Classifications

• • 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
  • B22D11/0674—Accessories therefor for treating the casting surfaces, e.g. calibrating, cleaning, dressing, preheating for machining
• • 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
  • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
• • 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
• • 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
  • B22D11/0697—Accessories therefor for casting in a protected atmosphere
• • 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
  • B22D11/16—Controlling or regulating processes or operations

Definitions

• the invention relates to a method and a system for the continuous production of a thin steel strip with at least two casting rolls and optionally side plates arranged laterally, wherein a casting reservoir can be formed during operation between the casting rolls and the side plates, from which liquid steel melt can be applied to the casting rolls.
• the cast strip produced especially when using the two-roll casting method known from the prior art, often has cracks and surface defects, as a result of which the quality of the steel strip produced is significantly reduced.
• the casting rolls are the casting rolls used in a two-roll casting process.
• all other mold wall surfaces known from the prior art are also encompassed by the term cast roller.
• the surface of a casting roll is preferably produced by machining, in particular by turning and / or grinding.
• tapes with the casting rolls known from the prior art in particular according to the Two-roll casting processes, as well as with RSF values between 100 N / mm and 250 N / mm (roll separating force) common in the state of the art, not only show clear cracks on the belts produced, but also very large temperature differences across the belt width and belt length , which indicate strong fluctuations in force and uneven solidifications.
• a crack-free band with a good band profile in particular a good band curvature
• a more homogeneous strip temperature across the width of the strip can already be achieved just below the mold or the casting rolls, in particular within a range of +/- 25 K.
• the tape produced by the method according to the invention generally has no thermal diagonal stripes and is characterized by a good quality of the tape edges.
• two casting rolls are provided for operating a two-roll casting process, depressions being arranged on the surfaces of both casting rolls in a random pattern, uniformly distributed over the surface of the casting roll.
• the surface structure of the casting roller used is characterized by recesses which are distributed essentially uniformly.
• these depressions are, for example, mechanically generated notches and / or indentations in the surface of the casting roll, with a height distance of 3 to 80 micrometers between the edge, in particular the ridge, and the deepest point of a depression, in particular from 20 to 40 micrometers.
• between 1 and 20 depressions per mm 2 of the casting roll surface are arranged on the casting roll surface in a random pattern - evenly distributed over the casting roll surface.
• the Si content of the steel melt is set to less than 0.35% by weight of Si.
• this measure according to the invention can be used to produce a steel strip with particularly high-quality mechanical properties, in particular with improved toughness.
• the at least partially solidified cast strip is pulled off the casting rolls at a speed of more than 30 m / min.
• this measure according to the invention enables a particularly high-quality surface quality to be achieved, while at the same time increasing the cost-effectiveness of the method.
• overrun and wrinkling of the belt surface are observed with increasing frequency (often associated with surface cracks).
• the average roughness of the surface of at least one of the casting rolls is set to more than 3 ⁇ m, the stochastic distribution of the depressions taking place by mechanical processing of the casting roll surface, in particular by shot peening.
• the mechanical treatment of the casting roll surface is carried out by shot peening with balls with a target diameter D in the range from 0.5 mm to 2.2 mm, 1 to 250 balls per shot being peened in the shot peened area of the surface of the casting roll mm 2 surface.
• the balls used for shot peening deviate at most with a maximum standard deviation of 30% from said target diameter D.
• the melt reservoir is laterally delimited by the two casting rollers and by suitable side plates and is at least partially covered at the top by a suitable cover and largely protected against the ingress of foreign media, in particular dust-containing air and / or oxidizing gases.
• the melt reservoir is exposed to an essentially inert atmosphere, the inert gas supplied being formed to 0-100% by volume from N 2 and the rest from argon or another ideal gas or CO 2 .
• the inert gas supplied has up to 7% H 2 .
• the space between the melt reservoir and the upper cover is at least partially filled or flushed by a gas which is essentially inert towards the steel melt.
• the inert atmosphere is used its content of oxygen to a maximum content of 0.05 vol .-% restricted to act on the melt reservoir with respect to 0. 2
• the strip curvature of the cast strip and the edge drop are determined on a measuring section at the casting roll outlet.
• the band curvature and the edge drop are defined in accordance with the DIN standard.
• the casting rolls are cold-profiled in such a way that the steel strip at the mold exit
• the warm profile of the casting rolls is determined during casting by one or more suitable actuators arranged on the casting rolls, depending on one or more of the following casting parameters: • Gas composition
• a band curvature of between 30 ⁇ m and 90 ⁇ m and an edge drop of less than 100 ⁇ m are set in the cast strip.
• the roughness of the casting roll surface in at least one of the casting rolls is set to be very smooth in an edge region of the casting roll of 3 to 30 mm, in particular with an average roughness of at most 2 ⁇ m.
• the casting roll separation force is regulated and / or controlled with an accuracy of at least ⁇ 15N / mm with respect to a casting roll separation force target value.
• a preferred application of the method is for steel grades in which the steel melt has the following composition:
• the invention is further characterized by a system according to claim 19.
• 1 to 20 depressions per mm 2 are provided on the casting roll surface.
• the casting roller surface is one by shot peening, in particular one with balls with a diameter between 0.5 mm to 2.2 mm and a scattering of the diameter of the balls of less than 30% (based on a diameter interval in the said range Target diameter D), preferably provided with 1 to 250 balls per mm 2 of blasted, produced surface structure.
