56 results about "Acicular ferrite" patented technology

The present application relates to a kind of large thickness submarine pipeline steel plate and its production method, by the optimization design steel plate component of low-carbon low-alloy component, production method is with the special controlled rolling process of five-stage heating+recrystallization zone low temperature large reduction rolling+intermediate billet instant cooling+non-recrystallization zone high temperature large reduction rolling, and the multi-stage controlled cooling process of high temperature zone air cooling redistribution+ferrite zone cooling+waiting temperature+bainite zone cooling+air cooling self tempering cooling.The product steel plate of the present application has higher acicular ferrite proportion, and the average grain size of ferrite is finer, 3~6 μm, so that the steel plate has good strength and toughness match, the steel plate has higher strength, yield strength ≥500MPa, tensile strength ≥630MPa, and impact energy KV2 At-60 ℃, ≥250J.

The application provides a multi-wire submerged arc welding method and device for straight-seam steel pipes, and belongs to the technical field of welding. The method comprises the following steps: adopting a multi-wire submerged arc welding process to perform double-sided submerged arc welding on a straight-seam steel pipe, and when welding an outer weld, an ultrasonic auxiliary device arranged at the back of a molten pool generates ultrasonic waves and inputs the ultrasonic waves into the molten pool through a horn, so that the formation of intergranular ferrite in the weld zone is inhibited, the content of intragranular acicular ferrite is increased, and the toughness and hydrogen brittleness resistance of the weld zone are improved. The device comprises a three-wire submerged arc welding device, an ultrasonic auxiliary device and a telescopic cantilever beam; the ultrasonic auxiliary device is installed at the front end of the telescopic cantilever beam and comprises three ultrasonic transducers arranged side by side; a horn is installed at the output end of the ultrasonic transducer; the ultrasonic transducer generates ultrasonic waves and inputs the ultrasonic waves into the molten pool through the horn. The application solves the problems that the existing ultrasonic auxiliary arc welding cannot control the content of acicular ferrite and the effect of reducing residual stress in the weld zone is not obvious.

The application provides a corrosion-resistant super-large line energy welding steel plate and a production method thereof, relates to the technical field of alloys, and the steel plate adopts a corrosion-resistant alloying component system with composite addition of Ce, Sn and Cu. The addition of Ce can improve the corrosion resistance of the steel plate, and Ce is easy to combine with oxygen to generate spherical oxides and has the ability to induce the nucleation of intracrystalline acicular ferrite, thereby improving the welding performance of the steel plate. On the basis of the comprehensive design of chemical components, the process parameters of rolling and cooling processes are accurately controlled to obtain the corrosion-resistant super-large line energy welding steel plate with good comprehensive performance.

The invention discloses a pipeline steel plate with uniform residual stress distribution and a production method thereof. According to the steel plate, an alloying scheme of low Cr, Ni and Mo is adopted, the structure is polygonal ferrite, acicular ferrite and tempered bainite, the residual stress is smaller than or equal to 120 MPa, and the residual stress fluctuation is smaller than or equal to 40 MPa. The production method comprises the following steps: heating a casting blank; a hot rolling process; a water cooling process; an air cooling process; and in the tempering heat treatment process, the heating rate is 8-15 DEG C / min, the tempering temperature T is Bs + (-105-55) DEG C, the tempering heat preservation duration t1 is controlled according to the formula that (T + 273.15) * (20 + 1g (t1 / 60)) / 1000 is larger than or equal to 13.7, and the unit of t1 is min. The tempering temperature and the tempering heat preservation time are jointly controlled in the tempering heat treatment, so that the adverse effect of chemical components or the process on stress is avoided, and the steel plate with excellent performance and low and uniform residual stress is obtained.

