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CN-121976110-A - Production method of cold-rolled product for high deep drawing based on twin-roll casting and rolling

CN121976110ACN 121976110 ACN121976110 ACN 121976110ACN-121976110-A

Abstract

The invention belongs to the technical field of metallurgy and metal material processing, and relates to a production method of a cold-rolled product for high deep drawing based on twin-roll casting and rolling. According to the invention, by combining high scrap ratio smelting with a high-efficiency impurity control technology, on the premise of ensuring low carbon emission, the cleanliness of molten steel is obviously improved, excellent deep drawing performance is obtained while the yield strength of 170MPa is kept at the minimum, and the SCS high scrap ratio authentication is passed, so that the international green purchasing standard is satisfied.

Inventors

  • Guo tianyang
  • FENG QINGXIAO
  • LI NING
  • ZHANG XIANGZE
  • LI HUALONG
  • SHI YIXIN

Assignees

  • 张家港中美超薄带科技有限公司
  • 江苏省沙钢钢铁研究院有限公司
  • 江苏沙钢集团有限公司
  • 江苏沙钢钢铁有限公司

Dates

Publication Date
20260505
Application Date
20260120

Claims (10)

  1. 1. A method for producing a cold rolled product for high deep drawing based on twin roll casting, characterized in that it comprises the steps of: 1) Smelting in a high scrap ratio electric furnace, namely smelting molten steel in the electric furnace, wherein the proportion of scrap steel is 70% -90%; 2) High-efficiency purification refining; 3) Casting and rolling by using double rollers; 4) Hot rolling and on-line heat preservation; 5) Cold rolling; 6) And (5) annealing.
  2. 2. The production method according to claim 1, wherein in step 1), 0.05% -0.12% Ti, 0.01% -0.04% Nb and 0.0003% -0.0015% Se are added to the molten steel for suppressing aging, securing strength and improving cast-rolling wettability, respectively.
  3. 3. The method according to claim 1, wherein in step 2), the total oxygen content T [ O ] is 15ppm or less and the inclusion size is 10 μm or less in the steel by using LF+RH twin refining and calcium treatment.
  4. 4. The production method according to claim 1, wherein in the step 3), refined molten steel flows into a twin-roll casting machine through a tundish and a transition ladle, and is subjected to strip casting under the protection of inert atmosphere, wherein the thickness of a casting strip is 1.2-2.0 mm, the casting speed is 40-90 m/min, the pressure of a molten pool is 5-25 Pa, and the casting force is 6-9N/mm.
  5. 5. The production method according to claim 1, wherein in the step 4), the cast strip is subjected to heat preservation by a hot box protected by inert gas at a temperature of 1100-1250 ℃, hot rolled once, a rolling reduction of 15-40%, a thickness after rolling of 0.8-1.5 mm, an outlet temperature of 850-950 ℃, the hot rolled strip enters an online heat preservation tunnel, a cooling rate is controlled to be less than or equal to 10 ℃ per second, and a coiling temperature is controlled to be 650-720 ℃.
  6. 6. The production method according to claim 1, wherein in step 5), after pickling, the hot rolled coil is subjected to single-frame or multi-frame cold rolling, and the total rolling reduction is 70-85%, so as to obtain a chilled coil with a thickness of 0.3-0.8 mm.
  7. 7. The method of claim 1, wherein in step 6), a continuous annealing process is used.
  8. 8. The method according to claim 1, wherein the method further comprises the step 7) of galvanization, In the step 7), the annealed strip steel can be subjected to hot galvanizing or electrogalvanizing treatment, the plating weight is 30-150 g/m < 2 >, and the strip steel is subjected to finishing rolling after plating so as to improve the surface roughness and the coating adhesive force.
  9. 9. The production method according to claim 1, wherein after annealing, the yield strength of the product is 170-220 MPa, the elongation is more than or equal to 40%, the plastic strain ratio r m is more than or equal to 2.0, and the aging index DeltaY is less than or equal to 30MPa.
  10. 10. A cold rolled product for high deep drawing, characterized in that the product is produced by the production method of any one of claims 1-9, has yield strength of 170-220 mpa, elongation of not less than 40%, r m ≥2.0、n m of not less than 0.22, carbon footprint of not more than 1.2tCO 2 /t steel, and passes SCS high scrap ratio certification.

