191 results about "Martensitic microstructure" patented technology

The invention discloses a preparation method of a heterogeneous-heterogeneous double structure of a high-strength copper / steel composite board, which comprises the following steps: realizing metallurgical bonding between copper and steel heterogeneous metals through the synergistic effect of a laser energy field and a rolling force, and promoting formation of a martensite structure near a composite interface; then, the surface of the steel side is subjected to online heat treatment through a flat-topped laser beam, and the purposes that the outer surface layer structure of the steel side is completely converted into martensite, the martensite structure at a bonding interface is converted into tempered sorbite, the residual stress of the copper side is reduced, and a heterogeneous structure with the grain size in gradient distribution is formed on the copper side are synchronously achieved; the tensile strength, the interface bonding strength and the toughness of the copper-steel composite plate are synergistically improved.

The invention belongs to the technical field of bearing manufacturing, and particularly relates to a quenching and tempering heat treatment method for a large heavy-duty bearing ring piece, which is suitable for quenching and tempering heat treatment of a thick large-section ring piece. And the thick and large-section ferrule ring piece is heated to the quenching temperature in a segmented and stepped mode, the ferrule ring piece is hoisted to a circulating water pool to be subjected to water cooling after heat preservation is completed, cooling is conducted till the surface temperature of the ring piece is lower than 100 DEG C, and the quenched ferrule ring piece is timely charged into a furnace to be tempered twice. The surface of the ferrule ring subjected to quenching and tempering heat treatment is free of cracks, the deformation degree is small, a martensite structure with the full cross section quenched thoroughly can be obtained, and the uniformity of the surface layer, the core structure and the performance of the ferrule ring with the thick and large cross section can be greatly improved. In addition, the quenching and tempering heat treatment process is simple to operate, and the consistency of the performance of the ferrule ring pieces in all batches is easily ensured. The method is not limited to a process of a large heavy-duty bearing ring piece, is also very suitable for thermal refining of other large forgings, and solves the defect problems of non-uniform structure, unstable performance and the like.

The invention relates to the technical field of additive manufacturing, in particular to a direct aging treatment process of an SLM molded Ti-6Al-4V alloy and a product thereof, and the direct aging treatment process comprises the following steps: firstly, manufacturing a Ti-6Al-4V alloy sample by adopting an SLM technology, and then putting the SLM molded Ti-6Al-4V alloy sample into a vacuum heat treatment furnace for direct aging treatment, and finally, taking out the sample after furnace cooling or air cooling. According to the method, through direct aging treatment, a natural alpha'martensite structure in the Ti-6Al-4V alloy formed through SLM is decomposed into an alpha + beta double-phase structure, the front solid solution-quenching process in traditional solid solution aging treatment is not needed, and the purposes of optimizing structure uniformity and improving plasticity are achieved. The aging treatment cost and the quenching risk of the SLM titanium alloy are reduced, and the plasticity of the SLM titanium alloy can be remarkably improved while high strength is kept. The method is simple in process, low in cost and suitable for large-scale industrial application.

The invention discloses a processing method of a high-toughness stainless steel / carbon steel composite plate, which comprises the following steps: compounding a high-strength carbon steel plate and a stainless steel plate through a rolling compounding process under the action of laser-assisted heating; then, the stainless steel / carbon steel composite sheet is subjected to temperature control type online periodic laser surface annealing treatment, so that a corrosion-resistant structure with a non-uniform structure in which coarse grains (a soft region) and fine grains (a hard region) are alternately arranged can be obtained on the stainless steel surface layer, and the corrosion resistance of the composite plate is improved; and meanwhile, the stress relief effect induced by laser surface annealing treatment is combined with high-temperature tempering softening of a martensitic structure on the carbon steel side part at the interface, and a heterogeneous structure induced by laser surface annealing treatment can synchronously improve the obdurability of the stainless steel / carbon steel composite plate.

