Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
  • B21B13/14—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories having counter-pressure devices acting on rolls to inhibit deflection of same under load; Back-up rolls
  • B21B13/147—Cluster mills, e.g. Sendzimir mills, Rohn mills, i.e. each work roll being supported by two rolls only arranged symmetrically with respect to the plane passing through the working rolls

Definitions

• the present invention relates to a process for manufacturing steel strips adapted to receive a surface coating which is resisting to oxidation by using anti- oxidizing elements such as aluminum, chromium or nickel, copper, etc., and in particular tin for producing tin-plate.
• anti- oxidizing elements such as aluminum, chromium or nickel, copper, etc.
• tin for producing tin-plate.
• for depositing the above- mentioned coating metals use is made of the electrolytic method or, whenever possible, heat treatment methods.
• the second cold rolling step occurs after annealing with 2-3 stands of the "High-Four" type to bring the strip to the final thickness of 0.14-0.18 mm before tin coating.
• a plant of this type is schematically shown in fig. 1 and, as already stated, its main limit is the dimensional one, as it extends over very large areas, thus rendering the investment costs particularly high.
• Object of the present invention is that of providing a medium-productivity process for ultrathin strips adapted to receive an oxidation-resisting surface coating that does not require to be carried out in plants extended over too large areas, and consequently involving high investments costs.
• Figure 1 schematically shows the portions of a high productivity plant and relevant processing steps for obtaining a steel strip ready to be surface coated, according to the prior art, as above discussed;
• Figure 2 schematically shows a "thin-slab” plant for producing hot strips as starting material for the subsequent processes, particularly according to WO 2004/026497, as already described above;
• Figure 3 schematically shows a plant for carrying out the process according to the invention, downstream of a thin-slab plant of the type according to figure 2.
• the strips used as a substrate for the surface coating, preferably for producing tin-plate are ultrathin hot strips of 0.7-1.0 mm thickness, obtained from a "thin-slab" plant, such as of the type schematically shown in figure 2.
• the process according to the invention is illustrated in its processing steps downstream of the production of hot rolled strip having the desired thickness as above indicated, being obtained e.g. according to process and plant of figure 2.
• the strip having a thickness of 0.7-1.0 mm, after pickling is fed to a cold rolling mill of the Sendzimir 6Zhi type, in particular with three stands as illustrated, which is very compact and consequently needs to occupy more reduced area, thus limiting the investment costs.
• the strip thickness is brought to the desired final value and thereafter the strip is subjected to either an endless or batch annealing and skin-pass with return to the same cold rolling mill.
• the Sendzimir stands are more compact and allow more sensible reductions, as much smaller rolls are used to this effect, whereby the contact cross-section is reduced and the specific pressure, for the same value of applied force, is higher.
• the prior art had used (while adopting the corresponding processes) plants in which, like in figure 1, the hot rolling mills are provided with a plurality of stands of the High-Four tandem-type.
• Sendzimir stands should not be used since, due to their reduced cross-section of contact, they would have enhanced the geometrical defects of the strip, instead of reducing the same, such as under the aspect of parallelism.
• the Sendzimir 6Zhi rolling mill with three stands can be used, starting again from a hot rolled strip having thickness comprised between 0.7 and 1.0 mm to produce either directly the tin-plate strips of SR type upon simple reduction, after cold rolling up to 0.14-0.18 mm, annealing and skin- passing, or those of the DR type, half-raw or upon double reduction, preferably but not exclusively cold rolled until a thickness of 0.20-0.25 mm, annealed and thereafter reduced to a thickness ⁇ 0.18 mm with reductions of about 30%.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Metal Rolling (AREA)
• Heat Treatment Of Sheet Steel (AREA)

Priority Applications (7)

Applications Claiming Priority (1)

Publications (1)

Family

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Family Applications (1)

Country Status (7)

Citations (4)

Family Cites Families (11)

• 2006
  • 2006-01-26 BR BRPI0621257A patent/BRPI0621257A2/pt not_active IP Right Cessation
  • 2006-01-26 JP JP2008551961A patent/JP2009524526A/ja active Pending
  • 2006-01-26 WO PCT/IT2006/000043 patent/WO2007086085A1/en active Application Filing
  • 2006-01-26 CA CA002636546A patent/CA2636546A1/en not_active Abandoned
  • 2006-01-26 US US12/161,675 patent/US20100242558A1/en not_active Abandoned
  • 2006-01-26 CN CNA2006800518160A patent/CN101336305A/zh active Pending
  • 2006-01-26 AU AU2006336815A patent/AU2006336815A1/en not_active Abandoned

Patent Citations (4)

Non-Patent Citations (2)

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