31results about How to "Increase Si content" patented technology

The invention discloses 800 MPa grade cold-rolled double-phase steel and a production method thereof. The production method comprises a hot rolling process and a cold rolling continuous annealing process. The chemical compositions of a casting entering the hot rolling process comprise, in percent by mass, 0.14-0.17% of C, 0.45-0.55 of Si, 1.6-1.8 of Mn, 0.55-0.65% of Cr, P<=0.016%, S<=0.008%, 0.02-0.05% of Als, N<=0.004%, and the balance Fe. In the double-phase steel, the Si content is increased and the Mn content is reduced on the basis of the compositions of C-Si-Mn-Cr, so that the strength is increased without adding Al, Nb, Mo, Ti and other high-cost elements, and the purposes of reducing production difficulty and production cost while not influencing smelting castability are realized. The method improves the Si content, reduces the Mn content, improves the composition system of the C-Si-Mn-Cr system and realizes the purpose of reducing production cost. By improving the smelting, hot rolling and cold-rolling continuous annealing technologies, the cold-rolled double-phase steel with the tensile strength of 800-850 MPa, the yield strength of 450-550 MPa and the elongation percentage of 15-17% is produced, and the production method has the characteristics of simple technology, low cost and stable product quality.

The invention discloses a method for producing ultra-low carbon steel on the basis of flexible thin slab casting (FTSC). The method includes the following steps of (1) molten iron desulfurization, (2) smelting with a converter, (3) Ruhstahl Hausen (RH) vacuum treatment and (4) FTSC. The ultra-low carbon steel comprises, by mass, 0-0.010% of C, 0.06%-0.35% of Mn, 0.12%-0.28% of Si, 0-0.020% of P, 0-0.020% of S, 0-0.09% of Ti, 0-0.0050% of N, and the balance iron and inevitable impurities. According to the method, the ultra-low carbon steel is produced through FTSC, the components, suitable for FTSC production, of the ultra-low carbon steel are redesigned, and ultra-low carbon steel continuous casting slabs meeting the performance requirement are produced by strictly controlling process parameters of all procedures of steel making.

The invention provides a plastic mold steel with excellent high-temperature strength and a preparation method thereof. The components of the mold steel are as follows by weight percentage: C: 0.30%-0.40%, Si: 1.10%-1.30%, Mn: 0.9% ‑1.1%, P≤0.015%, S≤0.015%, Cr: 10.0%‑11.0%, Mo: 0.42%‑0.60%, V: 0.1%‑0.2%, Ta: 0.10%‑0.20%, Co: 0.40% -0.60%, wherein, Mo+V+Ta=0.7%-0.9%, the balance is Fe and unavoidable impurities. The preparation method includes molten iron pretreatment—smelting—LF—RH—continuous casting—slab heating—rolling—straightening—slow cooling—normalizing—tempering; the hardness of the mold steel obtained by applying the present invention is 44-46HRC, which is the same as that of the slab. Difference ≤ 2HRC; Rm of the transverse core at room temperature ≥ 1460MPa; Rm of the transverse core at 500°C ≥ 710MPa; at the same time, this kind of mold steel has good acid corrosion resistance.

The invention discloses a 450MPa grade hot-dip galvanized dual-phase steel and a production method thereof, belonging to the technical field of cold-rolled strip production. The chemical composition of the dual-phase steel by mass percentage is: C 0.03%-0.10%, Si 0.20-0.60%, Mn 1.20%-2.00%, P≤0.020%, S≤0.010%, Als 0.015%-0.070%, N ≤0.0060%, the remaining elements are Fe and inevitable impurities; its microstructure is: 90-96% ferrite and 4-10% martensite by volume percentage. The preparation method includes the steps of smelting, hot rolling, pickling and hot-dip galvanizing. The production method of the dual-phase steel of the present invention adopts the sparse cooling method, which is beneficial to the stable control of the microstructure and properties; the opening and closing methods of the descaling and the cooling water between the racks are defined, which is beneficial to obtain a good surface quality. Combined with the smelting and hot-dip galvanizing process, the good mechanical properties and surface quality of the 450MPa hot-dip galvanized dual-phase steel sheet have been obtained, which has good market competitiveness.

The invention relates to a 30MnSiBCa hot-rolled wire rod for a PC steel bar and a preparation method of the 30MnSiBCa hot-rolled wire rod; B and Ca elements are added into the 30MnSiBCa hot-rolled wire rod, and the hardenability and delayed fracture resistance of the wire rod are improved by controlling the ratio of B to Cr, Mn and Si and the content of Ca and B; meanwhile, an existing preparationprocess of the hot-rolled wire rod is optimized, molten steel is smelted by a converter / electric furnace; lF refining is carried out, and the 30MnSiBCa hot-rolled wire rod is prepared through the process route of continuous casting of steel billets and hot rolling and controlled cooling, so that the same batch of head and tail and different batches of hot-rolled wire rods are stable in performance and small in component fluctuation, the purity of steel is greatly improved, and the technical effects of avoiding frequent adjustment of the subsequent PC steel bar production process and being high in cost are achieved.

