597 results about "Austenite grain" patented technology

Provided is a steel sheet which is characterized by having a specific chemical composition, wherein: the metal structure contains, in terms of percentage by area, 90.0% or more of martensite and 3.0% or less of retained austenite; the average grain size of the prior austenite grains is 30.0 μm or less; the standard deviation of the grain size of the prior austenite grains is less than 4.0 μm; and the standard deviation of the dislocation density at seven positions corresponding to 5%, 10%, 15%, 20%, 25%, 30%, and 50% of the entire width of the steel sheet from an end in the width direction to the center in the width direction at a position corresponding to 1 / 4 the sheet thickness is 1.50 × 1015 / m2 or less. Also provided is a method for producing the steel sheet.

The invention discloses fine-grain high-cleanliness steel for a harmonic reducer flexible gear of an industrial robot and a preparation method, and belongs to the technical field of metallurgy. The steel for the flexible gear comprises the following chemical components in percentage by mass: 0.38 to 0.42 percent of C, 0.20 to 0.30 percent of Si, 0.60 to 0.90 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, 0.60 to 0.90 percent of Cr, 0.15 to 0.25 percent of Mo, 1.50 to 1.80 percent of Ni, 0.015 to 0.035 percent of Nb, less than or equal to 0.0006 percent of O and the balance of iron and inevitable impurity elements. The production method comprises the working procedures of vacuum induction furnace smelting, electroslag remelting, casting blank forging, bar heating, bar rolling and rolled material cooling. The steel for the flexible gear has fine austenite grains and high cleanliness, and the technical requirements of the steel for the harmonic reducer flexible gear of the industrial robot are met.

The invention relates to high-performance low-cost microalloyed steel for an automobile I-shaped front axle and a preparation method of the microalloyed steel, and belongs to the technical field of materials. The steel comprises the following chemical components in percentage by weight: 0.20 to 0.60 percent of C, 0.2 to 1.0 percent of Mn, 0.1 to 0.5 percent of Si, 0.6 to 1.2 percent of Cr, 0.01 to 0.10 percent of Nb, 0.01 to 0.06 percent of Mo and the balance of Plt, 0.01%, Slt; 0.01%, Olt; 0.0040%, and the balance being iron. According to the invention, the contents of Nb and C key alloy elements in the material are accurately controlled, so that Nb can be completely dissolved into a matrix in the smelting process, and the phenomenon of one-time NbC liquation is avoided. Heat treatment is directly carried out after smelting and casting, and the component control strategy is adopted, so that the precipitation of nano-sized dispersed NbC on an original austenite grain boundary is promoted, austenite grains are effectively pinned, and a microstructure with uniform and fine grain size is obtained; a martensitic structure is obtained through quenching, and uniform dispersion and precipitation of NbC carbide are realized in the martensitic structure through a subsequent tempering process, so that the strength and the toughness of the I-shaped front axle are ensured to reach the best match.

The invention discloses a high-carbon high-alloy grinding ball steel rolling internal damage control method, and belongs to the technical field of metal material rolling machining. Comprising the following steps that high-carbon high-alloy grinding ball steel billets are subjected to high-temperature diffusion homogenization treatment and then subjected to staged temperature control rolling, the initial rolling temperature in the blooming stage is 1020-1080 DEG C, the single-pass reduction rate is 6-10%, the pass interval is larger than or equal to 20 seconds, the total reduction rate is 40-80%, and the core peak temperature is controlled to be smaller than or equal to 1150 DEG C; the finish rolling temperature is 800-850 DEG C; during rolling, atomized water is sprayed for dynamic cooling every 2-3 passes, and two-stage cooling (water cooling to 600-650 DEG C at 15-20 DEG C / s, and slow cooling to room temperature) is carried out after final rolling. According to the method, element diffusion, temperature rise inhibition and structure refinement are synergistically regulated and controlled, so that the core void ratio is reduced, the austenite grain size is larger than or equal to 8 grades, a uniform bainite and dispersed carbide composite structure is obtained, and the anti-fatigue performance of the grinding ball steel is remarkably improved.

