75 results about "Acicular ferrite" patented technology

The invention discloses ultra-thick L360 pipeline steel with excellent low-temperature toughness, which belongs to the technical field of materials and metallurgy and comprises the following components in percentage by weight: 0.050%-0.058% of C, 0.10%-0.20% of Si, 1.0%-1.1% of Mn, 0.040%-0.050% of Nb, 0.019%-0.021% of Ti, 0.18%-0.24% of Cr, 0.15%-0.20% of Ni, less than or equal to 0.015% of P, less than or equal to 0.003% of S, less than or equal to 0.004% of N, 0.118%-0.130% of Pcm and the balance of Fe and inevitable impurities. The low-carbon, low-manganese and low-Pcm alloy design is adopted, Nb and Ti are added to improve the strength, an acicular ferrite structure is obtained through the synergistic effect of Cr and Ni and a proper cooling system, and good obdurability matching is achieved.

The invention discloses a flux-cored wire for extra-thick marine steel high heat input EGW and a preparation method of the flux-cored wire, and relates to the technical field of metal welding, the flux-cored wire comprises an outer skin of a double-layer alloy steel strip and powder filled in the outer skin, the filling rate of the powder is 20 + / -5%, and the powder comprises Fe, Mn, Si, Cr, Ni, Mo, V, B, S, Al, MgAl2O4, MgO-TiO2, ReOx and a slag former. According to the preparation method, the metal powder is positively charged, the rare earth nanoparticles are negatively charged through an electrostatic self-assembly technology, the metal powder and the rare earth nanoparticles are mixed with a slag former after being mixed, filtered and freeze-dried, an alloy steel strip is filled with the powder, and then rolling and drawing forming is conducted. In the welding process, the composite inclusions form a core-shell structure, a weld metal structure is regulated and controlled, acicular ferrite nucleation is promoted, and grains are refined, so that the low-temperature toughness and crack arrest performance of a weld are remarkably improved, the rare earth elements are beneficial for changing irregular inclusions into spheres, nucleation sites are increased, interface energy is reduced, and the nucleation rate of acicular ferrite is increased.

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 invention provides a coal mine hydraulic support gas shield welding wire with the strength higher than 900 MPa and a preparation method of the coal mine hydraulic support gas shield welding wire. The gas shield welding wire comprises, by mass, 0.03%-0.06% of C, 0.51%-0.70% of Si, 1.35%-1.64% of Mn, smaller than or equal to 0.010% of P, smaller than or equal to 0.005% of S, 0.20%-0.38% of Cr, 2.35%-2.65% of Ni, 0%-0.09% of Cu, 0.45%-0.70% of Mo, 0.015%-0.030% of Ti, 0.025%-0.035% of Nb, 0.002%-0.006% of Ce, 0.0005%-0.0012% of B, smaller than or equal to 0.004% of O, smaller than or equal to 0.006% of N and the balance Fe and The invention has the following beneficial effects: (1) through reasonable design of chemical components, the yield strength of weld metal is greater than or equal to 820 MPa, the tensile strength is greater than or equal to 900 MPa, the ductility is greater than or equal to 21%, and the low-temperature impact toughness at-40 DEG C is greater than or equal to 75 J; (2) inclusions in a weld joint are dispersed and refined after the welding wire is welded, refined acicular ferrite instead of bainite and martensite is taken as a main structure, and the strength and toughness of the weld joint are excellent; and (3) the composition proportion of the welding wire is optimized, a stable welding wire preparation process is developed according to the components, and the comprehensive performance of the high-strength coal mine hydraulic support welding seam is considered.

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 invention discloses a wide and thick steel plate for a 600MPa-grade corrosion-resistant anti-fatigue marine tendon pipe and a production method of the wide and thick steel plate. According to the component design of the wide and thick steel plate, CEIIW is controlled to be 0.37%-0.42%, and CEPcm is controlled to be 0.14%-0.18%; the low-Nb and Mo-free design is adopted, the phase change temperature is increased, and phase change of polygonal ferrite is promoted; rE is fully utilized to exert the effects of solid solution, interface segregation and the like, grains are refined, the interface energy is reduced, and the corrosion resistance is improved; on the basis of component design, the production methods of low-temperature heating, rough rolling multi-stage thickness section high-temperature gradient deformation and low-temperature rolling, intermediate temperature-waiting blank rapid cooling after rough rolling is finished, finish rolling low-temperature deformation, multi-stage water cooling and the like are adopted to obtain a microstructure of polygonal ferrite, granular bainite and acicular ferrite; and the average deformation austenite height does not exceed 18 microns, and the proportion, the size and the distribution of each phase are ideally controlled, so that the method plays an important role in obtaining good comprehensive performance of the steel plate.

