287 results about "Ferrite pearlite" patented technology

The invention relates to a method for producing color-coated steel sheet for a structure. The method comprises the following steps of: smelting, namely desulfurizing by molten iron, smelting by a converter, casting continuously to form a blank and performing hot rolling; performing acid washing; performing cold milling; annealing continuously; performing hot dipping on aluminum and zinc; and polishing, straightening, performing color coating and packaging for later use. In the method, the yield strength RP 0.2 (or ReH) is between 550 and 600 MPa; the tensile strength Rm is between 560 and 610MPa; and the percentage elongation after break A80 mm is more than or equal to 6 percent. A neutral salt mist test is performed for 1,200 hours, a coating does not have bubbling and corrosion phenomena. At present, the annealed color-coated plate of which the metallographic structure is ferrite and pearlite or the ferrite and free cementite or the ferrite and the pearlite and less free cementite cannot achieve the effect, and the production cost can be reduced by 10 to 15 percent. By the method, special occasions which have high-yield strength and are used for cooling chambers of automobiles,arch coverings and the like can be met, and a process is simple and easy to implement.

The invention relates to a normalized-condition delivered 180-200mm-thick EH36 steel plate and a preparation method thereof. Chemical components of the steel plate are based on the national standards GB712 or the classification society rule, wherein Al is utilized to substitute an element Ti while V with relatively high content is added. The preparation method comprises the following steps: electric furnace smelting, LF refining, VD refining, die casting, steel ingot heating, break-down rolling, controlled slow cooling, steel billet heating, rolling, normalizing treatment and the like, which are sequentially carried out. The obtained steel plate does not have an obvious gradient structure in a thickness direction, and the structure of the steel plate is mainly a mixed mixture which comprises ferrite pearlite supplemented by little bainite. A microscopic structure is fine and uniform, an average crystal size is 8-12 mum, yield strength ranges from 380 MPa to 430 MPa, tensile strength ranges from 550 MPa to 600 MPa, and ductility is proper. The steel plate has an impact toughness value greater than or equal to 60 J at a temperature of 40 DEG C at a 1/4 part and a 1/2 part, and has excellent comprehensive mechanical property.

The invention relates to a method for controlling a strip tissue of pinion steel, which belongs to the technical field of the tissue of the pinion steel. The method adopts the following process flow for producing a continuous casting billet of the pinion steel: the pretreatment of molten iron, primary smelting in a converter, refining in a ladle refining furnace or refining in the ladle refining furnace and a vacuum degassing furnace, and continuous casting; the steel billet is heated and is subjected to continuous rolling through 20 short stress line high-rigidity closed-type red ring rolling machines; and different final rolling temperatures are respectively controlled to produce a hot-rolled round steel bar material in order that the level of a steel ferrite and pearlite strip tissue is less than or equal to 2.5. The method has the advantages that different specifications and different final rolling temperatures of the rolled steel are controlled by cooling and other means to realize the aim of enlightening the level of the strip tissue by the steel material with Phi of between 14 and 80 mm<2>. By effectively controlling the level of the strip tissue, the method can meet the requirement of a user on the high-quality pinion steel and improve the qualification rate of the quality of the high-quality pinion steel.

The invention discloses a steel plate for a heavy-gauge pressure vessel, and a preparation method thereof. Chemical components of the steel plate for the heavy-gauge pressure vessel are obtained through melting the following components, by weight, 0.15-0.18% of C, 0.25-0.50% of Si, 1.50-1.60% of Mn, 0.020% or less of P, 0.012% or less of S, 0.030-0.050% of Nb and 0.020-0.050% of Al; and the steel plate structure is a ferrite and pearlite structure. The design of the chemical components of the steel plate of the invention is characterized in that low price C and Mn are adopted for solution strengthening, small amounts of alloy elements are added, and water cooling is adopted after normalizing to accelerate cooling to make the steel plate have excellent mechanical performances, a uniform structure, good comprehensive performances and welding performances, and an enhanced market competitiveness. The steel plate has the following advantages: 1, the mechanical performances are good, and the yield strength and the tensile strength are largely higher than thinner specification performance indexes; 2, the low temperature impact energy is high, and the impact energy at -20DEG C is above 180J; and the largest thickness of the steel plate can reach 78mm.

