103 results about "Pearlite" patented technology

The present application belongs to the field of rail material research and manufacturing, and specifically discloses a rail structure for a subway humid environment. According to the distribution of pearlite lamellar spacing, the rail head cross-section structure can be divided into cap layer 1, cap layer 2, cap layer 3 and base material layer. The pearlite lamellar spacing distribution of cap layer 1 is 130-150 nm, the pearlite lamellar spacing distribution of cap layer 2 is 90-120 nm, the pearlite lamellar spacing distribution of cap layer 3 is 140-170 nm, and the pearlite lamellar spacing distribution of the base material layer is 200-230 nm. The present application designs cap-shaped structures with different depths and different pearlite lamellar spacing in the rail head. By accelerating the cooling speed of the heat treatment of the hot-rolled rail in different stages, the reasonable gradient structure distribution of the pearlite structure of the rail material is realized, the expansion speed of the rolling contact fatigue crack of the rail in the humid environment to the internal material is effectively slowed down, the rolling contact fatigue damage is reduced, and thus the comprehensive performance and service life of the rail are improved.

A hot-rolled steel sheet is provided comprising a predetermined chemical composition and a metallic structure comprising, in area ratio, pearlite: 90 to 100%, pseudo-pearlite: 0 to 10% and pro-eutectoid ferrite: 0 to 1%, wherein the pearlite has an average lamellar spacing of 0.20 µm or less, and the pearlite has an average pearlite block size of 20.0 µm or less.A method is provided for producing a hot-rolled steel sheet comprising heating a plate to 1100°C or more, rolling it by hot rolling, wherein a finish roll exit side temperature is 820 to 920°C, cooling the steel sheet by primary cooling to a point Ae1 by an average cooling rate of 40 to 80°C / s, then cooling the steel sheet by secondary cooling from point Ae1 to a coiling temperature at an average cooling rate of less than 20°C / s, and coiling the steel sheet at a coiling temperature of 540 to 700°C.

A process for manufacturing compact coils of ultra-fine grained martensite-free steel bars, the process comprising the following phases: a) rolling a billet by means of a roughing mill (1) of the steel bar; b) performing at least one first cooling stage (2) so that the steel bar has a surface temperature higher than the martensite start temperature (Ms) and at least one first equalization stage in air; c) rolling the steel bar by means of at least one intermediate mill (3); d) performing at least one second cooling stage (4) always keeping the surface temperature higher than the martensite start temperature (Ms) and at least one second equalization stage in air; e) rolling the steel bar by means of a finishing mill (5) in the non-recrystallization temperature range, keeping the entire cross section of the steel bar in said non-recrystallization temperature range and wherein the total reduction is between 25% and 50% with respect to the cross section of the steel bar at the inlet of the finishing mill, so as to obtain an ultra-fine grained austenitic matrix; f) winding the steel bar into compact coils by means of at least one winding device (7) so that the ultra-fine grained austenitic matrix transforms into a mixture of ferrite and pearlite. After the winding operation is completed, the compact coils can be conveyed to a storage area by means of a conveying device (8), for example a walking beam, in which the coils are subjected to natural cooling or forced cooling or delayed cooling.

This invention discloses a process for improving the hardenability of wind turbine main shafts during heat treatment, comprising the following steps: heating 42CrMo4 steel ingots to 1180~1220℃ for forging, with a forging ratio ≥4; air-cooling the forgings to 650~700℃ for the first time before loading them into a furnace, holding them at 300~350℃, then raising them to 640~660℃ for a second holding, with the holding time determined by the effective thickness × 1.5min / mm, followed by cooling to room temperature; vertically loading the forgings into tooling and heating them to 8... The surface is held at 40~860℃ for 1.2~1.5 min / mm (effective thickness × 1.2~1.5 min / mm) until the surface temperature drops to 780~800℃. Then, it is quenched in PAG solution within 3 minutes of quenching. After quenching, it is transferred to a tempering furnace and heated to 300℃ at a rate of ≤80℃ / h, held, and then heated to 540~580℃ at a rate of ≤100℃ / h, held for 2.0~2.5 min / mm (effective thickness × 2.0~2.5 min / mm). After tempering, it is cooled at a rate of ≤50℃ / h. This invention refines grains and carbides through forging and upsetting processes, controls pearlite cluster size through normalizing, and improves cooling uniformity through a density-layered dual-medium system during quenching. This method is suitable for improving the hardenability of large cross-sections in high-power wind turbine main shafts.