• a cover is provided above the two casting rolls, through which the melt reservoir can be covered.
• a suitable device is provided by means of which a gas atmosphere which is essentially inert towards the steel melt can be set in the area of the melt reservoir, above the steel melt, in particular in the space between the steel melt and the cover.
• a measuring section is provided for determining the strip curvature of the cast strip and / or the edge drop in the strip thickness between the strip edge and a distance of 40 mm from the strip edge.
• At least one of the casting rolls is cold pre-profiled.
• at least one actuator is provided on at least one of the casting rolls, by means of which the hot profile of the casting roll corresponds to one or more of the following casting parameters
• a control device is provided, by means of which the hot profile and / or cold profile of at least one of the casting rolls can be adjusted as a function of the measured strip curvature and the measured edge drop in strip thickness between the strip edge and a distance of 40 mm from the strip edge.
• At least one of the casting rolls has an average roughness of at most 2 ⁇ m in an edge region of 3 to 30 mm.
• a device for regulating the casting roll separating force with an accuracy of at least ⁇ 15 N / mm is provided.
• the casting rolls are arranged such that they can be adjusted to one another.
• a device for measuring the setting force and, on the other hand, a device for regulating the setting of the casters as a function of the measured forces are provided.
• a suitable device is provided, by means of which the crowning of at least one of the casting rolls can be changed during the operation of the system.
• a suitable device is provided, by means of which the hot shape of the edge region of at least one of the casting rolls can be changed during the operation of the system.
• a suitable device for measuring the meniscus angle and, if appropriate, a suitable device for regulating and / or controlling the meniscus angle are provided.
• a device for measuring the strip profile is provided.
• At least one of the casting rolls essentially consists of a good heat-conducting material, in particular of copper or a copper alloy.
• at least one of the systems has an internal cooling device.
• At least one of the casting rolls has a chrome coating on the outside with a minimum layer thickness of 10 ⁇ m.
• an at least 0.5 mm thick intermediate layer in particular an intermediate layer made of nickel and / or a Ni alloy, is provided below the chrome coating.
• a device for measuring the speed of at least one casting roll is provided and a setpoint speed value can be transmitted to the casting roll drives via a control circuit which takes into account some of the other important casting parameters, such as the current roll separation force and / or the current meniscus angle to set the determined target speed.
• a device for throttling and regulating the supply of liquid steel is provided, so that the desired target meniscus angle can be set, or can be regulated by means of a suitable control circuit which takes into account at least the actual value of the meniscus angle.
• a stainless steel with a C content of up to 0.5% is cast at casting speeds of over 30 m / min, in particular over 50 m / min, using one or more of the following parameters:
• Stable casting roll surface topology achieved by shot peening with steel balls of a certain diameter with accuracy d +/- 30%, where d is between 0.5 and 2.2 mm. In the shot peening process, 1 to 250 balls should hit a mm 2 casting roll surface
• the pouring sump between the two pouring rollers is covered above by a mold cover, a gas of the following composition being used to make the atmosphere above the pouring level inert: 0-100% N 2 ; Rest Ar or other ideal gas or C0 2 ; up to 7% H as well as minimal combinations, which can hardly be avoided in technical gases, allowed (at least less than 0.05% 0 2 )
• strip curvature (defined according to hot strip DIN standard) between 20 and 120 ⁇ m, preferably between 30 and 90 ⁇ m;
• the cast steel has the following composition:
• the casting rolls used have an average roughness depth of Ra> 3 ⁇ m, preferably of Ra> 6 ⁇ m.
• At least one of the casting rolls used has a chrome coating with a layer thickness of at least 10 ⁇ m and / or a nickel coating, which may be located under the chrome coating, with a layer thickness of at least 0.5 mm thickness.
• the jacket of the casting roll is made of copper, which may serve as the basis for any coatings on the roll.
• the casting roll has no appreciable roughness in an edge region of 3 to 30 mm (Ra 2,0 2.0 ⁇ m).
• liquid steel is fed between two counter-rotating, horizontally arranged casting rolls which have a suitable cooling device, in particular a water cooling device, which is arranged in the rolls.
• a suitable cooling device in particular a water cooling device, which is arranged in the rolls.
• the solidified strand or band is pulled off below the kissing point.
• the liquid metal can be poured from a pan into a smaller vessel, from which it is poured into the belt casting system or into the space above the kissing point between the two casting rollers via a suitable pouring tube.
• the poured-in metal forms a melting reservoir above the kissing point, which is limited on the one hand by the surfaces of the casting roller and on the other hand by suitable side plates or other suitable devices, for example suitable electromagnetic devices.
• the side plates are designed to be movable.
• Fig. 1 shows an apparatus and a method for producing a thin steel strip according to the invention
• Fig. 2 shows a detail of an apparatus and a method for producing a thin steel strip according to the invention
• the casting and rolling device shown in FIG. 1 shows a belt casting system 1 consisting of a ladle 2 with a pouring tube 3 and two pouring rollers 4, 5 rotating in opposite directions.
• the casting belt 6 is conveyed via a cooling section 7 to a roll stand 8.
• the metal strip is reduced in thickness by at least 10%.
• the strip thus rolled is conveyed through a warming and / or heating device 9 and coiled on a coiler 10.
• the coiled strip is heat-treated in a corresponding heat treatment plant (not shown).
• the meniscus angle ⁇ is determined using a normal cut (plane normal to the center line of the casting roll) between the connection
• the meniscus angle is measured, for example, by determining the height of the casting level.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Metal Rolling (AREA)
• Heat Treatment Of Sheet Steel (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=31192794

