WO2013164469A1 - Cylindre de laminoir moulé par centrifugation pour dernières cages finisseuses dans des laminoirs à bandes à chaud - Google Patents

Cylindre de laminoir moulé par centrifugation pour dernières cages finisseuses dans des laminoirs à bandes à chaud Download PDF

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Publication number
WO2013164469A1
WO2013164469A1 PCT/EP2013/059296 EP2013059296W WO2013164469A1 WO 2013164469 A1 WO2013164469 A1 WO 2013164469A1 EP 2013059296 W EP2013059296 W EP 2013059296W WO 2013164469 A1 WO2013164469 A1 WO 2013164469A1
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WIPO (PCT)
Prior art keywords
shell composition
roll
shell
roll according
composition
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PCT/EP2013/059296
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English (en)
Inventor
Jose Tinoco
Roger Finnström
Nils Bäckström
Jerôme Senaneuch
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Åkers AB
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Publication of WO2013164469A1 publication Critical patent/WO2013164469A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/06—Cast-iron alloys containing chromium
    • C22C37/08—Cast-iron alloys containing chromium with nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • 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
    • B21B27/02—Shape or construction of rolls
    • B21B27/03—Sleeved rolls
    • B21B27/032—Rolls for sheets or strips

Definitions

  • the invention relates to a process for producing a centrifugally cast composite roll intended for last finishing stands in hot strip mills having surface properties, oxidation properties and wear resistance that are highly desirable for use in the hot rolling of steel.
  • the present invention also relates to a method for producing such a roll.
  • a continuously moving steel workpiece (the strip) is passed through a rolling mill which commonly consists of several stands of rolls arranged in a straight line (in tandem) or reversing (steckel).
  • the strip cools as it passes through the rolling mill, such that each succeeding stand is at a lower temperature than its predecessor stand.
  • each succeeding stand is at a lower temperature than its predecessor stand.
  • the strip reaches the rolls of the last few mill stands there is a tendency of the strip to stick to the rolls through which it passes because of the lower temperature of the roll.
  • the results of such behavior can be a catastrophic failure of the rolling process which may cause damages to the rolling mill stands and surrounding structures, not to mention the grave threat to workers in the area.
  • Vanadium and Niobium is known to form extremely hard MC carbides and it is also known that these carbides tend to segregate during centrifugal casting.
  • WO96/39544 discloses an IC roll alloy composition with Niobium and a method of producing such a roll.
  • EP 0559899 Ai discloses a material of outer layer of the roll for rolling containing the following elements at respective ratio: C: 1.5-3.5 %' ⁇ > Si: 1.5 % or under; Mn: 1.2 % or under; Cr: 5.5-12.0 %; Mo: 2.0-8.0 %; V; 3.0-10.0 %; and Nb: 0.6-7.0 %, on condition that the following formulas: V + 1.8 Nb 27.5 C - 6.0 (%) and o.2 ⁇ Nb/V ⁇ 0.8 must be satisfied and, further, containing Fe and irremovable impurities as the remainder.
  • EP O 560 210 Al discloses a roll which provides a compound roll having a shell portion having a fine metal structure with excellent uniformity.
  • US 2009/0092852 Al discloses a roll comprising vanadium which is developed to have high amounts of carbides in the outer layer.
  • a centrifugally cast composite roll comprising an outer layer having a composition comprising by mass 2.5-9 % of C, 0.1-3.5 % of Si, 0.1-3.5 % of Mn, and 11-40 % of V, the balance being Fe and inevitable impurities.
  • an object of the invention is to find a roll with a high quality which is crucial for rolls suitable for last finishing stands with optimal oxidation properties is also desired in combination with improved wear resistance.
  • Figure 2 shows an exemplifying embodiment of how the basic principle of an analysis of three different scenarios of a thermal test sample.
  • Figure 3 shows an exemplifying embodiment of hardness of the roll according to the invention relative to the surface distance and comparison with a comparative roll.
  • Figure 4 shows an exemplifying embodiment of accumulated performance of the roll according to the invention and in comparison with a comparative roll.
  • Figure 5 shows an exemplifying embodiment of oxidation behavior of the roll according to the invention and in comparison with a comparative roll.
  • Figure 6 shows an exemplifying embodiment of a comparative study comparing thermal expansion of a roll according to the invention and a comparative roll.
  • Figure 7 shows an exemplifying embodiment of particle size distribution in the roll according to the invention and a comparative roll.
  • Figure 8 shows an exemplifying embodiment of the micro structure in the shell material of a roll according to the invention.
  • Figure 9 shows an exemplifying embodiment of the distribution of hard particles along the shell depth of the roll according to the invention.