Disclosed are a 60kg-level low-cost and high-toughness steel plate and a production method thereof. The 60kg-level low-cost and high-toughness steel plate comprises, in weight percentage, 0.145%-0.185% of C, not less than 0.30% of Si, 1.35%-1.65% of Mn, not less than 0.013% of P, not less than 0.003% of S, not less than 0.25% of Cu, not less than 0.25% of Ni, 0.005%-0.015% of AlS, 0.150%-0.190% of V, 0.015%-0.020% of N, 0.001%-0.003% of Ca, and the balance of Fe and unavoidable impurities. Based on an alloyed component system of medium C, low Si, high Mn, ultralow AlA and high V with metallurgical technical control, RCR-NT (recrystallization controlled rolling-normalized tempering) processes are optimized, the microstructure of the finished steel plate includes even and small ferrite, pearlite and trace granular bainite, average grain size of the ferrite is smaller than 15 micrometers, even and fine match of high toughness and high plasticity is obtained, and the steel plate has extremely fine low-temperature toughness. The steel plate is especially applicable to large-sized steel structured containers, such as bearing components, petroleum storage tanks, mobile tankers and the like.

The invention discloses a corrosion-resistant high-strength pearlite steel rail and a preparation method thereof, and belongs to the technical field of metallurgy. The steel rail comprises the following chemical components of, in percentage by mass, 0.65%-0.80% of C, 0.45%-0.85% of Si, 1.0%-1.5% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.68%-0.95% of Cr, 0.03%-0.06% of Nb, 0.8%-1.6% of Cu, 0.002%-0.006% of B, the balance Fe and unavoidable impurities. The steel rail is prepared through the processes of molten iron pretreatment, converter smelting, refining,vacuum treatment, continuous casting, rolling, online heat treatment and the like. According to the the steel rail designed by the preparation method, the room-temperature structure is fine lamellar pearlite and a small amount of ferrite, the lamellar spacing of the pearlite is 90-120nm, the tensile strength Rm is 1280-1350 MPa, the elongation A is 11%-13%, the tread hardness is 360-390 HB, and the room-temperature impact energy AKU is greater than 20 J.

The invention discloses a 440 MPa-grade continuous-annealed and cold-rolled structural steel plate and a production process thereof. The steel plate comprises the following components in percentage by mass: 0.06-0.12% of C, 0-0.10% of Si, 1.25-1.50% of Mn, 0.002-0.006% of N, 0-0.025% of P, 0-0.010% of S, 0.015-0.050% of Als, and the balance of Fe and unavoidable impurities, as well as ferrite with a volume ratio of 90-95% and pearlite with a volume rate of 5-10%; and the production method of the steel plate comprises the steps of continuous casting, hot rolling, cooling, coiling, cold rolling, continuous annealing and the like. According to the steel plate and the production process thereof disclosed by the invention, a 'low C-low Si-Mn' micro-alloying process thought is adopted in combination with techniques such as external refining, a controlled rolling and controlled cooling process, a process for controlling a relatively low cold rolling reduction ratio, a process of continuous annealing in a two-phase region, and the like, a fine-grained ferrite and pearlite structure containing cold-rolled structural steel plate is obtained.

