Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
  • B21B1/227—Surface roughening or texturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
  • B21B2001/228—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length skin pass rolling or temper rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2261/00—Product parameters
  • B21B2261/14—Roughness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
  • B21B27/005—Rolls with a roughened or textured surface; Methods for making same
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
  • C23C2/36—Elongated material
  • C23C2/40—Plates; Strips

Definitions

• the invention relates to a flat steel product coated and tempered with a hot-dip coating and to a method for producing a flat steel product coated and tempered with a hot-dip coating.
• flat steel products coated with a hot-dip coating are skin-passed using a textured skin-pass roll to impart the desired final mechanical properties to the steel flat product and to impart a certain roughness to the coating surface.
• the required textures on the skin-pass rolls can be applied using, among other methods, the SBT (shot blasting texturing), EDT (electro discharge texturing), EBT (electron beam texturing), grinding structures, or the TOPO-CROM ® (reactor coating) process. These processes involve the application of a stochastic surface topography to skin-pass rolls.
• EP 1 368 140 B1 discloses a corresponding example for EDT.
• the EBT process also enables the application of a non-stochastic, geometrically determined and thus deterministic texture.
• a completely different process for the application of stochastic as well as deterministic surface topographies is the laser beam texturing process (LT), particularly by single or multiple shots, which lead to ablation on the surface of the skin-pass roll material and thus to the establishment of a surface topography, see, for example, EP 0 184 568 B1 , JP 56-119 687 A , JP 03-267 319 A and DE 695 09 883 T2
• the skin-pass rolls can be finely ground in a grinding process after texturing. After this process, depending on the requirements of the skin-pass rolls, they are are provided with a metallic protective layer before they are (re)used in the skin-pass mill.
• rollers with a basic structure on their surface which is partially thermally spray coated, see for example EP 3 394 311 B1 .
• a coating with a sprayed layer comprising, among other things, tungsten-containing carbides only in an area between 10 and 90% of the entire surface.
• Figure 1c) discloses a non-smooth upper surface of a roller with a thermally sprayed coating along a thermally sprayed first area, with the rest of the upper surface remaining uncoated as a second area.
• the sprayed layer is applied locally as a so-called “pepper spray” and, due to the high randomness of the coating, is not in accordance with the teaching of EP 3 394 311 B1 stands.
• the WO 2017/144407 A1 a flat product made of a metal material with a surface structure with stochastically distributed and stochastically large depressions is known, wherein the depressions have a depth in the range of 15 to 90 ⁇ m.
• dome-shaped bulges on the surfaces of skin-pass rolls are also known, see https://www.topocrom.com/be Anlagenmaschine/rollstructuring.
• a conflicting objective is that the steel sheet must not be too rough while simultaneously ensuring good paint adhesion, especially with increasingly thinner paint layers.
• the object of the invention is therefore to provide a hot-dip coated and skin-passed steel sheet with a surface which meets the requirements, in particular a hot-dip coated flat steel sheet with excellent adhesion properties, good formability and improved paintability, as well as a process for its production.
• the problem relating to a flat steel product coated with a hot-dip coating and temper-passed is solved by the features of claim 1.
• the problem relating to a method for producing a flat steel product coated with a hot-dip coating and temper-passed is solved by the features of claim 6.
• a first teaching of the invention relates to a flat steel product coated with a hot-dip coating and tempered, wherein the surface of the hot-dip coating has a texture comprising stochastically distributed valleys and peaks, wherein subtextures are present at least in some of the valleys and at least in sections within the valleys, wherein the subtextures each occupy an area between 1 ⁇ m 2 to 20,000 ⁇ m 2 , wherein within the subtextures several dome-shaped impressions are contained, each having a diameter between 20 nm and 8,000 nm.
• the area of the respective subtextures can in particular be at least 2 ⁇ m 2 , 5 ⁇ m 2 , 10 ⁇ m 2 , 15 ⁇ m 2 , 20 ⁇ m 2 , preferably at least 25 ⁇ m 2 , 50 ⁇ m 2 , 40 ⁇ m 2 , 50 ⁇ m 2 , and in particular at most 15000 ⁇ m 2 , 12000 ⁇ m 2 , 8000 ⁇ m 2 , 6000 ⁇ m 2 , preferably at most 5000 ⁇ m 2 , 4000 ⁇ m 2 , 30000 ⁇ m 2 , 2000 ⁇ m 2 , 1000 ⁇ m 2 .
• the diameter of the respective dome-shaped impressions can be, in particular, at least 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, preferably at least 90 nm, 100 nm, 120 nm, 150 nm, and in particular at most 7500 nm, 7200 nm, 6500 nm, 6000 nm, preferably at most 5500 nm, 5200 nm, 4900 nm, 4700 nm, 4500 nm.