The invention provides a novel underwater wet welding flux-cored wire and a preparation method thereof. The flux-cored wire comprises a metal sheath and a flux core, the flux core is prepared by sintering a flux core base material and a flux core additive; the flux core base material comprises the following raw materials in percentage by mass: 20-40% of rutile, 15-35% of fluoride, 2-7% of titanate, 3-10% of aluminum powder, 5-15% of manganese powder and 10-15% of composite nano metal oxide; the composite nano metal oxide at least comprises the following raw materials: nano aluminum oxide, nano zirconium dioxide, nano yttrium oxide, nano cerium oxide and nano lanthanum oxide; and the flux-cored additive is linear aliphatic epoxy resin. The specific mixed nano metal oxide powder is added into the flux-cored wire, grain refinement is achieved, a quenched martensite structure is reduced, the mechanical property of a weld joint is improved, meanwhile, the specific epoxy resin and the flux-cored base material are mixed, filled and sintered, a proper amount of carbon element is introduced while all raw material components of the flux-cored wire are dispersed uniformly and stably, and the welding quality of the flux-cored wire is improved. And metal is prevented from being oxidized in the welding process.

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.

The invention relates to a high-toughness corrosion-resistant titanium alloy, which comprises the following chemical components in percentage by weight: 1.2-2.8% of Ni; 5.0 to 7.0 parts of Al; 3.0 to 7.0 parts of Cu; 3.0 to 5.0 parts of V; 0.3 to 0.7 part of Si; 0.15 to 0.35 part of O; and the balance of Ti. The invention relates to a preparation method of a high-toughness corrosion-resistant titanium alloy. The preparation method sequentially meets the following steps and content requirements: smelting an ingot by adopting a consumable electrode vacuum furnace; the forging blank is subjected to heat preservation for 1-3 hours at the temperature of 1000 DEG C or above, and then quenching is conducted to obtain a full- Elements of Cu, Si, Ni and O are added, so that the width of the martensite lath after refining and quenching is realized; performing hot rolling to obtain a nano ultra-fine grain structure; and after solid solution treatment, quenching is conducted, and the high-toughness corrosion-resistant titanium alloy is obtained. According to the method, the equipment requirement is low, and the strength of the titanium alloy is greatly improved under the condition that the plasticity and toughness of the material are not reduced; and the composite material has excellent comprehensive mechanical properties and can be widely applied to many important fields such as aerospace, biomedical treatment, petrochemical engineering, automobile industry and ocean engineering.

The invention provides 1700MPa-grade hot-formed steel with high cold bending performance and a preparation method and application thereof. The surface layer of the hot-formed steel has a soft-phase ferrite structure, the secondary surface layer of the hot-formed steel has a mixed structure of soft-phase ferrite and martensite, and the core layer of the hot-formed steel has a carbon-poor martensite structure. The preparation method comprises any one or a combination of at least two of the following conditions: (A) the coiling temperature after hot rolling is 650-700 DEG C; (B) the pickling speed is less than or equal to 150m / min; (C) the continuous annealing temperature is 780-830 DEG C; (D) the atmosphere in the furnace is mixed gas of nitrogen and hydrogen; and (E) the dew point temperature is-35 DEG C to-17 DEG C. Through fine component design and process integration, the contradiction between the strength and the toughness of the material is successfully solved, double guarantee of high strength and high toughness is achieved, meanwhile, the requirement for light weight is met, and the competitiveness of an existing product is improved.

The invention discloses a heat treatment process for improving the obdurability of die steel, and belongs to the technical field of metal heat treatment. The invention relates to a heat treatment process for improving the toughness of die steel, which adopts a die steel material with a specific component proportion, and the die steel material comprises carbon, chromium, molybdenum, vanadium, tungsten, nickel, niobium, niobium carbide and trace boron element. By sequentially implementing austenitizing, quenching, deformation heat treatment, multi-stage subzero treatment, pulsed magnetic field assisted tempering, gradient surface hardening and nano-precipitation regulation treatment, the hardness and toughness of the die steel are remarkably improved. Particularly, through the synergistic effect of multiple advanced heat treatment means, the martensite structure is effectively refined, carbide precipitation is strengthened, the surface hardness and the core toughness are improved, the comprehensive performance of toughness and toughness is achieved, and the method is suitable for the field of high-performance injection molds and hot-working molds.

