42results about How to "Prevent transverse cracking" patented technology

The invention relates to a production method of high magnetic induction oriented silicon steel, comprising the steps of smelting, continuous casting, hot rolling, normalization, decarbonization and annealing, MgO coating, high-temperature annealing and insulation coating, wherein the normalization comprises the steps that: normalization is carried out on a hot rolling plate, nitridation is finished synchronously, the temperature of normalization and nitridation is 1050-1150 DEG C, the atmosphere is 5-35% NH3 (volume percentage), and the balance of gas is N2; after the normalization and nitridation, the N content nitrided into the hot rolling plate is 60-250ppm; and normalization cooling is carried out, the initial temperature of fast cooling is 700-950 DEG C, and the fast cooling speed with the temperature of being reduced to 550 DEG C is 15-40 DEG C/sec. The production method solves the problem of difficult nitridation in the decarbonization procedure when a low-temperature plate blank heating technology is used for producing the high magnetic induction oriented silicon steel, carries out synchronous nitridation on the hot rolling plate in the normalization procedure, and leads the following procedure of decarbonization and annealing techniques to be simplified and easily controlled, thus not only being capable of obtaining a high magnetic induction oriented silicon steel product with excellent performance and simultaneously leading the production cost to be reduced.

The process of making cast steel supported roller is suitable for integral casting of cast steel supported roller of 5-100 ton weight. The present invention has adopts computer simulation, coating iron mold with sand, rotary cavity filling, heat insulating casting head technology, electrically casting head heating technology and sliding roller neck technology; and designs pouring system and casting mold design by means of new design principle and successive solidification principle. Adopting sliding roller neck technology and electrically casting head heating technology can avoid cracking in the cast steel supported roller.

The invention relates to a method and device for decreasing transverse corner cracks of castling blanks. The method includes the steps of S1, disposing a smoke hood above a conveying roller way for cut casting blanks to collect high-temperature air; S2, delivering the collected high-temperature air under pressure; S3, delivering the high-temperature air to air nozzles disposed in a second casting blank cooling area and at corners of the casting blanks; and S4, allowing the high-temperature air to pass through the air nozzles to cover the corners of the casting blanks. The device comprises the smoke cover (3), a first heat-resistant pipe (4), a booster fan (5), a second heat-resistant pipe (6), heat-resistant branch pipes (7) and the air nozzles (8). The high-temperature compressed air can be blown to the corners of the casting blanks to prevent excessively fast cooling of the corners of the casting blanks, so that the corners of the casting blanks can be kept at the temperature higher than the upper limit of a low-temperature brittleness area before entering a straightening area, precipitation of various carbo-nitrides from the corners of the casting blanks is avoided, corner plasticity of the casting blanks is improved and transverse cracking of the corners of the casting blanks is effectively prevented during straightening.

The invention discloses a continuous casting stop-casting blank tail discharge and top sealing method. First and second stopper rods of a tundish of a two-machine and two-current continuous casting machine are opened; and first and second currents of molten steel flow into first and second crystallizers. When the height of the molten steel of the tundish is from 1130 mm to 680 mm, the continuous casting pull speeds of the first and second currents of molten steel in continuous casting are both reduced to 0.09-0.11 m/min at different accelerations; at this time, after the first and second stopper rods in the tundish are respectively closed, first and second blind plates are pushed in; first and second casting water ports are taken out from the first and second crystallizers; first and second cooling rods are put in the first and second crystallizers; and the continuous casting pull speeds are increased to 0.38-0.42 m/min for keeping by not shorter than 2 min. When the tail part of a continuous casting blank is discharged from lower ports of the crystallizers, and a foot roll section casting blank totally enters the tail part of the casting blank, the tail part of the casting blank is shrunk to form a recess area, and the tail discharge and the top sealing of the casting blank are finished. The top sealing method is excellent in tail discharge and top sealing of the casting blank, increases the molten steel yield, and has the popularization value.

The invention relates to a sulfuric acid resistant ferritic stainless steel and a manufacturing method thereof. The sulfuric acid resistant ferritic stainless steel comprises the following chemical components by weight: 0.002-0.015% of C, 0.002-0.015% of N, 0.2-1.0% of Si, 0.2-0.5% of Mn, less than or equal to 0.030% of P, less than or equal to 0.003% of S, 28-30% of Cr, 1.5-3% of Ni, 2.0-4.0% of Mo, 0.1-0.3% of V, 0.10-0.30% of Ti, 0.2-0.5% of Nb, 0.05-0.1% of Al, with the sum of Cr+3.3*Mo being greater than or equal to 38%, and Ti+Nb being greater than or equal to 16(C+N), less than or equal to 0.005% of O, and the balance Fe and inevitable impurities. The ferritic stainless steel provided by the invention can tolerate the corrosion of various concentration sulfuric acids at a temperature of less than 60 DEG C and at a concentration of less than or equal to 98wt%, also has good impact toughness and welding performance. With a pitting resistance equivalent PREN of greater than or equal to 38, the ferritic stainless steel has corrosion resistance far superior to conventional ferritic stainless steel, and is equivalent to superaustenitic stainless steel and nickel based alloys.