  • the invention relates to a process for producing a centrifugally cast composite roll intended for last finishing stands in hot strip mills and its shell composition composed of (weight %); C: 2.5-4.0%, Nb: 1.1-6.0%, V: 0.7-3.0, Ni: 4.2-4.6%, ⁇ : ⁇ .3- ⁇ 3%, Cr: 1.5-2.2%, Si: 0.7-1.6%, Mn:o.7-i.o%, Zr: 3% or less, Ti: 3% or less, P: 0.12% or less, S: 0.08% or less and balance with Fe and unavoidable impurities and the produced roll and its use.
  • the invention relates to a process for producing a centrifugally cast composite roll intended for last finishing stands in hot strip mills and its shell composition composed of (weight %); C: 2.5-4.0%, Nb: 1.1-6.0%, V: 0.7-3.0, Ni: 4.2-4.6%, ⁇ : ⁇ .3- ⁇ 3%, Cr: 1.5-2.2%, Si: 0.7-1.6%, Mn:o.7-i.o%, Zr: 3% or less, Ti: 3% or less, P: 0.08% or less, S: 0.08% or less and balance with Fe and unavoidable impurities and the produced roll and its use.
  • the shell composition for a roll according to the invention is composed of (weight %); C: 2.5-4.0%, Nb: 1.1-6.0%, V: ⁇ .7-3. ⁇ , Ni: 4.2-4.6%, Mo:0.3-l.3%, Cr: 1.5-2.2%, Si: 0.7-1.6%, Mn:o.7-i.o%, optionally Zr: 3% or less, optionally Ti: 3% or less, P: 0.12% or less, S: 0.08% or less and balance with Fe and other unavoidable impurities.
  • the invention comprises the following alternatives and combinations.
  • the following relationship must be maintained: 8.0 ⁇ A/B ⁇ 8.8 or for example 8.0675 ⁇ A/B ⁇ 8.7699.
  • a centrifugal cast roll formed with a shell composition according to the invention 1-6 and a core selected from nodular cast iron and wherein the shell composition comprises 1-5 area % or 0.5-3-2 area % of graphite.
  • a centrifugal cast roll according to the invention formed with a shell composition according to any of the claims 1-6 and a core and wherein the shell composition comprises 2-3 % of MC carbides with a particle size of 7-35 ⁇ .
  • a centrifugal cast roll according to the invention formed with a shell composition according to any of the claims 1-6 and a core and wherein the shell composition comprises MC carbides and wherein at least 65 % of said MC carbides have a particle size larger than 8 ⁇ or wherein at least 65 % of said MC carbides have a particle size larger than 9 ⁇ and is evenly spread within the shell material.
  • a centrifugal cast roll according to the invention formed with a shell composition according to any of the claims 1-6 and a core selected from nodular iron and wherein the shell composition has oxidation kinetics measured at 900 seconds of 2-7 mg/cm 2 or 3.4-4.5 mg/cm 2 or 7 mg/cm 2 or less or 4 mg/cm 2 .
  • a centrifugal cast roll according to to the invention formed with a shell composition according to any of the claims 1-6 and a core and wherein the shell composition comprises 25-30 area % of cementite (200) and a total amount of 60-70 area % of bainite (202), martensite (204) and some residual austenite.
  • a centrifugal cast roll according to the invention formed with a shell composition according to any of the claims 1-6 and a core selected from nodular iron and wherein the shell composition has a hardness drop of 0.5-1,5 ShC per 10 mm shell depth.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition of any of claims 1-6, comprising the steps of; a) providing a roll shell composition according to the invention and b) produce a molten batch comprising the shell composition according to the invention casting the molten batch comprising the shell composition according to the invention
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition to the invention, comprising the steps to the invention and wherein the core material is nodular iron.
  • a production method for a centrifugal cast roll according to the invention comprising the composition according to the invention and wherein the production of said molten batch involves controlling melt inoculation by testing that said molten batch has a temperature increase during solidification which is 3-50 °C above the liquidus temperature of said batch.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, comprising roll according to the invention and wherein said testing is performed at a temperature of 1500-1520 °C of the melt.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, wherein the casting of the shell composition is performed at a centrifugal force of 110-130G or at 120G.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, and wherein the casting of the shell composition further comprises a step of applying flux material in 7-201/m 2 thickness on the inner part of the shell composition (106) which gives the roll a protective surface during casting of the core.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, and wherein the production method further comprising a tempering step performed by selecting a combination of hardness and residual austenite obtained optimum condition in the temperature range of 450-600 °C .
