EP1100638B1 - Giessen eines stahlbandes - Google Patents

Giessen eines stahlbandes Download PDF

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Publication number
EP1100638B1
EP1100638B1 EP99938060A EP99938060A EP1100638B1 EP 1100638 B1 EP1100638 B1 EP 1100638B1 EP 99938060 A EP99938060 A EP 99938060A EP 99938060 A EP99938060 A EP 99938060A EP 1100638 B1 EP1100638 B1 EP 1100638B1
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EP
European Patent Office
Prior art keywords
casting
rolls
coating
nip
substrate
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EP99938060A
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English (en)
French (fr)
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EP1100638A4 (de
EP1100638A1 (de
Inventor
Lazar Strezov
Kannappar Mukunthan
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Castrip LLC
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Castrip LLC
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0637—Accessories therefor
    • B22D11/0665—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating
    • B22D11/0668—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating for dressing, coating or lubricating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0637—Accessories therefor
    • B22D11/0648—Casting surfaces
    • B22D11/0651—Casting wheels

Definitions

  • This invention relates to the casting of steel strip.
  • nip is used herein to refer to the general region at which the rolls are closest together.
  • the molten metal may be poured from a ladle into a smaller vessel or series of vessels from which it flows through a metal delivery nozzle located above the nip so as to direct it into the nip between the rolls, so forming a casting pool of molten metal supported on the casting surfaces of the rolls immediately above the nip and extending along the length of the nip.
  • This casting pool is usually confined between side plates or dams held in sliding engagement with end surfaces of the rolls so as to dam the two ends of the casting pool against outflow, although alternative means such as electromagnetic barriers have also been proposed.
  • twin roll casting has been applied with some success to non-ferrous metals which solidify rapidly on cooling, there have been problems in applying the technique to the casting of ferrous metals.
  • One particular problem has been the achievement of sufficiently rapid and even cooling of metal over the casting surfaces of the rolls.
  • it has proved difficult to obtain sufficiently high cooling rates for solidification onto casting rolls with smooth casting surfaces and it has therefore been proposed to use rolls having casting surfaces which are deliberately textured by a regular pattern of projections and depressions to enhance heat transfer and so increase the heat flux achieved at the casting surfaces during solidification.
  • our United States Patent 5,701,948 discloses a casting roll texture formed by a series of parallel groove and ridge formations. More specifically, in a twin roll caster the casting surfaces of the casting rolls may be textured by the provision of circumferentially extending groove and ridge formations of essentially constant depth and pitch.
  • This texture produces enhanced heat flux during metal solidification and can be optimised for casting of steel in order to achieve both high heat flux values and a fine microstructure in the as cast steel strip.
  • the depth of the texture from ridge peak to groove root should be in the range 5 microns to 50 microns and the pitch of the texture should be in the range 100 to 250 microns for best results. For optimum results it is preferred that the depth of the texture be in the range 15 to 25 microns and that the pitch be between 150 and 200 microns.
  • the crocodile-skin defect occurs when ⁇ and ⁇ iron phases solidify simultaneously in shells on the casting surfaces of the rolls in a twin roll caster under circumstances in which there are variations in heat flux through the solidifying shells.
  • the ⁇ and ⁇ iron phases have differing hot strength characteristics and the heat flux variations then produce localised distortions in the solidifying shells which come together at the nip between the casting rolls and result in the crocodile-skin defects in the surfaces of the resulting strip.
  • a light oxide deposit on the rolls having a melting temperature below that of the metal being cast can be beneficial in ensuring a controlled even heat flux during metal solidification on to the casting roll surfaces.
  • the oxide deposit melts as the roll surfaces enter the molten metal casting pool and assists in establishing a thin liquid interface layer between the casting surface and the molten metal of the casting pool to promote good heat flux.
  • the oxides then resolidify with the result that the heat flux decreases rapidly. This problem has been addressed by endeavouring to keep the build up of oxides on the casting rolls within strict limits by complicated roll cleaning devices.
  • roll cleaning is non-uniform there are variations in the amount of oxide build up with the resulting heat flux variations in the solidifying shells producing localised distortions leading to crocodile-skin surface defects.
  • Chatter defects are initiated at the meniscus level of the casting pool where initial metal solidification occurs.
  • One form of chatter defect called “low speed chatter” is produced at low casting speeds due to premature freezing of the metal high up on the casting rolls so as to produce a weak shell which subsequently deforms as it is drawn further into the casting pool.
  • the other form of chatter defect called “high speed chatter”, occurs at higher casting speeds when the shell starts forming further down the casting roll so that there is liquid above the forming shell. This liquid which feeds the meniscus region, cannot keep up with the moving roll surface, resulting in slippage between the liquid and the roll in the upper part of the casting pool, thus giving rise to high speed chatter defects appearing as transverse deformation bands across the strip.