The present application relates to the technical field of rail production process, in particular to a production method for improving wear resistance of channel rail for tram. After universal rolling, compressed air is applied to the channel rail for forced cooling in parts. In the first stage, supersonic air jet cooling is applied to the rail head tread, rail head running edge, rail head left side, rail lip and rail bottom to control the cooling speed of each part. In the second stage, supersonic air jet cooling is continuously applied to each part of the rail to control the cooling speed of each part. In the third stage, subsonic air jet cooling is applied to each part of the rail to control the cooling speed of each part, and then the rail is naturally cooled in air. The quenching effect of the channel rail tread and running edge is improved, the pearlite interlamellar spacing is refined, the rail strength and hardness are improved, and the channel rail has good wear resistance.

The present invention provides a welded structure having excellent heat-affected zone (HAZ) toughness and suppressed strength inhomogeneity in the HAZ, and a steel plate from which such a welded structure can be obtained. [Solution] The steel sheet according to this disclosure has the chemical composition described in the specification, wherein f1 as defined by formula (1) satisfies 0.35 to 0.47, f2 as defined by formula (2) satisfies 0.21 or less, and in the central part of the thickness of the steel sheet, the microstructure consists of 28.0 to 45.0% ferrite, 0 to 15.0% pearlite, 0.01 to 5.00% MA structure, and the remainder being bainite, with a dislocation density of 0.7 × 10 14 ~3.0×10 14 m -2 It satisfies the condition. f1=C+Mn / 6+Si / 24+Ni / 40+Cr / 5+Mo / 4+V / 14 (1) f2=C+Si / 30+Mn / 20+Cu / 20+Ni / 60+Cr / 20+Mo / 15+V / 10+5B (2)

The invention discloses a high-toughness corrosion-resistant pearlite steel wire with an adjustable honeycomb structure characteristic as well as a preparation method and application of the high-toughness corrosion-resistant pearlite steel wire, and belongs to the technical field of pearlite steel wire processing. The surface of the steel wire is provided with an aluminum alloy coating which is metallurgically bonded with a base body and has the thickness of 8-10 microns; the steel wire is subjected to ultrasonic treatment to generate a structure with a honeycomb characteristic, and the obtained cementite lamella serves as a hard phase to form a regular'honeycomb wall ', so that a core supporting effect is achieved; the ferrite serving as a plastic phase is coordinated and deformed under the action of external force by forming a honeycomb unit with uniform size, so that more energy is absorbed and crack propagation is hindered; and an Al2O3 protective film is instantaneously formed on the surface of the aluminum alloy coating, so that the aluminum alloy coating has excellent corrosion resistance and better mechanical properties. The Vickers hardness of the aluminum alloy reaches up to 830-850 HV < 0.1 >, the tensile strength of the aluminum alloy reaches 3100-3200 MPa, and the ductility of the aluminum alloy reaches 16-20%.

The present invention provides a welded structure having excellent HAZ toughness and suppressed strength heterogeneity in the HAZ, and a steel plate from which such a welded structure can be obtained. [Solution] The steel sheet according to this disclosure has the chemical composition described in the specification, and f1 as defined by formula (1) satisfies 0.35 to 0.44, and f2 as defined by formula (2) satisfies 144 or more, and in the central part of the thickness of the steel sheet, the microstructure consists of less than 20 to 50% ferrite by area %, 0 to 5.0% pearlite, 0 to 5.0% MA structure, and the remainder being bainite, and the dislocation density is 0.70 × 10 14 ~3.00 x 10 14 m -2 It satisfies the condition. f1=C+Mn / 6+Si / 24+Ni / 40+Cr / 5+Mo / 4+V / 14 (1) f2=119+55Cu+27Ni+49Cr+95Mo (2)