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, comprising and wherein the casting of the shell composition further comprises a step of applying flux material in 5-121/m 2 or 7-81/m 2 thickness on the inner part of the shell composition (106) which gives the roll a protective surface during casting of the core.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, and wherein the shell composition (2) in the casted roll has a thickness of 6-12% of the roll diameter.
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, wherein the method further comprising a solidification step and wherein the average solidification rate of the casted roll is 2-3mm/min
  • a production method for a centrifugal cast roll according to the invention comprising the shell composition according to the invention, wherein the tempering of the roll shall be performed twice at a tempering temperature, TA, in the interval of 450-475 °C, or at 450 °C, during a retention time of 10-305 h with intermediate cooling to room temperature.
  • a centrifugal cast roll and its shell composition are disclosed.
  • the roll with the shell composition according to the invention may be used in steel hot rolling applications in steckel and late finishing stands of hot strip mills for example suitable for last finishing stands.
  • the benefit of the roll according to the invention is that it allows longer rolling campaigns due to its improved wear resistance. This is achieved without compromising on its reliability and surface properties. This grade can be implemented in the mill without any changes in rolling parameters compared to standard or enhanced IC rolls.
  • the roll according to the invention is a roll suitable for last finishing stands.
  • Last finishing stands need to have special surface properties and also improved crack resistance compared to rolls suitable for earlier finishing stands.
  • the quality is crucial for rolls suitable for last finishing stands and there is a need for improving work performance and wear resistance to be able to improve the productivity in the mill.
  • Optimal oxidation properties are also desired in combination with improved wear resistance.
  • shell composition shall mean an iron-based alloy intended for use in centrifugal casting the shell of a rolling mill roll and generally having a composition comprising ( in weight %);
  • the shell of the centrifugal cast roll according to the invention comprises the shell composition and has a microstructure after casting that comprises MC carbides with a particle size between 7-35 ⁇ in 2-3 area fraction %, where at least 65% of said carbides have a particle size larger than 9 ⁇ or for example wherein less than 35% of the said carbides have a smaller size 9 ⁇ . which gives the roll according to the invention improved wear and abrasion resistance.
  • the iron-based alloy intended for use in centrifugal casting the shell of a rolling mill roll according to the invention has a composition comprising ( in weight %);
  • Carbon: 2.5 - 4.0 % C is an element for increasing for example hardness, and wear resistance in the roll material because it forms a hard carbide and is therefore required 2.5 %, preferably 3.3 % or more.
  • the crack resistance of the roll is however significantly lowered with a carbon content exceeding 4.0 %. Therefore, 4.0 % is set as the upper limit.
  • a preferred range is 3.3 - 3.8 % and even more preferred 3.4-3.8 %.
  • Si is a deoxidation agent. Si is an element necessary to maintain the casting ability, therefore 0.7% is set as lower limit. When the Si content is exceeding 1.6 % the crack resistance is not as effective and Si in larger quantities may promote defective graphite shapes in the structure. Si increases the carbon activity and promote carbide formation. A preferred range is 0,9-1.6%, and even more preferred 1.1-1.5 % ⁇
  • Mn is necessary for the same purpose to Si.
  • the lower limit is chosen due to the fact that it promotes phase transformations occurring during heat treatment. However, it is not desirable to contain Mn in the content exceeding 1.0 % for lowering of the crack resistance. Therefore, 1.0 % is set as the upper limit.
  • a preferred range is 0.8-1-0%.
  • Chromium 1.5 - 2.2 %
  • Cr is an essential element for a number of properties in the material but most important is to control the oxidation behavior in the material. Cr decreases the tendency of carbon to solidify as graphite. A preferred range is 1.6-2.2 %.
  • Mo is effective for forming the carbide and increasing wear resistance similarly to Cr, and, in addition, effective for strengthening the matrix by increasing hardenability. Therefore, Mo is added in the content of 0.3 %, preferably 0,5 % or more. However, when Mo content exceeds 1.3 %, the crack resistance is lowered. Therefore, 1.3% is set as the upper limit. A preferred range is 0.5-1.3, %, and even more preferred 0.7-1.2 %.
  • Nickel 4.2-4.6 %
  • Ni is effective for promoting the phase transformation in the material matrix during cooling.
  • the lower limit is chosen in order to avoid precipitation of unfavorable phases such as pearlite. Therefore, the lower amount is set to 4.2 %, preferably 4.3 %.
  • Ni serves for example for increasing the hardenability and strength of the matrix. It is though undesirable to contain Ni in a content exceeding 4.6 % for formation of unstable structure, such as retained austenite. Therefore, 4.6 % is set as the upper limit.