The invention relates to a high-strength complex-phase hot-rolled wire rod for a 2160MPa-grade stranded wire and a manufacturing method of the high-strength complex-phase hot-rolled wire rod, after high-carbon components containing trace Nb are rolled and spun into a wire rod, the wire rod is subjected to online molten salt micro-quenching isothermal treatment, so that the wire rod is firstly subjected to front-section molten salt treatment and enters a bainite phase region from an austenite state, part of the austenite is promoted to be converted into bainite, and then the high-strength complex-phase hot-rolled wire rod is obtained. The method comprises the following steps: carrying out high-temperature tempering on the residual austenite, carrying out post-section molten salt treatment, increasing the molten salt temperature, promoting the unconverted residual austenite to be decomposed and converted into sorbite, carrying out isothermal tempering, and finally carrying out roller way slow cooling to prepare the hot-rolled wire rod of which the microscopic structure comprises a complex-phase structure consisting of tempered bainite, ferrite and tempered sorbite, so that network carbides and martensite structures can be inhibited, and the tensile strength of the hot-rolled wire rod is improved. And the structure type and toughness are regulated and controlled on line, the tensile strength is 1472-1505MPa, the percentage reduction of area is 31%-36%, the work hardening rate and the production efficiency of the hot-rolled wire rod are improved, and the production energy consumption is reduced, so that a high-strength grade stranded wire is obtained.

The invention discloses martensite ultrahigh-strength steel and a preparation method thereof, and belongs to the technical field of steel and iron materials. The martensite ultrahigh-strength steel comprises the following chemical components in percentage by mass: 0.2 to 0.3 percent of C, 0.5 to 2 percent of Mn, 0.5 to 1.5 percent of Si, 6 to 10 percent of Ni, 1.5 to 2 percent of Al, 1 to 3 percent of Mo, 0.5 to 1 percent of Cr, 0.5 to 1 percent of W, 0.05 to 0.2 percent of V and the balance of Fe and inevitable impurity elements. By combining component design and a cyclic thermal mechanical treatment process, a nano-sized spherical precipitated phase and a band-shaped precipitated phase are introduced into a martensite lath at the same time, the dislocation storage density of a martensite structure in the deformation process is further improved, the tensile yield strength breaks through 2.4 GPa, the tensile strength reaches 2.5 GPa or above, and the tensile strength reaches 2.5 GPa or above. And good elongation at break is maintained, so that the alloy has excellent comprehensive mechanical properties.

The invention discloses a microalloyed high-toughness martensitic stainless steel cutter head as well as a preparation method and a preparation mold thereof. Stainless steel comprises the following components in percentage by weight: 0.3%-0.7% of C, 0.3%-1.0% of Si, 0.5%-1.5% of Mn, 16%-18.5% of Cr, 1%-2% of Ni, 0.3%-0.8% of Mo, 0.1%-0.35% of V, 0.1%-0.25% of Nb, less than or equal to 0.02% of S, less than or equal to 0.02% of P and the balance of Fe. Firstly, raw materials are smelted into molten iron; then adding a deoxidizing agent and precoated sand into the molten iron for molding, and performing sand mold casting and pouring to obtain a cutterhead blank; carrying out heat treatment on the cutter head blank; and finally, shot blasting and polishing are conducted on the cutterhead subjected to heat treatment. The martensitic stainless steel cutterhead has a metallographic structure which takes a martensitic structure as a main structure, takes austenite as an auxiliary structure and dispersedly distributes CrC, VC and NbC particles, the hardness of the martensitic stainless steel cutterhead is 40-45 HRC, the impact toughness of the martensitic stainless steel cutterhead reaches 92-95 J / cm < 2 >, the abrasion resistance of the cutterhead is longer, the service life of the cutterhead is longer, and the abrasion loss of the martensitic stainless steel cutterhead is reduced by 70% compared with a cutterhead without alloy elements.

The invention relates to a 1450MPa-grade high-strength tool steel wire rod and a manufacturing method thereof.The method includes the steps that after Nb-V chemical component design rolling and spinning are conducted to form a wire rod, online molten salt phase change regulation and control quenching isothermal treatment is conducted, the wire rod is controlled to be cooled from a high-temperature austenite state at the front-section molten salt at the cooling speed larger than or equal to 36 DEG C / s, part of austenite is promoted to be converted into a martensite structure, and then the temperature of molten salt is reduced from the high-temperature austenite state at the cooling speed larger than or equal to 36 DEG C / s; the method comprises the following steps: heating to a sorbite phase region through a rear-section molten salt, promoting the transformation of austenite residues to a sorbite structure, carrying out isothermal tempering toughening destressing treatment on the structure, and finally carrying out roller way slow cooling to prepare the wire rod with a microscopic structure comprising isothermal sorbite and tempered martensite, so that the strength and plasticity matching of the wire rod can be improved, the tensile strength is 1410-1460 MPa, and the tensile strength is 410-460 MPa. The percentage reduction of area is 37%-42%, additional heat treatment is avoided after cold machining forming, tool steel parts are directly machined, the production energy consumption and cost of the high-strength tool steel are reduced, and the production efficiency is improved.