  • the casting surface provided in accordance with the invention is also relatively insensitive to conditions causing crocodile-skin defects and it is possible to cast steel strip without crocodile-skin defects.
  • a method of continuously casting steel strip comprising supporting a casting pool of molten steel on one or more chilled casting surfaces and moving the chilled casting surface or surfaces to produce a solidified strip moving away from the casting pool, wherein the or each casting surface is textured by a random pattern of discrete projections having peaks with a surface distribution of between 10 and 100 peaks per mm 2 and an average height of at least 10 microns.
  • the average height of the discrete projections is at least 20 microns.
  • the strip is moved away from the casting pool at a speed of more than 40 metres per minute. It may, for example, be moved away at a speed of between 50 and 65 metres per minute.
  • the molten steel may be a low residual steel having a sulphur content of not more than 0.025%.
  • the method of the present invention may be carried out in a twin roll caster.
  • the invention further provides a method of continuously casting steel strip of the kind in which molten metal is introduced into the nip between a pair of parallel casting rolls via a metal delivery nozzle disposed above the nip to create a casting pool of molten steel supported on casting surfaces of the rolls immediately above the nip and the casting rolls are rotated to deliver a solidified steel strip downwardly from the nip, wherein the casting surfaces of the rolls are each textured by a random pattern of discrete projections having peaks with a surface distribution of between 10 and 100 peaks per mm 2 and an average height of at least 10 microns.
  • the invention further extends to apparatus for continuously casting steel strip comprising a pair of casting rolls forming a nip between them, a molten steel delivery nozzle for delivery of molten steel into the nip between the casting rolls to form a casting pool of molten steel supported on casting roll surfaces immediately above the nip, and roll drive means to drive the casting rolls in counter-rotational directions to produce a solidified strip of metal delivered downwardly from the nip, wherein the casting surfaces of the rolls are each textured by a random pattern of discrete projections having peaks with a surface distribution of between 10 and 100 peaks per mm 2 and an average height of at least 10 microns.
  • a textured casting surface in accordance with the invention can be achieved by grit blasting the casting surface or a metal substrate which is protected by a surface coating to produce the casting surface.
  • the or each casting surface may be produced by grit blasting a copper substrate which is subsequently plated with a thin protective layer of chrome.
  • the casting surface may be formed of nickel in which case the nickel surface may be grit blasted and no protective coating applied.
  • the required texture of the or each casting surface may alternatively be obtained by deposition of a coating onto a substrate.
  • the material of the coating may be chosen to promote high heat flux during metal solidification.
  • Said material may be a material which has a low affinity for the steel oxidation products so that wetting of the casting surfaces by those deposits is poor.
  • the casting surface may be formed of an alloy of nickel chromium and molybdenum or alternatively an alloy of nickel molybdenum and cobalt, the alloy being deposited so as to produce the required texture.
  • Figures 1 and 2 illustrate a metal solidification test rig in which a 40 mm x 40 mm chilled block is advanced into a bath of molten steel at such a speed as to closely simulate the conditions at the casting surfaces of a twin roll caster.
  • Steel solidifies onto the chilled block as it moves through the molten bath to produce a layer of solidified steel on the surface of the block.
  • the thickness of this layer can be measured at points throughout its area to map variations in the solidification rate and therefore the effective rate of heat transfer at the various locations. It is thus possible to produce an overall solidification rate as well as total heat flux measurements. It is also possible to examine the microstructure of the strip surface to correlate changes in the solidification microstructure with the changes in observed solidification rates and heat transfer values.
  • the experimental rig illustrated in Figures 1 and 2 comprises an induction furnace 1 containing a melt of molten metal 2 in an inert atmosphere which may for example be provided by argon or nitrogen gas.
  • An immersion paddle denoted generally as 3 is mounted on a slider 4 which can be advanced into the melt 2 at a chosen speed and subsequently retracted by the operation of computer controlled motors 5.
  • Immersion paddle 3 comprises a steel body 6 which contains a substrate 7 in the form of a chrome plated copper block measuring 40mm x 40mm. It is instrumented with thermo-couples to monitor the temperature rise in the substrate which provides a measure of the heat flux.
  • the Arithmetic Mean Roughness Value which is generally indicated by the symbol R a .
  • This value is defined as the arithmetical average value of all absolute distances of the roughness profile from the centre line of the profile within the measuring length l m .
  • the centre line of the profile is the line about which roughness is measured and is a line parallel to the general direction of the profile within the limits of the roughness-width cut-off such that sums of the areas contained between it and those parts of the profile which lie on either side of it are equal.
  • the Arithmetic Mean Roughness Value may be defined as
  • the testing has further demonstrated that the sensitivity of ridged textures to crocodile-skin and chatter defects is due to the extended surfaces along the ridges along which oxides can build up and melt.