Family Applications (1)

Country Status (16)

Families Citing this family (25)

Family Cites Families (23)

• 2002
  • 2002-10-15 AT AT0156102A patent/AT412072B/de not_active IP Right Cessation
• 2003
  • 2003-06-10 UA UAA200504448A patent/UA78123C2/uk unknown
  • 2003-10-06 EP EP03748115A patent/EP1551579A1/de not_active Withdrawn
  • 2003-10-06 AU AU2003267431A patent/AU2003267431B2/en not_active Ceased
  • 2003-10-06 BR BR0315322-3A patent/BR0315322A/pt not_active Application Discontinuation
  • 2003-10-06 JP JP2004544076A patent/JP2006502862A/ja active Pending
  • 2003-10-06 RU RU2005114514/02A patent/RU2323063C2/ru not_active IP Right Cessation
  • 2003-10-06 PL PL03375471A patent/PL375471A1/xx not_active Application Discontinuation
  • 2003-10-06 CA CA002502141A patent/CA2502141A1/en not_active Abandoned
  • 2003-10-06 KR KR1020057006459A patent/KR20050050140A/ko not_active Ceased
  • 2003-10-06 MX MXPA05003855A patent/MXPA05003855A/es unknown
  • 2003-10-06 CN CNA2007100857043A patent/CN101015855A/zh active Pending
  • 2003-10-06 WO PCT/EP2003/011007 patent/WO2004035247A1/de not_active Ceased
  • 2003-10-06 CN CNB2003801013812A patent/CN100372631C/zh not_active Expired - Fee Related
  • 2003-10-07 TW TW092127766A patent/TWI313204B/zh not_active IP Right Cessation
• 2005
  • 2005-04-11 ZA ZA200502911A patent/ZA200502911B/en unknown
  • 2005-04-15 US US11/107,948 patent/US7156152B2/en not_active Expired - Fee Related
  • 2005-04-15 US US11/107,690 patent/US7328737B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events