To provide a highly durable wear-resistant component.SOLUTION: A crawler link 7, which is a wear-resistant component, comprises: a high-hardness part 7A that is composed of steel having a specific component composition, has a hardness of 57-60 HRC, and has a martensite structure; and a low-hardness part 7B that is a region other than the high-hardness part 7A, has a lower hardness than the high-hardness part 7A, and has a martensite structure. The high-hardness part 7A includes: a parent phase composed of martensite; and carbides 92 dispersed in a lath of the parent phase. The area ratio of the carbides 92 in the cross section of the high-hardness part 7A is at least 9%.SELECTED DRAWING: Figure 3

The invention discloses a production method of low-yield-ratio high-toughness 780MPa-grade steel for bridges. The steel comprises the following chemical components in percentage by mass: 0.05-0.06% of C, 0.1-0.2% of Si, 1.30-1.40% of Mn, less than or equal to 0.006% of P, less than or equal to 0.002% of S, 0.015-0.025% of Nb, less than or equal to 0.008% of Ti, 0.02-0.05% of AlT, 0.4-0.5% of Cr, 0.5-0.6% of Ni, 0.5-0.6% of Cu, 0.2-0.3% of Mo, 0.0035-0.0040% of B, less than or equal to 30PPM and the balance of Fe and inevitable impurities, the carbon equivalent Ceq is less than or equal to 0.50%, and the crack sensitivity index Pcm is less than or equal to 0.23%. The process comprises the following steps: the heating temperature of a plate blank is 1120-1150 DEG C, two-stage rolling is adopted, and the finish rolling temperature of finish rolling is in a two-phase region range of 840-880 DEG C; and then DQ online quenching is conducted to 260-300 DEG C, tempering heat treatment is conducted at 500 DEG C, and the low-yield-ratio and high-toughness 780 MPa grade bridge steel of a lath bainite and martensite structure is obtained.

The invention discloses a preparation method of medium and low carbon chromium manganese martensite cast steel. The preparation method comprises the following steps: step 1, preparing raw materials; 2, high-temperature smelting; step 3, deoxidizing and desulfurizing; step 4, casting molding; step 5, annealing treatment; step 6, quenching treatment; step 7, tempering treatment; step 8, surface treatment; according to the invention, the medium-low carbon martensitic cast steel is designed, and the hardness and toughness of the martensitic cast steel are balanced by controlling the content of carbon in the cast steel, so that the problem of lower toughness of the martensitic cast steel under high carbon is avoided; meanwhile, the phenomenon that carbon elements are combined with chromium elements to be dispersed and separated out from grain boundaries or martensite laths in a carbide mode is reduced in cooperation with a heat treatment process, the corrosion resistance of the martensite cast steel is improved, meanwhile, the heat treatment process more suitable for medium and low carbon chromium manganese martensite cast steel is matched, various properties are further balanced, internal stress is eliminated, and the corrosion resistance of the martensite cast steel is improved. And the martensite structure is more uniform and stable.

The invention relates to a method for improving high-temperature thermal stability of ferrite martensite steel and application, and relates to the technical field of nuclear structural materials.The method specifically comprises the following steps that an alloy steel ingot is sequentially subjected to forging, rolling, rolling, quenching and air cooling, and an alloy blank with a ferrite martensite structure is obtained; sequentially carrying out austenitizing at 1020-1080 DEG C, quenching, tempering at 700-750 DEG C and air cooling on the alloy blank so as to maintain a ferrite martensite structure in the alloy blank and increase the concentration of solute elements in the alloy blank; and finally, the alloy blank subjected to secondary heat treatment is subjected to severe plastic deformation processing treatment. According to the method, good plasticity can be maintained while the high-temperature tensile strength of the ferritic martensitic steel is improved, the high-temperature thermal stability is improved, and the application prospect of the ferritic martensitic steel in nuclear structural materials is improved.