The present invention provides a welded structure having excellent heat-affected zone (HAZ) toughness and suppressed strength inhomogeneity in the HAZ, and a steel plate from which such a welded structure can be obtained. [Solution] The steel sheet according to this disclosure has the chemical composition described in the specification, where f1 as defined by formula (1) is 0.35 to 0.40, f2 as defined by formula (2) is 120 or more, the microstructure in the center of the thickness of the steel sheet consists of 50 to 65% ferrite, 0 to 15% pearlite, 0 to 5.0% MA structure, and the remainder being bainite, and the ratio Rρ of the dislocation density ρ2 in the center of the thickness of the steel sheet to the dislocation density ρ4 in part t / 4 of the steel sheet, as defined by formula (3), is 0.60 to 1.00. f1=C+Mn / 6+Si / 24+Ni / 40+Cr / 5+Mo / 4+V / 14 (1) f2=119+6C+55Cu+27Ni+49Cr+95Mo (2) Rρ = ρ² / ρ₄ (3)

This invention relates to a steel for automobile engine pistons and its manufacturing method. The chemical composition of the steel, by weight percentage, is: C: 0.41–0.47%, Si: 0.15–0.35%, Mn: 0.70–1.00%, Cr: 1.10–1.40%, P: ≤0.020%, S: 0.015–0.035%, Mo: 0.17–0.27%, Al: 0.010–0.030%, N: 0.0040–0.0060%, with the balance being Fe and unavoidable impurities. The microstructure consists of ferrite and pearlite, with uniform distribution of ferrite and pearlite structures. The geometric center distance between each ferrite and pearlite structure is 15–30 μm. The hot-rolled hardness of the steel is ≤230 HBW, and the banded structure in the steel is ≤1.5 grade. The product features a narrow range of carbon deviation in cross-section, shallow decarburized layer and microcrack depth on the steel surface, low hot-rolled hardness, good banded structure, and high tensile strength after quenching and tempering.

A wire rod according to the present invention comprises, in weight%, 0.10-0.30% of C, 0.05-0.30% of Si, 1.0-2.0% of Mn, 0.03-0.20% of Ti, 0.01-0.04% of Al, 0.001-0.020% of N, 0.1% or less of P, 0.1% or less of S, and the remainder of Fe and inevitable impurities, has a microstructure including ferrite in an area fraction of 60-95% and the remainder pearlite, and includes Ti-based carbide having an average size of 2-10 nm.

This invention discloses a segmented controlled-cooling crystallizer for duplex rolls, belonging to the field of electroslag remelting technology. It includes a casting box with a central quenching zone for generating martensite and two side cooling zones for generating pearlite. A water tank has a cooler and a water pump connected to its two ends, respectively. The cooler and water pump are connected to the casting box via a return pipe and an inlet pipe, respectively. The water flow rate in the inlet pipe is controlled according to the water temperature change in the return pipe. The duration of a specific water flow rate in the inlet pipe is also controlled according to the water temperature change. This device achieves segmented controlled cooling through the quenching and cooling zones, resulting in martensite formation on the roll body and pearlite formation on the roll neck, thus differentiating the duplex structure. Furthermore, it adjusts the pump current and inlet duration according to water temperature changes, adaptively matching the cooling intensity to ensure sufficient phase transformation time in both the quenching and cooling zones, thereby achieving precise control of the duplex structure.

This invention belongs to the field of metal welding technology and relates to a heat treatment method for hypereutectoid rail steel after flash welding, comprising the following steps: post-weld cooling: the welded joint is allowed to cool naturally in air after flash welding; normalizing treatment: the welded joint is heated to a normalizing temperature above the austenitizing temperature and held at that temperature; controlled cooling: the temperature of the weld heat-affected zone of the welded joint is cooled from the normalizing temperature to the isothermal transformation temperature within the pearlite phase transformation temperature range at a first cooling rate, held at that temperature until the austenite undergoes pearlite transformation, and then the welded joint is cooled from the isothermal transformation temperature to below 200°C at a second cooling rate lower than the first cooling rate. The method of this invention can effectively eliminate the network cementite structure in the flash welding heat-affected zone, while avoiding the introduction of harmful structures such as martensite or bainite, ensuring that the microstructure of the weld heat-affected zone is pearlite with fine lamellar spacing.

