30results about How to "Improve center segregation" patented technology

The invention discloses a method for improving the segregation and shrinkage of the center of a square and round billet; when a cast billet is cooled, the growth rate of solidified shells of the cast billet in an inner arc direction and an outer arc direction is relatively higher while the growth rate of solidified shells of the cast billet in a left side direction and a right side direction is relatively lower through a cooling method according to which the cooling strength in the inner arc direction and the outer arc direction of the cast billet is consistent, the cooling strength in the left side direction and the right side direction is consistent but the cooling strength in the inner and the outer arc directions is higher than that in the left and the right side directions, so that a liquid core on a solidified tail end of the cast billet is a rectangular area which is squashed in the inner and the outer arc directions and elongated in the left and the right side directions. According to the method for improving the segregation and shrinkage of the center of the square and round billet, because segregation solute elements and the distribution methods of solidification and shrinkage are controlled, the center of the cast billet is prevented from being segregated and enriched in a small area, so that the segregation and shrinkage of the center of the square and round billet and other continuous casting billets with similar width and thickness of cross sections are effectively improved, the effect is significant and stable, the use is simple and easy, the cost is low, and the cost performance in implementation is high. Simultaneously, a dynamic slight compression technology in continuous casting and a tail end electromagnetic stirring technology can be implemented.

The invention relates to a method for producing wire and bar materials, which sequentially comprises the steps of smelting, secondary refining, square billet continuous casting, heavy forcing down, rolling and controlled cooling, and finished product collecting and coiling. The method adopts a heavy forcing down process to save the steps of casting blank stacking slow cooling, square billet downward delivery and square billet heating after the step of the square billet continuous casting, and organically compresses and combines a past steel plant with a past high-wire plant or bar material plant to form a short-flow production method of the wire and bar materials and greatly reduce the energy source consumption; besides, the production cost is far lower than that of the conventional long-flow process and is more lower than that of an overlong-flow process with secondary fire material formation, the benefit advantages are obvious, and the quality in producing high-carbon wire and bar materials is far better than that of the conventional art.

The invention discloses a preparation method for high-quality continuously cast mother billets of a plastic mould steel extra-thick plate. The preparation method is characterized in that in a continuous casting process, billet pulling speed is controlled to be 0.80m / min-0.90m / min; solidification end is heavily pressed down; and press-down amount is distributed according to a solid phase rate under light pressing and heavy pressing. The preparation method disclosed by the invention improves internal quality of cast billets by a solidification end dynamic heavy-pressing technology, so that the center segregation defect and the center porosity defect of cast billets are improved; under the target of producing the extra-thick plate with specification of 120 mm (compression ratio only being 2.12 to 1), internal quality of a flaw detection thick plate with a low compression ratio is effectively improved, and a flaw detection qualification rate of the flaw detection thick plate with the low compression ratio in a production process is controlled to be 99% or higher. Cast billets industrially produced by the method are good in effect after being implemented, and can efficiently meet use requirements of mould steel.

The invention discloses an ultra-thin high-strength steel plate that can be used under the condition of -60°C. The chemical composition is calculated as mass percent: C≤0.05, Si 0.20-0.40, Mn≤1.0, Nb+Ti+V≤0.15 , Cr≤0.30, P≤0.008, S≤0.0008, N≤0.002, O≤0.0010, H≤0.0001, P+S+[N]+[O]+[H]≤100ppm; Ni≤0.30, Cu≤0.30, Mo≤0.30, the balance is Fe and unavoidable impurities; the structure of the steel plate is uniform quasi-polygonal ferrite; the thickness is 4‑8mm, the yield strength is 460‑560MPa, the tensile strength is 550‑630MPa, and the impact energy at ‑60°C ≥200J. The technological process is KR hot metal pretreatment-converter-LF refining-RH vacuum degassing-slab continuous casting-slow cooling-rolling-cooling. The application fills up the production blank of high-strength, low-temperature and high-toughness ultra-thin steel plates in the market.

The invention discloses a high-sulfur free-cutting steel square billet continuous casting method. Molten steel comprising, by mass, 0.1-0.3% of C, 0.1-0.3% of S, 0.02-0.1% of Si, 1.0-1.5% of Mn, and the balance Fe and impurities is subjected to continuous casting through a continuous casting machine, and the section of a casting billet manufactured by the continuous casting machine is 250-350 mm wide and 400-500 mm high. According to the characteristics of the high-sulfur free-cutting steel continuous casting billet and the continuous casting machine, the casting speed of the continuous casting billet is reasonably controlled, the water distribution amount of a secondary cooling zone is optimized, the secondary cooling area is divided into a plurality of loops, the water amount of each loop is adjusted independently, the size of a columnar zone and the size of a center equiaxed zone of the continuous casting billet are controlled by changing heat transfer of all cooling zones, thus, the structure solidification process during continuous casting can be controlled, the high-sulfur free-cutting steel continuous casting billet is prevented from generating intercrystalline cracks and center cracks, the center equiaxed crystal ratio of the casting billet is increased, and center segregation and center porosity of the continuous casting billet are perfected.