The invention belongs to the technical field of metal processing technologies, and particularly relates to a gradient heat treatment steel strengthening and toughening technology optimization method which comprises the steps that a cooling tank is arranged, a vertical channel is formed in the inner side face of the cooling tank and communicates with a liquid layer in the cooling tank and the outer portion of the cooling tank, and quenching liquid is added into the cooling tank till the vertical channel is submerged; a proper amount of quenching oil is added, so that the quenching liquid and the quenching oil are layered, and a lower liquid layer and an upper oil layer are formed respectively; gradient heating is conducted on a target area of the workpiece in a local heating mode, and austenitizing is achieved; after the workpiece is austenitized, subarea gradient cooling is conducted, the workpiece is put into a cooling tank, quenching oil wraps the workpiece through an oil layer and continues to penetrate into a liquid layer, the surface layer of the workpiece reaches the martensite transformation termination temperature, and austenite is transformed into a martensite structure; the influence of a steam film generated when quenching liquid is used for quenching on the machining stability and the machining quality of a workpiece can be reduced.

The invention relates to a high-strength large-size structural part and a forming and manufacturing method thereof, and belongs to the technical field of forming and manufacturing of high-strength structural parts. The forming manufacturing method comprises the following steps: heating a steel plate to austenitizing temperature for heat preservation; the steel plate is discharged out of the furnace after heat preservation and cooled to the pressing temperature; pressing and forming by adopting a press, keeping the pressure for a certain time and then moving out of the mold; and cooling a formed part to room temperature to obtain the high-strength large-size structural part. A martensite structure with high tensile strength and good low-temperature toughness is obtained by controlling a heating treatment procedure and a pressing procedure of temperature-controlled forming and matching with a steel plate of a specific component system; the tensile strength is 1700 MPa or above, and the impact toughness at-40 DEG C is 35 J or above.

The invention discloses 3GPa ultrahigh-strength corrosion-resistant rigging steel, which comprises the following chemical components in percentage by weight: 0.6-1.0 percent of C, 0.6-1.0 percent of C, 0.2-1.0 percent of Cr, 0.2-1.0 percent of Mo, 0.2-1.0 percent of Mo 2.2 to 3.8 parts of Al; 0.3 to 1.1 parts of Mo; and the balance of Fe. The preparation method of the 3GPa ultrahigh-strength corrosion-resistant rigging steel meets the following requirements that the initial structure of a hot-rolled blank is a full-martensite structure, multi-pass hot rolling is conducted on the structure in an (alpha + gamma) two-phase region at the temperature of 800-880 DEG C, and an ultra-fine grain structure is obtained. According to the rigging steel provided by the invention, equipment, a mold and a preparation process are greatly simplified; the strength and corrosion resistance of the rigging steel are greatly improved. The ultrahigh-strength corrosion-resistant rigging steel provided by the invention can be applied to a plurality of important fields of cables for ships, long-span bridge cables, cables for heavy cranes and the like.

The invention belongs to the technical field of heat treatment, and particularly relates to a wind power planet wheel carburizing and quenching process, which comprises the following steps: carrying out temperature equalization treatment twice before carburizing, carrying out strong carburizing once and diffusion treatment twice in a carburizing stage, quickly cooling to a high return temperature, carrying out temperature equalization, entering a slow cooling pit, cooling to a certain temperature, discharging from a furnace, and carrying out air cooling. Preheating in a tempering furnace before quenching, entering the furnace at high temperature and high carbon potential, entering a salt bath for quenching after austenitizing, controlling the water content of the salt bath, and improving the quenching intensity. According to the method, it can be guaranteed that the temperature of a workpiece rises at a slow speed before carburizing, the thermal stress influence caused by too large temperature difference is avoided, carbon deposition is reduced through two-time diffusion, and it is guaranteed that the surface metallographic structure meets the technical requirement; preheating is conducted before quenching, high-temperature and high-carbon-potential furnace feeding is conducted, it is guaranteed that a workpiece is rapidly heated in a nucleation temperature interval, and a good martensite structure is obtained; by controlling the water content of the salt bath, the quenching cooling speed can be increased, the formation of a bainite structure is reduced, and meanwhile, the requirement of the wind power planet wheel for the inner hole hardness is met.