  • the melted oxide flows along the ridges to produce continuous films which dramatically increase heat transfer over substantial areas along the ridges. This increases the initial or peak heat flux values experienced on initial solidification and result in a subsequent dramatic reduction in heat flux on solidification of the oxides which leads to crocodile-skin defects.
  • a casting surface having a texture formed by a random pattern of sharp peaked projections the oxides can only spread on the individual peaks rather than along extended areas as in the ridged texture. Accordingly, the melted oxides cannot spread over an extended area to dramatically increase the initial heat flux. This surface is therefore much less sensitive to crocodile-skin defects and it has been also shown that it does not need to be cleaned so thoroughly as the ridged texture to avoid such defects.
  • the random pattern texture is much less prone to chatter defects and permits casting of low residual steels with low sulphur content at extremely high casting speeds of the order of 60 metres per minute. Because the initial heat flux on solidification is reduced as compared with the ridged texture low speed chatter defects do not occur. At high speed casting, although slippage between the melt and the casting surface will occur, this does not result in cracking. It is believed that this is for two reasons. Firstly because the initial heat transfer rate is relatively low (of the order of 15 megawatts/m 2 as compared with 25 megawatts/m 2 for a ridged texture), the intermittent loss of contact due to slippage does not result in such large local heat transfer variations in the areas of slippage. Moreover, the randomness of the pattern of the texture pattern results in a microstructure which is very resistant to crack propagation.
  • Figure 3 plots heat flux values obtained during solidification of steel samples on two substrates, the first having a texture formed by machined ridges having a pitch of 180 microns and a depth of 60 microns and the second substrate being grit blasted to produce a random pattern of sharply peaked projections having a surface density of the order of 20 peaks per mm 2 and an average texture depth of about 30 microns, the substrate exhibiting an Arithmetic Mean Roughness Value of 7 Ra. It will seen that the grit blasted texture produced a much more even heat flux throughout the period of solidification.
  • Figure 4 plots maximum heat flux measurements obtained on successive dip tests using a ridged substrate having a pitch of 180 microns and a ridge depth of 60 microns and a grit blasted substrate.
  • the tests proceeded with solidification from four steel melts of differing melt chemistries.
  • the first three melts were low residual steels of differing copper content and the fourth melt was a high residual steel melt.
  • the substrate was cleaned by wire brushing for the tests indicated by the letters WB but no brushing was carried out prior to some of the tests as indicated by the letters NO. No brushing was carried out prior to any of the successive tests using the grit blasted substrate.
  • the grit blasted substrate produced consistently lower maximum heat flux values than the ridged substrate for all steel chemistries and without any brushing.
  • the textured substrate produced consistently higher heat flux values and dramatically higher values when brushing was stopped for a period, indicating a much higher sensitivity to oxide build-up on the casting surface.
  • Figure 7 is a photomicrograph of the surface of a shell solidified onto a ridged texture of 180 microns pitch and 20 micron depth from a steel melt containing by weight 0.05% carbon, 0.6% manganese, 0.3% silicon and less than 0.01% sulphur.
  • the shell was deposited from a melt at 1580°C at an effective strip casting speed of 30m/min.
  • the strip exhibits a low speed chatter defect in the form of clearly visible transverse cracking. This cracking was produced during initial solidification and it will be seen that there is no change in the surface microstructure above and below the defect.
  • Figure 8 is a longitudinal section through the same strip as seen in Figure 7. The transverse surface cracking can be clearly seen and it will also be seen that there is thinning of the strip in the region of the defect.
  • Figures 9 and 10 are photomicrographs showing the surface structure and a longitudinal section through a shell deposited on the same ridged substrate and from the same steel melt as the shell as Figures 7 and 8 but at a much higher effective casting speed of 60m/min.
  • the strip exhibits a high speed chatter defect in the form of a transverse zone in which there is substantial thinning of the strip and a marked difference in microstructure above and below the defect, although there is no clearly visible surface cracking in the section of Figure 10.
  • Figures 11, 12, 13 and 14 are photomicrographs showing surface nucleation of shells solidified onto four different substrates having textures provided respectively by regular ridges of 180 micron pitch by 20 micron depth (Figure 11); regular ridges of 180 micron pitch by 60 micron depth (Figure 12); regular pyramid projections of 160 micron spacing and 20 micron height (Figure 13) and a grit blasted substrate having a Arithmetic Mean Roughness Value of 10 Ra (Figure 14).
  • Figures 11 and 12 show extensive nucleation band areas corresponding to the texture ridges over which liquid oxides spread during initial solidification.
  • Figures 13 and 14 exhibit smaller nucleation areas demonstrating a smaller spread of oxides.
  • Figure 15 plots respective oxide coverage measurements derived by image analysis of the images advanced in Figures 11 to 14 and provides a measurement of the radically reduced oxide coverage resulting from a pattern of discrete projections. This figure shows that the oxide coverage for the grit blasted substrate was much the same as for a regular grid pattern of pyramid projections of 20 micron height and 160 micron spacing.