Description

Production method of cold-rolled product for high deep drawing based on twin-roll casting and rolling Technical Field The invention belongs to the technical field of metallurgy and metal material processing, and particularly relates to a method for producing a cold-rolled product with high deep drawing performance based on a thin strip double-roller casting and rolling process and a product thereof, which are suitable for the application field of thin plates with high requirements on formability, such as automobiles, household appliances, buildings and the like. Background The cold rolled steel sheet for high deep drawing is required to have excellent formability, uniform mechanical properties, good surface quality and welding properties. The traditional production process generally adopts a multi-process flow of continuous casting, hot rolling, cold rolling, annealing and galvanization, has long production period, high energy consumption and high cost, is easy to have the problems of element segregation, surface decarburization, uneven texture and the like, and affects the deep drawing performance. As a short-flow and near-net-shape manufacturing process, the double-roller casting and rolling technology has the advantages of rapid solidification, uniform structure, no segregation, good surface quality and the like. However, the existing twin roll casting technology focuses on hot rolled thin strip or medium and low strength steel grades, and for cold rolled products requiring high deep drawability, particularly deep drawn steels requiring excellent r-values (plastic strain ratio) and n-values (work hardening index), no systematic study and application has been seen. At present, low-carbon aluminum killed steel or IF steel (interstitial free) is mostly adopted as deep drawing steel, microalloy elements such as Ti, nb and the like are added to fix C, N, and multiple cold rolling and long-time annealing are needed to develop favorable textures. The process is complex, the cost is high, and the thin specification and the high formability are difficult to be combined. Conventional deep drawing steel products typically have yield strengths in the range of 140-180MPa, but face the contradiction that formability and strength are difficult to compromise. Furthermore, with the implementation of low carbon trade policies such as the european union carbon boundary regulation mechanism (CBAM), steel products face increasingly stringent carbon emission constraints. The traditional long-process steelmaking has high carbon emission intensity, and development of a green steel manufacturing technology with high scrap steel ratio and short process is needed. However, high scrap ratios can lead to increased levels of residual elements (e.g., cu, sn, as, etc.) and inclusions in the molten steel, severely affecting the cleanliness, formability, and aging tendency of the steel, limiting its use in high-end deep drawing steels. Therefore, the invention aims to develop a cold-rolled product for high deep drawing based on a double-roll casting-rolling short-flow process and a production method thereof, and the high scrap ratio smelting is combined with an efficient impurity control technology, so that the cleanliness of molten steel is obviously improved, the yield strength of the minimum 170MPa is kept, and meanwhile, the excellent deep drawing performance is obtained on the premise of ensuring low carbon emission, and the high scrap ratio certification of SCS (Sustainable Choice Standard) is passed, so that the international green purchasing standard is met. Disclosure of Invention Based on the background technology, the invention aims to provide a method for producing a cold-rolled product for high deep drawing based on a double-roll casting and rolling process, which realizes remarkable improvement of molten steel cleanliness while guaranteeing low carbon emission and weakening of ageing tendency and excellent deep drawing performance on the basis of guaranteeing the minimum 170MPa yield strength through a synergistic technical route of high scrap ratio smelting, high-efficiency purification, double-roll casting and rolling short flow and refined heat treatment, and meets the requirements of high-end deep drawing application. More specifically, the invention adopts the following technical scheme. According to a first aspect of the present invention, a method for producing a cold rolled product for high deep drawing based on twin roll casting is presented, characterized in that it comprises the following steps: 1) Smelting in a high scrap ratio electric furnace, namely smelting molten steel in the electric furnace, wherein the proportion of scrap steel is 70% -90%; 2) High-efficiency purification refining; 3) Casting and rolling by using double rollers; 4) Hot rolling and on-line heat preservation; 5) Cold rolling; 6) And (5) annealing. According to the production method of the present invention, preferably, in step 1), 0.05% -0