The invention provides a high-strength electric resistance welding casing pipe and a manufacturing method thereof. The casing pipe comprises, by weight percentage, 0.26-0.30% of C, 0.15-0.30% of Si, 1.30-1.60% of Mn, less than or equal to 0.020% of P, less than or equal to 0.008% of S, 0.010-0.030% of Ti, 0.02-0.05% of Als, 0.36-0.46% of Cr, less than or equal to 0.008% of N and the balance Fe and inevitable elements. The manufacturing method comprises the steps of smelting and continuous casting, reheating of a casting blank, rolling, cooling, reeling, pipe manufacturing conducted through ERW and heat treatment conducted on the whole pipe, wherein hot continuous rolling is conducted after heating is completed, the finish rolling temperature is 840-900 DEG C, and a rolled steel strip is cooled at the cooling speed of 5-10 DEG C/s and reeled at the temperature of 630-680 DEG C; and after pipe manufacturing conducted through ERW is completed, the whole pipe is heated to 880-940 DEG C, the temperature is preserved for 60-80 minutes, and water cooling is conducted. According to the high-strength electric resistance welding casing pipe and the manufacturing method thereof, medium carbon and Cr-containing design is adopted, and alloy cost is low; the plate roll structure in the hot-rolling state is ferrite-pearlite, and subsequent pipe manufacturing and formation can be conducted easily; and the whole pipe is subjected to quenched-tempered heat treatment, the final structure is tempered sorbite, the casing pipe is at the level of P110 in performance, and performance consistency of a pipe body and welding seams is guaranteed.

The invention relates to an ultrathin-specification broad hot strip with the tensile strength as 600MPa and a producing method thereof. The ultrathin-specification broad hot strip comprises the chemical components, by weight percentage, of 0.06-0.10% of C, smaller than or equal to 0.30% of Si, 0.90-1.10% of Mn, smaller than or equal to 0.020% of P, smaller than or equal to 0.015% of S, 0.030-0.050% of Nb, 0.01-0.03% of Ti, 0.010-0.045% of Als, the balanced of Fe and unavoidable impurity elements. The producing method comprises the steps of smelting of molten iron through a rotary kiln, LF refining, continuous casting of slabs, slab heating, scale removal through high-pressure water, controlled rolling, controlled-rolling cooling and winding. The ultrathin-specification broad hot strip can be manufactured through the steps of the producing method. The thickness of the broad hot strip is reduced to 1.2mm, the tensile strength of the broad hot strip is larger than 600MPa, the yield strength of the broad hot strip is larger than 500MPa, and the elongation of the broad hot strip is larger than 30%. The organization of the broad hot strip is ferrite and pearlite, the ferrite occupies about 10%, and the grain size of the broad hot strip is larger than or equal to grade 12. The broad hot strip is mainly used as a high-intensity cold-bent structural member, and the structural self weight and the raw material cost are greatly reduced.

This invention provides a steel wire rod/steel bar having excellent cold forgeability. This steel wire rod/steel bar is provided with a predetermined chemical component composition in the condition immediately after hot rolling, wherein the depth d (mm), from the surface, of a surface layer region having a mean hardness HV0.2 that is at least 20 higher than the mean hardness HV0.2 of the region from the cross-section radius (R)×0.5 (mm) to the center satisfies formula (1); the steel structure of the surface layer region comprises ferrite in a fraction of 10% or less by area ratio, with the balance being made up of one or more types of steel structure from amongst martensite, bainite, and pearlite; the steel structure from the cross-section radius (R)×0.5 (mm) to the center is a ferrite-pearlite or ferrite-bainite steel structure; and the surface roughness (Ra) in the circumferential direction when scales adhering to the surface have been removed is equal to or less than 4 mum.

The invention discloses carbon manganese low-temperature steel for a liquefied gas boat and a manufacturing method of the carbon manganese low-temperature steel. The carbon manganese low-temperature steel comprises, by weight, 0.03%-0.08% of C, 0.10%-0.30% of Si, 0.60%-1.30% of Mn, not larger than 0.015% of P, not larger than 0.005% of S, 0.010%-0.080% of Nb, 0.010%-0.060% of Al and the balance Fe and inevitable impurities. The clean steel smelting-continuous casting process is adopted in the method, and a high-purity homogenous continuous casting slab is manufactured; and through two-stage control rolling and control cooling, a wee ferrite and pearlitic structure is obtained. The carbon manganese low-temperature steel for the liquefied gas boat has the beneficial effects that the steel is pure, the texture is even, the grain size is in the 10.0 level to 13.5 level, and the ductile-brittle transition temperature is lower than -80 DEG C; building requirements of a cargo tank and a boat body structure of the liquefied gas boat are met; and meanwhile, the carbon manganese low-temperature steel has the beneficial effects of being simple in chemical component and low in cost.