  • Figures 16 and 17 are photomicrographs showing transverse sections through shells deposited at a casting speed of 60m/min from a typical MO6 steel melt (with residuals by weight of 0.007% sulphur, 0.44% Cu, 0.009% Cr, 0.003% Mo, 0.02% Ni, 0.003% Sn) onto a grit blasted copper substrate with a chromium protective coating (Figure 16) and onto a ridged substrate of 160 micron pitch and 60 micron depth cut into a chrome plated substrate ( Figure 17). It will be seen that the ridged substrate produces a very coarse dendrite structure as solidification proceeds, this being exhibited by the coarse dendrites on the side of the shell remote from the chilled substrate. The grit blast substrate produces a much more homogenous microstructure which is fine throughout the thickness of the sample.
  • the randomness of the texture is very important to achieving a microstructure which is homogenous and resistant to crack propagation.
  • the grit blasted texture also results in a dramatic reduction in sensitivity to crocodile-skin and chatter defects and enables high speed casting of low residual steels without sulphur addition.
  • Our experimental results and calculations indicate that in order to achieve this result the projections must have an average height of at least 10 microns and that the surface density of the peaks must be between 10 and 100 peaks per mm 2 .
  • An appropriate random texture can be imparted to a metal substrate by grit blasting with hard particulate materials such as alumina, silica, or silicon carbide having a particle size of the order of 0.7 to 1.4mm.
  • hard particulate materials such as alumina, silica, or silicon carbide having a particle size of the order of 0.7 to 1.4mm.
  • a copper roll surface may be grit blasted in this way to impose an appropriate texture and the textured surface protected with a thin chrome coating of the order of 50 microns thickness.
  • the coating material may be chosen so as to contribute to high thermal conductivity and increased heat flux during solidification. It may also be chosen such that the oxidation products in the steel exhibit poor wettability on the coating material, with the steel melt itself having a greater affinity for the coating material and therefore wetting the coating in preference to the oxides.
  • two suitable materials are the alloy of nickel, chromium and molybdenum available commercially under the trade name "HASTALLOY C" and the alloy of nickel, molybdenum and cobalt available commercially under the trade name "T800".
  • Figure 18 plots maximum heat flux measurements obtained on successive dip tests using a ridged chromium substrate and in similar tests using a randomly textured substrate of "T800" alloy material.
  • the heat flux values increased to high values as the oxides build up.
  • the oxides were then brushed away after dip No 20 resulting in a dramatic fall in heat flux values followed by an increase due to oxide build up through dips Nos 26 to 32, after which the oxides were brushed away and the cycle repeated.
  • the substrate was not cleaned and any oxide deposits were simply allowed to build up throughout the complete cycle of tests.
  • heat flux values obtained with the ridged chromium substrate are higher than with the "T800" substrate but exhibit the typical variations associated with melting and resolidification as the oxides build up which variations cause the crocodile-skin defects in cast strip.
  • the heat flux measurements obtained with the "T800” substrate are lower than those obtained with the ridged chrome surface but they are remarkably even indicating that oxide build up does not create any heat flux disturbances and will therefore not be a factor during casting.
  • the "T800" substrate in these tests had an R a value of 6 microns.
  • FIG. 21 is a photomicrograph of a shell solidified onto such a substrate.
  • This shell is not quite as uniform or as thick as the shell deposited on the "T800" substrate as illustrated in Figure 20. This is because the respective MO6 steel exhibits slightly lower wettability on the "HASTALLOY C” substrate than on the "T800” substrate and so solidification does not proceed so rapidly. In both cases, however, the shell is thicker and more even than corresponding shells obtained with ridged chromium surfaces and the testing has shown that the solidification is not affected by oxide build up so that cleaning of the casting surfaces will not be a critical factor.
  • FIGS 22 to 26 illustrate a twin roll continuous strip caster which may be operated in accordance with the present invention.
  • This caster comprises a main machine frame 11 which stands up from the factory floor 12.
  • Frame 11 supports a casting roll carriage 13 which is horizontally movable between an assembly station 14 and a casting station 15.
  • Carriage 13 carries a pair of parallel casting rolls 16 to which molten metal is supplied during a casting operation from a ladle 17 via a distributor 18 and delivery nozzle 19 to create a casting pool 30.
  • Casting rolls 16 are water cooled so that shells solidify on the moving roll surfaces 16A and are brought together at the nip between them to produce a solidified strip product 20 at the roll outlet.
  • This product is fed to a standard coiler 21 and may subsequently be transferred to a second coiler 22.
  • a receptacle 23 is mounted on the machine frame adjacent the casting station and molten metal can be diverted into this receptacle via an overflow spout 24 on the distributor or by withdrawal of an emergency plug 25 at one side of the distributor if there is a severe malformation of product or other severe malfunction during a casting operation.
  • Roll carriage 13 comprises a carriage frame 31 mounted by wheels 32 on rails 33 extending along part of the main machine frame 11 whereby roll carriage 13 as a whole is mounted for movement along the rails 33.