  • a preferred range is 4.3-4.6 % and even more preferred 4.4-4.6 %
  • Ti and Zr are optional elements and may be added to suppress formation of large eutectic carbide and to improve wear resistance and crack resistance. However, when the contents of Ti and Zr exceed 3.0 %, it may deteriorate configuration of composite carbide of V and Nb and conversely lower the wear resistance. Therefore, the upper limits of Ti and Zr are respectively set at 3.0 %. Preferably, Ti and Z are only present as not intentionally added and are only present as unavoidable residuals from the raw material. In one embodiment both Ti and Zr is 0%. In other embodiments, Zr is between 0-3% or 0.1- 3% and Ti is 0%. Or for example in one embodiment Zr is 0% and Ti is 0-3% or 0.1-3%. In another embodiment according to the invention both Zr and Ti is 0%. In another alternative embodiment Ti+Zr is together 0-3% or 0,1-3%.
  • V 0.7-3-0 % or 0.8-3.O %
  • Nb 1.1-6.0 %
  • V and Nb are important elements in the present invention together with Mo. The combined addition of these elements in the composition and conditions for their relations limits therefore important features of the invention.
  • composition according to the present invention may for example satisfy at least one of the following formulas: (1001) (V + Mo) / Nb > 0,35
  • V is an essential element for forming MC or M4 C3 carbides which are the most effective carbides for increasing the wear resistance. In order to attain the effect, it is required to be added in the content of 0.8 % or more. However, if it exceeds 3.0 %, the material becomes excessively brittle and difficult to handle. Therefore, the upper limit is set at 3.0 %. A preferred range is 0.8-1.2 %, and even more preferred 0.8-1.1 %.
  • Nb also forms MC carbide similarly to V, which is effective for increasing the wear resistance.
  • Nb when Nb is solely added, it forms large size carbide block that due to its size and density tend to segregate towards the outer periphery making impossible to obtain an even distribution. Therefore, Nb shall be added in combination with V in order to provide a desired carbide distribution.
  • the graphite to carbide ratio may be regulated by Nb. A preferred range is 1.1-1.4 %, and even more preferred 1.2-1.4 % ⁇
  • Phosphorus ⁇ 0.12 % or ⁇ 0.08 % should be kept as low as possible.
  • Sulphur ⁇ 0.08 % should be kept as low as possible.
  • composition according to the present invention may for example satisfy the following formulae in order to get the desired balance between hard wear resistant carbides and a tough matrix.
  • the following relation between Carbon/Silicon and the carbide forming elements (Mo, Cr, V and Nb) is preferred:
  • the shell composition in an IC roll results in a shell containing MC carbides which are homogenously distributed in the matrix of the roll shell.
  • the shell composition in the roll according to the invention comprises 2.-3 area % of MC carbides having a particle size between 7- 35 ⁇ , M being mainly V and Nb, and some Mo.
  • the MC carbides with particle size between 7- 35 ⁇ gives the roll according to the invention improved wear and abrasion resistance. Occasional Mo-rich M2C carbides were also observed, which also contained some Nb and V.
  • a comparison of the particle size distribution of the MC carbides in an IC roll according to the invention and a comparative roll is seen in figure 7 and it is seen that the amount of carbides having maximum size of 6 ⁇ has been reduced in favour for higher amounts of carbides having larger sizes.
  • an improved distribution over the shell depth is achieved which results in better roll performance and increased lifespan.
  • the composition of the comparative roll 12 is seen in Table 2 in this patent.
  • the comparative roll 12 is also further disclosed in patent WO96/39544.
  • the shell of a roll made from the shell composition according to the invention further has a matrix having an even distribution of 25-30 area % of cementite 200 and a total amount of 60-70 area % of bainite 202 and martensite 204 and some residual austenite, see figure 8.
  • Figure 8 shows the micro structure in the shell material of a roll according to the invention, the light dots are MC carbides 206 and the deep black pattern are graphite 208 darker gray pattern is cementite 200 and lighter grey pattern is bainitic 202 and martensitic 204 matrix.
  • the bainite and martensite balance is controlled so that the amount of martensite is larger than the amount of bainite in order to reduce the amount of retained austenite, which is undesired since roll performance is deteriorated.
  • the shell of an IC roll made from the shell composition according to the invention further contains 2.0-3.0 area % MC carbides 206 and 0,5-3 are % graphite 208 homogenously distributed in the matrix 210.
  • the microstructure in the shell of the roll according to the invention is showed in figure 13.
  • the composition of the comparative roll 12 is evident from Table 2.
  • the comparative roll 12 is also further disclosed in patent WO96/39544.
  • the present invention further includes a centrifugally casted IC roll formed from the shell composition alloy according to the invention produced by a method according to the invention including several steps:
  • the roll according to the invention is prepared in several steps using centrifugal casting technique.