The invention relates to a composite shaving board, which contains wood materials and bamboo skin materials and comprises a surface layer, an inner layer and an intermediate layer. The surface layer is made of long wood single plates, a shaving layer is laid in the intermediate layer, the long wood single plates of the surface layer are longitudinally arrayed in the grain direction, short bamboo skin layers or short wood single plate layers which are transversely arrayed are arranged on inner sides of the long wood single plates, namely the inner layer, and longitudinally arrayed long bamboo skin layers are laid on inner sides of the transversely arrayed short wood single plate layers. Manufacturing process of the wood and bamboo composite shaving board includes that the long wood single plates can be spliced or longitudinally arrayed along the grain direction; the short wood single plates or bamboo curtains are transversely arrayed by the aid of gluing; and then long bamboo curtains or bamboo mats are longitudinally arrayed on the short wood single plates or bamboo curtains along the grain direction. A wood and bamboo composite board with a three-layered structure is assembled, and the shaving board layer is manufactured, the wood and bamboo composite board is provided with the transversely arrayed short bamboo skin layers or wood single plate layers, transverse strength of the composite shaving board can be improved, transverse cracking of the board is prevented, transverse nail holding force is increased, and longitudinal static bending intensity of the board is enhanced.

The invention discloses a post-cast strip structure of a prestressed concrete plate. The post-cast strip structure comprises two longitudinal post-tensioning unbonded prestressed reinforcing bars (3) arranged in precast concrete (1) on two sides of a first longitudinal non-prestressed reinforcing bar (6) and second longitudinal non-prestressed reinforcing bars (7) substituting original post-cast strips' longitudinal post-tensioning unbonded prestressed reinforcing bars (4) by adopting an equal-strength principle and in post-cast strips (2), the second longitudinal non-prestressed reinforcing bars (7) are located on two horizontal sides of the longitudinal post-tensioning unbonded prestressed reinforcing bars (3) in the precast concrete (1), and two ends of the second longitudinal non-prestressed reinforcing bars (7) extend to the precast concrete (1) of one end of a post-cast strip. By the arrangement, same bearing force can be guaranteed, cement consumption can be reduced, the construction of the post-cast strip is simplified, and concrete cracks in the post-cast strip are prevented.

The invention provides 30CrMnSiNi2A high-strength steel for aviation and a production method thereof. The 30CrMnSiNi2A high-strength steel for aviation comprises the following chemical components in percentage by weight: 0.27 to 0.34 percent of C, 0.90 to 1.20 percent of Si, 1.00 to 1.30 percent of Mn, 0.90 to 1.20 percent of Cr, 1.40 to 1.80 percent of Ni, 0.015 to 0.03 percent of Al, 0.02 to 0.03 percent of Mo, 0.02 to 0.03 percent of V, 0.015 to 0.025 percent of Ti, 0.15 to 0.2 percent of W, less than or equal to 0.012 percent of P, less than or equal to 0.01 percent of S and the balance of Fe. According to the 30CrMnSiNi2A high-strength steel for aviation and the production method provided by the invention, a smelting process comprising electric furnace die casting, external refining and electroslag remelting which is always adopted abroad is completely replaced by the method comprising electric furnace continuous casting, external refining and electroslag remelting, so that the effect of improving the material structure property and the fatigue property is obvious. By means of the method, batch, systematic and energy-saving production can be carried out, and energy and cost are obviously saved.