  • Carriage frame 31 carries a pair of roll cradles 34 in which the rolls 16 are rotatably mounted.
  • Roll cradles 34 are mounted on the carriage frame 31 by interengaging complementary slide members 35, 36 to allow the cradles to be moved on the carriage under the influence of hydraulic cylinder units 37, 38 to adjust the nip between the casting rolls 16 and to enable the rolls to be rapidly moved apart for a short time interval when it is required to form a transverse line of weakness across the strip as will be explained in more detail below.
  • the carriage is movable as a whole along the rails 33 by actuation of a double acting hydraulic piston and cylinder unit 39, connected between a drive bracket 40 on the roll carriage and the main machine frame so as to be actuable to move the roll carriage between the assembly station 14 and casting station 15 and vice versa.
  • Casting rolls 16 are contra rotated through drive shafts 41 from an electric motor and transmission mounted on carriage frame 31.
  • Rolls 16 have copper peripheral walls formed with a series of longitudinally extending and circumferentially spaced water cooling passages supplied with cooling water through the roll ends from water supply ducts in the roll drive shafts 41 which are connected to water supply hoses 42 through rotary glands 43.
  • the roll may typically be about 500 mm diameter and up to 2000 mm long in order to produce 2000 mm wide strip product.
  • Ladle 17 is of entirely conventional construction and is supported via a yoke 45 on an overhead crane whence it can be brought into position from a hot metal receiving station.
  • the ladle is fitted with a stopper rod 46 actuable by a servo cylinder to allow molten metal to flow from the ladle through an outlet nozzle 47 and refractory shroud 48 into distributor 18.
  • Distributor 18 is formed as a wide dish made of a refractory material such as magnesium oxide (MgO).
  • MgO magnesium oxide
  • One side of the distributor receives molten metal from the ladle and is provided with the aforesaid overflow 24 and emergency plug 25.
  • the other side of the distributor is provided with a series of longitudinally spaced metal outlet openings 52.
  • the lower part of the distributor carries mounting brackets 53 for mounting the distributor onto the roll carriage frame 31 and provided with apertures to receive indexing pegs 54 on the carriage frame so as to accurately locate the distributor.
  • Delivery nozzle 19 is formed as an elongate body made of a refractory material such as alumina graphite. Its lower part is tapered so as to converge inwardly and downwardly so that it can project into the nip between casting rolls 16. It is provided with a mounting bracket 60 whereby to support it on the roll carriage frame and its upper part is formed with outwardly projecting side flanges 55 which locate on the mounting bracket.
  • a refractory material such as alumina graphite.
  • Nozzle 19 may have a series of horizontally spaced generally vertically extending flow passages to produce a suitably low velocity discharge of metal throughout the width of the rolls and to deliver the molten metal into the nip between the rolls without direct impingement on the roll surfaces at which initial solidification occurs.
  • the nozzle may have a single continuous slot outlet to deliver a low velocity curtain of molten metal directly into the nip between the rolls and/or it may be immersed in the molten metal pool.
  • the pool is confined at the ends of the rolls by a pair of side closure plates 56 which are held against stepped ends 57 of the rolls when the roll carriage is at the casting station.
  • Side closure plates 56 are made of a strong refractory material, for example boron nitride, and have scalloped side edges 81 to match the curvature of the stepped ends 57 of the rolls.
  • the side plates can be mounted in plate holders 82 which are movable at the casting station by actuation of a pair of hydraulic cylinder units 83 to bring the side plates into engagement with the stepped ends of the casting rolls to form end closures for the molten pool of metal formed on the casting rolls during a casting operation.
  • the ladle stopper rod 46 is actuated to allow molten metal to pour from the ladle to the distributor through the metal delivery nozzle whence it flows to the casting rolls.
  • the clean head end of the strip product 20 is guided by actuation of an apron table 96 to the jaws of the coiler 21.
  • Apron table 96 hangs from pivot mountings 97 on the main frame and can be swung toward the coiler by actuation of an hydraulic cylinder unit 98 after the clean head end has been formed.
  • Table 96 may operate against an upper strip guide flap 99 actuated by a piston and a cylinder unit 101 and the strip product 20 may be confined between a pair of vertical side rollers 102.
  • the coiler is rotated to coil the strip product 20 and the apron table is allowed to swing back to its inoperative position where it simply hangs from the machine frame clear of the product which is taken directly onto the coiler 21.
  • the resulting strip product 20 may be subsequently transferred to coiler 22 to produce a final coil for transport away from the caster.
  • the copper peripheral walls of rolls 16 may be grit blasted to have a random texture of discrete peaked projections of the required depth and surface density and this texture may be protected by a thin chrome plating.
  • the copper walls of the rolls could be coated with nickel and the nickel coating grit blasted to achieve the required random surface texture.
  • an alloy such as HASTALLOY C or T800 alloy material may be electrodeposited on the copper walls of the casting rolls.
  • Figure 27 represents a typical surface texture produced according to the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Chemically Coating (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)
  • Table Devices Or Equipment (AREA)
  • Glass Compositions (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Claims (30)