The invention relates to an austenite structure display and grain size rating method, and belongs to the technical field of hot continuous rolling finishing mill production methods. According to the technical scheme, the method comprises the steps that an eroded sample is manufactured, and an austenite structure display graph is obtained; carrying out deep learning network training and grain boundary processing to obtain a boundary skeleton diagram; and grading the grain size by adopting a straight line intercept point method. The method has the beneficial effects that the Inconel 625 austenite structure with a uniform erosion surface and a clear and complete austenite grain boundary can be obtained, grain size rating is carried out on the austenite structure image through a deep learning algorithm, and compared with manual rating, the efficiency and accuracy of grain size rating are greatly improved.

The invention provides a stainless steel sheet with grain size and martensite phase double gradient distribution and a preparation method thereof, and the stainless steel sheet comprises the following composition elements in percentage by mass: 18-22 wt% of Cr, 7-9 wt% of Ni, 0.8-1.5 wt% of Mn, 0.4-1.2 wt% of Si, and the balance of Fe and inevitable impurities, the austenite grain size and the martensite grain size in the microstructure of the prepared stainless steel sheet are in gradient distribution from the center to the edge, the martensite phase content is in gradient distribution from the edge to the center, and the preparation method of the stainless steel sheet with double gradient distribution comprises induction melting, axial cold rolling treatment and heat treatment. According to the stainless steel sheet, the yield strength and hardness of the material are remarkably improved, meanwhile, high plasticity is kept, the method is simple and efficient, and industrial large-scale application can be achieved.

The present disclosure provides a steel material having high yield strength and excellent fracture toughness in a low-temperature sour environment. The steel material according to the present disclosure has a chemical composition as described in the specification and has a yield strength σ YS The Mo content in the vicinity of the prior austenite grain boundary in the steel is 758 MPa or more. Mo The steel material according to the present disclosure further has a yield strength σ YS When the value of Fn1 defined by the formula (1) is less than 862 MPa, the yield strength σ YS is 862 MPa or more, Fn1 defined by formula (1) satisfies −520 or more. Fn1 = 83 × (γ Mo -10 -7 ×√ρ)-σ YS (1) Here, γ in equation (1) Mo is substituted with the Mo content in the vicinity of the prior austenite grain boundary in mass%, and ρ in equation (1) is the dislocation density m -2 and σ in Eq. (1) YS is substituted for the yield strength in MPa.

The invention relates to high-performance low-cost microalloyed steel for an automobile I-shaped axle and a preparation method of the microalloyed steel, and belongs to the technical field of materials. The steel comprises the following chemical components in percentage by weight: 0.35%-0.50% of C, 0.50%-0.60% of Mn, 0.1%-0.5% of Si, 0.65%-0.85% of Cr, 0.01%-0.10% of Ti, 0.03%-0.04% of Mo, Plt and the balance of Fe and inevitable impurities. 0.01%, Slt; 0.01%, Olt; 0.0040%, Nlt; 0.0050%, and the balance being iron. Heat treatment is directly carried out after casting, and by adopting the component control, dispersion precipitation of nano-sized TiC on an original austenite grain boundary is promoted, austenite grains are effectively pinned, and a microstructure with uniform and fine grain size is obtained; a martensite structure is obtained through quenching, uniform dispersion and precipitation of TiC carbides are achieved in the martensite structure through a subsequent tempering process, and it is guaranteed that the mechanical strength and toughness of the automobile I-shaped axle are optimally matched.