The present invention relates to a large-thickness submarine pipeline steel plate and a production method therefor. Steel plate components are designed by means of optimization of low-carbon low-alloy components, and the production method uses a matching special controlled rolling process of five-stage heating, low-temperature high-reduction rolling in a recrystallization region, instant cooling of intermediate slabs and high-temperature high-reduction rolling in a non-recrystallization region, and a matching multi-stage controlled cooling process of high-temperature region air cooling for redistribution, ferrite region cooling, temperature maintaining, bainite region cooling and air cooling self-tempering cooling. The steel plate product of the present invention has a relatively high proportion of acicular ferrite, and a relatively fine average ferrite grain size of 3-6μm, thus endowing the steel plate with good combination of strength and toughness. The steel plate has high strength, wherein the yield strength is ≥500MPa, the tensile strength is ≥630MPa, and the impact energy KV2 at -60℃ is ≥250J.

The invention discloses steel for a hydrogen transmission pipeline and a production method of the steel, and belongs to the technical field of ferrous metallurgy, the steel comprises the following chemical components in percentage by mass: 0.03%-0.05% of C, 0.15%-0.35% of Si, 0.7%-1.30% of Mn, less than or equal to 0.015% of P, less than or equal to 0.0010% of S, 0.010%-0.030% of Nb, 0.035%-0.055% of V, 0.008%-0.030% of Ti, 0.15%-0.35% of Cr, 0.30%-0.50% of Ni, 0.050%-0.150% of Mo, 0.10%-0.20% of Cu, 0.010%-0.050% of Al, less than or equal to 0.00050% of B, less than or equal to 0.0060% of N, less than or equal to 0.0002% of According to the production method, high-purity low-carbon phosphorus-sulfur molten steel is obtained through a converter, refining and continuous casting, alloy steel mainly comprising acicular ferrite is obtained through a hot mechanical rolling technology, and the hydrogen conveying requirement of products is met.

The present application belongs to the technical field of hot stamping part preparation, and particularly relates to a tailor-welded part, a manufacturing method thereof and a welding wire applied to the tailor-welded part. The tailor-welded part comprises a welded joint, and a weld seam of the welded joint comprises acicular ferrite and martensite. The average length of the acicular ferrite is not greater than 80 microns, the average diameter is not greater than 15 microns, and the volume percentage of ferrite in the weld seam is 0.1-10%. The tailor-welded part is a part after hot stamping treatment. The joint elongation of the tailor-welded part is greater than 4%, the weld seam structure is martensite and ferrite, the fracture position is located in the base material during the quasi-static tensile test, and the weld seam has good strength and ductility.

The application discloses a process method for producing a limited specification X80 pipeline steel in a high water temperature season, and ideal mechanical properties and organizational morphology are obtained through control of components, heating, rolling, cooling, and laminar flow cooling water temperature and the like processes and technologies. 50 The steel is composed of acicular ferrite+granular bainite+M-A, in particular, the M-A component content is controlled to be 4-8%, and the average size of the short axis of the austenite grain of the large-angle grain boundary is 7.4um. The yield strength of the steel is 605-635MPa, the tensile strength is 720-750MPa, the elongation after fracture A is 35-40%, the yield strength ratio is ≤0.85, the low-temperature impact energy (-60℃) is 400-430J, the impact shear area is 100%, the -40℃ drop hammer shear area is 95-100%, and the requirements of the X80 pipeline steel standard are completely met. The steel can be used in pipeline engineering prone to large plastic deformation such as liquefied sedimentation, ground slip deformation and submarine pipeline laying.

The invention relates to the technical field of steel plate surface treatment in the metallurgical industry, and solves the problem of buckling of needle-shaped ferrite steel plates. The cross straightening anti-buckling process of the needle-shaped ferrite steel plate comprises the following steps: firstly, after being straightened for the first time, a rolled steel plate is conveyed to a first cooling bed to be subjected to stress recovery; after the next rolled steel plate is straightened for the first time, the steel plate is temporarily stored in a material waiting buffer area of the second cooling bed; then, the steel plate subjected to stress recovery is blanked and straightened for the second time and the third time, and meanwhile the steel plate in the buffer area is transferred to a first cooling bed to be subjected to stress recovery; and finally, the steel plate which is straightened for the third time is conveyed to a second cooling bed, and the steel plate on the first cooling bed is synchronously blanked, straightened for the second time and straightened for the third time and then transferred to the first cooling bed. And the steps are repeated, and cross straightening of the multiple steel plates is achieved. Through the rolling mill, the ultra-fast cooling device, the straightening machine, the first cooling bed and the second cooling bed which are arranged in sequence in cooperation with a temperature-rolling reduction parameter combination, the steel plate yield is increased.

