Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/38—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for roll bodies
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12951—Fe-base component
  • Y10T428/12958—Next to Fe-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12951—Fe-base component
  • Y10T428/12972—Containing 0.01-1.7% carbon [i.e., steel]
  • Y10T428/12979—Containing more than 10% nonferrous elements [e.g., high alloy, stainless]

Definitions

• the present invention relates to working rolls for cold rolling of ferrous and non-ferrous metals, which are of the composite type and obtained by casting.
• the internal tensions induced by the water quenching treatment are such that it may be necessary to resort to remelting under slag, in order to obtain a perfect crystallization.
• the chromium content of these cylinders can then reach 5 to 7%.
• FR-A-2 081 561 describes such a cylinder in which the metal of the external layer is a cast iron with a high chromium content and the core is in lamellar or nodular cast iron.
• the present invention aims to remedy these two important drawbacks, while retaining the qualities inherent in this type of cylinder obtained by molding, the essential qualities of which are good resistance to softening and a great depth of the usable part over the diameter. .
• the present invention thus relates to a bimetallic composite cylinder for cold rolling obtained by molding, and consisting of a ferrous alloy casing and a core of lamellar or nodular cast iron, characterized in that the casing metal consists of a steel having a chromium content of 8 to 16% and a carbon content of 0.65 to 0.95%, the chromium / carbon ratio being between 11 and 16 and the structure of the shell metal being martensitic with a residual austenite content less than 10% and a hardness greater than 700 HV.
• the structure of the metal cylinder is preferably obtained by a heat treatment process which consists first of all in subjecting the cylinder to an austenitization treatment at a temperature above 900 ° C. for a time from 8 to 24 hours, then after quenching in air or in the blown himid air stopped at a temperature of 450 to 550 ° C, the temperature is maintained at 500-550 ° C for 8 to 24 hours, then cooled the cylinder by air quenching to room temperature and finally the cylinder is subjected to an income for reactivation of the austenite at a temperature between 400 and 450 ° C for a time of 8 to 24 hours.
• the austenitization treatment is preferably carried out at a temperature between 1000 and 1050 ° C., for a time of 8 to 24 hours.
• the cylinder is then subjected to quenching by blowing ambient air or himid air or any other equivalent known means, which is preferably stopped when the cylinder temperature reaches 500 to 520 ° C.
• the cylinder is then maintained for 8 to 24 hours, in an enclosure brought to the temperature indicated above from 500 to 550 ° C, in order to balance the temperatures between heart and skin.
• the cylinder temperature is then brought back to the value of the ambient temperature by a new quenching in air.
• the cylinder is finally subjected to a tempering treatment at a temperature between 400 and 450 ° C, for 8 to 24 hours.
• the composite cylinder according to the present invention comprises a layer of envelope metal having a preferred thickness of 30 to 70 mm, which is preferably produced by centrifugation.
• This shell metal is a steel with a high chromium and carbon content, preferably having the following composition:
• the core metal is preferably a nodular cast iron having the following composition:
• composition and heat treatments defined above make it possible to explain the obtaining of the five properties set out above for the following reasons.
• the low-alloyed core metal therefore consists of a nodular or lamellar cast iron which makes it possible to obtain both good mechanical characteristics and good cirstallization, these two properties being essential to withstand the tensile stresses induced by the martensitic quenching of the envelope metal.
• the analysis of the envelope metal is chosen with a composition close to that of the matrix of cold working cylinders made of high chromium content cast iron previously used in the art.
• the income used on the highly alloyed steel grade according to the present invention does not lead to a transformation of the austenite into bainite, but to a reactivation of the residual austenite which is transformed, upon cooling, into martensite, at l exclusion of any bainite training.
• the new composite cylinder according to the present invention achieves a hardness of 700 HV (Vickers hardness) with a residual austenite content of 30 to 40%.
• composition of the new alloy according to the present invention is calculated, in particular with regard to the carbon and chromium content, to achieve a slightly hypereutectoid composition, in order to avoid the presence of these harmful ledeburitic carbides.
• Chromium can be considered to have an equivalent carbon coefficient of 0.05.
• the best report which determines the chromium content of the matrix with the austenitization temperature, has been determined experimentally on a whole series of carbon-chromium alloys, and should preferably be between 11 and 16.
• the other elements namely Si and Mn, are found in the usual ranges for analyzes of cast steels.
• Nickel and manganese are deliberately limited to 0.7% to avoid their stabilizing effect on the residual austenite.
• Molybdenum and vanadium improve the hardening resistance of austenite and are found in the usual grades of cold working chrome steels (classes 80 and 90 of the American classification).
• New molded bimetallic composite cylinders are thus obtained which exhibit exceptional softening resistance by tempering the matrix.
• a cylinder according to the present invention has been produced using an envelope metal and a core metal having the following compositions.
• the cylinder thus obtained is subjected to an austenitization treatment for 24 hours at 1000 ° C., then to a quenching with blown air which is stopped at a temperature of 520 ° C. The temperature of the cylinder is then maintained at a value of 520 ° C. for 20 hours, then the cylinder is cooled to ambient temperature by air quenching.
• This cylinder is then subjected to tempering at a temperature above 400 ° C., for 20 hours, which makes it possible to obtain, at the end of the treatment, a hardness of 780 HV over 50 mm on the radius.
• This cylinder was used for the cold rolling of thin sheets and confirmed the advantages stated previously in the course of the description.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
• Heat Treatment Of Articles (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)
• Laminated Bodies (AREA)
• Fluid-Damping Devices (AREA)
• Diaphragms For Electromechanical Transducers (AREA)

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Publications (2)

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Citations (1)

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• 1980
  • 1980-10-31 FR FR8023316A patent/FR2493191A1/fr active Granted
• 1981
  • 1981-10-14 DE DE8181401594T patent/DE3163662D1/de not_active Expired
  • 1981-10-14 AT AT81401594T patent/ATE7463T1/de not_active IP Right Cessation
  • 1981-10-14 EP EP81401594A patent/EP0051511B1/fr not_active Expired
  • 1981-10-29 BE BE0/206381A patent/BE890909A/fr not_active IP Right Cessation
  • 1981-10-29 IT IT68406/81A patent/IT1145572B/it active
  • 1981-10-29 US US06/316,487 patent/US4436791A/en not_active Expired - Lifetime
  • 1981-10-30 ES ES507388A patent/ES8503921A1/es not_active Expired
  • 1981-10-31 JP JP56175563A patent/JPS57108242A/ja active Granted
• 1982
  • 1982-12-15 ES ES518633A patent/ES8401342A1/es not_active Expired
• 1984
  • 1984-01-05 US US06/568,431 patent/US4548653A/en not_active Expired - Lifetime

Patent Citations (1)

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