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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
  • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
• • 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
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
  • C21D8/1283—Application of a separating or insulating coating
• • 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
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
• • 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
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
  • C23D5/00—Coating with enamels or vitreous layers
  • C23D5/10—Coating with enamels or vitreous layers with refractory materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/14766—Fe-Si based alloys
  • H01F1/14775—Fe-Si based alloys in the form of sheets
  • H01F1/14783—Fe-Si based alloys in the form of sheets with insulating coating

Definitions

• the application is related to certain copending cases belonging to the assignee of this case and including:
• Oriented magnetic materials, and in particular siliconiron sheet stock are made by various routings generally including refining the base metal by known methods and forming the metal into an intermediate gauge product while hot.
• the intermediate gauge product can be made by continuous casting procedures or by producing ingots and then hot rolling to the intermediate gauge either as an uninterrupted procedure or by producing slabs which are reheated and rolled on the. continuous hot mill. Older methods such as producing sheet bars and hot rolling these in a hand-fed mill or mills can also be employed, but the newer methods are more advantageous cost-wise.
• the intermediate gauge hot-reduced material either in sheet or strip form is preferably subjected to an annealing treatment. prior to cold rolling.
• the material is cold rolled to a final desired gauge in one. or more cold rolling treatments, with an intermediate anneal or anneals if plural-stage cold rolling is practiced.
• a decarburization treatment will be given the material at some stage of the processing, preferably a'fter cold rolling.
• a final treatment comp ises a box anneal or its. equivalent at a high temperature to develop the optimum magnetic characteristics.
• the secondary recrystallization which is productive of the cube-on-edge orientation proceeds 'best when the primary recrystallization takes place in the presence of a substantial quantity of sulfur or sullfides segregated at the grain boundaries,
• sulfur or sulfides inhibits the grain growth which would normally occur after the primary recrystallization and produces a product in which the cube-on-edge nuclei occupy the lowest energy position so that the product can be substantially completely converted during the secondary recrystallization by the grain boundary energy form of grain growth.
• the presence of the glassy layer is not always advantageous, however. Where stampings or punchings have to be made, the glassy substance has an abrasive action on the .dies employed. It is also disadvantageous where the stock is to be given a further cold rolling treatment after the formation of the glass. It is very difficult t-o pickle the glass from the surfaces of the silicon-iron.
• a more specific object of the invention therefore is the provision of a procedure which can be relied upon to minimize silica inclusions in the metal after the high temperature anneal.
• magnesia is preferred. It is generally applied in the form of a water slurry of magnesium oxide which has substantial adhesive characteristics.
• the oxide slurry may be applied to the silicon-iron stock in various ways as by knifing, roller coating, spraying and the like.
• the coated silicon-iron is then heated to a low temperature to drive ofif the water vehicle.
• the magnesia will be tightly adherent to the silicon-iron base stock so that coated sheets or coated coils will withstand that degree of handling necessary to dry them and to transfer them to the annealing furnace in which the heat treatment is to be carried on.
• Magnesia as so applied has the disadvantage first noted herein. It will form a tightly adherent glassy coating which can be removed by pickling or otherwise only with extreme difiiculty.
• the objects of this invention are attained by mixing with the magnesium oxide slurry, or with the magnesia itself, alkali metal compounds such as sulfides or hydroxides of sodium or potassium. In most instances potassium sulfide is preferred. These sulfides and hydroxides are Water soluble so that it is easy to mix them with a magnesium oxide slurry. It is not intended to limit this invention to the use of magnesium oxide slurries.
• a dry mixture of magnesia and the sulfides and hydroxides of potassium and sodium may be produced at the outset and deposited on the surfaces of the silicon-iron sheet stock in any suitable way as by dusting or electrostatic deposition.
• Usable additions of the alkali metal sulfides or hydroxides, or mixtures of them, may be made within the general range of from .5% to about by weight of the magnesia in the coating. Within this general range, the alkali metal compounds may be used in greater or lesser quantities dependent upon the type of magnesia used. More active magnesias require less alkali metal compounds than magnesia of low activity.
• the annealing separator of the present invention produces a surface film that is easily removable by short-time pickling.
• magnesia is used without the addition of the stated alkali metal compounds, a tightly adherent glassy coating is formed on thesurface of the silicon-iron.
• the nature of the surface film produced is changed in such a way that the film may be easily and completely removed by a single pickling operation during which the metal is immersed in a pickling solution for a matter of 10 seconds or less. Excellent results have been achieved in single pickling operations having an immersion time of 5 seconds.
• the most common acid used for pickling iron or steel is sulfuric acid.
• the tightly adherent glassy coatings formed by conventional magnesia separators are extremely difficult to remove with sulfuric acid alone.
• Mixed acids such as sulfuric acid and hydrofluoric acid are commonly used.
• Pickling solutions of about 25% sulfuric acid and less than 10% hydrofluoric acids are conventionally used.
• the film formed by the annealing separator of the present invention can be pickled by sulfuric acid alone in concentrations as low as 10% or less or by acid mixtures of weaker than conventional concentrations. In either case the time required is lessened due to the alkali metal compounds added to the annealing separator. This results in the ability to run greater tonnages per hour through the pickling operation.
• Example A A coil was processed to a final gauge of .014" by a standard two-stage process.
• the ladle analysis of the starting material was as follows:
• the strip was coated with magnesia containing approximately 3.5% by weight of potassium sulfide. Weight of coating was about .065 oz./ft. of silicon-iron.
• the coated strip was box annealed in a hydrogen atmosphere at 2175 F. for 24 hours.
• Example B (1) A coil was processed to a final gauge of .012" by a standard two-stage process.
• the ladle analysis of the starting material was as follows:
• the coated strip was box annealed in a hydrogen atmosphere at 2200 F. for thirty hours.
• Example C Strip samples of the decarburized material of Example B were coated with magnesia containing 3.6% by Weight of sodium hydroxide (NaOH) (2) The coated strips were box annealed in a hydrogen atmosphere at 2200 F. for thirty hours.
• NaOH sodium hydroxide
• Example D (l) The :same decarburized material as that used in Example B was coated with magnesia containing 5% by weight of potassium hydroxide -(KOH).
• silicon-iron in general a ferrous material containing from about 2.0% to 4.0% silicon, and from about .03% to .15% manganese and about .-015% to about .030% sulfur.
• the carbon content should be usually about .025%, the balance of the alloy being sub stantially all iron excepting for normal trace impurities incident to the mode of manufacture.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Electromagnetism (AREA)
• Dispersion Chemistry (AREA)
• Power Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Manufacturing Of Steel Electrode Plates (AREA)
• Chemical Treatment Of Metals (AREA)

Priority Applications (7)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (7)

Cited By (5)

Citations (7)

• 1965
  • 1965-06-09 US US462708A patent/US3375144A/en not_active Expired - Lifetime
• 1966
  • 1966-06-04 DE DE19661508365 patent/DE1508365A1/de active Pending
  • 1966-06-07 GB GB25275/66A patent/GB1145408A/en not_active Expired
  • 1966-06-08 FR FR64704A patent/FR1482649A/fr not_active Expired
  • 1966-06-08 SE SE7853/66A patent/SE305461B/xx unknown
  • 1966-06-08 BE BE682238D patent/BE682238A/xx unknown
  • 1966-06-08 ES ES0327704A patent/ES327704A1/es not_active Expired

Patent Citations (7)

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