  • the shell material in the roll according to the invention is the outermost 6-12% of the total roll diameter.
  • the rest of the roll comprises of core material for example nodular iron.
  • the product is manufactured by centrifugal casting. Prior to the actual casting the melting and alloying procedure is performed in order to achieve the optimal balance between the different phases present in the shell material.
  • One feature in the new material is the increased amount of hard particles, i.e. more carbides having larger sizes (see figure 7). Additionally, the hard particles are more homogenously distributed long the shell depth.
  • Another feature is that the material shows a more even distribution of the different phases in the matrix (cementite, graphite and bainite/martensite) long the shell depth.
  • a controlled balance between martensite and bainite is also beneficial for the properties of the roll shell.
  • Yet another feature is an increased hardness of the shell material. The fundamental properties such as overall hardness are determined by the balance between cementite and graphite. This balance is controlled by the casting procedure.
  • the microstructure is controlled by adjusting the level of inoculation in the melt.
  • the tapping temperature is 150-300 degrees above the material liquidus temperature.
  • the tapping sequence is further carefully timed to specified set points between the different parts of the roll.
  • the processing of the blank consists of a heat treatment where the temperature and holding times have been selected in order to obtain high toughness and stability in the matrix as well as a low residual stress level.
  • the size distribution of the hard particles in the shell material 2 determines its wear resistance.
  • a modification of the size has been achieved without compromising its distribution long the shell depth.
  • the matrix in the shell of the roll 1 according to the invention consists of similar amounts of the existing phases in as in a comparative roll (see Table 2). However the matrix hardness is approximately 20% higher in the roll according to the invention compared to the comparative roll (which roll composition is described in Table 2).
  • the casting sequence is described in relation to figure 1.
  • the roll comprises mainly two parts: a core and a shell.
  • the shell 2 comprising the shell composition according to the invention is tapped first.
  • the shell 2 is prepared using a casting pipe and is cast at a high rotational speed.
  • the rotational speed is selected depending on the size of the roll and the diameter of the roll in order to obtain a force of gravitation of approximately 100-150 G, which is required for obtaining an even thickness of the roll shell.
  • the shell 2 is allowed to solidify and the temperature of the solidified shell 2 is allowed to cool to a certain temperature.
  • the core is then tapped in three steps with intermediate solidification and cooling while forming three core parts.
  • the different parts may be seen in figure 1; the roll bottom core part 4, a top-neck core part 5, and an outer core part 3 and the shell 2.
  • the casting of the outer shell and the core is made by casting in sequence from two (or more) different furnaces.
  • the casting from the different furnaces is controlled by controlling a set point (500) and the tapping into the casting ladle from the different furnaces is timed so that the casting of the core starts when the shell 2 has a desired temperature in order to avoid undesired remelting of the shell but still allow sufficient bonding between the core and the shell.
  • the shell temperature reaches the desired setpoint
  • casting of outer core part 3 of the core starts. Tapping of the bottom core part 4 into the casting ladle starts before the setpoint for the outer core part 3 is reached so that casting of the roll bottom core part 4 may start when the setpoint is reached.
  • Casting of the top-neck core part 5 is controlled in an analogous manner.
  • the set point timing depends on thickness of core and heating capacity of the material.
  • the present invention includes an enhanced roll produced by a method comprising, but not limited to the following steps: providing an steel melt having a composition according to the invention casting the molten batch of shell composition according to the invention, and casting at least one, preferably at least two other molten batches of core composition to form a bottom core part 4, a top-neck core part 5 and optionally an outer core part 3 to achieve a roll according to the invention.
  • the present invention includes a roll produced by a method comprising the following steps: providing a roll shell composition according to the invention, and adding Niobium in the induction furnace at a temperature of 1400-1600 °C, a temperature where all Niobium is dissolved, and in an amount sufficient to produce a molten batch containing 1.1 to 6.0% niobium based on the total weight of said molten shell batch, providing a stoichiometric amount of excess carbon to form niobium carbide.
  • the molten batch is kept at this temperature for 10-60 minutes or until an analysis of the molten metal indicates that the niobium content is within the specification and
  • Performing a thermal analysis test for indication of the hardness of the roll shell by checking behavior of cooling curve for a test sample taken from the molten shell batch at a temperature between 1500-1520 °C, optionally adjusting the behavior of the cooling curve so that the temperature increase during
  • the bainite and martensite balance is controlled so that the amount of martensite is larger than the amount of bainite in order to reduce the amount of retained austenite, which is undesired because it deteriorates roll performance.
  • the shell of a roll made from the shell composition according to the invention further contains 2.5-3.0 area % MC carbides (206) and 0.5-3 area % graphite.