The invention relates to the technical field of metallurgy, in particular to a hot galvanizing low-alloy high-strength steel plate which comprises the following chemical components in percentage by mass: 0.06%-0.08% of C, 0.20%-0.25% of Si, 1.20%-1.35% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.020%-0.060% of Alt, 0.035%-0.050% of Nb, 0.010%-0.020% of Ti, less than or equal to 0.0050% of O, less than or equal to 0.0060% of N and the balance of Fe and inevitable impurities. The contents of C, Si and Mn in the chemical components are controlled, the welding performance of the hot-dip galvanizing low-alloy high-strength steel and the surface quality of a finished product are considered, Nb microalloying is mainly adopted, a proper amount of microalloy element Ti is added to form TiN, austenite grain coarsening is limited in the slab heating and heat preservation process, and fine and dispersed precipitated phases are finally obtained in combination with process control; the hot-dip galvanized low-alloy high-strength steel finished product is good in structure form and excellent in comprehensive performance.

The invention discloses a heat treatment method for optimizing a gear steel structure and refining grains, and belongs to the technical field of heat treatment process control. The method is particularly suitable for a production scene of cold forging gear parts such as three pin shafts; according to the method, a pre-normalizing or annealing heat treatment process with specific parameters is added after cold forging forming and before carburizing, so that an AlN precipitated phase in the steel forms segregation again at a grain boundary, the grain boundary is effectively pinned, and austenite grain growth is inhibited, and therefore the phenomenon of mixed crystals is avoided, the structure is refined, and the fatigue performance is improved. Experiments prove that after normalizing pretreatment at the temperature of 900 DEG C or above or annealing pretreatment at the temperature of 720 DEG C is adopted, the original cold forging mixed crystal area with the grain size of 0-4 grade can be increased to 7 grade or above, grains are uniform and compact, and the structure property is remarkably improved. The process parameters are clear, the flow is controllable, and the method is suitable for optimization and application of the batch gear steel heat treatment process.

The invention discloses a method for measuring the original austenite grain size of medium carbon steel. The method comprises the following steps: heating a medium carbon steel sample to a temperature above an original austenitizing temperature, and keeping the temperature for a period of time to precipitate carbides from an original austenite grain boundary; cutting and embedding the heat-treated medium carbon steel sample to prepare a medium carbon steel metallographic sample; carrying out grinding and fine polishing treatment on the medium carbon steel metallographic sample, and carrying out ultrasonic cleaning on the medium carbon steel metallographic sample in alcohol; immersing and corroding for a certain time by using nitric acid alcohol, then cleaning the surface of the medium carbon steel metallographic sample by using alcohol, and drying until an austenite grain boundary is clearly displayed; completing microscopic image rating; and calculating the austenite grain grade by adopting an intercept point method. According to the method, the original austenite grain boundary can be clearly displayed, and the effective size of the original austenite grain size of the medium carbon steel can be rapidly and accurately obtained.

Provide a steel material having high strength and excellent hydrogen embrittlement resistance characteristics. The steel material according to the present disclosure has a chemical composition in mass %, C: 0.25 to 0.30%, Si: 0.10 to 0.50%, Mn: 0.05 to 0.60%, P: 0.050% or less, S: 0.0100% or less, Al: 0.001 to 0.100%, Cr: 0.50 to 1.50%, Mo: 0.80 to 2.00%, Ti: 0.002 to 0.010%, V: 0.08 to 0.30%, Nb: 0.010 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0100% or less, O: 0.0100% or less, and the balance consisting of Fe and impurities, a tensile strength of 900 to 1100 MPa, an original austenite grain size of 20.0 μm or less, and a dislocation density of 7.0×10 14 m -2 or less, and the Q value obtained from the line profile of X-ray diffraction is 2.35 or more.

The invention relates to the technical field of metallurgy, in particular to a production method for reducing casting blank cracks, which comprises the following procedures: (1) pre-desulfurizing molten iron; (2) smelting in a converter; (3) LF refining; (4) RH refining; (5) slab continuous casting; and (6) hot charging and rolling. By optimizing the chemical components and the mass percentage of the continuous casting billet and regulating and controlling the technological parameters of multiple procedures such as converter smelting, LF refining, RH refining, slab continuous casting and hot charging rolling, the austenite grain size in the microstructure of the surface layer of the continuous casting billet is refined, the high-temperature plasticity of the continuous casting billet is improved, and cracks on the surface of the continuous casting billet are reduced.