The invention relates to a manufacturing method of ultrahigh-strength and high-toughness steel which is used under the condition of high bearing pressure and has ultrahigh strength and high toughness. The ultrahigh-strength and high-toughness steel comprises the following components in percentage by mass: 35%-42% of C, 1.2%-1.9% of Cr, 3.5%-4.5% of Ni, 0.75%-1.2% of Mo, 0.25%-0.45% of V and the balance of iron. Electric arc furnace smelting, vacuum refining and electroslag remelting smelting are carried out; through three-time upsetting and three-time drawing, large and uniform deformation is generated in the steel ingot, the transverse performance of a workpiece is effectively improved, and internal defects of the steel ingot are forged and combined; through normalizing after forging, hydrogen diffusion annealing and tempering, the structure and the grain size are refined; through quenching and graded water cooling, the structure is fully transformed, a fine martensite structure is obtained, uniform and fine tempered sorbite is obtained through tempering, the final mechanical property sigma r0.2 is larger than or equal to 1350 MPa, the impact energy AKV at the temperature of-40 DEG C is larger than or equal to 25 J, and the requirements of products for ultrahigh pressure and light weight are met.

The invention aims to provide a heat treatment-liquid nitrogen treatment-cryogenic forging composite forming method for obtaining an alpha '+ alpha' double-phase martensitic structure titanium alloy, and belongs to the technical field of titanium alloy plastic processing and heat treatment. Through liquid nitrogen treatment, the sample obtains a uniform cryogenic temperature and stabilizes an alpha'martensite phase structure; alpha'martensite to alpha '' martensite phase transformation of the alloy is promoted through cryogenic forging. And finally, obtaining the needle-shaped alpha '+ alpha' 'biphase martensitic structure titanium alloy forge piece based on the synergistic effect of heat treatment, liquid nitrogen treatment and cryogenic forging. Compared with traditional cryogenic forming of the titanium alloy, the method can achieve uniform distribution of nanoscale alpha '+ alpha' 'biphase martensite in the titanium alloy forge piece, meanwhile, the technological process is simple, and actual production is easy.

The invention provides a post-forging heat treatment method and an auxiliary tool for a fountain forge piece, and relates to the technical field of heat treatment of steel. During normalizing treatment of an intermediate sample of the fountain forge piece formed through forging, when relevant process steps of transformation from an austenite structure to a martensite structure exist, the normalizing process is carried out; a middle sample of the water bucket forge piece is installed in the auxiliary tool, the bottoms of the two bucket side walls of the sample are clamped in the corresponding constraint notches, the inner walls of the left side and the right side of the upper ring are attached to the bucket side walls, and the auxiliary tool can play a role in restraining the sample from expanding in the process steps; therefore, external expansion and sagging of the bucket side wall of the middle sample of the water bucket forge piece can be inhibited. In the post-forging heat treatment process, external expansion and sagging of the bucket side wall of the middle sample of the water bucket forge piece formed through forging can be restrained through the method, and it is guaranteed that the water bucket forge piece has the fine grain size.

The invention relates to a 1500MPa-grade high-strength tool steel wire rod and a manufacturing method thereof.The method includes the steps that after Nb-V chemical component design is adopted for rolling and spinning to form a wire rod, online molten salt subcooling quenching isothermal treatment is conducted, molten salt of the wire rod at the front section is controlled to enter a martensite phase region from a high-temperature austenite state at the cooling speed larger than or equal to 37 DEG C / s, part of austenite is promoted to be converted into a martensite structure, and then the steel wire rod is rolled and spun; the method comprises the following steps of: heating to a sorbite phase region through a rear-section molten salt, promoting the transformation of austenite residues to a sorbite structure, carrying out isothermal tempering toughening destressing treatment on the structure, and finally slowly cooling through a roller way to prepare a wire rod of which the microscopic structure comprises tempered sorbite and tempered martensite, the material cost can be properly controlled, the phase change of the wire rod is powerfully regulated and controlled, the strength and plasticity matching of the wire rod is improved, the tensile strength is 1470-1520 MPa, and the percentage reduction of area is 52%-57%, so that additional heat treatment after cold machining is omitted, the production energy consumption and cost of the tool steel are reduced, and the efficiency is improved.

The invention discloses high-endurance-strength high-silicon martensite heat-resistant steel for a lead-bismuth reactor and a preparation method of the high-endurance-strength high-silicon martensite heat-resistant steel, and belongs to the technical field of corrosion-resistant and heat- The heat-resistant steel comprises C, Si, Cr, Ni, Mo, W, Mn, V, Nb and N, the Mo equivalent is 0.8-1.2, the CNB is smaller than 14, and the balance is Fe and inevitable impurities. The formation of a compact SiO2 protective film is promoted by increasing the content of Si, and meanwhile, Mo and W are adopted for synergistic solution strengthening and are matched with N, V and Nb to form a dispersed MX precipitated phase. The heat-resistant steel is prepared through the processes of smelting, homogenizing, forging, hot rolling, normalizing and tempering, and a full-martensite structure can be obtained. And the obtained material has good liquid lead and bismuth corrosion resistance, room-temperature and high-temperature mechanical properties and relatively high high-temperature endurance strength, and is suitable for structural materials serving in high-temperature liquid lead and bismuth environments such as a lead-cooled fast reactor and the like.

