Classifications

• • 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
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/001—Heat treatment of ferrous alloys containing Ni
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0273—Final recrystallisation annealing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2229/00—Details of cathode ray tubes or electron beam tubes
  • H01J2229/07—Shadow masks
  • H01J2229/0727—Aperture plate
  • H01J2229/0733—Aperture plate characterised by the material

Definitions

• the present invention relates to the manufacture of an alloy strip of the type iron-nickel obtained from a thin strip obtained by direct casting of a thin strip.
• Iron-nickel alloys are well known and used for their magnetic properties or for their expansion properties. Their composition chemical mainly comprises from 25% to 50% by weight of nickel, from 50% to 75% by weight of iron, possibly at least one alloying element taken from the cobalt, chromium and molybdenum, in contents of less than 5%. We know, by for example, alloys with very low expansion coefficients containing about 36% of nickel or about 33% nickel and about 4% cobalt, the rest being essentially iron, possibly some additional elements in small amounts, and impurities. These alloys with low coefficient of expansion are also used for their good magnetic properties, especially under form of cold rolled strip of thickness generally between one tenth and a few tenths of a millimeter. The magnetic properties obtained are characterized in particular by a coercive field less than 55 A / m.
• the alloy is poured in the form of ingots or slabs thicker than 100 mm, then hot rolling is carried out to obtain a hot strip of thickness less than 5 mm.
• This hot strip is cold rolled to obtain a cold strip which is annealed recrystallization at a temperature in the region of 750 ° C.
• This technique presents the disadvantage of requiring significant hot rolling operations.
• the alloy can be cast continuously directly in the form of a thin strip with a thickness of less than 10 mm.
• a continuous thin strip casting machine can be used between two rotary cylinders with horizontal axes.
• the inventors have found surprisingly that the cold rolled strips obtained from strips thin continuous castings have a significantly higher coercive field than that cold rolled strips from ingots or slabs.
• the object of the present invention is to remedy this drawback by proposing a means for manufacturing cold-rolled strips of alloy of the type iron-nickel obtained from a thin strip obtained by direct strip casting thin, having magnetic properties as good as the properties magnetic strips of the same alloy, made from ingots or slabs.
• the subject of the invention is a method of manufacturing an iron-nickel type alloy strip containing, mainly, from 25% to 50% by weight of nickel and from 50% to 75% by weight of iron. , and, optionally, one or more alloying elements such as, in particular, cobalt, chromium, molybdenum, manganese, silicon, vanadium, tantalum, titanium, aluminum, in contents lower than 8% by weight, the remainder being impurities resulting from the preparation, according to which a thin strip of thickness less than 10 mm is continuously cast, the thin strip is laminated, and a treatment is carried out before or after rolling.
• alloying elements such as, in particular, cobalt, chromium, molybdenum, manganese, silicon, vanadium, tantalum, titanium, aluminum, in contents lower than 8% by weight, the remainder being impurities resulting from the preparation, according to which a thin strip of thickness less than 10 mm is continuously cast, the thin strip is laminated, and a treatment is carried out before or after
• the sum of the contents of cobalt, chromium, molybdenum, manganese, silicon, vanadium, tantalum, titanium and aluminum is less than or equal to 8%.
• the standard nickel segregation rate is less than 0.35%.
• Homogenization treatment can be carried out on the thin strip directly from continuous casting or after hot rolling of the strip thin, or even after a cold rolling operation.
• a cold rolling to the final thickness of the strip, so as to give the band a controlled texture.
• the field coercive Hc is less than 45 A / m after annealing at 750 ° C for 15 minutes.
• the coercive field Hc is less than 55 A / m after annealing at 750 ° C for 15 minutes.
• the inventors have found, in a new and completely surprising manner, that the magnetic properties of iron-nickel alloys were affected by the micro segregation of nickel in interdendritic spaces resulting from the solidification.
• the hot strip intended to be cold rolled can be a thin strip obtained directly by continuous thin strip casting and possibly having undergone hot rolling or additional heat treatment.