The present application relates to a kind of 500MPa grade weathering steel welding process and application in low temperature service environment.The welding method of prior art 500MPa grade weathering steel has the defect that cannot meet the requirement of low temperature service, the present application provides a kind of based on flux-cored wire and cold metal transition welding process, the composition of flux-cored wire is optimized, the nucleation rate of weld metal acicular ferrite is increased, the low temperature impact toughness of joint is guaranteed;On the other hand, cold metal transition welding process is used, short-circuit current is controlled, welding heat input is reduced, and the burning loss of alloy element is reduced.Weathering steel welded joint prepared based on the process of the present application has good low temperature impact toughness, and can meet the use demand of low temperature service environment.

The application discloses a large liquid carbon dioxide ship low-temperature steel plate and a preparation method thereof, and belongs to the field of steel metallurgy. The main chemical components of the steel plate are C, M, Si, Ni, Ni+Cu+Cr, Nb, Al, Ti, Nb+Al+Ti, S, P, and the rest are Fe and inevitable impurity elements. The clean steel smelting process is adopted to prepare a large-thickness continuous casting billet with high purity and high homogenization. The fine quasi-polygonal ferrite+acicular ferrite+carbide-free bainite structure is obtained through low-temperature large reduction (compression ratio greater than or equal to 7) hot mechanical coupling rolling+two-stage controlled rolling and controlled cooling. The large liquid carbon dioxide ship low-temperature steel plate is produced by adopting the TMCP process, has the advantages of large thickness, high strength, -60 DEG C CTOD and the like, meets the construction requirements of the large liquid carbon dioxide ship with low temperature and low pressure, has the advantages of simple manufacturing process, short production period and low alloy cost, and will greatly promote the large-scale development of the liquid carbon dioxide ship.

The present invention provides a high-strength thick hot-rolled steel plate with excellent elongation and a method for manufacturing the same. The high-strength thick hot-rolled steel plate of the present invention comprises, by weight, 0.05-0.15% C, 0.01-1.0% Si, 1.0-2.0% Mn, 0.01-0.1% acid-soluble aluminum (Sol.Al), 0.005-1.0% Cr, 0.001-0.02% P, 0.001-0.01% S, 0.001-0.01% N, 0.001-0.01% Nb, 0.005-0.07% Ti, and the remainder iron and inevitable impurities, and satisfies the following relational expression 1. The high-strength thick hot-rolled steel plate has a fine structure, and by area %, the fine structure comprises: 25-50% polygonal ferrite, 30-50% bainitic ferrite and acicular ferrite, and 20% or less bainite. 2 ) with a diameter of 0.5 μm or more and the sum of the area fractions of the carbides and pearlite structure observed within: less than 5%, and the MA phase (martensite-austenite component): less than 5%.

The present invention relates to an 800MPa-grade marine underwater additive repair welding wire and a production, use and evaluation method thereof. The chemical composition of the welding wire is as follows by weight: C: 0.03-0.09%, Si≤0.15%, Mn: 1.0-2.0%, P<0.004%, S<0.004%, Ni: 2.5-4.5%, Cu: 0.15-0.30%, Ti: 0.010-0.025%, O≤0.005%, Ce: 0.001-0.01%, and the balance is Fe and unavoidable impurity elements; the invention adds The addition of rare earth element Ce increases the fluidity of the molten pool, improves the post-weld forming effect, and strengthens the bonding between the repair body and the additive body. Ce oxide promotes the nucleation of acicular ferrite, effectively reducing the hardened structure during underwater additive repair. Physical and chemical methods are used to remove the iron oxide scale on the surface of the wire rod. The welding wire produced by multiple wire drawing and annealing processes makes the deposited metal after welding have good corrosion resistance and cutting performance, which is more suitable for fine weld repair. The yield strength reaches ≥690MPa, the tensile strength reaches ≥800MPa, and the impact resistance at ‑40℃ is not less than 47J.