The invention belongs to the technical field of heat-resistant alloy, and specifically relates to radiation-resistant martensite heat-resistant steel having excellent compatibility with Pb and Pb-Bi. The steel comprises the components in weight percentage: 0.05-0.2% of C, 9.0-12.0% of Cr, 1.0-3.0% of Si, 0.3-3.0% of Mn, 1.0-3.0% of W, 0.1-0.4% of V, 0.03-0.3% of Ta, 0.03-0.15% of N, less than or equal to 0.05% of Al, less than or equal to 0.05% of Ti and the balance of Fe. According to the invention, the content of Si is increased; part of C element is replaced by N; the precipitation of Cr23C6 is reduced so as to ensure the Cr content in matrix, so that a rich Si compact oxide film is formed on the surface when the material serves in the Pb and Pb-Bi under high temperature, and a structure is protected to be free of lead corrosion; activating elements Mo, Ni and Nb are replaced by W, Mn and Ta, so that the low activation is ensured, and the irradiation resistance performance is improved; the types and appearance of the precipitated phase can be controlled according to a reasonable proportion between the C+N content and V+Ta content, so as to ensure the high-temperature performance in the serving process; and the novel martensite heat-resistant steel which serves under a strong radiation condition and has high-temperature resistance, lead corrosion resistance and irradiation resistance can be obtained.

The invention discloses a cold-rolled hot-dip galvanized steel, whose chemical element mass percentage ratio is: C: 0.06-0.14%, Mn: 1.3-2.4%, Si: 0.1-1.0%, and the balance is Fe and unavoidable Impurities; its microstructure is ferrite + martensite + bainite + retained austenite. In addition, the present invention also discloses the manufacturing method of the above-mentioned cold-rolled hot-dip galvanized steel, which includes the steps: (1) smelting and casting; (2) hot rolling; (3) pickling; (4) cold rolling; (5) ) Hot-dip galvanizing recrystallization annealing: heating the cold-rolled sheet to the soaking temperature T 1 heat preservation for a period of time; then the steel plate after soaking is brought to the intermediate temperature T at the first cooling rate 2 , and then cooled to T at the second cooling rate 3 , hold for a period of time and then heat up to the zinc pool temperature T 4 Keep warm for a period of time; among them, the cooling rate is less than the second cooling rate, 640℃≤T 2 ≤T 1 , Ms<T 3 ≤T 4 (6) cooled to room temperature.

The invention relates to a welding material, in particular to an improved welding material which improves surfacing electrodes or flux-cored wires and resists the corrosion of liquid zinc and aluminium-zinc-based alloy. According to the portions by weight, the electrode coating or flux-cored wire of the welding material comprises the components as follows: 0.1-8 portions of graphite, 1-8 portionsof rutile, 8-25 portions of marble, 9-30 portions of fluorite, 5-16 portions of feldspar, 1-5 portions of mica, 0.1-25 portions of chrome powders, 10-40 portions of ferrosilicon, 10-15 portions of ferromanganese, 10-20 portions of molybdenum powder, 0.1-15 portions of aluminium powder, 0.1-25 portions of nickel powder, 1-10 portions of titanium dioxide, 5-20 portions of ferrotitanium, 0.1-5 portions of rare earth, 0.1-15 portions of ferrotungsten, and 1-10 portions of ferroboron. By adopting the proposal of the invention, the usage temperature of the welding material is ranged from 480 to 550DEG C; furthermore, the welding material of the invention effectively improves the anti-corrosion of zinc and the improved anti-corrosion of liquid zinc and aluminium-zinc-based alloy.

The invention discloses molten forging steel for manufacturing crane wheels and a smelting method thereof. The molten forging steel for manufacturing the crane wheels has the following chemical components in percentage by weight: 0.32-0.38 wt% of C, 1.10-1.30 wt% of Si, 1.10-1.25 wt% of Mn, 0.20-0.30 wt% of Cr, 0.015-0.030 wt% of Ti, S not more than 0.004 wt%, P not more than 0.012 wt%, O not more than 0.0010 wt%, H not more than 0.00015 wt%, and the balance of Fe and inevitable impurities. The preparation method comprises such process steps as KR method molten iron pretreatment deep desulfurization, converter smelting, LF steel ladle furnace refining and VD furnace vacuum refining. The molten steel, provided by the invention, is high in cleanness and low in inclusion content; and the forging steel for manufacturing the crane wheels is high in strength and toughness and excellent in wear and corrosion resistance, prominently improves the impact toughness and the fatigue resistance of the crane wheels in the use process, and prolongs the service life of the crane wheels.