The invention relates to the technical field of metallographic microstructure detection, and discloses a method for displaying the austenite grain size of a martensitic structure in stainless steel, which comprises the following steps: S1, sample preparation: cutting, grinding and polishing a stainless steel sample until no macroscopic scratch exists on the surface; s2, preparing an electrolyte: mixing 50%-70% of nitric acid and 30%-50% of deionized water to form a basic solution, and adding 3ml-7ml of phosphoric acid and 1ml-5ml of sulfuric acid into every 100ml of the basic solution; and S3, assembling an electrolysis device: a sample clamp made of martensitic stainless steel is adopted as an anode, austenitic stainless steel is adopted as a cathode, and the soaking area of the cathode is not less than 1500mm. By optimizing the electrolyte formula and process parameters, the original austenite grain size of the martensitic structure in the stainless steel can be clearly displayed. The method solves the problem of unclear display of the stainless steel grain boundary in a traditional method, is not only suitable for martensitic stainless steel, but also suitable for precipitation hardening type stainless steel, and has high universality and applicability.

A high strength steel sheet having 1180 MPa or higher tensile strength and a method for manufacturing the same are disclosed. The high strength steel sheet has a specific chemical composition and is such that in a region at ¼ sheet thickness, the area fraction of martensite is 80% or more, the volume fraction of retained austenite is 3% or more and 15% or less, the area fraction of the total of ferrite and bainitic ferrite is 10% or less, the average grain size of prior austenite is 20 μm or less, and the average of the proportions of packets having the largest area in prior austenite grains is 70% by area or less of the prior austenite grain.

This component is formed from a steel plate which has a predetermined chemical composition and in which, in a region extending from a depth of 1 / 8 the plate thickness from a surface to a depth of 3 / 8 the plate thickness from the surface, prior-austenite grains have an average aspect ratio of 3.00-5.50, the areal proportion of bainite is 70-95%, and the areal proportion of martensite is 5-30%, wherein the ratio of the total amount of Ti and Nb analyzed as electroextraction residues at a depth of 1 / 60 the plate thickness from the surface to the total amount of Ti and Nb analyzed as electroextraction residues at a depth of 1 / 4 the plate thickness from the surface is 1.5 or greater.

The invention provides a method for eliminating delta ferrite in austenitic stainless steel and the austenitic stainless steel, and belongs to the technical field of metal materials. The method comprises the following steps that an austenitic stainless steel ingot containing the delta ferrite is subjected to heat preservation for first set time at the first set temperature for first heat treatment; heating the austenitic stainless steel ingot subjected to the first heat treatment to a second set temperature, and carrying out heat preservation for a second set time at the second set temperature for second heat treatment; and cooling the austenitic stainless steel ingot subjected to the second heat treatment, or sequentially and repeatedly carrying out the first heat treatment and the second heat treatment on the austenitic stainless steel ingot subjected to the second heat treatment for at least one time, and then cooling to obtain the austenitic stainless steel subjected to delta ferrite elimination. The first heat treatment and the second heat treatment are performed, and the second set time is limited, so that the austenitic stainless steel is prevented from being in a high-temperature environment for a long time, and austenite grains are prevented from obviously growing.

The invention relates to a display agent of SA-508Gr. 3 steel for nuclear power and application of the display agent, and relates to the technical field of metallographic detection. The developer is composed of sodium chloride and a solvent. By means of the display agent, a clear and complete complex structure of tempered martensite and / or tempered bainite structure of SA-508Gr.3 steel and an austenite grain boundary can be obtained through an electrolytic method, and the austenite grain size evaluation result is real and effective.