The present invention relates to a high-plasticity, toughness and fatigue-resistant X60 grade catenary riser steel plate and a production method thereof. The chemical composition of the steel plate is as follows by weight: C: 0.060% to 0.080%, Si: 0.10% to 0.20%, Mn: 1.30% to 1.45%, P≤0.015%, S≤0.0015%, Cr: 0.10% to 0.21%, Nb: 0.010% to 0.030%, Ti: 0.010% to 0.025%, Al: 0.026% to 0.050%, and the balance is Fe and inevitable impurities; using cheap elements such as C, Mn, Cr and trace amounts of Nb, through the interaction between the elements, and with appropriate heating, rolling and cooling processes, the final structure type of polygonal ferrite + acicular ferrite is obtained. The total content of alloy elements does not exceed 2%, the amount of alloy added is small, the alloy cost is low, the transverse yield strength of the steel plate is 415~475MPa, the tensile strength is 520~600MPa, and the strength reaches X60 level; the impact energy of the steel plate at -30℃ is ≥350J, the CTOD at -10℃ is ≥1.2mm, 10 7 The cyclic fatigue strength is ≥340MPa, the longitudinal elongation of the steel plate is 57% to 68%, and the uniform elongation is ≥13%.

The embodiment of the invention discloses low-cost, high-yield-ratio and low-temperature-impact-resistant 700MPa-grade automotive beam steel as well as a preparation method and application thereof. The automobile beam steel comprises the following components in percentage by mass: 0.05 to 0.12 percent of C; si: less than or equal to 0.10%; mn: 1.2 to 2.0%; n: < = 0.005%; 0.015% to 0.03% of Nb; 0.03 to 0.08% of Ti; less than or equal to 0.3% of Cr; 0.001 to 0.003 percent of B and the balance of Fe; according to the automobile beam steel, the tensile strength Rm is not smaller than 750 MPa, the yield strength R0.2 or ReL is not smaller than 700 MPa, the total elongation A after fracture is not smaller than 20%, and the yield ratio is 0.90-0.95. The Charpy impact absorbing energy KV2 at-20 DEG C is not less than 140J; the Charpy impact absorbing energy KV2 at-40 DEG C is not less than 120J; the microscopic structure of the automobile beam steel is composed of acicular ferrite, pearlite and granular bainite, the effective grain size of the acicular ferrite is 3-5 microns, and the volume fraction of the pearlite is smaller than or equal to 10%.

The invention relates to the technical field of ferrous metallurgy, discloses a production process of Nb-containing coiled snails, and aims to solve the problems that existing vanadium-containing coiled snails are high in production cost, and the Nb-containing coiled snails are easily unobvious in yield, unqualified in yield-strength ratio and the like due to abnormal structures. According to the process, chemical components of steel are optimized, and full-process control of steelmaking, square billet high-temperature heating, rolling, graded cooling and air cooling is combined, so that the final structure of the coiled steel with the specification of phi 6-12 mm is a small amount of acicular ferrite and blocky ferrite and pearlite thereof, and no tempered martensite exists. Nb replaces V to achieve alloying, the production cost of per ton of steel is reduced, the surplus amount of the yield strength and the tensile strength of the coiled steel is sufficient, a tensile curve has an obvious yield platform, and the method is suitable for large-scale low-cost production of the coiled steel for buildings.