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 antibacterial and hydrogen induced cracking resistant X80 pipeline steel and a production method thereof. The pipeline steel comprises the following chemical components in percentage by weight: 0.045 to 0.065 percent of C, 0.15 to 0.3 percent of Si, 0.6 to 1.2 percent of Mn, 0.21 to 0.26 percent of Cr, 0.017 to 0.027 percent of Nb, 0.015 to 0.028 percent of V, 0.008 to 0.018 percent of Ti and the balance of Fe. 0.20 to 0.27% of Mo; 0.75% to 1.2% of Cu; 0.5%-1% of Ni; n is less than or equal to 0.0030%; the production method comprises the following steps: heating a plate blank, rolling the plate blank, and carrying out aging treatment on the plate blank. The microscopic structure of the X80 pipeline steel is a uniform acicular voxel body, and the X80 pipeline steel is good in obdurability matching, antibacterial and resistant to hydrogen induced cracking.

The invention relates to X80 pipeline steel hot rolled steel and a preparation method and application thereof, and relates to the field of microalloy high-strength steel manufacturing, and the X80 pipeline steel hot rolled steel comprises the following components in percentage by mass: 0.055-0.065% of C, 0.16-0.2% of Si, 1.7-1.8% of Mn, less than or equal to 0.012% of P, less than or equal to 0.004% of S, 0.18-0.22% of Ni, 0.2-0.24% of Cr, 0.2-0.24% of Mo, 0.03-0.05% of Nb, 0.04-0.06% of V, 0.01-0.018% of Ti, and the balance of Fe and inevitable impurities. According to the X80 pipeline steel hot rolled steel provided by the invention, through reasonable matching of alloy components, uniform distribution of acicular ferrite structures and uniform dispersion and precipitation of carbonitrides such as Nb and V are realized, so that the uniformity and stability of the mechanical property of the hot rolled steel strip are ensured on the basis of meeting the obdurability.

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 invention relates to high heat input welding resistant steel for a deep sea jacket and a preparation method thereof, and belongs to the technical field of iron-based alloys. The steel plate comprises, by mass, 0.08%-0.10% of C, 0.15%-0.25% of Si, 1.55%-1.70% of Mn, smaller than or equal to 0.0070% of P, smaller than or equal to 0.0030% of S, 0.008%-0.020% of Ti, 0.0020%-0.0040% of N, 0.20%-0.30% of Cu, 0.45%-0.60% of Ni, 0.010%-0.025% of V, 0.0010%-0.0020% of B and the balance Fe and inevitable impurity elements, the yield ratio of the steel plate is 0.84%-0.88, the yield strength is 430 MPa to 480 MPa, the tensile strength is 520 MPa to 580 MPa, and the ballistic work at the temperature of 40 DEG C below zero and 50 DEG C below zero is larger than or equal to 200 J. On the basis that the steel grade component range of the European standard En10025-4 S420ML is met, the carbon content is further reduced, Mn, Ni, Cu-, V and B elements beneficial to the toughness of the steel plate are added, in the TMCP rolling process, the pass reduction is increased, the total pass number is controlled, and the yield of the steel plate is increased. And the steel plate for high heat input welding, which has a mixed structure mainly consisting of acicular ferrite and a small amount of blocky ferrite, is obtained.

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 invention provides a multi-wire submerged arc welding method and device for a straight seam steel pipe, and belongs to the technical field of welding. The method comprises the steps that a multi-wire submerged arc welding process is adopted for conducting double-face submerged arc welding on the straight seam steel pipe, when an outer side welding seam is welded, ultrasonic waves are generated through an ultrasonic auxiliary device arranged on the back face of a welding pool and input into the welding pool through an amplitude-change pole, formation of intergranular ferrite in a welding seam area is restrained, the content of intracrystalline acicular ferrite is increased, and the welding quality of the straight seam steel pipe is improved. The toughness and the hydrogen embrittlement resistance of a weld zone are improved. The device comprises a three-wire submerged arc welding device, an ultrasonic-assisted 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, amplitude-change poles are installed at the output ends of the ultrasonic transducers, and the ultrasonic transducers generate ultrasonic waves and input the ultrasonic waves into the molten pool through the amplitude-change poles. The problems that according to existing ultrasonic-assisted arc welding, the acicular ferrite content cannot be adjusted and controlled, and the effect of reducing the residual stress of a weld zone is not obvious are solved.

