus (VODC furnace) for special metal materials and its refining method, belonging to the technical field of metallurgical refining equipment. It solves the problems of complex structure and high manufacturing and production costs associated with existing VOD furnace vacuum systems. This invention separates the vacuum system from the blowing system through modular design, employs a movable vacuum sealing structure and optimized furnace design, achieving a significant reduction in equipment and production costs. The refining method, by controlling the vacuum degree, oxygen blowing parameters, and stirring intensity, reduces non-metallic inclusions in the steel, achieving a hydrogen content of less than 1.5 × 10⁻⁶. ‑6 Oxygen content less than 2.0 × 10 ‑5 The chromium recovery rate in stainless steel reaches 98%-99%, and the refined steel possesses superior properties. Production efficiency is significantly improved while ensuring product quality. Compared with traditional equipment, this invention reduces equipment investment costs by more than 30%, shortens the refining cycle by 25%, and reduces energy consumption by 20%, making it particularly suitable for small-batch, multi-variety production of high-end specialty metal materials.

The invention relates to a method for purifying molten iron in a furnace based on a decomposable foaming sand core, and belongs to the technical field of foundry metallurgy. According to the method, an alkaline phenolic resin sand core internally provided with sodium bicarbonate is adopted, and the alkaline phenolic resin sand core extends into the position, 100-200 mm away from the bottom, in the furnace through a special clamp in the molten iron standing stage. Sodium bicarbonate in the sand core is slowly decomposed at high temperature to release a large number of microbubbles, and non-metallic inclusions in molten iron are effectively captured and brought out in the floating process. Deep and uniform purification of the molten iron is achieved through a slow-release foaming mechanism, the purity of the molten iron and the casting quality are remarkably improved, and the method has the advantages of being easy and convenient to operate, low in cost and free of additional equipment and is particularly suitable for the production process of cast iron smelting in an intermediate frequency furnace.

The present application relates to a kind of steel rail steel hydrogen content prediction and control method, belong to steel metallurgy steelmaking method technical field.The technical scheme of the present application is: collecting steelmaking whole process smelting process data, non-metallic inclusion inspection data and environmental state data;Data is preprocessed, constructs characteristic variable, especially introduces "inclusion hydrogen trap index" quantification microstructure to the influence of hydrogen behavior;Based on metallurgical thermodynamics and data regression analysis, establish specific hydrogen content prediction formula model;Real-time prediction of molten steel hydrogen content is carried out using the model, and the RH vacuum refining process parameters and casting blank slow cooling strategy are dynamically adjusted according to the prediction result.The beneficial effects of the present application are: by fusing macro smelting parameters and micro inclusion characteristics, the correlation mechanism between non-metallic inclusions and hydrogen content is quantified using specific calculation formula, accurate prediction and low-cost control of hydrogen content are realized, and the problems of high cost and strong hysteresis of existing technology are solved.

The invention discloses a production process of high-efficiency low-inclusion large-specification steel for a wind power main shaft bearing ring, and belongs to the technical field of steel for wind power bearings. According to the process, a CaO-SiO-AlO-MgO quaternary refining slag system is adopted, so that the inclusion adsorption efficiency and the slag system stability are improved; a crystallizer, a secondary cooling zone and tail end three-stage electromagnetic stirring are adopted, and the casting blank with the ultra-large specification of phi 800-1200 mm is adapted; eAF-CONARC short-process smelting is integrated, and energy consumption and residual element fluctuation are reduced; and a segmented slow cooling process is adopted, and hydrogen diffusion and stress release are enhanced. The casting blank produced through the method is compact in macrostructure (the center porosity is smaller than or equal to 1.0 grade), the non-metallic inclusion grade is smaller than or equal to 0.5 grade, the molten steel O is smaller than or equal to 0.0007%, the H is smaller than or equal to 0.00005%, the smelting period is shortened by 16.7%, the energy consumption per ton of steel is reduced by 13.3%, and the mechanical property and the hardening layer depth after hardening and tempering meet the requirements of the ultra-large-specification wind power main shaft bearing ring.

The present invention belongs to the technical field of alloy steel, and relates to a large-size medium-carbon bainite non-quenched and tempered steel for direct cutting processing and a production process thereof. The composition is: C 0.35-0.45%, Si 0.3-1.0%, Mn 1.5-2.0%, P≤0.012%, S≤0.006%, Cr 0.6-1.2%, V 0.04-0.2%, Nb 0.01-0.03%, Mo 0.15-0.2%, B 0.0005-0.00015%, Al 0.02-0.04%, Ti 0.015-0.025%, Ni 0.1-0.2%, O≤15ppm, N 110-180ppm, with the balance being Fe and unavoidable impurities. By combining optimized composition and process, the present invention achieves good control of non-metallic inclusions and macrostructure, with yield strength all above 750 MPa, demonstrating broad application prospects.