  • the preparation of the alloy requires heating a metal charge having an overall compositional range (selected from table 1) required for a roll shell according to the invention.
  • the preparation method of the shell alloy according to the invention comprises a step for controlling melt inoculation
  • the melting comprises several steps (a-g).
  • the composition according to the invention is in step a heated up to 1550 °C and is then kept at 1550 °C for 20 minutes in step b.
  • Niobium is added in an amount sufficient to produce a molten batch containing 1.1 to 6.0% niobium based on the total weight of said molten batch.
  • step c the molten batch is cooled and kept at a temperature of 1450 °C for 10 minutes and the amount Niobium is checked during this period.
  • step d amounts of other elements (except Niobium) is adjusted.
  • step g a thermal test is performed in step g in order to determine the need of possible adjustment of the level of inoculation in the shell alloy in order to determine final hardness of the shell.
  • the thermal test (performed in step g, figure 2) is a test which allows for adjustment of carbide formers. A small sample of the melt is taken out and solidification rate is analyzed by analyzing the course of cooling of the sample melt.
  • FIG. 2 shows the basic principles of three different scenarios (3a-3c) when a thermal test sample is analyzed. The thermal test is made in order to be able to adjust the composition before casting.
  • Scenario b) in figure 2 shows an "ideal scenario” and allows for the melt to be cast without any adjustments of the composition.
  • the solidification of the sample takes place during generation of a certain amount of excessive heat (exothermic reaction) resulting in a temperature increase in the sample.
  • the temperature increase amounts to max 30 above or for example 50 °C above the liquidus temperature.
  • Scenario shows a thermal test wherein the composition needs to be adjusted or the shell will have insufficient hardness.
  • the solidification of the sample takes place during continued temperature reduction of the sample, i.e. no heat generation.
  • the molten batch may be adjusted by addition of a suitable amount of chromium.
  • Scenario c shows a thermal test wherein the composition needs to be adjusted, or the shell will become too hard.
  • the solidification takes place during too high generation of excessive heat, resulting in an increase of the sample temperature in the order of more than 50 °C.
  • the molten batch may be adjusted by the addition of a suitable amount of silicon.
  • the roll may comprise flux material (108), of a thickness of 5-201/m 2 .
  • the flux material (108) may be applied on the inner part of the outer shell (106) before casting of the core (112) and gives the roll a protective surface during casting of the core.
  • Tempering of the roll according to the invention should be performed by selecting an optimum condition in the temperature range of 400 - 600 °C. More precisely, the tempering of the roll shall be performed at a tempering temperature, TA, in the interval of 450-475 °C, preferably at 450 °C, during a retention time, ta, of 10-305 h.
  • TA tempering temperature
  • the heat treatment mainly consists of a tempering process. In this process stress are relieved and the final adjustment of the hardness and residual austenite are done.
  • the cycle consists of a heating step (10-30 0 C/hour depending on barrel diameter), a holding step at 470 °C and a cooling step (20-30 °C per hour depending on diameter). This cycle can be repeated in order to achieve the desired hardness at temperatures between 400-450 °C.
  • the roll made according to the described method greatly enhances the abrasion resistance of the type of roll without reducing its resistance to welding to the strip or its resistance to initiation of cracks under shock loading, by maintaining a balance between free graphite and carbides in the chilled zone during eutectic solidification.
  • the roll according to the invention shows a more even distribution of the different phases (cementite, graphite and
  • the use of niobium and vanadium in the roll according to the invention allows the addition of a relatively large amount of a strong carbide forming element to a roll alloy which will retain its essential partially graphitized chilled structure evenly distributed in the roll.
  • the present invention provides a roll composition that overcomes the problems associated with the prior art.
  • Alloys of this composition are well known in the art and will produce a proper balance or equilibrium between carbide formers and free graphite formers at the eutectic solidification temperature.
  • Alloys having graphite present in quantities greater than 8% of the total volume are generally too soft to be employed as the outer shell of the rolling mill roll, while alloys containing less than 0.5 % free graphite are not suitable to be deployed as a chill roll outer shell because they are not sufficiently resistant to thermal shock and do not have sufficient graphite to reliably prevent welding of the workpiece to the roll.
  • the roll has a hardness drop of 0.5-1.5 ShC per 20 mm in shell (see figure 3). See figure 5 for a comparison of the hardness profile between the roll according to the invention (see for example table 1) and a comparative roll (see Table 2, for a comparative roll 12).
  • the roll according to the invention 1 has a density is between 7400 and 7500 kg/m3.
  • the Young modulus is around 170-190 GPa and tensile strength is 375-475 MPa.
  • the rolls according to the invention 1 greatly increase the life expectancy compared to the prior art rolls.