The invention relates to medium-carbon low-alloy wheel steel for metro and a manufacturing method of the wheel steel. The medium-carbon low-alloy wheel steel is composed of the following chemical components in percentage by weight: 0.50-0.60% of C, 0.80-1.20% of Si, 0.90-1.10% of Mn, 0.15-0.35% of Cr, 0.010-0.030% of Als, less than or equal to 0.015% of P, less than or equal to 0.015% of S and the balance of Fe and inevitable impurity elements. The manufacturing method comprises an electric furnace smelting step, an ingot slicing and rolling step and a thermal treatment step. A wheel manufactured by use of the wheel steel is obviously improved in strength and hardness while the tenacity of the rim of the wheel basically keeps unchanged; the wear-resisting property of the wheel is effectively improved, and the probability of stripping and abrasion of the wheel in the use process is reduced. Meanwhile, the wheel manufactured by use of the wheel steel is capable of keeping the ferrite-pearlite structure state of the previous wheel without increasing the wheel manufacturing difficult.

A high-strength untempered steel for fracture splitting and a steel component for fracture splitting comprising C: 0.23-0.35%, Si: 0.70-1.30%, Mn: 0.76-1.17%, P: 0.040-0.080%, S: 0.040-0.118%, Cr: 0.05-0.20%, Al: 0.010% or less, V: 0.27-0.45%, N: 0.0050-0.0145%, by mass percent, and the remainder Fe and unavoidable impurities, and comprising a ferrite-pearlite structure wherein the values of the composition restraints for three components satisfy the prescribed values, hot rolling properties are ensured, and the ferrite fraction is at least 60% when air cooled or cooled with forced air after hot casting.

The invention relates to the technical field of hot-rolled ribbed steel bars, and discloses steel for a 635 MPa level high-strength hot-rolled steel bar. The steel is prepared from, by weight, 0.22-0.30% of C, 0.50-0.80% of Si, 1.40-1.60% of Mn, not larger than 0.025% of P, not larger than 0.025% of S, 0.015-0.035% of Nb, 0.105-0.145% of V, 0.15-0.35% of Cr, 0.018-0.025% of N and the balance Fe. According to the steel for the 635 MPa level high-strength hot-rolled steel bar and a machining method thereof, by adopting C, C is a cheap element, the strength of the steel can be remarkably improved, the extension performance of the steel can be lowered, meanwhile, the cold brittleness and aging sensitivity of the steel are improved, the integrated ingredients are reasonable, the comprehensive performance of the whole steel is improved, the stability of the steel performance is enhanced, the overall performance of the steel on the aspects of yield strength, tensile strength, the high yield ratio, the percentage elongation after fracture, the total elongation percentage under the maximum force and the like is good, meanwhile, the steel metallographic structure is ferrite+pearlite, the granularity is 11.5, the good fatigue resistance is achieved, the steel is suitable for large-scale industrial production, and benefits are remarkable.

The invention discloses a method for producing level 600MPa fine-grain high-strength aseismic reinforced bars, which comprises the following steps of firstly, detecting a steel billet and putting the steel billet into a furnace, wherein the steel billet comprises the following chemical compositions in percentage by mass: 0.24-0.28% of carbon, 0.62-0.80% of silicon, less than 1.30% of manganese, less than 0.035% of phosphorus, less than 0.035% of sulfur, 0.10-0.20% of vanadium, 0.20-0.50% of chromium, and the balance of iron; then, heating the steel billet by using a heat furnace, and rolling the steel billet by using a bar mill; enabling the obtained object to pass through water so as to control the obtained object to be cooled; naturally cooling by using a cooling bed, shearing, finishing and warehousing. In the method for producing level 600MPa fine-grain high-strength aseismic reinforced bars, chrome and vanadium microalloyed components are adopted, so that a V (C, N) compound is formed in steel by using vanadium, thereby greatly increasing the strength of the steel; meanwhile, a certain amount of chromium is added, so that the aseismic performance of reinforced bars is obviously improved, and finally, the mechanical performance index of the reinforced bars meets the level 600MPa fine-grain high-strength aseismic requirements. The metallographic structure of each reinforced bar is as follows: an edge part and a core part are respectively of ferrite and pearlite as well as bainite and edge tempered structure having no influence on usability.