Provided is a hot-rolled steel sheet by which excellent LME resistance can be achieved. A hot-rolled steel sheet according to the present disclosure contains, in terms of mass%, 0.030-0.110% C, 0.01-0.50% Si, 0.50-1.50% Mn, 0.025% or less P, 0.010% or less S, 0.010-0.070% Al, 0.0070% or less N, 0.055-0.200% Ti, 0.030-0.150% Nb, 0.0010-0.0050% B, 0-0.20% V, and 0-1.00% Cr, with the remainder consisting of Fe and impurities. The area ratio of bainitic ferrite is 85% or greater, and in a surface layer region from the surface of the hot-rolled steel sheet to a depth position of 0.2 mm in the sheet thickness direction, the total length of the prior austenite grain boundary in which BO2 - is detected by time-of-flight secondary ion mass spectrometry is 1.20-5.00 mm per 100 μm × 100 μm, and the B segregation degree at the prior austenite grain boundary is 40 or greater.

The present invention provides an Fe-Cr-Ni alloy material which has high strength and decreased strength anisotropy. An Fe-Cr-Ni alloy material according to the present disclosure contains, in mass%, 0.030% or less of C, 0.01-1.00% of Si, 0.01-2.00% of Mn, 0.040% or less of P, 0.0050% or less of S, 0.01-0.50% of Al, 28.0-36.5% of Ni, 19.0-27.5% of Cr, 2.00-6.00% of Mo, 0.01-3.00% of Cu, not less than 0.010% but less than 0.220% of N, 0.01-2.00% of Co, and 0.010% or less of O, with the balance being made up of Fe and impurities. In the microstructure, the standard deviation of the crystal grain size number of the austenite grains is 0.60 or less, and the tensile yield strength is 758 MPa or more.

A coated steel sheet and press hardened steel part having a composition including, by weight percent: C 0.15-0.25%, Mn 0.5-1.8%, Si 0.1-1.25%, Al 0.01-0.1%, Cr 0.1-1.0%, Ti 0.01-0.1%, B 0.001-0.004%, P≤0.020%, S≤0.010%, N≤0.010% the remainder of the composition being iron and unavoidable impurities resulting from the smelting. The press hardened steel part includes a bulk having a microstructure including, in surface fraction, more than 95% of martensite and less than 5% of bainite, a coating layer at the surface of the steel part, a ferritic interdiffusion layer between the coating layer and the bulk, and a ratio between the ferritic grain width in the interdiffusion layer GWint over prior austenite grain size in the bulk PAGSbulk, satisfying following equation (GWint / PAGSbulk)−1≥30%.

The present invention provides a thick, fatigue-resistant, easily weldable, high-strength steel plate for wind power generation and a preparation method thereof. The steel plate comprises the following chemical composition by mass: C: 0.12% to 0.15%, Si: 0.15% to 0.35%, Mn: 1.30% to 1.50%, P ≤ 0.015%, S ≤ 0.005%, Nb: 0.015% to 0.030%, V: 0.015% to 0.030%, Ti: 0.005% to 0.020%, Al: 0.005% to 0.030%, with the remainder being Fe and unavoidable impurities. The preparation method comprises the steps of smelting, refining, continuous casting, heating, and rolling. The use of a low-C, high-Mn, Nb+V+Ti composite microalloying significantly inhibits austenite grain growth. The use of a normalizing rolling process results in a short process flow, low cost, and strong production line adaptability.

The invention discloses an ultrahigh-strength suspension spring steel wire for a new energy automobile and a preparation method of the ultrahigh-strength suspension spring steel wire. The ultrahigh-strength suspension spring steel wire comprises the following chemical components in percentage by mass: 0.58%-0.66% of C, 1.6%-2.0% of Si, 0.4%-0.8% of Mn, 0.8%-1% of Cr, 0.10%-0.30% of V, 0.05%-0.15% of Mo, 0.01%-0.06% of Nb, 0.001%-0.003% of B, less than or equal to 0.02% of P and less than or equal to 0.02% of S. The V / Mo / Nb / B multi-element synergistic addition is adopted, so that the hardenability of the steel wire is remarkably improved, and meanwhile, a precipitated phase is formed to inhibit the growth of austenite grains. After the induction heating quenching and tempering process is adopted, the tensile strength of the ultrahigh-strength suspension spring steel wire is 2050-2150 MPa, the percentage reduction of area is larger than 40%, and the suspension spring steel wire not only can meet the high strength of a coarse-specification suspension spring steel wire for a new energy automobile, but also has the advantages of being high in steel wire product precision, high in coil spring yield and the like.