This invention relates to the field of new energy infrastructure materials technology, and in particular to a high-strength weather-resistant steel for large-diameter monopile foundation structures and its preparation method. The invention utilizes the synergistic design and optimization of Nb and Ti microalloying elements, combined with controlled rolling and cooling processes, to effectively promote the formation of fine acicular ferrite and lower bainite structures and the dispersed precipitation of nano-reinforcing phases such as Ti(C,N) and Nb(C,N). While ensuring the alloy steel possesses high strength, high plasticity, and excellent corrosion resistance, it significantly reduces dependence on precious metal alloying elements such as Ni and Mo, resulting in outstanding cost-effectiveness. This steel can be used as a steel for wind power monopile foundations in harsh marine environments, solving the problems of low strength, poor corrosion resistance, and high cost in existing diameter monopile foundation structures.

Disclosed is a 500 MPa-grade wind power steel having high strength, toughness and high crack arrest toughness, comprising the following alloy components in percentage by mass: 0.06-0.09% of C, 0.20-0.60% of Si, 1.48-1.80% of Mn, 0.15-0.30% of Ni, 0.02-0.04% of Al, 0.02-0.08R of Nb+V+Ti, 0.2-0.4% of Cr, 0.01-0.02% of Cu, 0.01-0.03% of Zr, P≤0.008%,,S≤0.003%, and the balance being Fe and other inevitable impurity elements. The present invention is based on a low-carbon equivalent composition design. The microstructure of the resulting steel plate is a heterogeneous structure composed of coarse quasi-polygonal ferrite and fine acicular ferrite. The steel plate has a thickness of 20-60 mm, a yield strength ≥ 500 MPa, a tensile strength ≥ 660MPa, a percentage elongation after fracture ≥ 20%, an impact energy at -40ºC ≥ 250 J, a CTOD value at -20ºC ≥ 0.8 mm, a fatigue strength > 640 MPa under the conditions of a stress ratio of 0.5 and 107 cycles, and a critical crack length > 25 mm when fatigue failure occurs. The present invention can meet the development requirements of wind power steel.

The invention relates to a high-toughness flange steel plate used under low-cost, high-hardness and ultralow-temperature conditions and a manufacturing method thereof, and belongs to the technical field of iron-based metallurgy. The steel plate comprises the following chemical components in percentage by mass: 0.10 to 0.30 percent of C and 0.10 to 0.50 percent of Si; p < = 0.005%; s < = 0.002%; 1.20% to 1.80% of Mn; 0.02 to 0.04 percent of Al; 0.04% to 0.08% of Nb; v is less than or equal to 0.01%; 0.50 to 0.80 percent of Mo and Ni; the microstructure of the steel plate is composed of fine needle-shaped ferrite, carbide and Nb-containing precipitates. The production thickness of the steel plate is 100-150mm, the impact energy at-80 DEG C is greater than or equal to 90J, and the Rockwell hardness is greater than or equal to 40HRC. The steel plate for the flange is produced by adopting a low-speed large-rolling-reduction rolling + high-temperature DQ + tempering process, so that the impact property of the steel plate for the flange at-80 DEG C is greater than or equal to 90J, the Rockwell hardness is greater than or equal to 40HRC, and the use requirements of the steel for the flange under the service condition of an ultralow-temperature environment are met.

The present application relates to a kind of low crack sensitivity coefficient 550MPa grade low alloy high-strength steel plate and its manufacturing method, belong to metallurgical technical field.The chemical composition of the steel plate is C:0.05~0.09%, Si:0.10~0.30%, Mn:1.40~1.60%, Nb:0.040%~0.060%, Ti:0.008%~0.018%, Al:0.020~0.040%, B:≤0.0010%, Ca:0.0005~0.0015%, P:≤0.012%, S:≤0.002%, O:≤0.002%, N:≤0.0035%, H:≤0.0001%, the balance is Fe and inevitable impurity element;Carbon equivalent CEV:≤0.37%, Pcm≤0.19%.Production thickness is 50~70mm, microstructure is mainly uniform acicular ferrite and bainite mixed structure.From the angle of element composition design, base material organization, rolling deformation, small water cooling etc., it is guaranteed that the steel plate has high strength, high toughness, excellent cold bending performance and welding cracking resistance, can be widely used in engineering machinery, high-rise building, bridge, ocean platform etc., and the manufacture of large-scale engineering machinery equipment or steel structure that has strict requirements to formability, weldability.