The invention provides a method for reducing central segregation of low-alloy steel continuous casting slabs, aiming at the problem of low qualified rate of internal segregation of low-alloy high-strength steel slabs. First, according to the continuous casting slab production data of the target continuous casting machine, analyze and obtain the carbon equivalent range of the target steel continuous casting slab with qualified center segregation of the target steel continuous casting slab, and back-calculate the composition content of the target steel continuous casting slab , to optimize the range of the optimum composition content of the molten steel corresponding to the carbon equivalent of the target steel in production and the optimum pouring parameter range of the target molten steel. Therefore, according to the above-mentioned optimal composition content range and optimal pouring parameter range, the low-alloy target steel type continuous casting slab with qualified center segregation can be produced. Optimizing the molten steel composition and pouring parameters according to the carbon equivalent range can more accurately find out the production conditions for preparing target steel continuous casting slabs with qualified internal segregation quality, thereby effectively improving the central segregation of low alloy steel continuous casting slabs and improving Internal segregation quality of low alloy steel continuous casting slabs.

The invention discloses an electromagnetic stirring device and a method for a secondary cooling zone of slab continuous casting. The device comprises a main body of the electromagnetic stirring device, an opening adjustment assembly and a secondary cooling assembly. The main body of the stirring device includes a protective shell (3), a phase sequence control component, an iron core (4) and an electromagnetic coil (5), and electromagnetically stirs the molten steel in a direction-changing manner by changing the phase sequence of the three-phase current; the opening adjustment component includes a cylinder (7) , the fixed seat (8), the movable joint shaft (12) and the silicon steel sheet group insert (13), the opening degree of the closed annular iron core can be adjusted online through the movable joint structure; the secondary cooling assembly includes the cooling water inlet (9) and the cooling The water nozzle (10) soaks the cooling water to cool the electromagnetic coil and the iron core, and then is sprayed onto the surface of the billet (1) through the cooling water nozzle for secondary cooling. The invention has less magnetic field leakage or loss, high electromagnetic stirring efficiency, online adjustment of the opening degree of the stirrer, alternate change of stirring direction, and improves the internal quality and performance of the slab.

The invention belongs to the technical field of metallurgy and particularly relates to a rolling process beneficial to spheroidizing annealing of a Cr and Mo steel. The rolling process is carried out according to the following steps of: carrying out cogging, rolling and spinning on a continuously cast steel billet; then always carrying out heat preservation to about 300 to 350 DEG C on a roll table cooling line and carrying out coil collection so as to obtain a Cr and Mo steel rolled product. According to the invention, by cogging heating control, steel rolling temperature control and after-rolling cooling control, segregation at the position of one second of R and center segregation are improved, grains are refined and growth of abnormal grains is avoided. Meanwhile, generation of large granular ferrite and pearlite is controlled, martensite is controlled below 35 percent; tissues mainly comprising bainite is formed, and carbide of the tissues is more uniformly distributed on a matrix. Moreover, according to a product produced by using the process, time of spheroidizing annealing is greatly shortened, an annealing process is simplified and spheroidized cementite is more dispersively and finely distributed.

The invention discloses a preparation process of composite casting blanks for a high-toughness thick steel plate. The preparation process adopts continuous casting blanks with different furnace numbers, the same steel grades and different carbon contents to compound so as to meet the requirements for overall strength and core toughness, thus the composite continuous casting blanks for an extra-thick steel plate with high surface quality and excellent core impact toughness are obtained. The low carbon design of an inner layer greatly improves the metallurgical quality of the central portion andprovides strong support for improving the toughness of the center and the whole. The high carbon design of an outer layer provides a carbon source for the whole compositions to ensure the whole strength, the uniformity of the compositions is achieved through diffusion, finally the whole compositions with both toughness and strength are obtained, and the occurrence rate of surface cracks is reduced.

A slab is continuously cast in such a manner that the slab is intentionally bulged and thereafter the slab having an unsolidified layer is compressed under conditions controlled to prevent the bulging from causing a breakout of the slab and from causing internal cracks in a solidified shell of the slab to reduce central segregation in the slab and positive segregation near a core portion of the slab. A slab 10 is guided on slab-supporting rolls 6 disposed with constant roll gaps from immediately below a casting mold to a point where the thickness of a solidified shell 11 of the slab reaches 15 mm. Thereafter, the slab is bulged on rolls disposed with gradually increased roll gaps with a total amount of bulging of 3 to 20 mm, and is thereafter guided on rolls disposed with constant roll gaps in a zone 0.5 to 5.0 m in length toward the downstream in the casting direction. Subsequently, when the solid phase fraction in a core portion of the slab is from 0.2 to 0.9, the slab is compressed by at least one pass through reduction rolls 7 under such conditions that the product of the compressing rate multiplied by the casting speed is 0.3 to 1.0 mm·m / min 2 .