The invention provides a rolling method of cathode flat steel, which comprises the following steps: firstly, heating a casting blank to obtain a heated blank, then carrying out surface descaling on the heated blank, and carrying out multi-pass rough rolling to obtain an intermediate blank; the heating treatment comprises a preheating section and a soaking section; the heating treatment is specifically a heating treatment process for controlling the austenite grain size of the casting blank; the multi-pass rough rolling comprises multi-pass rough rolling of which the reduction rate is sequentially reduced; and carrying out multi-pass finish rolling on the intermediate billet obtained in the previous step, carrying out on-line cooling, and then carrying out stacking slow cooling to obtain the rolled and formed cathode flat steel. According to the method, directional improvement of the conductivity of the electrolytic aluminum cathode flat steel is achieved through rolling process optimization, heating under a rolling path of a low-temperature ferrite area and rolling pass reduction distribution design are focused, the ferrite grain size and the conductive texture of a material are cooperatively regulated, the normal conductivity of the cathode flat steel is improved, and the conductivity of the cathode flat steel is improved. And a core material support is provided for reducing ineffective current loss in the electrolytic aluminum industry.

The invention belongs to the technical field of ultralow-temperature materials, and discloses high-strength and high-plasticity steel for an ultralow-temperature environment and a preparation method of the high-strength and high-plasticity steel. A high-manganese and high-nitrogen component system is adopted, based on the austenite stabilization theory, low-cost manganese replaces expensive nickel to achieve austenite stabilization, and a high-manganese stable-phase and high-nitrogen reinforced synergistic mechanism is formed through the promotion effect of manganese and chromium on nitrogen solubility. The structure uniformity is guaranteed by strictly controlling the heating and finish forging temperature in the forging stage, sufficient solid solution of manganese and nitrogen is promoted through homogenization treatment before hot rolling, the finish rolling temperature is precisely controlled by adopting a controlled rolling process so as to retain high-proportion deformed austenite grains, the material strength is further improved, the cost of each ton of alloy is reduced by 75% or above, and meanwhile, the product quality is improved. The performance of the ultralow-temperature material is improved in a leap-over mode, and the excellent strength and plasticity matching that the yield strength is larger than or equal to 1600 MPa, the tensile strength is larger than or equal to 1900 MPa and the ductility is larger than or equal to 20% at the temperature of-269 DEG C is obtained.

Steel part having a chemical composition comprising, by weight %, 0.18 ≤ C ≤ 0.27, 0.18 ≤ Si ≤ 0.30, 1.0 ≤ Mn ≤ 1.5, 0.14 ≤ Cr ≤ 0.25, 0.02 ≤ Al ≤ 0.06, 0.02 ≤ Ti ≤ 0.06, 0.0020 ≤ B ≤ 0.0040, 0 ≤ S ≤ 0.008, 0 ≤ N ≤ 0.020, the remainder of the composition being iron and unavoidable impurities resulting from the elaboration process, having a microstructure comprising, in surface fraction, 95% or more of martensite and a prior austenite grain skin refinement ratio equal to or above 1.2, said ratio being defined as PAGS_B / PAGS_S, wherein PAGS_B is the average prior austenite grain diameter in the bulk (3) expressed in µm and PAGS_S is the average prior austenite grain diameter in the skin (2), also expressed in µm.