The invention discloses a high heat input welding maritime work steel plate and a preparation method thereof. Primarily smelting the molten iron and the scrap steel to obtain primarily smelted molten steel; carrying out LF refining and RH refining on the primary smelting molten steel, casting to obtain a casting blank, and then slowly cooling the casting blank; heating the slowly cooled casting blank to obtain a hot casting blank; carrying out rough rolling and finish rolling on the hot casting blank to obtain a steel plate; and the steel plate is subjected to water cooling and then slow cooling, and the steel plate for high heat input welding ocean engineering is obtained. The low-C low-carbon equivalent component design is adopted, elements such as Mg, Ti, Zr and O are properly proportioned, the size and number of Ti-Mg-Zr-O composite inclusions in the steel are controlled, the dispersed composite inclusions promote acicular ferrite nucleation and pinning austenite grain boundary movement, and the low-temperature toughness of a welding heat affected zone is effectively improved.

The application provides a high-toughness high-strength steel alkaline electrode and a preparation method thereof. The electrode comprises a core and a coating, and the coating is formed by mixing solid components and liquid components. The solid components comprise the following raw materials in parts by weight: 42-50 parts of marble, 25-33 parts of fluorite, 7-10 parts of carbonate, 5-7 parts of manganese iron, 4-5 parts of sodium fluoride, 2-3 parts of phlogopite and 2-3 parts of high-entropy rare earth oxide. The liquid components are binders, which comprise the following raw materials in parts by weight: 78-82 parts of modified potassium-sodium water glass, 17-20 parts of hydroxyethyl cellulose and 1-2 parts of lithium hydroxide. The liquid components account for 21-24% of the mass of the solid components. The high-toughness high-strength steel alkaline electrode can increase the high-temperature stability of the coating, inhibit the desorption of diffusible hydrogen at the welding temperature, reduce the content of diffusible hydrogen in the weld, refine the alloy structure, increase the content of metal acicular ferrite in the weld and improve the toughness of the weld.

The application provides a Ti-Ca treated hydrogen storage pressure vessel steel plate and a manufacturing method thereof. The steel plate comprises the following components in percentage by weight: C: 0.09% to 0.12%, Si: 0.25% to 0.40%, Mn: 1.10% to 1.30%, P: ≤0.015%, S: ≤0.005%, Cr: 0.30% to 0.40%, Ni: 0.20% to 0.30%, Mo: 0.15% to 0.25%, V: 0.09% to 0.15%, Nb: 0.01% to 0.02%, Ti: 0.01% to 0.02%, Al: 0.003% to 0.005%, Ca: 0.006% to 0.008%, V / C≥1, Ti / Ca: 1 to 3, and the balance of Fe and inevitable impurities. The production method of the steel plate comprises smelting, continuous casting, heating, rolling, cooling and heat treatment. The microstructure of the steel plate is tempered sorbite + acicular ferrite, and the volume percentage of the tempered sorbite structure is 92% to 96%. The yield strength ReL of the steel plate is greater than or equal to 650 MPa, the tensile strength Rm is 800 to 920 MPa, the elongation A is greater than or equal to 21%, the low-temperature impact toughness KV2 at-50 DEG C is greater than or equal to 100 J, the tensile yield strength ReL at-50 DEG C is greater than or equal to 660 MPa, the tensile strength Rm is 820 to 930 MPa, and the elongation is greater than or equal to 21%. The steel plate is welded by using large linear energy of 100 to 140 kJ / cm, the yield strength R eL of the heat-affected zone (HAZ) is greater than or equal to 690 MPa, the tensile strength R m is 830 to 950 MPa, the elongation is greater than or equal to 17%, and the impact toughness KV2 of the heat-affected zone (HAZ) at-50 DEG C is greater than or equal to 70 J.