The invention discloses a smelting method for producing steel for cord using pure scrap steel in an electric furnace, comprising scrap steel sorting, electric furnace primary smelting, deoxidation alloying, LF refining, argon blowing and continuous casting. Compared with the traditional blast furnace → converter (or electric furnace) → LF refining → continuous casting process, the smelting method for producing steel for cord using pure scrap steel in an electric furnace adopts an aluminum-free deoxidation process and a low-basicity slag desulfurization process, combined with a specific deoxidizer, etc., to effectively control residual elements, non-metallic inclusions and center segregation on the material in the steel, and is economical to realize mass production and meet the use requirements of downstream industries.

[Problem] To provide a method for manufacturing a compression-processed product in which the size of gaps formed between non-metal inclusions and a matrix included in a steel material is appropriately controlled in consideration of a deformation phenomenon occurring in the non-metal inclusions and the matrix in compression processing. [Solution] A method for manufacturing a compression-processed product in which a steel material containing non-metal inclusions is subjected to multiple iterations of compression processing, wherein the rolling reduction rate for the steel material in each of the multiple iterations of the compression processing is set to within a range not greater than an upper limit rolling reduction rate, the upper-limit rolling reduction rate corresponding to a target gap area ratio in relationship information derived in advance from the relationship between the rolling reduction rate in a compression process performed on a target steel containing non-metal inclusions and the gap area ratio of gaps formed between the non-metal inclusions and a matrix by the compression process, the target gap area ratio being the target value of the gap area ratio after completion of the plurality of compression processes performed on the steel.

The invention discloses an electroslag smelting method of low-Si low-Al B-containing heat-resistant stainless steel. According to the electroslag smelting method, the qualification rate of head and tail components of a steel ingot of an electric furnace casting rod after electroslag remelting reaches 100% through a quaternary slag system, and the sum of a fine system and a coarse system of non-metallic inclusions meets the requirement of not higher than grade 3; the thermal stress and phase change stress cracking of the steel ingot is prevented through stress relief annealing of the steel ingot, the tensile stress generated due to thermal expansion and cold contraction in the cooling process of the steel ingot and the phase change stress generated due to structural transformation are eliminated through the low-temperature annealing process, the steel ingot is prevented from cracking during long-time storage or saw cutting, many defects in the prior art are overcome, and the quality of the steel ingot is improved. The method has a remarkable industrial application prospect.

The present invention relates to an Fe-Ni alloy consisting of C: 0.001 to 0.2 mass%, Si: 0.001 to 0.2 mass%, Mn: 0.005 to 0.7 mass%, Ni: 30.0 to 45.0 mass%, Cr: 0.3 mass% or less, Al: 0.001 to 0.1 mass%, Ti: 0.001 to 0.020 mass%, O: 0.007 mass% or less, Mg: 0.0030 mass% or less, N: 0.010 mass% or less, Ca: 0.0015 mass% or less, Na: 0.00005 to 0.001 mass%, the balance being Fe and unavoidable impurities, wherein non-metallic inclusions containing CaO-SiO2-Al2O3-MgO-MnO-Na2O-based complex oxides as essential components, and further containing one or more non-metallic inclusions of CaO, MgO, MgO·Al2O3, MnO·SiO2, and Na2O as optional components, wherein the number ratio of CaO-SiO2-Al2O3-MgO-MnO-Na2O inclusions is 40% or more in all non-metallic inclusions, thereby producing an Fe-Ni alloy having excellent surface properties.

This invention discloses a medium carbon steel for steering screws in new energy vehicles and its production method. The chemical composition of the medium carbon steel, by mass percentage, is as follows: C: 0.45%~0.70%, Si: 0.25%~0.55%, Mn: 0.45%~1.05%, Cr: ≤0.40%, Mo≤0.40%, Ni≤0.40%, P≤0.035%, S: 0.015%~0.035%, O≤0.0012%, with the balance being Fe and unavoidable impurities. The production method includes a complete process: molten iron pretreatment – ​​converter smelting – LF refining – RH furnace vacuum degassing – continuous casting – rolling – quenching and tempering – finishing – sub-critical quenching – low-temperature tempering. By controlling the composition to reduce the addition of expensive alloying elements, and through a composite heat treatment of "quenching and tempering + sub-critical quenching + low-temperature tempering," a hardness gradient of ≥60HRC on the surface and 22~28HRC in the core is achieved, with no decarburized layer on the surface. Simultaneously, strict control of non-metallic inclusions enhances the purity of the steel. This invention's product is compatible with cyclone milling processes, exhibits minimal quenching deformation, and can be straightened, meeting the high precision and long service life requirements of steering screws in new energy vehicles.