The invention belongs to the technical field of metal materials, and discloses precipitation-hardening stainless steel and a preparation method thereof. Through cooperative regulation and control of component design and process innovation, the traditional contradiction of'strength-plasticity inversion 'in additive manufacturing of the precipitation-hardened stainless steel is broken through, and the precipitation-hardened stainless steel with excellent strength and plasticity is prepared. On one hand, the N element is introduced into the precipitation-hardening stainless steel raw material powder, so that transformation from ferrite to austenite in the additive manufacturing process is promoted; on the other hand, in the additive manufacturing process, the substrate is subjected to in-situ heating to be close to the martensite phase transformation initial temperature, and transformation of austenite to martensite is restrained; and after printing is finished, global martensite phase transformation is triggered through natural cooling or air cooling, so that a total martensite structure with fine grains and high dislocation density is obtained. And finally, through aging treatment, precipitation of a nano Cu phase is induced, formation of austenite is reversed, and therefore the strength and plasticity of the precipitation-hardened stainless steel are improved at the same time.

The application discloses a laser welding method for inhibiting formation of aluminum-rich phase in a weld, and belongs to the technical field of metal material processing. Firstly, welding edges of two steel plates are butted and fixed, laser wire filling welding is performed, the excess height on the surface of the weld is removed, and a welded plate is obtained; then the welded plate is kept in a heating furnace at 900-960 DEG C for 3-10 min, and the welded plate is taken out and quenched immediately; after quenching, the steel plate and the weld form martensite structures. The laser wire filling welding method is used to add welding wires into the weld, the composition of the weld metal is optimized, the aluminum-rich phase free weld structure is obtained, the welding wires entering the weld increase the volume and weight of the weld metal, the mass percentage content of the aluminum alloy in the weld metal is further reduced, the generation of the aluminum-rich phase in the weld is weakened, the joint strength after welding of the plated steel plate is greater than the base material strength, after hot forming of the welded joint, the weld is a complete martensite structure, and the weld strength is greater than or equal to 1500 MPa.

The invention discloses a low-temperature tempering method for improving the performance of bulletproof steel, which comprises the following steps: heating at the temperature of 1250 + / -15 DEG C to reach a complete austenitizing temperature, so that the slab structure is completely austenitized; the finish rolling temperature of laboratory hot rolling is 900 + / -15 DEG C, it is guaranteed that finish rolling is conducted in a completely non-recrystallization temperature area, recrystallization growth of austenite is avoided, crystal grains are lengthened and fragmented, and then uniform and fine austenite crystal grains are obtained; and the heat treatment quenching temperature is 870 + / -10 DEG C, heat preservation is conducted for 20-40 min, the tempering temperature is 150-220 DEG C, heat preservation is conducted for 60-80 min, and finally the low-temperature tempered martensite structure is obtained. According to the low-temperature tempering method for improving the performance of the bulletproof steel, the quenching and low-temperature tempering heat treatment technology is adopted, so that the steel obtains a low-temperature tempered martensite structure and good obdurability cooperation, and it is guaranteed that the best bulletproof steel performance is obtained.

The present invention provides a steel sheet having a tensile strength of 1310 MPa or more and excellent press formability in a steel having a martensite structure as a main body and excellent delayed fracture resistance. The steel sheet is characterized by having a composition consisting of, in mass%, C: 0.12% to 0.40%, Si: 1.5% or less, Mn: 1.7% or less, P: 0.05% or less, S: 0.010% or less, sol. Al: 1.00% or less, N: 0.010% or less, Ti: 0.002% to 0.080%, and B: 0.0002% to 0.0050%, with the remainder being Fe and inevitable impurities, and a metal structure in which the area ratio of a martensite to the entire structure is 95% or more, the length L S of sub-block boundaries in the martensite is 0.5 to 2.0 μm, and the ratio L B / L S of the length L B of the sub-block boundaries to the length L of the block boundaries satisfies a prescribed formula (1), and the tensile strength is 1310 MPa or more.