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
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the heat treatment
  • C21D8/1255—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the heat treatment with diffusion of elements, e.g. decarburising, nitriding
• • 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
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/06—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases
  • C23C10/08—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases only one element being diffused
• • 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
• • 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
• • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the heat treatment
  • C21D8/1272—Final recrystallisation annealing

Definitions

• the present invention relates to a method of treating sheet metal for the purpose of improving its magnetic characteristics, particularly iron sheets used as laminations in electrical machinery and containing, in addition to the iron, 4.5% or even only up to 3.5% silicon, depending on whether the sheets are to be only hot-rolled or whether, after the hot-rolling, they are still to be coldrolled.
• an object of the present invention to provide a method by means of which the silicon content can be increased above the customary limit despite the fact that such a material cannot, for all practical purposes, be cold-rolled.
• the present invention resides in a method of improving the magnetic characteristics of sheets for use in electrical apparatus, wherein sheets of customary silicon content which have been put through the cold-rolling process are thereafter additionally siliconized by annealing in a SiCh-containing non-oxydizing protective gas, after which the sheets are subjected to a homogenizing treatment carried out by means of a second annealing step.
• the method according to the present invention is able to raise the silicon content of the sheets to approximately 7%, this silicon content being distributed evenly over the entire cross section of the sheets. It has been found that this is possible by annealing, i.e., heat treating the sheet metal in a SiCl -containing protective gas atmosphere "ice which has but a relatively small proportion of silicon tetrachloride, preferably only up to 4% by volume.
• the protective carrier gas may, for instance, be nitrogen or argon.
• the same should be sutficiently pure so that no oxide layer is formed at the surface of the sheets, because such an oxide layer would impede a homogeneous siliconization. For this reason, the sheets to be siliconized should first have any oxide layers removed.
• the sheets are preferably kept at a temperature of between 1100 and 1250 C.
• the silicon is diffused into the sheet metal and, so long as the proportion of silicon tetrachloride is kept no greater than 4% by volume and the temperature at which the siliconization--this term being used throughout the instant specification to refer to a diffusion rather than a plating processtakes place is kept within the above-mentioned limits, the rate at which silicon is deposited is less than the rate at which iron silicide (Fe Si) is formed, so that there is no opportunity for any iron silicide layer to be formed in the first place, instead, the silicon will diffuse into the metal. It is in the course of this annealing step, then, that the silicon is deposited and diff-used into the sheet metal.
• the magnetic characteristics can be improved even further by heating the homogenized sheets to a temperature of about 800 C. and thereafter cooling them in a magnetic field.
• the magnetic field should have a field strength of more than 10 oersteds and be applied in such a manner as to be oriented in the preferred magnetic direction as dictated by the desired crystalline structure, i.e., the lines of fiux or" the magnetic field should be so oriented as to produce the desired crystalline and hence magnetic anisotropy of the sheets.
• the sheets can be cooled at a rate of for example C. per minute.
• the siliconization can be carried out in a furnace which surrounds a gas-tight tube.
• the strip of sheet metal to be siliconized is passed through the tube while there flows through this tube a gas mixture composed of the silicon tetrachloride and the protective carrier gas, e.g., nitrogen or argon.
• the amount of SiCl, which is drawn out of the silicon tetrachloride reservoir, the latter being kept at a constant temperature depends on the temperature and speed of the gas, and can be adjusted to any desired amount by changing these variables. tice, it will be most expedient to keep the proportion of the silicon tetrachloride under 4% by volume.
• the starting material was constituted by sheets usable for transformer laminations, which sheets, after being cast, were cold-rolled to a thickness of 0.32 millimeter.
• the silicon content was 3.2%.
• Previously formed oxide layers were removed by etching in diluted hydrochloric acid with bromide admixed.
• the furnace was moved at a constant speed along the sheet web.
• the annealing zone was 5 centimeters long, the temperature was approximately 1150 C.
• the V -value is decreased by increasing the silicon content and thereafter cooling the sheets in the magnetic field. With the latter step, the silicon contents has to be approximately 7% before the V -value is reduced.
• the minimum magnetostriction saturation was found in sheets having a silicon content of approximately 6%.
• sheets of relatively high silicon contents are obtained without it being necessary, however, to forego the cold-rolling process for making the sheets.
• This is accomplished, as described above, by first completing the cold-rolling process of the sheet metal having a silicon content sufficiently low to allow the sheet metal to have been cold-rolled in the first place, i.e., about 3.5%, and only thereafter subjecting the thus cold-rolled sheets to a treatment which raises the silicon contents to the desired level, the latter being a level above that permissible for cold-rolling.
• the present invention is not limited specifically to the use of silicon tetrachloride as the voltatile silicon compound, the latter term being deemed to refer to a silicon compound which is volatile at the annealing temperature during which sheet metal is siliconized.
• the volatile silicon compound can be one of the other silicon halides, namely, SiFl SiBr and 5H,, or silicon tetraacetate, silicon sulfide dibromide (SiSBr or silane (SiH or one of the substituted silanes, e.g.
• SiCl H or silicon tetrathiocyanate Si(SCN)
• Si(SCN) silicon tetrathiocyanate
• the siliconized sheets need not be cooled to room temperature after being rendered homogeneous by annealing, but may be cooled to approximately 800 C., from which temperature they are cooled to room temperature in a magnetic field as described above.
• a method of improving the magnetic characteristics of cold-rolled sheet metal having a silicon content sufficiently low to allow said sheet metal to have been coldrolled comprising the step of subjecting the sheet metal to a temperature of between 1100 and 1250" C. in an atmosphere of a gas mixture composed of a non-oxydizing carrier gas and a volatile silicon compound, wherein the total silicon contents in said gas mixture is no greater than /a% by volume of the total gas, to diffuse silicon into the sheet metal to a level above that permissible for cold-rolling; and homogenizing the diffused silicon by annealing the sheet metal.
• A. method as defined in claim 2, comprising the further steps of heating the sheet metal subsequent to the homogenizing step, and thereafter cooling the sheet metal while the same is exposed to a magnetic field.
• a method of improving the magnetic characteristics of cold-rolled sheet metal having a silicon content of not more than approximately 3.5% comprising the steps of:
• a method of improving the magnetic characteristics of cold-rolled sheet metal having a silicon content of not more than approximately 3.5% comprising the steps of:
• a method of making sheet metal for use in electrical apparatus comprising the steps of:

Landscapes

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

Applications Claiming Priority (1)

Publications (1)

Family

ID=7269105

Family Applications (1)

Country Status (2)

Cited By (7)

Citations (10)

Family Cites Families (3)

• 1961
  • 1961-11-29 DE DEL40575A patent/DE1237154B/de active Pending
• 1962
  • 1962-11-21 US US239340A patent/US3224909A/en not_active Expired - Lifetime

Patent Citations (10)

Also Published As

Similar Documents