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CN-117418173-B - Preparation method for producing thin low-density steel plate in lap rolling mode

CN117418173BCN 117418173 BCN117418173 BCN 117418173BCN-117418173-B

Abstract

The invention relates to a preparation method for producing a thin low-density steel plate in a rolling mode, which comprises the steps of blank preparation, blank combination, blank welding, composite blank heating, composite blank rolling, steel plate separation and composite blank straightening, wherein the steel plate comprises ：C：0.70～1.20％,Si：0.10～0.50％,Mn：16.00～24.00％,P：≤0.015％,S：≤0.003％,Al：7.00～10.00％,Ni：4.00～8.00％,Nb+Ti：0.02～0.20％, percent of chemical components in percentage by mass and the balance of iron and unavoidable impurity elements. And (3) selecting a low-density steel intermediate billet with a certain thickness and the same length and width as a rolling blank, and producing a thin low-density steel plate with the thickness of 3-6 mm and the width of 2000-3500mm on a medium plate rolling mill through welding and compounding. The steel plate adopts Fe-Mn-Al-C series, and the density is 6.90-7.10g/cm 3 . The yield strength of the finished steel plate is more than or equal to 1000MPa, the tensile strength is more than or equal to 1100MPa, the elongation is more than or equal to 20 percent, and the Charpy V impact energy at minus 40 ℃ is more than or equal to 20J. The plate shape of the laminated steel plate is uniform and good, the thickness tolerance is less than or equal to +/-0.25 mm, and the unevenness is less than or equal to 4mm/m.

Inventors

  • LI CHENXIAO
  • CHENG WEIDONG
  • YUAN ZHEN
  • ZHANG LEI
  • BAI YUN
  • HUANG JUN
  • HOU MEILING
  • SUN FENGYUAN
  • LI JINGTAO
  • LIN TAO
  • WANG XIAOSHUANG
  • WANG CHUNBO

Assignees

  • 江阴兴澄特种钢铁有限公司

Dates

Publication Date
20260505
Application Date
20230828

Claims (8)