  • the roll according to the invention results in a more consistent surface finish to the strip between regrinding because of the lower amount of wear of the surface of the roll.
  • the present invention provides significant advantages over the prior art.
  • the subject invention overcomes the problems in the prior art, such as to provide rolls that have increased abrasion resistance, thereby allowing for longer periods of operation before regrinding of the roll is necessary.
  • the invention also provides for the production of a smooth workpiece due to improved abrasion resistance.
  • the subject invention also increases the hardness of the roll, which further provides for a smoother workpiece. The improvement in oxidation behavior prevents the degradation of the roll surface and prolongs the roll initial profile.
  • Normal tempering means tempering at a temperature between 300-400 °C
  • Modified tempering means a tempering according to the invention at 450-530 °C.
  • FIG. 5 is shown a comparative study comparing oxidation of a roll, in terms of weight gain per unit of exposed area in a thermogravimetric test at high temperature, according to the invention (1) and a comparative roll (12).
  • the roll according to the invention 1 is significantly improved in respect of oxidation properties seen as lower weight increase and thinner oxide scale compared to a comparative roll 12 (composition described in table 2).
  • a roll according to the invention has oxidation kinetics at the roll surface which results in less oxidation of the material, measured as increase of the weight in the surface of the shell layer.
  • the weight increase due to oxidation of the shell material is in the order of 3.4-4.5 mg/cni2 measured after 900 seconds which is the average contact time between every specific spot of a shell roll and the hot strip during a normal rolling campaign.
  • the accumulated performance of the roll according to the invention is between 3660 tons/mm and average performance of the roll according to the invention is 3200mm/tons compared to the accumulated performance of a comparative roll (12) which is 2200 tons/mm and which has an average performance of 2500mm/tons, see figure 4.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)

Abstract

L'invention porte sur un procédé pour la production d'un cylindre de laminoir composite moulé par centrifugation destiné à des dernières cages finisseuses dans des laminoirs à bandes à chaud et sur sa composition d'enveloppe constituée, en % en poids, de : 2,5-4,0 % de C, 1,1-6,0 % de Nb, 0,7-3,0 de V, 4,2-4,6 % de Ni, 0,3-1,3 % de Mo, 1,5-2,2 % de Cr, 0,7-1,6 % de Si, 0,7-1,0 % de Mn, 3 % ou moins de Zr, 3 % ou moins de Ti, 0,12 % ou moins de P, 0,08 % ou moins de S, le reste étant du Fe et des impuretés inévitables, et sur son utilisation.
PCT/EP2013/059296 2012-05-04 2013-05-03 Cylindre de laminoir moulé par centrifugation pour dernières cages finisseuses dans des laminoirs à bandes à chaud WO2013164469A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP20120166893 EP2660344A1 (fr) 2012-05-04 2012-05-04 Rouleau de moulage par centrifugation pour les derniers socles de finition dans des laminoirs de tôles chaudes
EP12166893.3 2012-05-04

Publications (1)

Publication Number Publication Date
WO2013164469A1 true WO2013164469A1 (fr) 2013-11-07

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EP (1) EP2660344A1 (fr)
WO (1) WO2013164469A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019183276A (ja) * 2018-03-30 2019-10-24 日立金属株式会社 熱間圧延用遠心鋳造複合ロール及びその製造方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6516093B2 (ja) * 2015-03-25 2019-05-22 日立金属株式会社 連続鋳掛け肉盛鋳造製圧延用複合ロール
JP6474038B2 (ja) * 2015-03-25 2019-02-27 日立金属株式会社 連続鋳掛け肉盛鋳造製圧延用複合ロール

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57149452A (en) * 1981-03-10 1982-09-16 Kubota Ltd Composite mill roll
EP0525932A1 (fr) * 1991-07-09 1993-02-03 Hitachi Metals, Ltd. Cylindre composite et procédé pour sa fabrication