This steel sheet is characterized by having a desired chemical composition, wherein: at a position corresponding to 1 / 4 of the sheet thickness, the average value of the aspect ratios of prior austenite grains is 3.0-10.0, the area ratio of bainite is 70-95%, the total area ratio of martensite and retained austenite is 5-30%, the area ratio of pearlite is less than 5%, and the area ratio of ferrite is at most 15%; and in a surface layer region, the average value of the equivalent circle diameters of martensite and retained austenite is at most 3.0 μm, and the area ratio of ferrite is at least 10%. This component is manufactured using said steel sheet.

The object of this invention is to provide a high-strength hot-rolled flat steel product and a method for producing such a flat steel product, thus achieving a combination of high strength with high local cold formability and high economy in terms of steel. This is achieved through a high-strength hot-rolled flat steel product with high local cold formability, having a tensile strength Rm of at least 760 MPa, a yield strength ratio of at least 0.8, and a porosity of at least 30%, advantageously at least 40%, particularly advantageously at least 50%, at least 10%, preferably at least 16%, an elongation at break of at least 0.12, advantageously at least 0.17, and a ratio of local cold formability to overall cold formability of at least 5 and at most 13, and a microstructure consisting of more than 50% (by volume) bainite, no more than 10% (by volume), advantageously no more than 5% (by volume) carbon-rich microstructure such as martensite, retained austenite, pearlite, etc. The steel has a ferrite-based microstructure and the following chemical composition (wt%): C: 0.04–0.08; Si: 0.1–0.6; Mn: 1.0–2.0; P: maximum 0.06; S: ​​maximum 0.01; N: maximum 0.012; Al: not more than 0.06; Ti: not more than 0.18 and / or Nb: not more than 0.08; Mo: not more than 0.35; Ti+Nb greater than 0.06, wherein carbon and nitrogen exist in excess of stoichiometry according to the following formula: 1.0 < (C / 12 + N / 14) / (Ti / 48 + Nb / 93 + Mo / 96), the remainder being iron, including unavoidable steel-related elements.

The application provides a kind of anti-thermal damage heavy load wheel steel and wheel, wheel production method and application, composition: C 0.67-0.70%, Si 0.90-1.00%, Mn 0.80-0.90%, P≤0.015%, S 0.006-0.015%, V 0.05-0.15%, Cr 0.20-0.30%, N 0.0050-0.0100%, the rest is Fe and inevitable impurity element;Compared with prior art, by the reasonable control of C, Mn, Si, Cr, V element, the quenching heating temperature formula is designed, the heat treatment method of flow increment type quenching, constant flow quenching, obtains ideal fine pearlite + ferrite structure, not only the rim mechanical property level is higher, effectively improves the wear resistance of wheel, and improves the toughness of wheel, enhances the anti-thermal damage ability of wheel.

According to one embodiment of the invention, the wire for securing a wind turbine comprises, by weight percent: 0.20% to 0.40% C, 0.10% to 0.40% Si, 0.30% to 0.50% Mn, 1.00% to 1.50% Cr, 0.01% to 0.10% Ti, and 0.0005% to 0.0100% B, with the remainder being Fe and other unavoidable impurities. The microstructure after hot rolling comprises, by area fraction, 30% to 60% pearlite and 40% to 70% ferrite, and satisfies the following formula (1). Formula (1): (where [C], [Mn], and [Cr] represent the weight percent of each element).

The wire according to the present disclosure contains, by weight %, 1.00 to 1.20% of C, 1.00 to 1.50% of Si, 0.10 to 0.50% of Mn, 0.30 to 0.80% of Cr, and 0.50 to 1.50% of Al, the balance of Fe and other unavoidable impurities, wherein the microstructure observed at a cross section of 1 / 2D to 3 / 2D (D: diameter) contains 95% or more of pearlite and 5% or less of blocky pro-eutectoid cementite having an average thickness of 1 μm or more in a region of 100 μm 2 2.