The application discloses a low-cost large-heat-input welding method for common high-strength steel, selects common high-strength steel plates with thickness of 20mm-120mm and tensile strength of 450-650MPa as base materials, firstly melts thin-layer weld metal in a groove by small-line-energy gas shielded welding, forms fine and dispersed inclusions in the weld by Ti, Si, Al and Mn oxides and MnS complex, and induces generation of slender acicular ferrite (AF) structure, and then completes welding by vertical gas-electric vertical welding with large heat input, so that the thin-layer weld metal is used as new heat affected zone (HAZ), the inclusions inhibit austenite grain growth, and the AF structure is transformed into equiaxed ferrite. The application can realize large-heat-input efficient welding of common high-strength steel without special large-heat-input welding steel, the low-temperature impact toughness of each region of the joint is excellent, the material cost is greatly reduced, the welding efficiency is improved, and the application is suitable for thick plate welding fields such as shipbuilding and offshore platform.

The invention relates to a composite powder particle of a chromium wear-resistant alloy in submerged arc surfacing. The composite powder particle with the particle size of 12-15 meshes is prepared by the following preparation process steps: screening and weighing powder components contained in the composite powder particle, carrying out dry powder mixing, adding water glass, carrying out wet mixing, bonding and granulating wet powder, sintering at low temperature and screening the powder particle. The composite powder particles are melted and preset through an electric arc, the composite powder particles and H08A solid welding wire molten drops are fused together to form a surfacing weld pool, and the surfacing weld pool is cooled and solidified to form the wear-resistant alloy. The alloy component types and content of the composite powder particles are optimized, the matrix and wear-resistant phase structure types, number and distribution pattern of the surfacing alloy are regulated and controlled, and an organization structure comprising a (Fe, Cr) 7C3 phase distributed in a strip shape, a strip (Fe, Cr) 3C phase distributed intermittently side by side along the boundary, an intracrystalline strengthened point-shaped TiC phase and an elastic matrix composed of acicular ferrite and acicular martensite is obtained. In other words, the medium-chromium alloy with excellent wear resistance, high toughness and excellent cost performance is overlaid. The composite powder particle can be used for surfacing a wear-resistant alloy layer bearing a certain impact load for parts, such as a toothed plate of a jaw crusher.

Provided are TMCP (Thermo-Mechanical Control Process)-state low-cost low-temperature structural steel for high-heat-input welding and a manufacturing method, relating to the technical field of steel production. By adopting a low-carbon niobium-free composition design and a smelting process based on oxide metallurgy technology, fine-sized, dispersed and hybridized oxide particles are formed in steel. Fine and dispersed inclusion particles with high thermal stability are used to pin an austenite grain boundary of a welding heat-affected zone under a high heat input condition to refine the austenite grains. In addition, oxides are used as nucleation points of intragranular acicular ferrite (IAF), so that an IAF structure with good strength and toughness is formed in the welding heat-affected zone, and then the toughness of the welding heat-affected zone with high heat input is significantly improved. High-strength ship plate steel is produced using TMCP technology combined with high-temperature, low-speed and heavy-reduction rolling, no heat treatment is required, the cost is reduced, and a stable production process is ensured.

The present invention discloses an ultra-thick L360 pipeline steel with excellent low-temperature toughness, belonging to the field of materials and metallurgy technology. The steel comprises: C: 0.050% to 0.058%, Si: 0.10% to 0.20%, Mn: 1.0% to 1.1%, Nb: 0.040% to 0.050%, Ti: 0.019% to 0.021%, Cr: 0.18% to 0.24%, Ni: 0.15% to 0.20%, P≤0.015%, S≤0.003%, N≤0.004%, and Pcm: 0.118% to 0.130%, with the remainder being Fe and unavoidable impurities. The present invention adopts a low-carbon, low-manganese, low-Pcm alloy design, adds Nb and Ti to improve strength, obtains an acicular ferrite structure through the synergistic effect of Cr and Ni and a suitable cooling system, and achieves a good balance of strength and toughness.