• the thin strip obtained directly by continuous casting of thin strip has a thickness between 1 mm and 10 mm.
• the "standard segregation rate" defined by the inventors is the estimator unbiased standard deviation of the nickel content distribution in thickness a cold rolled strip of thickness less than 0.2 mm, which has been annealed recrystallization at 850 ° C for 15 minutes.
• the "standard segregation rate" of nickel is greater than 0.5% for a cold strip from a thin hot strip obtained directly by direct continuous thin strip casting, when it is less than 0.35% for a cold strip from an ingot.
• an alloy of the electric arc is produced and by refining in a pocket iron-nickel type as defined above, and for which we aim for example a content 36% nickel and a manganese content preferably between 0.02% and 0.5%, the remainder being iron and impurities resulting from processing.
• the liquid alloy thus obtained is cast in the form of a thin strip using a continuous thin strip casting machine which has two cylinders arranged horizontally, parallel to each other, so as to form a width slot less than 10 mm, and generally between 1 mm and 5 mm. Both cylinders rotate in opposite directions from each other, about their respective axes, by so as to drive the alloy down by passing it through the slot.
• Both rollers are cooled by an internal circulation of water, so that the alloy is cooled in contact with the cylinders and leaves their grip in the form of a strip solidified thickness substantially equal to the width of the air gap of the cylinders.
• the thin strip is then wound up using a winder to obtain a reel which is allowed to cool, in general, naturally.
• the thin strip can optionally undergo rolling with warm, preferably after reheating between 1050 ° C and 1300 ° C.
• the hot strip thus obtained is then cold rolled after pickling. to obtain a cold strip having the desired final thickness which can be between 0.1 mm and 0.25 mm.
• this cold rolling is done in several stages separated by recrystallization annealing at temperatures of around 1000 ° C. For example, a first step achieves a thickness between 0.5 mm and 2 mm, a second step allows to reach a thickness of 0.15 mm to 0.3 mm, and a final step leads to the thickness final.
• Cold rolling is not only used to obtain the final thickness, but also to give the strip a texture which, preferably, must be of the type "Cubic", and to control the size of the grain which should preferably have an index AFNOR between 8 and 9, approximately.
• the production of the strip is completed by a homogenization treatment consisting in at least one maintenance of a duration t (in hours) at a temperature T (in ° C), such than : t ⁇ A exp (38000 / (T + 273))
• the coefficient A is greater than or equal to 0.5 x 10 -12 , and preferably greater than 1 x 10 -12 .
• the homogenization treatment is all the more effective and easy to realize that the product on which it is made is thin, when cold rolling end of the cold strip is intended, in particular, to impart a texture and a size of grain, the homogenization treatment must be carried out before this final cold rolling. Otherwise, it would destroy the structure and make the grain.
• the homogenization treatment When the homogenization treatment is finished on the thin strip, the latter or the resulting cold-rolled strip is characterized by a “rate of standard "segregation” of nickel less than 0.4% or even 0.35%. When the homogenization treatment is only completed on the cold rolled strip, only this is characterized by a “standard segregation rate” of nickel less than 0.4% or 0.35%.
• the cold rolled strip according to the invention is made of a low-alloy coefficient of expansion mainly containing 35% to 37% nickel, its Hc coercive field is less than 45 A / m after annealing at 750 ° C for 15 minutes.
• the cold rolled strip is made of a low coefficient alloy expansion mainly containing from 32% to 34% of nickel and from 3.5% to 6.5% of cobalt, its coercive field Hc is less than 55 A / m after annealing at 750 ° C for 15 minutes.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Manufacturing Of Steel Electrode Plates (AREA)
• Soft Magnetic Materials (AREA)
• Continuous Casting (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9510417

Family Applications (1)

Country Status (5)

Families Citing this family (3)

Citations (8)

• 1997
  • 1997-08-21 FR FR9710533A patent/FR2767538B1/fr not_active Expired - Fee Related
• 1998
  • 1998-08-07 EP EP98402020A patent/EP0905263A1/de not_active Withdrawn
  • 1998-08-20 CN CN98118466A patent/CN1083894C/zh not_active Expired - Fee Related
  • 1998-08-20 JP JP23405698A patent/JPH11131146A/ja active Pending
  • 1998-09-14 TW TW87113819A patent/TW416873B/zh not_active IP Right Cessation

Patent Citations (8)

Non-Patent Citations (3)

Also Published As

Similar Documents

Legal Events