• the smaller the diameter the more advantageously the toothing mechanism can be designed and thus the adhesion properties can be improved.
• the multiple dome-shaped impressions within the subtextures can have the same or different diameters.
• Multiple dome-shaped impressions within a subtexture in the sense of the invention, means that at least five or more impressions are contained per subtexture.
• An upper limit can be mathematically determined, for example, depending on the size of the area of the substructures and the diameter of the dome-shaped impressions. Based on the theoretically largest area and the theoretically smallest diameter, an upper limit of a maximum of 500,000 dome-shaped impressions would be possible. Indentations are possible.
• the upper limit can be, in particular, 200,000, 100,000, 50,000, 20,000, 10,000, preferably 5,000, 2,000, 1,000, 500, or 300.
• the number of indentations per subtexture can be, in particular, at least 10, 15, 20, 25, preferably at least 40, 50, 70, 80, 90, or 100.
• Stochastically distributed textures on the surface of a hot-dip coating are irregular textures characterized by an irregular statistical distribution of design features such as valleys and/or peaks, which in turn vary or can vary from one another in terms of distance, shape and size.
• the dome-shaped impressions within the subtextures can each fill an area between 5 and 100% of the total area of the subtextures.
• the proportion of the area can be at least 7%, 9%, 10%, 12%, 15%, preferably at least 20%, 25%, 27%, 30%, preferably at least 35%, 40%, 50%, 60%, and in particular a maximum of 99%, 97%, 96%, preferably a maximum of 94%, 93%, 92%.
• the higher the proportion relative to the area the more advantageous the effect on the gearing mechanism.
• all subtextures comprise dome-shaped impressions that essentially fill the entire surface of the subtextures. Essentially means that up to 5%, in particular up to 3%, preferably up to 2% of the surface of the subtextures are free of dome-shaped impressions, especially at the edge of the impressions.
• the flat steel product or cold-rolled strip may preferably be a cold-rolled steel according to DIN EN 10346.
• a WCCo powder with tungsten-containing carbides with an FSSS (Fisher Sub-Sieve Size) grain size between 0.9 and 1.5 ⁇ m was used, containing a cobalt content of approximately 12 wt.%.
• FSSS Fisher Sub-Sieve Size
• the captured image area was 0.65 mm2 .
• Imagic Stamm kau AG's "ImageAccess IMS V23H2" software was used for analysis and display.
• the captured image area can vary, for example, between 0.2 and 2.0 mm2 .
• the locally thermally applied spray layer covered approximately 15% of the captured image area.
• the thermally applied spray layer thus includes substructures, which are dome-shaped bulges on the substructures, each occupying an area between 5 and 100% of the total area of the substructures.
• the substructures which are applied particularly to the mountains of the structure, are embossed into the surface of the hot-dip coating during the tempering process and thus form at least in some of the valleys and at least in sections within the valleys subtextures, whereby, for example, the subtextures within the valleys can each fill an area between 5 and 90% based on the total area of the valleys, within the subtextures several dome-shaped impressions are contained, each having a diameter between 20 nm and 8000 nm.
• FIG. 2 The left image shows a skin-passed surface of a steel flat product coated with a ZM hot-dip coating in partial plan view using a reflected light microscope according to the state of the art.
• the skin-pass roller used for skin-passing had a stochastic structure applied by EDT, comparable to the purely dark image in Figure 1 .
• a striking difference can be seen compared to the left illustration, which shows a dressing roller, which is used as an example in Figure 1 shown and which also had the white structure in addition to the dark one.
• subtextures are present, each of which covers an area between 1 ⁇ m 2 and 20000 ⁇ m 2.
• dome-shaped impressions within the subtextures are several dome-shaped impressions, each of which can have a diameter between 20 nm and 8000 nm.
• the area of the subtexture is 1872 ⁇ m 2 with a number of 179 dome-shaped impressions with a varying diameter between 153 nm and 4130 nm.
• the determination of the area of the subtexture, recording the number of impressions and the diameter was carried out by image analysis of the scanning electron microscopy image using the software "ImageAccess IMS V23H2" Imagic Marshstoff AG.
• the skin-pass ratio was 0.8%.
• the flat steel product in each case was a cold-rolled strip of grade DC04 with a thickness of 0.7 mm and a ZM hot-dip coating with a thickness of approximately 9 ⁇ m.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Coating With Molten Metal (AREA)

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Citations (8)

• 2024
  • 2024-03-11 EP EP24162606.8A patent/EP4616969A1/fr active Pending

Patent Citations (8)

Non-Patent Citations (1)

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