  1. Verfahren zum Stranggießen von Stahlband mit den folgenden Schritten: Halten eines Gießbads aus geschmolzenem Stahl auf einer oder mehreren gekühlten Gießflächen und Bewegen der gekühlten Gießfläche(n), um ein sich vom Gießbad wegbewegendes erstarrtes Band herzustellen, wobei die oder jede Gießfläche durch ein Zufallsmuster diskreter Vorsprünge mit spitzzulaufenden Spitzen mit einer Oberflächenverteilung zwischen 10 und 100 Spitzen pro mm2 und einer mittleren Höhe von mindestens 10 Mikrometern texturiert ist.
  2. Verfahren nach Anspruch 1, wobei die mittlere Höhe der diskreten Vorsprünge mindestens 20 Mikrometer beträgt.
  3. Verfahren nach Anspruch 1 oder Anspruch 2, wobei das Band mit einer Geschwindigkeit von mehr als 40 Metern pro Minute vom Gießbad wegbewegt wird.
  4. Verfahren nach Anspruch 3, wobei das Band mit einer Geschwindigkeit zwischen 50 und 65 Metern pro Minute vom Gießbad wegbewegt wird.
  5. Verfahren nach einem der vorstehenden Ansprüche, wobei der geschmolzene Stahl ein rückstandsarmer Stahl mit einem Schwefelgehalt von höchstens 0,025 % ist.
  6. Verfahren nach einem der vorstehenden Ansprüche, wobei ein Paar der Gießflächen vorhanden ist, die durch Umfangsflächen eines Paars paralleler Gießwalzen gebildet sind, die einen Spalt dazwischen bilden, der geschmolzene Stahl in den Spalt zwischen den Gießwalzen eingeleitet wird, um das Gießbad zu erzeugen, das auf den Gießflächen der Walzen unmittelbar über dem Spalt gehalten wird, und die Gießwalzen gedreht werden, um das erstarrte Band nach unten aus dem Spalt abzugeben.
  7. Verfahren nach Anspruch 6, wobei der geschmolzene Stahl in den Spalt zwischen den Gießwalzen über eine Metallabgabedüse abgegeben wird, die über dem Spalt angeordnet ist.
  8. Verfahren nach einem der vorstehenden Ansprüche, wobei die oder jede Gießfläche durch einen sandgestrahlten Untergrund gebildet ist, der durch eine Schutzbeschichtung abgedeckt ist.
  9. Verfahren nach Anspruch 8, wobei die Schutzbeschichtung eine elektroplattierte Metallbeschichtung ist.
  10. Verfahren nach Anspruch 9, wobei der Untergrund Kupfer ist und die plattierte Beschichtung aus Chrom besteht.
  11. Verfahren nach einem der Ansprüche 1 bis 7, wobei die oder jede Gießfläche eine sandgestrahlte Oberfläche ist.
  12. Verfahren nach Anspruch 11, wobei die sandgestrahlte Oberfläche aus Nickel gebildet ist.
  13. Verfahren nach einem der Ansprüche 1 bis 7, wobei die oder jede Gießfläche durch eine Beschichtung gebildet ist, die auf einen Untergrund abgeschieden ist, um die Zufallstextur dieser Oberfläche zu erzeugen.
  14. Verfahren nach Anspruch 13, wobei die Beschichtung durch chemisches Abscheiden gebildet ist.
  15. Verfahren nach Anspruch 13, wobei die Beschichtung durch elektrolytisches Abscheiden gebildet ist.