A non-heat treated connecting rod which comprises, by mass %, C: 0.25-0.35%, Si: 0.50-0.70%, Mn: 0.60-0.90%, P: 0.040-0.070%, S: 0.040-0.130%, Cr: 0.10-0.20%, V: 0.15-0.20%, Ti: 0.15-0.20% and N: 0.002-0.020%, and the balance Fe and impurities, with chemical compositions being less than 0.80 in the value of C+(Si/10)+(Mn/5)+(5Cr/22)+1.65 V−(5S/7) using the symbol of the element as its content, the microstructure of the Big end of the said connecting rod being ferrite-pearlite, all-region hardness of the said big end being 255 to 320 in Vickers hardness, the ferrite-region hardness in the said ferrite-pearlite of the Big end being 250 or more in Vickers hardness and the ratio of the said ferrite-region hardness to the said all-region hardness of the said Big end being 0.80 or more, is excellent in machinability, fracture splitting ability, and fatigue resistance, although no Pb at all is added. Therefore, this non-heat treated connecting rod can be utilized as a low cost type connecting rod in automobile engines or the like.

The invention relates to a Mo-containing steel plate being high in high-temperature strength and good in low-temperature impact toughness. The steel plate comprises the following chemical components in percentage by mass: 0.14-0.18% of C, 0.25-0.35% of Si, 0.75-0.85% of Mn, 0.25-0.35% of Mo, 0.02-0.05% of Al, no more than 0.012% of P, no more than 0.05% of S, no more than 0.20% of Cu, no more than 0.20% of Cr, 0.20-0.30% of Ni, 0.010-0.020% of Nb and/or 0.010-0.025% of Ti, and the balance of Fe and inevitable impurities, wherein the following carbon equivalent (Ceq) formula is met: Ceq = [C + Mn]/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15]*100%, that is, the Ceq ranges between 0.36 and 0.40. A technological manufacturing process of the steel plate comprises the following steps: blowing in a converter; LF refining; vacuum degassing; continuous casting; primary slow cooling; heating; rolling; cooling control; secondary slow cooling; heat treatment; fine inspection; flaw detection; performance examination; and packaging and warehousing. The steel plate provided by the invention is relatively high in high-temperature strength; meanwhile, the low-temperature impact toughness is relatively good, the Ceq is relatively low and the welding performance is good; and the steel plate adopts a ferrite-pearlite structure, and is delivered in the normalized state.

The invention relates to the field of steel wire rod hot rolling, in particular to a rolling method of a high-strength car spring steel wire rod. The rolling method comprises the procedures of steel blank heating, controlled rolling and controlled cooling. In the heating procedure, the heating temperature of a steel blank in a heating furnace is 1000 to 1080 DEG C, the total heating time is 70 to150 min, the remaining oxygen of the heating furnace is smaller than or equal to 3.0%, in the controlled rolling procedure, the wire rod finish rolling temperature is 850 to 980 DEG C, the spinning temperature is 850 to 950 DEG C, in the controlled cooling procedure, the wire rod after spinning is rapidly cooled to 780 DEG C, the cooling speed C1 is controlled to 5.0 to 10.0 DEG C/s, when the wirerod is from 780 DEG C to 600 DEG C, the average cooling speed C2 is controlled to 0.5 to 4.0 DEG C/s, the obtained wire rod is of a ferrite + pearlite + sorbite structure, and the surface is free offull decarburization.