The invention discloses a low-hardness high-toughness submerged arc welding wire which comprises the following chemical components in percentage by weight: 0.03 to 0.06 percent of C, 0.80 to 1.00 percent of Mn, less than or equal to 0.25 percent of Si, less than or equal to 0.005 percent of S, less than or equal to 0.008 percent of P, 0.30 to 0.50 percent of Mo, 0.70 to 0.90 percent of Ni, 0.03 to 0.08 percent of Ti, 0.002 to 0.008 percent of B and the balance of iron and inevitable impurities. And the chemical components meet the condition that C + Mn / 10 + Mo / 5 is less than or equal to 0.20%. The components of the welding wire are subjected to quantitative control of low-carbon and solid solution strengthening elements, a Mn-Mo-Ni-Ti-B alloy system is adopted, a welding seam with acicular ferrite as a main component is obtained, the problem that hardness and toughness of a traditional welding wire are difficult to consider at the same time is effectively solved, good matching of low hardness and high toughness is achieved, the hydrogen resistance of the welding seam is further remarkably improved, and the welding wire has good application prospects. The results of the crack sensitivity rate, the length rate and the thickness rate of the welding wire in a standard HIC test are zero, and the welding wire is particularly suitable for welding of hydrogen conveying pipeline steel pipes, low-temperature fine-grain carbon steel pipes and other severe environments.

This invention relates to a high-ductility, high-toughness, fatigue-resistant X65 grade steel plate for catenary risers and its production method. The chemical composition of the steel plate, by weight percentage, is: C: 0.040%–0.060%, Si: 0.10%–0.20%, Mn: 1.50%–1.65%, P≤0.015%, S≤0.0015%, Cr≥0.10%, Cr+Ni: 0.22%–0.33%, Cu: ≤0.20%, Nb: 0.030%–0.050%, Ti: 0.010%–0.025%, Al The alloy composition is 0.026%–0.050%, with the balance being Fe and unavoidable impurities. Using inexpensive elements such as C, Mn, Cr, and Cu, supplemented with trace amounts of Nb and Ni, and employing appropriate heating, rolling, and cooling processes, a fine-grained polygonal ferrite + acicular ferrite microstructure is obtained. The alloy addition is low, resulting in low alloy cost. The steel plate exhibits a transverse yield strength of 476–540 MPa and a tensile strength of 540–640 MPa, achieving X65 strength level. The steel plate has an impact energy ≥350 J at -30℃, a CTOD ≥1.0 mm at -10℃, and a strength of 10... 7 The fatigue strength after each cycle is ≥350MPa, the longitudinal elongation after fracture of the steel plate is 57%~68%, and the uniform elongation is ≥12%, which meets the technical requirements for manufacturing X65 grade deep-water steel catenary risers.

The invention discloses a permanent magnet surface coating material and a preparation method thereof, and belongs to the technical field of corrosion prevention of permanent magnet materials. The coating material comprises a component A and a component B in a weight ratio of (10-12): 1, wherein the component A comprises 50-70 parts of epoxy resin, 3-5 parts of functionalized graphene, 3-8 parts of a modified ferrite nanofiller, 60-100 parts of an organic solvent and an auxiliary agent; and the component B comprises 15-20 parts of a polyamide curing agent and 15-20 parts of an organic solvent. The functionalized graphene is prepared by modifying triglycidyl isocyanurate through a ball milling method, so that the dispersity and the interface bonding force are effectively improved; the modified ferrite nano-filler is needle-shaped ferrite treated by a silane coupling agent, the length-diameter ratio of the modified ferrite nano-filler is 5: 1-10: 1, and the modified ferrite nano-filler can be embedded into pores of a permanent magnet matrix by virtue of magnetism, so that the adhesive force and the impermeability are enhanced. The coating has excellent binding force, acid and alkali resistance and long-acting corrosion resistance, the preparation process is simple and convenient, and the coating is suitable for industrial surface protection of the neodymium-iron-boron permanent magnet.