  1. 1. A preparation method for producing a thin low-density steel plate in a rolling mode is characterized in that the steel plate comprises the following chemical components in percentage by mass, the balance of ：C：0.70～1.20%,Si：0.10～0.50%,Mn：16.00～24.00%,P：≤0.015%,S：≤0.003%,Al：7.00～10.00%,Ni：4.00～8.00%,Nb+Ti：0.02～0.20%,, iron and unavoidable impurity elements, wherein the gas content is less than or equal to 12ppm, less than or equal to 50ppm, less than or equal to 2.0ppm, the steel plate is designed to be Fe-Mn-Al-C series, and the density is 6.90-7.10 g/cm 3 , and the method comprises the following steps: 1) The blank manufacturing, namely selecting a low-density steel intermediate blank with the thickness of 40-80mm and the width of 2000-3200 mm as a rolling blank, wherein the thickness tolerance of the rolling blank is controlled to be +/-0.2 mm, and the length and width tolerance of the rolling blank is controlled to be +/-5 mm; 2) Blank compounding, namely performing shot blasting on the upper surface and the lower surface of a blank by rolling, selecting a blank to-be-contacted surface according to the design requirement of two-blank rolling or three-blank rolling after shot blasting, polishing the surface of the to-be-contacted surface, uniformly spraying a spacer with the thickness of 0.5-1.5mm on the to-be-contacted surface after polishing the blank, naturally airing after spraying, and welding the upper layer blank and the lower layer blank by adopting a laser welding mode around the blank contact surface; 3) Heating the blank, namely, heating the blank at a preheating section temperature of 600-900 ℃ for 1.0-2.0 h, heating the blank at a first section temperature of 1000-1100 ℃ for 1.0-2.0 h, heating the blank at a second section temperature of 1100-1180 ℃ for 1180-1230 ℃, heating the blank at a second section and soaking the blank at a soaking section temperature of 1180-1230 ℃, and heating the blank at a total temperature of 1.5-2.0 h for 4.0-6.0 h, wherein the temperature of the steel tapping center of the blank is more than or equal to 1170 ℃, and removing scales by high-pressure water after discharging, wherein the descaling water pressure is more than 20MPa; 4) The rolling stage adopts a high-temperature rapid rolling mode, the initial rolling temperature is 1080-1150 ℃, the final rolling temperature is more than or equal to 880 ℃, the rolling speed of the first four passes is 1.5-2.5 m/s, the rolling speed of the fifth pass to the last pass is 3.0-5.0 m/s, the total rolling passes are 12-16, the accumulated rolling reduction rate of the first four passes is more than or equal to 45%, and the rolled steel plate is straightened by a pre-straightening machine for 1-2 times; 5) Separating the steel plates, namely cutting four edges of the stacked steel plates by using a flame cutting machine at the cutting speed of 400-600min/mm, hoisting the stacked steel plates by using a vacuum chuck after cutting, and separating the upper layer steel plates and the lower layer steel plates; 6) Cutting the steel plate, namely cutting the fixed-length steel plate by using a plasma cutting or sawing mode, wherein the head and tail cutting amount of the laminated steel plate is 200-400mm, and the bilateral cutting amount is 150-200 mm; 7) Straightening the steel plate, namely carrying out strong straightening on the separated steel plate by a nine-roller straightener, wherein the unevenness of the straightened finished steel plate is less than or equal to 4mm/m.
  2. 2. The method for manufacturing a thin low-density steel sheet by a rolling method according to claim 1, wherein the thickness of the steel sheet is 3-6 mm and the width is 2000-3500mm.
  3. 3. The method for manufacturing the thin-specification low-density steel plate by the rolling mode according to claim 1, wherein the yield strength of the steel plate is more than or equal to 1000MPa, the tensile strength is more than or equal to 1100MPa, the elongation is more than or equal to 20%, the Charpy V impact energy at-40 ℃ is more than or equal to 20J, the shape of the rolled steel plate is uniform and good, the thickness tolerance is less than or equal to +/-0.25 mm, and the unevenness is less than or equal to 4mm/m.
  4. 4. The method for manufacturing the thin-specification low-density steel plate by using the rolling mode as set forth in claim 1, wherein the number of the rolling blanks in the step 1) is 2-3, steel ingots or continuous casting blanks are used as raw materials for blank preparation, and intermediate blanks with the same thickness, width and length are manufactured by cogging and rolling.
  5. 5. The method for manufacturing the thin-specification low-density steel plate by the rolling method according to claim 1, wherein the method for polishing the surface of the surface to be contacted in the step 2) is that a milling machine or a grinding machine is adopted to polish the surface to be combined of the low-density steel plate blank, the polishing thickness is 1-2 mm, and then compressed air is used for blowing the surface to be contacted clean.
  6. 6. The method for manufacturing a thin low-density steel plate by a rolling method according to claim 1, wherein the air holes are formed in each side of the weld joint of the blank after welding in the step 2), rolling bulging of the steel plate is prevented, and the number of the air holes formed in each side of the weld joint of the rolled blank is 4-10.
  7. 7. The method for manufacturing the thin-specification low-density steel plate by the rolling mode according to claim 1, wherein the laser welding parameters in the step 2) are that the defocusing amount is-3 mm, the laser inclination angle is 5 degrees, the laser power is 10-30KW, the welding speed is 1.0+/-2 m/min, and finally the laser welding seam penetration is more than or equal to 10mm.
  8. 8. The method for producing a thin-gauge low-density steel sheet by a rolling method according to claim 1, wherein the composition of the isolating agent in the step 2) is formed by mixing 30% -50% by weight of a binder and 50% -70% by weight of an isolating powder, the sum of the two raw materials is 100% by weight, the isolating powder comprises 40% -70% by weight of magnesia powder, 30% -60% by weight of silica powder, and the binder is a nano silica aqueous solution, wherein the weight percentage of nano silica particles is 30% -40%.