The invention relates to a steel tempering process, in particular to a quick normalizing heat treatment method for Q345R steel, which comprises the following steps of: heating: making a steel plate enter a furnace with the temperature of 750 DEG C from a room temperature state, calculating the heating time according to unit thickness temperature equilibrium time of 0.8-1.1 min/mm, and segmentally heating to the target temperature of 910 DEG C, or uniformly setting temperature control areas of a scale-free roller-type heat treating furnace as 910 DEG C and making the steel plate directly enters the furnace with the temperature of 910 DEG C; keeping the temperature: after the steel plate is heated to 910 DEG C, and calculating the holding time according to unit thickness temperature equilibrium time of 0.8-0.9 min/mm for keeping the temperature; and cooling: cooling to room temperature. On the premise of ensuring that various properties meet requirements, the heating time and the holding time are shortened, the heat treatment capacity is improved, and problems that normalizing warmup time is too long so as to make various mechanical properties of steel meet requirements and ferrite-pearlite zonal textures refined, the capacity is lower and the like in the prior art are solved.

The present invention provides a low-carbon resulfurized free machining steel product excellent in machinability typified by finished surface roughness even though toxic Pb or special elements such as Bi or Te are not added, and a suitable production method thereof. A steel product has a specific composition, has contents of Mn and S satisfying the following conditions: 0.40 Mn*S 1.2 and Mn/S 3.0, and contains a ferrite-pearlite structure as the metallographic structure, in which the average width ( m) of sulfide inclusions in the steel product is 2.8* (log d) or more, wherein d (mm) is the diameter of the steel product, and pro-eutectoid ferrite in the metallographic structure has a hardness HV of 133 to 150 or a difference in deformation resistance at a strain of 0.3 between 200 DEG C and 25 DEG C is 110 MPa or more and 200 MPa or less, the deformation resistances being determined in a compression test at a deformation rate of 0.3 mm/min.

The invention provides a device and a technique for processing a rope drill rod in a medium-frequency induction way, and solves the problems of low production efficiency, poor evenness of integral heat treatment of the drill rod, and low energy utilization rate in the traditional heat treatment techniques for producing long steel pipes. The device mainly comprises a quenching induction coil, a quenching spraying cooling water loop, a tempering induction coil, a tempering spraying water loop and a variable-frequency adjustable-speed roller way. The technique is realized in a way that: using a production mode of section-by-section advance continuous induction heating; and quickly heating to the austenite temperature before quenching the drill rod, thereby forming an ultrafine martensitic structure during quenching and forming a fine-grain ferrite-pearlite structure during normalizing. Since the induction heating has the advantage of short tempering time, the precipitated small-grain carbides can be evenly distributed on the fine-grain martensitic substrate. The invention carries out the section-by-section advance continuous heating by utilizing the electromagnetic induction of the medium-frequency current, and can simultaneously carry out the quenching and the tempering. The invention ensures the heat treatment evenness of the drill rod body and achieves the goal of enhancing the comprehensive mechanical properties of the drill rod.

The invention discloses a preparation method of Q460 hot rolled round steel for a rare earth low-temperature-resistant automobile part. A steelmaking process flow of the preparation method comprises converter- external refining-VD vacuum treatment-continuous casting; and a steel rolling process flow comprises casting blank heating-high pressure water dephosphorization-Q850 mm cogging mill-phi700 mm*3+phi550 mm*4 continuous rolling mill rolling-saw cutting-slow cooling- nondestructive testing-stacking-examination-coping-bundling- putting in storage-delivery. The control technical parameters inthe rolling process are as follows: the heating temperature is 1200-1250 DEGC, the insulating time is greater than or equal to 2.5 hours, the opening rolling temperature is smaller than or equal to 1150 DEG C, the finishing temperature is smaller than or equal to 850 DEG C, and the slow cooling time is greater than or equal to 48 hours. Rolled tissues are ferrite+pearlite tissues. The invention aims to provide the preparation method of Q460 hot rolled round steel for the rare earth low-temperature-resistant automobile part. Delivered in a hot rolled state, a complex thermal treatment process is not needed, so that the preparation method has a relatively wide process window.