  16. Verfahren nach einem der Ansprüche 13 bis 15, wobei die Beschichtung aus einem Material gebildet ist, das eine geringe Affinität für die Oxidationsprodukte im geschmolzenen Stahl hat, so daß der geschmolzene Stahl selbst größere Affinität für das Beschichtungsmaterial hat und daher vorzugsweise eher die Beschichtung als die Oxidationsprodukte benetzt.
  17. Verfahren nach einem der Ansprüche 13 bis 16, wobei die Beschichtung aus einer Legierung aus Nickel, Chrom und Molybdän gebildet ist.
  18. Verfahren nach einem der Ansprüche 13 bis 16, wobei die Beschichtung aus einer Legierung aus Nickel, Molybdän und Cobalt gebildet ist.
  19. Vorrichtung zum Stranggießen von Bandstahl mit einem Paar Gießwalzen, die einen Spalt dazwischen bilden, einer Abgabedüse für geschmolzenen Stahl zum Abgeben von geschmolzenem Stahl in den Spalt zwischen den Walzen, um ein Gießbad aus geschmolzenem Stahl zu bilden, das auf den Gießwalzen unmittelbar über dem Spalt gehalten wird, und einer Walzenantriebseinrichtung, um die Gießwalzen in gegenläufigen Drehrichtungen anzutreiben, um ein erstarrtes Stahlband zu erzeugen, das aus dem Spalt nach unten abgegeben wird, wobei die Gießflächen der Walzen jeweils durch ein Zufallsmuster diskreter Vorsprünge mit spitzzulaufenden Spitzen mit einer Oberflächenverteilung zwischen 10 und 100 Spitzen pro mm2 und einer mittleren Höhe von mindestens 10 Mikrometern texturiert sind.
  20. Vorrichtung nach Anspruch 19, wobei die mittlere Höhe der diskreten Vorsprünge mindestens 20 Mikrometer beträgt.
  21. Vorrichtung nach Anspruch 19 oder Anspruch 20, wobei die Gießflächen der Walzen jeweils durch einen sandgestrahlten Untergrund gebildet sind, der durch eine Schutzbeschichtung abgedeckt ist.
  22. Vorrichtung nach Anspruch 21, wobei die Schutzbeschichtung eine elektroplattierte Metallbeschichtung ist.
  23. Vorrichtung nach Anspruch 22, wobei der Untergrund Kupfer ist und die plattierte Beschichtung aus Chrom besteht.
  24. Vorrichtung nach Anspruch 19 oder Anspruch 20, wobei die Gießflächen der Walzen sandgestrahlte Oberflächen sind.
  25. Verfahren nach Anspruch 24, wobei die sandgestrahlten Oberflächen der Walzen aus Nickel gebildet sind.
  26. Vorrichtung nach Anspruch 19 oder Anspruch 20, wobei die Gießflächen der Walzen jeweils durch eine Beschichtung gebildet sind, die auf einen Untergrund abgeschieden ist, um die Zufallstextur der Oberfläche zu erzeugen.
  27. Vorrichtung nach Anspruch 26, wobei die Beschichtung durch chemisches Abscheiden gebildet ist.
  28. Vorrichtung nach Anspruch 26, wobei die Beschichtung durch elektrolytisches Abscheiden gebildet ist.
  29. Vorrichtung nach einem der Ansprüche 26 bis 28, wobei die Beschichtung aus einer Legierung aus Nickel, Chrom und Molybdän gebildet ist.
  30. Vorrichtung nach einem der Ansprüche 26 bis 28, wobei die Beschichtung aus einer Legierung aus Nickel, Molybdän und Cobalt gebildet ist.
EP99938060A 1998-08-07 1999-08-06 Giessen eines stahlbandes Expired - Lifetime EP1100638B1 (de)