The invention provides welding wire steel for welding ultralow-temperature high manganese steel, a welding wire, a preparation method of the welding wire and a welding method. The welding wire steel for welding the ultralow-temperature high manganese steel comprises the following components in percentage by mass: 0.05 to 0.1 percent of C; 0.5 to 0.6 percent of Si; 24% to 25% of Mn; p is less than or equal to 0.01%; s is less than or equal to 0.01%; 0.05% to 0.1% of Al; 0.12 to 0.2 percent of Ni; 0.02% to 0.06% of N; 0.08% to 0.15% of Ti; v, 0.08% to 0.15%; 0.08% to 0.15% of Nb; 0.05% to 0.1% of Mo; and the balance of Fe and inevitable impurities. The welding wire composition design is optimized, only a small amount of Ni element is added, W and other high-melting-point elements are not added, and a small amount of C, N, Ti, V, Nb and other alloy elements are transited to a welding seam through the welding wire, so that nitride, carbide and other pinning grain boundaries are formed in the welding seam at the high temperature, austenite grain growth is effectively prevented, the austenite grain size is reduced, and the low-temperature impact toughness of the welding seam is improved; in addition, a small amount of Si element is transited to the welding seam through the welding wire, molten pool fluidity is improved, slag floating is promoted, and slag inclusion of the welding seam is avoided.

Provided is a hot-rolled steel sheet that exhibits excellent LME resistance. The hot-rolled steel sheet according to the present disclosure contains, in mass%, 0.030-0.110% of C, 0.01-0.50% of Si, 0.50-1.50% of Mn, 0.025% or less of P, 0.010% or less of S, 0.010-0.070% of Al, 0.0070% or less of N, 0.055-0.200% of Ti, 0.020-0.100% of W, 0.0010-0.0050% of B, and the balance being Fe with impurities. In the microstructure, the area ratio of bainitic ferrite is 85% or more. In a surface layer region from the surface of the hot-rolled steel sheet to a depth of 0.2 mm in the sheet thickness direction, the total length of the old austenite grain boundary in which BO2 - is detected by the time-of-flight secondary ion mass spectrometry is 0.80-5.00 mm per 100 μm x 100 μm. The B segregation degree at the old austenite grain boundary is 80 or more.

The present invention provides a heavy-gauge, fatigue-resistant, easy-to-weld, and high-strength steel plate for wind power and a manufacturing method therefor. The steel plate is composed of the following chemical components in percentage by mass: C: 0.12%-0.15%, Si: 0.15%-0.35%, Mn: 1.30%-1.50%, P≤0.015%, S≤0.005%, Nb: 0.015%-0.030%, V: 0.015%-0.030%, Ti: 0.005%-0.020%, and Al: 0.005%-0.030%, with the balance being Fe and unavoidable impurities. The manufacturing method comprises the steps of smelting, refining, continuous casting, heating, rolling and the like. Low-C and high-Mn Nb+V+Ti composite microalloying is used to significantly inhibit the growth of austenite grains; and a normalizing rolling process is used, so that the process flow is short, the cost is low, and the production line adaptability is strong.

The invention relates to a corrosive agent and a corrosion method for displaying a 32CrNi3MoVE crystal boundary of alloy steel, which are characterized in that a common chemical product is used as an electrolytic corrosive agent after being simply proportioned, and the 32CrNi3MoVE steel quenched and tempered state original austenite crystal boundary is clearly displayed by a proper corrosion method. Chemical reagents used by the corrosive are economical and applicable, the corrosive is composed of alum, oxalic acid, dishwashing liquid, distilled water and the like which are existing in a laboratory, the proportioning of the corrosive is the key, the electrolytic corrosion method is simple to operate, alum can effectively display the grain boundary, oxalic acid provides a weak acid environment for oxidation reduction, and the corrosion effect is good. The dishwashing liquid slows down the corrosion rate of weak acid electrolyte to a metallographic specimen, weakens structure display, and improves the definition of crystal boundary display. The corroded sample is lightly polished in a polishing machine, and the corrosive agent ratio and the electrolytic corrosion method are combined to form an efficient novel corrosion method. The traditional corrosive agent capable of completely replacing saturated picric acid and a proper amount of detergent and the corrosion method effectively solve the problem of 32CrNi 3MoVE steel quenched and tempered state original austenite grain boundary display.