Description

Preparation method for producing thin low-density steel plate in lap rolling mode Technical Field The invention belongs to the technical field of special steel smelting, and particularly relates to a preparation method for producing a thin low-density steel plate in a rolling mode. Background Along with the trend and the requirement of industrial development of low carbon, energy conservation and environmental protection, equipment, automobiles and the like continuously provide a development target of light weight. Low density steel is a new class of materials that has been developed, and compared with nonferrous metals such as titanium alloys, aluminum alloys, magnesium alloys, etc., low density steel has significant advantages in terms of economy, low carbon manufacturing, workability, etc. Among the different types of low-density steels, fe-Mn-Al-C-based low-density steels have been the focus of attention at home and abroad due to their low density, high toughness, high elongation and good ductility. The Fe-Mn-Al-C low density steel can reduce the density of the traditional steel grade by more than 10% through reasonable component design. By preparing a complex phase structure taking austenite as a matrix, the stability of the austenite is reasonably controlled, and the mechanism such as TRIP effect, TWIP effect, MBIP effect and the like is generated in the impact process, so that the composite material has excellent toughness, welding performance, cold bending, stamping and other technological properties, and has remarkable application potential in the fields of automobile anti-collision, armor equipment bulletproof and the like. At present, the large-scale industrial preparation of Fe-Mn-Al-C low-density steel is successfully realized by the company, and the production technologies of pouring, heating, rolling, heat treatment and the like of a large steel ingot are mastered. The lower limit of the thickness specification of the current direct-rolling low-density steel is 6mm, and the specification product is rolled by a steckel mill under the limitation of production equipment and steel type characteristics. Disclosure of Invention The technical problem to be solved by the invention is to provide a preparation method for producing a thin-specification low-density steel plate in a rolling mode aiming at the prior art, which can use a heavy and medium plate mill to produce a low-density steel plate with the thickness of 3-6mm and the thickness of 2000-3500mm, realize the industrialized production of low-density steel with thinner thickness, has higher thickness precision control, and has important significance for the light weight development in the fields of special vehicles, weaponry, ships and the like. The technical scheme adopted by the invention for solving the problems is that a thin low-density steel plate is produced by a rolling mode, a metallographic structure is austenite at normal temperature, and the steel plate comprises the following chemical components in percentage by weight ：C：0.70～1.20％,Si：0.10～0.50％,Mn：16.00～24.00％,P：≤0.015％,S：≤0.003％,Al：7.00～10.00％,Ni：4.00～8.00％,Nb+Ti：0.02～0.20％, and the balance of iron and unavoidable impurity elements. The main functions and design basis of the steel are as follows: C is a stable austenite element, can prevent the austenite structure from generating martensitic transformation during deformation, and promotes the formation of single-phase austenite. Meanwhile, C can be dissolved into a steel matrix in a solid solution mode, and the strength of the steel is improved through solid solution strengthening. The content of C in the invention is 0.70-1.20%. Si-Si improves the strength of the steel and the mechanical stability of the retained austenite, but Si is also a solid solution strengthening element. However, too high a silicon content can reduce the solubility of C in austenite, increase the amount of kappa carbide, and reduce the toughness of the steel. Therefore, the Si content in the invention is controlled to be 0.10-0.50%. Mn element can enlarge an austenite region, inhibit the transformation from austenite to martensite, and play a role in stabilizing the austenite. Mn can keep high work hardening rate of steel in austenite structure by TRIP effect and TWIP effect, improves plasticity, and is beneficial to obtaining good strong plastic fit. However, as the Mn content increases, the cracking tendency of the steel slab during rapid heating and cooling increases, and too high Mn content is detrimental to welding performance. Therefore, the Mn content in the invention is 16.00-24.00%. Al is taken as a light element, and 3 percent of Al is added to reduce the density of steel to 7.4g/cm 3, which is the main element for reducing the density of steel in the invention. In addition, al can improve the stacking fault energy, not only can inhibit the transformation from austenite to martensite, but also is beneficial to the formation of deformation twin