Applications Claiming Priority (3)

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AUPP515198 1998-08-07
AUPP5151A AUPP515198A0 (en) 1998-08-07 1998-08-07 Casting steel strip
PCT/AU1999/000641 WO2000007753A1 (en) 1998-08-07 1999-08-06 Casting steel strip

Publications (3)

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EP1100638A1 EP1100638A1 (de) 2001-05-23
EP1100638A4 EP1100638A4 (de) 2001-10-17
EP1100638B1 true EP1100638B1 (de) 2004-04-21

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JP (1) JP4336043B2 (de)
KR (1) KR100621084B1 (de)
CN (1) CN1278799C (de)
AT (1) ATE264723T1 (de)
AU (1) AUPP515198A0 (de)
BR (1) BR9912861A (de)
CA (1) CA2337246C (de)
DE (1) DE69916617T2 (de)
ID (1) ID28068A (de)
IL (2) IL140943A0 (de)
MY (1) MY123243A (de)
NZ (1) NZ509246A (de)
TR (1) TR200100379T2 (de)
TW (1) TW478985B (de)
WO (1) WO2000007753A1 (de)
ZA (1) ZA200100310B (de)

Cited By (1)

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EP1677927A1 (de) * 2003-10-03 2006-07-12 Novelis Inc. Oberflächenstrukturierung von giessbändern für stranggussmaschinen

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AUPP852599A0 (en) † 1999-02-05 1999-03-04 Bhp Steel (Jla) Pty Limited Casting steel strip
US7073565B2 (en) 1999-02-05 2006-07-11 Castrip, Llc Casting steel strip
US7690417B2 (en) 2001-09-14 2010-04-06 Nucor Corporation Thin cast strip with controlled manganese and low oxygen levels and method for making same
US7485196B2 (en) 2001-09-14 2009-02-03 Nucor Corporation Steel product with a high austenite grain coarsening temperature
US7048033B2 (en) 2001-09-14 2006-05-23 Nucor Corporation Casting steel strip
AT412072B (de) 2002-10-15 2004-09-27 Voest Alpine Ind Anlagen Verfahren zur kontinuierlichen herstellung eines dünnen stahlbandes
AU2004205421B2 (en) 2003-01-24 2009-11-26 Nucor Corporation Casting steel strip
US20040144518A1 (en) * 2003-01-24 2004-07-29 Blejde Walter N. Casting steel strip with low surface roughness and low porosity
US7484551B2 (en) 2003-10-10 2009-02-03 Nucor Corporation Casting steel strip
JP4843318B2 (ja) * 2005-03-30 2011-12-21 株式会社神戸製鋼所 クロムめっき部材
US9999918B2 (en) 2005-10-20 2018-06-19 Nucor Corporation Thin cast strip product with microalloy additions, and method for making the same
US10071416B2 (en) 2005-10-20 2018-09-11 Nucor Corporation High strength thin cast strip product and method for making the same
US9149868B2 (en) 2005-10-20 2015-10-06 Nucor Corporation Thin cast strip product with microalloy additions, and method for making the same
AU2008100847A4 (en) 2007-10-12 2008-10-09 Bluescope Steel Limited Method of forming textured casting rolls with diamond engraving
US20110277886A1 (en) 2010-02-20 2011-11-17 Nucor Corporation Nitriding of niobium steel and product made thereby
US20110036531A1 (en) * 2009-08-11 2011-02-17 Sears Jr James B System and Method for Integrally Casting Multilayer Metallic Structures
MX2012004885A (es) * 2009-10-30 2012-08-03 Nucor Corp Metodo y aparato para controlar grosor de cubierta variable en cinta de colado.

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JP2733776B2 (ja) * 1988-12-28 1998-03-30 日新製鋼株式会社 薄板連鋳方法および装置
JP3248942B2 (ja) * 1992-03-24 2002-01-21 ティーディーケイ株式会社 冷却ロール、永久磁石材料の製造方法、永久磁石材料および永久磁石材料粉末
EP0679114B2 (de) * 1993-11-18 2004-11-03 Castrip, LLC Giessen eines kontinuierlichen stahlbandes auf eine oberfläche mit bestimmter rauhigkeit
AUPN937696A0 (en) * 1996-04-19 1996-05-16 Bhp Steel (Jla) Pty Limited Casting steel strip

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1677927A1 (de) * 2003-10-03 2006-07-12 Novelis Inc. Oberflächenstrukturierung von giessbändern für stranggussmaschinen
EP1677927A4 (de) * 2003-10-03 2007-04-04 Novelis Inc Oberflächenstrukturierung von giessbändern für stranggussmaschinen
US7448432B2 (en) 2003-10-03 2008-11-11 Novelis Inc. Surface texturing of casting belts of continuous casting machines

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MY123243A (en) 2006-05-31
KR100621084B1 (ko) 2006-09-07
EP1100638A4 (de) 2001-10-17
ZA200100310B (en) 2002-02-21
CN1278799C (zh) 2006-10-11
JP2002522226A (ja) 2002-07-23
EP1100638A1 (de) 2001-05-23
DE69916617T2 (de) 2005-04-28
CA2337246C (en) 2007-07-31
WO2000007753A1 (en) 2000-02-17
KR20010072298A (ko) 2001-07-31
CA2337246A1 (en) 2000-02-17
IL140943A (en) 2006-08-01
DE69916617D1 (de) 2004-05-27
BR9912861A (pt) 2001-05-08
ATE264723T1 (de) 2004-05-15
JP4336043B2 (ja) 2009-09-30
ID28068A (id) 2001-05-03
TW478985B (en) 2002-03-11
CN1311721A (zh) 2001-09-05
IL140943A0 (en) 2002-02-10
TR200100379T2 (tr) 2001-05-21
NZ509246A (en) 2002-09-27
AUPP515198A0 (en) 1998-09-03

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