The invention provides a narrow-face copper plate taper back draft process for a continuous casting sheet billet chamfering crystallizer and belongs to the technical field of steelmaking-continuous casting. The length of a contour line of an applicative chamfer ranges from 35 mm to 70 mm and the applicative continuous casting billet normal work pulling speed ranges from 0.65 m/min to 1.50 m/min. When low-carbon steel with the [C] content lower than or equal to 0.08% is poured through the continuous casting sheet billet chamfering crystallizer, the narrow-face taper back draft of a copper plate ranges from 1.1%/m to 1.5%/m; when medium-carbon steel with the [C] content higher than or equal to 0.09% and lower than or equal to 0.2% is poured through the continuous casting sheet billet chamfering crystallizer, the back draft of the copper plate ranges from 1.2%/m to 1.6%/m; when high-carbon steel with the [C] content higher than 0.2% is poured through the continuous casting sheet billet chamfering crystallizer, the narrow-face taper back draft of the copper plate ranges from 1.1%/m to 1.45%/m. The narrow-face copper plate taper back draft process has the advantages that the reasonable chamfer copper plate back draft is adopted, so that great significance in guaranteeing even and stable growth of a billet shell in a chamfered position and avoiding generation of transverse cracks on the surface of a continuous casting billet is achieved.

The invention discloses a chain type butt strap structure based on a seamless bridge. The chain type butt strap structure comprises a bridge abutment, a girder, a bridge deck and two or more butt straps, wherein the bridge abutment, the girder and the bridge deck form the main bridge section, and the butt straps are arranged at the end of the main bridge section in parallel and in the length direction of the main bridge section. Expansion joints are formed between the main bridge section and the butt strap closest to the main bridge section and between every two adjacent butt straps. The main bridge section and the butt strap closest to the main bridge section and every two adjacent butt straps are connected through dumbbell-shaped-structure steel bars, each dumbbell-shaped-structure steel bar is composed of a linear steel bar and two annular steel bars connected to the two ends of the linear steel bar, and the two annular steel bars are fixed inside the main bridge section and the butt strap or respectively fixed inside two butt straps. According to the invention, cracks in the joints of the butt straps at the rear part and the bridge abutment of the seamless bridge and pavement cracks in the joints of the tail ends of the butt straps and a roadbed can be eliminated, the stress performance of the butt straps of the seamless bridge can be effectively improved, and therefore the drive comfort of vehicles can be improved.

The invention discloses a stress segmentation-type pavement structural layer. Joint-type stress bars are laid longitudinally in a structural layer of asphalt concrete pavement, the joint-type stress bars laid on an upper layer can prevent cracks generated by traffic loads and climate change, laid on a lower layer can prevent reflection cracks of a base layer, and laid on the base layer can preventcracks appearing on the base layer in the hardening process. According to the stress segmentation-type pavement structural layer, the problem of the horizontal cracks of a road is solved, the servicelife of the road is prolonged, later supporting of the road is delayed, the thickness of a pavement surface layer is reduced, and a pavement structure of a strong-base thin surface can be realized.

The invention provides a steel ladle, and belongs to the technical field of steel ladles. According to the steel ladle, refractory bricks are arranged on the lower middle portion of a steel ladle lining, aluminum-magnesium spinel castable is arranged on the ladle edge of the upper portion of the steel ladle lining, the refractory bricks and the aluminum-magnesium spinel castable are connected through special-shaped bricks, each special-shaped brick comprises a bottom face, a top face and four side faces, the bottom faces and the top faces are both rectangular faces or trapezoid faces or sector faces, the bottom faces are horizontal faces, the top faces are inclined faces, and the height of the side faces close to the molten steel side in the vertical direction is larger than that of the side faces close to the steel shell side. By improving the structure and the material of the steel ladle, the technical problem of serious slag bonding of the steel ladle is effectively solved, the problem of damage generated in the process of treating the edge of the steel ladle is avoided, the safety risk in the production process is reduced, and the product quality is improved. The invention further provides a steel ladle building method.

The invention relates to the technical field of oriented silicon steel, and discloses an atmosphere control process of high-magnetic-induction oriented silicon steel with excellent magnetism. The atmosphere control process comprises the following steps of 1, smelting, specifically, smelting in a converter and RH refining to obtain molten steel, introducing air in the smelting process, and setting the total air inflow to be 100-300Nl/min and the oxygen content in the introduced air to be 20-21%. According to the atmosphere control process of the high-magnetic-induction oriented silicon steel with the excellent magnetism, the content of oxygen and the content of nitrogen in a certain proportion are added in different processes, the atmosphere control precision of each stage is effectively improved, therefore the obtained final high-magnetic-induction oriented silicon steel is excellent, the influence of air pressure, flow and other factors on the magnetic effect of the final high-magnetic-induction oriented silicon steel is avoided, the FeO content in the slag is reduced, the steel recovery rate is increased, the service life of a furnace lining is prolonged, the effect of reducing the production cost is achieved, accurate atmosphere control is conducted, the smelting effect is better in the smelting process of the high-magnetic-induction oriented silicon steel, and the magnetism of the smelted high-magnetic-induction oriented silicon steel is more excellent.