A method for controlling the work hardening of hot-rolled bucket tooth steel, comprising the following steps: blank heating and cogging; rough rolling and intermediate rolling; precision rolling temperature control rolling; cold bed heat preservation cover slow cooling; cold bed temperature field dynamic regulation and control; pit slow cooling; the round steel after the cover is transferred to the slow cooling pit and covered with heat preservation material to slowly cool to room temperature. The application controls the final rolling temperature of the precision rolling to be stable at 800-860 DEG C, the cooling rate of the cold bed is less than or equal to 0.3 DEG C / s, promotes the full formation of pearlite and ferrite soft structure, effectively inhibits the generation of hard and brittle structures such as bainite and martensite, and stably controls the hardness of the hot-rolled product to be 230-260 HBW, the hardness overproof rate is reduced to less than or equal to 5%; at the same time, the customer tool wear rate is reduced by more than 40%, the processing efficiency is improved by more than 30%, the additional annealing process is saved, the cost per ton is saved by 200-300 yuan, the cycle is shortened by more than 24 hours, and the hardness dispersion of the same batch is less than or equal to 1.5 HRC.

This invention discloses wire, steel wire, and a method for manufacturing the same. The wire according to the invention comprises, by weight %: C: 0.60~1.00%, Si: 0.1~0.4%, Mn: 0.2~0.6%, Cr: less than 0.3% (inclusive), and the balance Fe and other unavoidable impurities, having a fine microstructure comprising pearlite, wherein the average interlamellar spacing L (in μm) of the pearlite is controlled within a specific range with respect to carbon equivalent (Ceq).

The application discloses a heat treatment method for improving the width uniformity of a heat affected zone of a rail welded joint, and the method comprises the following steps: moving a rail through flash welding to obtain a welded rail; naturally cooling the welded joint of the welded rail to room temperature; using an electric induction coil to perform full-section induction heating on the welded joint; controlling the width of the heating area of the rail welded joint by using a cooling device during the heating process; and immediately spraying air to cool after heating to a predetermined temperature. The heat treatment method mainly aims at the technical problems that the width of the heat affected zone of the rail flash welded joint after post-weld heat treatment is not uniform, the width of the heat affected zone is too large, and the use performance and driving safety of the rail are affected. After the method is used, a pearlitic rail flash welded joint with high comprehensive performance, high uniformity of the width of the heat affected zone and small width of the heat affected zone is finally obtained.

A steel plate made of steel having the following composition, wherein the composition comprises C: 0.3% to 0.4%, Mn: 0.5% to 1.0%, Si: 0.4% to 0.8%, Cr: 0.1% to 1.0%, Mo: 0.1% to 0.5%, Nb: 0.01% to 0.1%, Al: 0.01% to 0.1%, Ti: 0.008% to 0.03%, B: 0.0005% to 0.003%, P ≤ 0.020%, Ca ≤ 0.001%, S ≤ 0.004%, N ≤ 0.005%, and optionally Ni < 0.5%, the steel plate having a microstructure comprising 60% to 95% ferrite by surface fraction, the remainder being martensite-austenite islands, pearlite, or bainite, and comprising a bulk and a surface layer occupying the outermost 10% thickness on both sides of the bulk, the surface layer having an oxide surface fraction equal to or less than 60 × 10⁻⁶. ‑6 Surface inclusions.

The present invention provides: a thin steel sheet which has excellent formability; a member; and production methods thereof.　Provided is a thin steel sheet which has a component composition containing specific amounts of C, Si, Mn, P, S, Al, N, Cu, Ni and Sn, and satisfying formula (1) and formula (2), with the balance being made up with Fe and inevitable impurities, and which has a steel structure containing, by area ratio, 60-98% of ferrite and 2-35% of pearlite, and having an average crystal grain diameter of ferrite of 5 µm to 35 µm inclusive and an average crystal grain diameter of pearlite of 15 µm or less, wherein the precipitation density of MnS having an equivalent circle diameter of 5 µm or more is 100 per mm2 or less. Formula (1): 0.10 × (%Cu) + 1.5 × (%Sn) ≤ (%Ni) ≤ 5.0 × (%Cu) + 75 × (%Sn) Formula (2): (%Mn) × (%S) / (0.5 × (%Cu) + (%Sn)0.5) ≤ 1.00