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 invention discloses a low-alloy corrosion-resistant welding wire and a welding method, and relates to the technical field of welding. The low-alloy corrosion-resistant welding wire comprises the following chemical components: 0.03%-0.10% of C, 0.2%-0.3% of Si, 0.8%-2.4% of Mn, 0%-1.5% of Ni, 0.4%-1.5% of Cr, less than or equal to 0.005% of S, less than or equal to 0.005% of P, less than or equal to 0.02% of Als and Fe. The components of the welding wire do not comprise alloy elements such as Cu, Mo and Ti, a proper amount of Cr and Ni are added, and the compactness of a welding line rust layer, especially the compactness of an inner rust layer can be remarkably improved by adding Cr into the welding wire, so that the welding wire has excellent corrosion resistance; and by adding a proper amount of Ni element, grains can be refined, so that the structure is more easily converted into acicular ferrite, and the toughness of a welding seam is improved. By the adoption of the welding wire, the impact toughness of obtained weld metal reaches 80% or above of that of low-alloy corrosion-resisting steel, under the flowing accelerated corrosion condition, the corrosion step of the weld and a heat affected zone / base metal is smaller than 30 microns, the flowing medium corrosion resistance and impact resistance of a steel pipe are remarkably improved, and application and popularization of the low-alloy corrosion-resisting steel in a heat supply pipe network are promoted.

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 invention discloses a production method of extra-thick 500MPa-grade high-toughness steel for ocean engineering. The steel comprises the following chemical components in percentage by mass: 0.01%-0.029% of C, 0.15%-0.20% of Si, 1.20%-1.50% of Mn, less than or equal to 0.010% of P, less than or equal to 0.003% of S, 0.02%-0.15% of Mo, 0.02%-0.05% of Nb, 0.01%-0.03% of Ti, 0.01%-0.03% of V, 0.15%-0.2% of Cr, 0.3%-0.5% of Ni, 0.25%-0.55% of Cu and the balance of Fe and inevitable impurities. On the basis of extremely low carbon equivalent, Cu precipitation, NbTi carbide and other microalloying component design are supplemented, and TMCP technological parameters are strictly controlled; the thickness structure of the steel plate mainly comprises equiaxed ferrite, pearlite, acicular ferrite and bainite. At the 1 / 4 thickness position, the yield strength is larger than or equal to 450 MPa, the tensile strength is larger than or equal to 550 MPa, the ductility is larger than or equal to 20%, and the impact energy is gt at And the high-strength and high-toughness welding wire has good obdurability and welding performance, and the requirements of ocean engineering equipment are met.

The invention relates to the technical field of welding materials, and discloses a high-weldability gas shielded solid welding wire and a production method and application thereof.By controlling the content of Si, Mn and Ti, the polymerization degree of a welding slag glass network is reduced, and the viscosity of welding slag is reduced; meanwhile, the S content is controlled, the surface tension of a molten pool is reduced, the surface tension and electric arc force borne by the molten pool are balanced, welding slag is gathered, and the distribution area of the welding slag is reduced; in conclusion, under the synergistic effect of silicon, manganese, titanium and sulfur, it is ensured that welding slag generated on the surface of a welded joint is easy to remove, the welding slag removing time is remarkably shortened, and the production efficiency is improved; besides, by controlling the content of C, Si, Mn and Ti, it is ensured that a welding seam contains a large amount of acicular ferrite, generation of side batten ferrite and bainite is reduced, on the basis, the content of P and S is controlled, cold brittleness is reduced, hot cracks are avoided, and therefore the impact toughness is improved.

The invention belongs to the field of steel production, and relates to a method for producing 355MPa-grade hot-rolled thin strip steel based on double-roller cast rolling. Molten steel is subjected to double-roller continuous casting and sub-rapid solidification to form a cast strip, is subjected to one-pass hot rolling to form a thin strip, is subjected to aerial fog cooling to 630-750 DEG C and is coiled, the coiled thin strip is placed in a cover type annealing furnace to be heated and subjected to heat preservation for 1-2 days, and a hot-rolled thin strip finished product is obtained after finishing. According to the method, a medium-carbon low-manganese low-silicon microalloy-element-free component system is adopted, the hot-rolled thin strip with the high strength is produced through a short-process double-roller cast rolling production line, and the production energy consumption and the alloy cost are remarkably reduced. The needle-shaped ferrite with a large-size interlocking structure in crystal grains is obtained by fully utilizing the online waste heat annealing process design, and the strength uniformity and the plasticity are obviously improved. The finished product is thin in thickness, good in low-temperature toughness, obviously superior to a traditional hot-rolled low-alloy product in isotropy, and suitable for producing thin-specification components with complex shapes through cold bending and punch forming.

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.