To provide a method for evaluating inclusions to enlarge an observation surface in a test piece, thereby enabling accurate measurement of the size and the type of nonmetallic inclusions that cause fatigue fracture in a desired steel material in a short time and at low cost.SOLUTION: A method for evaluating an inclusion evaluation includes: performing a tensile test on a test piece obtained by introducing hydrogen into a precursor metal piece having an internal hardness of more than 400 HV and a surface hardness of 250-400 HV, to cause fracture originating from a nonmetallic inclusion affected by the introduced hydrogen, and measuring the size and / or identifying the type of the nonmetallic inclusion acting as the fracture origin.SELECTED DRAWING: Figure 1

The utility model discloses an anti-blocking rod for continuous casting, which comprises a stopper rod body (1) and a stopper rod head (2), and is characterized in that a variable-diameter transition area (3) of which the diameter is suddenly reduced is arranged between the stopper rod body (1) and the stopper rod head (2), and the maximum diameter of the stopper rod head (2) can be reduced to 88%-92% of the diameter of the stopper rod body (1) by the variable-diameter transition area (3). According to the stopper rod, the obvious reducing transition area of which the diameter is suddenly reduced is arranged between the stopper rod body and the stopper rod head, so that the inflow angle of molten steel can be locally changed, and non-metallic inclusions in the molten steel can be effectively prevented from being deposited on the stopper rod head, so that the anti-blocking effect is achieved, the continuous casting flow control is improved, and the service life of the stopper rod is prolonged. Irregular oscillation or rod punching caused by inclusion deposition of the stopper rod is reduced, and finally the quality of a continuous casting steel billet is improved.

The application belongs to the technical field of liquid metal purification, and provides a CaO-ZrO2 porous ceramic filter and a preparation method and application thereof. The application obtains a preform by impregnating a reticular porous template in slurry A and drying; sprays slurry B on the preform to obtain an embryo, and obtains the CaO-ZrO2 porous ceramic filter after calcination. The application adopts a template replication method-air spraying-in-situ sintering technology, and has the advantages of simple preparation process and low cost. The slurry B is attached to the surface of the zirconia hole rib through the air spraying process on the preform, defects are filled, and the CaO-ZrO2 composite hole rib is constructed. The composite hole rib improves the mechanical properties, thermal shock resistance and non-metallic inclusion adsorption efficiency in the molten metal liquid. The application can be used in the molten metal filtering environment of 1600 DEG C to 1800 DEG C.

The invention discloses a composite material ceramic filter screen for casting and a photocuring 3D printing preparation method. Ansys Fluent fluid dynamics software is used, modeling analysis is conducted on the flowing state of molten metal liquid flowing through the filter screen in the pouring process, and the optimal filter screen design is obtained. The photocuring 3D printing silicon oxide ceramic filter screen comprises the following components in percentage by mass: 65-80% of silicon oxide powder, 10% of magnesium oxide powder, 2-8% of a dispersing agent, 1-3% of a photoinitiator, 9-15% of photosensitive resin and 1% of an anti-settling agent. According to the method, a porous polyurethane plastic carrier is not needed, the filter screen ceramic biscuit is directly obtained by using the silicon oxide slurry and the silicon oxide and magnesium oxide composite slurry in a photocuring 3D printing mode, and then the finished silicon oxide ceramic filter screen is obtained through degreasing and high-temperature sintering. According to the method, it is guaranteed that the product has meshes which are completely consistent in size and shape, the structural strength is high, and the product is not prone to being damaged, large-size inclusions in molten metal are physically screened through the meshes, non-metallic inclusions (such as AlO, SiO and sulfide) are actively captured through the reaction of magnesium oxide and the inclusions, and through the double means of physical interception and chemical capture, the content of impurities in the molten metal is greatly improved. The filtering performance is effectively ensured. In the production process of the product, ceramic chips without structural support are not generated, so that the production process link is simplified, and meanwhile, the emission of toxic and harmful waste materials is reduced.