This invention discloses a high-modulus ductile iron, composed of the following raw material components by mass percentage: C: 3.2%~3.9%, Si: 2.1%~2.7%, Cu: 0.5%~2.0%, Mn: 0.2%~2.0%, Cr: 0%~0.5%, Mg: 0.01%~0.05%, RE: 0.01%~0.03%, with the balance being Fe. The total mass percentage of all the above components is 100%, and the total addition of Mn and Cr is not higher than 2.0%. This invention also discloses a method for preparing the high-modulus ductile iron and its applications. The ductile iron of this invention promotes the formation of pearlite and significantly refines the pearlite lamellae due to the Cu element. After the lamellae spacing is reduced, the interface area between ferrite and cementite increases, which can effectively hinder dislocation slip and improve strength. At the same time, the deformation of ferrite lamellae is restricted to a short distance, the stress distribution is uniform, and local excessive deformation and fracture are avoided, so that the cast iron can maintain high elongation under high strength.

This invention belongs to the field of metallic materials technology, and provides a low-temperature environment, preheat-free, high-strength ship plate and its manufacturing method. It employs a low-carbon, low-manganese chemical composition system to reduce the carbon equivalent of the steel plate and the segregation tendency of the continuously cast billet. Microalloying elements such as V-N and Ti are added to refine the grain size, precisely controlling the (Ti+V) / N ratio. The microstructure includes ferrite, tempered sorbite, and dispersed pearlite, with ferrite comprising 55.0%~70.0%, tempered sorbite 20.0%~30.0%, and pearlite 9.0%~20.0%, and the average size of the precipitated phases is 40~60 nm. The ship plate steel produced using this invention has a yield strength of 400~470 MPa, a tensile strength of 530~580 MPa, an elongation after fracture ≥28.0%, an impact energy at -80℃ ≥270 J, a tensile strength of 560~580 MPa after welding at -10℃, and an impact energy at -60℃ ≥170 J in the heat-affected zone.

The utility model discloses annealing equipment, include: annealing furnace, air inlet pipe, fixedly inserted in the bottom of annealing furnace, the circumferential surface of air inlet pipe is equipped with multiple groups along the axial distribution's through -hole no. 2, the air inlet pipe has the screw rod of coaxial rotation and inserts, the utility model discloses the cooperation of fan, series heat exchange pipe and water tank baffle, forms multistage cooling system, and high -temperature gas is fully heat exchanged with cooling medium in heat exchange pipe, and baffle prolongs cooling medium flow path, and the heat exchange efficiency is greatly promoted, realizes the step -by -step reduction of gas temperature, simultaneously, the design of air inlet pipe screw rod and plugging piece can quantize the opening area of through -hole no. 2, and the input of low -temperature gas is controlled, thereby realizes the multi -stage cooling curve of " heat preservation slow cooling fast cooling", matches austenite decomposition, pearlite transformation etc. Phase change demand in material annealing process, effectively avoids the material performance defect caused by improper cooling.

The present application relates to the technical field of steel material preparation, in particular to a high-hole-expanding-rate fine-grain 380MPa-grade hot-rolled pickling low-alloy high-strength steel and a preparation method thereof.The chemical composition of the steel material contains elements such as C, Si, Mn, Nb, Ti, Cu and Ni, and satisfies Ti / N=3.2-4.8, (Nb+Ti) / C=0.45-0.75 and Cu / Ni=2.5-3.5.The preparation method comprises molten iron pretreatment, converter smelting, LF+RH refining, continuous casting, slab heating, hot rolling, controlled cooling, coiling, flattening and pickling.The present application obtains fine-grain ferrite+pearlite structure through Ti-Nb-Cu-Ni composite micro-alloying and slab low-temperature heating process, and the product has high strength, excellent formability and good surface quality, while energy consumption and cost are reduced.