WO1993014931A1 (fr) 1992-02-04 1993-08-05 Forcast International Cylindre de travail composite pour laminage a chaud de produits plats et procede de laminage en comportant application
EP0559899A1 (fr) 1991-09-12 1993-09-15 Kawasaki Steel Corporation Materiau pour la couche exterieure d'un cylindre de laminage et cylindre composite fabrique par coulee par centrifugation
EP0560210A1 (fr) 1992-03-06 1993-09-15 Hitachi Metals, Ltd. Cylindre composite et procédé pour sa fabrication
EP0593408A1 (fr) 1992-09-11 1994-04-20 BÖHLER Edelstahl GmbH Cylindre composite
US5403670A (en) 1992-12-21 1995-04-04 Hitachi Metals, Ltd. Compound sleeve roll and method for producing same comprising chamfered axial ends
EP0665068A1 (fr) 1993-03-31 1995-08-02 Hitachi Metals, Ltd. Cylindre de laminage a chaud resistant a l'usure et au grippage
JPH0881731A (ja) * 1994-07-11 1996-03-26 Kawasaki Steel Corp 熱間圧延用ロール及びその製造方法
WO1996039544A1 (fr) 1995-06-06 1996-12-12 Bo Tommy Kage Nylen Cylindre en fonte en coquille indefinie produit par addition de niobium
JPH1143735A (ja) 1997-07-24 1999-02-16 Kubota Corp 耐肌荒れ性にすぐれる黒鉛晶出ハイス系鋳鉄材
US6805757B1 (en) * 1999-04-22 2004-10-19 Eisenwerk Sulzau-Werfen R. & E. Weinberger Ag Casting material for indefinite rollers with sleeve part and method for producing the same
JP2005232519A (ja) 2004-02-18 2005-09-02 Jfe Steel Kk 熱間圧延用ロール外層材および熱間圧延用複合ロール
EP1832665A1 (fr) * 2004-09-13 2007-09-12 Hitachi Metals, Ltd. Couche externe obtenue par coulage centrifuge pour cylindre de laminage et procede de fabrication de celle-ci
EP1975265A1 (fr) 2005-12-28 2008-10-01 Hitachi Metals, Ltd. Rouleau composite de coulage par centrifugation

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2506288B1 (fr) 1981-05-19 1985-06-14 Saint Gobain Vetrotex Filiere pour la fabrication par etirage par fluide de fibres de verre discontinues

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57149452A (en) * 1981-03-10 1982-09-16 Kubota Ltd Composite mill roll
EP0525932A1 (fr) * 1991-07-09 1993-02-03 Hitachi Metals, Ltd. Cylindre composite et procédé pour sa fabrication
EP0559899A1 (fr) 1991-09-12 1993-09-15 Kawasaki Steel Corporation Materiau pour la couche exterieure d'un cylindre de laminage et cylindre composite fabrique par coulee par centrifugation
WO1993014931A1 (fr) 1992-02-04 1993-08-05 Forcast International Cylindre de travail composite pour laminage a chaud de produits plats et procede de laminage en comportant application
US5484372A (en) 1992-03-06 1996-01-16 Hitachi Metals, Ltd. Compound roll and method of producing same
EP0560210A1 (fr) 1992-03-06 1993-09-15 Hitachi Metals, Ltd. Cylindre composite et procédé pour sa fabrication
EP0593408A1 (fr) 1992-09-11 1994-04-20 BÖHLER Edelstahl GmbH Cylindre composite
US5403670A (en) 1992-12-21 1995-04-04 Hitachi Metals, Ltd. Compound sleeve roll and method for producing same comprising chamfered axial ends
EP0665068A1 (fr) 1993-03-31 1995-08-02 Hitachi Metals, Ltd. Cylindre de laminage a chaud resistant a l'usure et au grippage
JPH0881731A (ja) * 1994-07-11 1996-03-26 Kawasaki Steel Corp 熱間圧延用ロール及びその製造方法
WO1996039544A1 (fr) 1995-06-06 1996-12-12 Bo Tommy Kage Nylen Cylindre en fonte en coquille indefinie produit par addition de niobium
JPH1143735A (ja) 1997-07-24 1999-02-16 Kubota Corp 耐肌荒れ性にすぐれる黒鉛晶出ハイス系鋳鉄材
US6805757B1 (en) * 1999-04-22 2004-10-19 Eisenwerk Sulzau-Werfen R. & E. Weinberger Ag Casting material for indefinite rollers with sleeve part and method for producing the same
JP2005232519A (ja) 2004-02-18 2005-09-02 Jfe Steel Kk 熱間圧延用ロール外層材および熱間圧延用複合ロール
EP1832665A1 (fr) * 2004-09-13 2007-09-12 Hitachi Metals, Ltd. Couche externe obtenue par coulage centrifuge pour cylindre de laminage et procede de fabrication de celle-ci
EP1975265A1 (fr) 2005-12-28 2008-10-01 Hitachi Metals, Ltd. Rouleau composite de coulage par centrifugation
US20090092852A1 (en) 2005-12-28 2009-04-09 Hitachi Metals, Ltd. Centrifugally cast composit roll

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019183276A (ja) * 2018-03-30 2019-10-24 日立金属株式会社 熱間圧延用遠心鋳造複合ロール及びその製造方法
JP7302232B2 (ja) 2018-03-30 2023-07-04 株式会社プロテリアル 熱間圧延用遠心鋳造複合ロール及びその製造方法

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