Classifications

• • 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 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
• • 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
• • 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
  • H01F1/16—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 in the form of sheets
• • 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
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1233—Cold rolling

Definitions

• the present invention relates to magnetic silicon steel for electrical uses, such as in transformers, motors and other electromagnetic apparatus, and more particularly to such electrical steel having improved grain orienta- Patented Nov. 17, 1959 "ice verse effect on the development of a high degree of magnetic anisotropy unless controlled within narrow limits.
• secondary grain growth or secondary recrystallization is meant the process whereby in the final texture-producing annealing treatment, strain-free crystal grains grow in size by absorbing each other.
• Such secondary grain growth follows primary recrystallization, which is defined as a process whereby the distorted grain structure of a cold-worked metal is replaced by a new strain-free grain structure by annealing above a specific minimum temperature.
• the initially formed steel strip containing about 3% silicon is hot rolled and then subjected to a series of cold rolling and intervening annealing treatments to reduce the gauge of the strip and to remove carbon, sulfur, oxygen, and other elements, and also to control the amount of nitrogen at a suitable level. If sulfur in certain critical amounts is added, in accordance with the invention, to the iron melt prior to its formation into a sheet or strip and the silicon steel is thereafter subjected to the usual rolling, annealing and purifying treatments, the grain orientation of the metal is substantially improved over that of silicon steel to which sulfur has not been similarly added.
• the ingots were made from startingiron, material (raw iron) as received from the supplier having a normal sulfur content of about .025-.035% by weight, and were prepared by melting down the iron, adding about 3% f sili on, and then n o uc ng the s l de c mp u d-
• the m lts we e p u d i ed a e y aft r the u fid addition.
• the poured ingots were hot rolled to a band of 100 mils thickness, then cold rolled to 14 ,mil strip in the usual two-stage process including intervening heat treatments (anneals), and finally subjected to box annealing in dry hydrogen at 1100 C.
• the finished strips were then given the integrated disc test, described below, to determine the degree of anisotropy. Chemical analysis was conducted for total sulfur, as well as other constituents.
• the integrated disc test I.D. T. involved the use .of a spinning disc tester which is an apparatus for the rapid measurement of magnetic anisotropy in sheet or strip material.
• the tester comprises a motor having a shaft to which is attached a chamber which holds the specimen in the form of a thin disc.
• the disc is spun ata uniform speed about an axis normal to the surface of the .disc and passing through its center.
• the device also includes a magnetic .circuit which provides a constant field parallel to the plane of the disc, a set of search coils arranged about the disc in such manner that'any change in the magnetic flux passing through the disc will produce a voltage in the coils, and an oscillograph or other device for detecting any voltage developed across the search coils due to flux variations through the disc.
• the instrument is calibrated by measuring the voltage developed by specimens whose magnetic anisotropy had been determined by known methods. Since the degree of magnetic anisotropy is a function of the amount of texture, i.e., crystal orientation in the sheet or strip, it is possible to calibrate the spinning disc tester in terms of crystal orientation.
• the data presented in the table below were obtained from an instrument so calibrated and are in terms of a percentage of perfection that was obtained. Perfection was considered to be a disc which had been prepared from a single crystal of the material under examination. In order to obtain an overall picture of average sheet or strip orientation, the disc size was so chosen that several individual crystals were contained in the specimen.
• the present process thus makes it possible to obtain magnetic steel strip of good .quality from raw iron of so-called poor grades, and the careful selection of the starting iron 'or the close control of processing condi tions to ensure good .quality strip as heretofore required in 'prior procedures can largely be dispensed with.
• thin gauge magnetic strip is desirable for use in electrical induction apparatus in view of the lower eddy current losses which can be thereby obtained.
• difficulties have been experienced in the industry in attempts to obtain very thin gauges of silicon steel (e.g., less than 7 mils) having the desired degrees of preferred orientation,
• thin gauge steels have been provided with suitable orientation by employing a series of carefully controlled processing steps to which conventionally oriented strip of substantial thickness, i.e., over 7 mils, is subjected.
• a metallic sulfide such as manganese sulfide, in sufficient amount to provide from .005 to 0.1% sulfur by weight of the melt.
• temperature of the melt adjusted to about 1600 C.
• the mixture is poured into an ingot mold. After solidification, the ingot is hot rolled to a strip 100 mils thick, and then cold rolled to an intermediate gauge, e.g., 30 mils.
• the strip is then heat treated in an open anneal, cooled and cold rolled to the desired final gauge.
• the strip is then decarburized by heat treatment in wet air at 800 C. and thereafter subjected to anneal at about 1100 C. for a sufiicient period to grow secondary crystals of optimum size and proper orientation and to further purify the strip by the removal of residues of carbon, sulfur, oxygen and other impurities.
• the invention in its broad aspects contemplating merely the forming from the ironsilicon-sulfur melt a steel strip which may be rolled directly to the desired gauge and then annealed to refine it and develop the proper grain orientation therein.
• sheet material and sheet as used in the appended claims are intended to include such forms as sheets, strips, tapes and other laminar shapes.
• the method of making silicon steel sheet material comprising forming a melt containing iron, about 14% silicon and sulfur wherein about 0.005 to 0.1% by Weight of sulfur has been added to the melt, producing a metal sheet from said melt, and annealing said metal sheet to refine the same and to develop grain-orientation therein.
• the method of making silicon steel sheet material comprising forming a melt containing iron and adding thereto about 1 to 4% silicon and about 0.005 to 0.1% sulfur, producing a metal sheet from said melt, and annealing said metal sheet to refine the same and to develop grain-orientation therein.
• the method of making silicon steel sheet material comprising forming a melt containing iron and about 1 to 4% silicon, adding thereto a sufficient amount of a metallic sulfide to provide about 0.005 to 0.1% sulfur, producing a metal sheet from said melt, and annealing said metal sheet to refine the same and to develop grainorientation therein.
• the method of making silicon steel sheet material comprising forming a melt containing iron and about 1 to 4% silicon, adding thereto a sufficient amount of a metallic sulfide to provide about 0.04% sulfur, producing a metal sheet from said melt, and annealing said metal sheet to refine the same and to develop grainorientation therein.
• the method of making silicon steel sheet material comprising forming a melt containing iron, about l-4% silicon and sulfur wherein about 0.005 to 0.1% by weight of sulfur has been added to the melt, solidifying said melt, producing a silicon steel sheet of desired thickness therefrom by alternately rolling and annealing the same, and annealing the thus obtained steel sheet to remove impurities therefrom and to develop preferred crystal orientation therein.
• the method of forming thin gauge silicon steel sheet material comprising forming a melt containing iron, about 14% silicon and sulfur wherein about 0.005 to 0.1% by weight of sulfur has been added to the melt, producing a metal sheet of about 14 to mils thickness from said melt, rolling the thus produced metal sheet to a thin sheet having a thickness of about 3 to 6 mils, and annealing the thus produced thin metal sheet to refine the same and to develop grain-orientation therein.
• the method of forming thin gauge silicon steel sheet material comprising forming a melt containing iron, about 14% silicon and sulfur wherein about 0.005 to 0.1% by weight of sulfur has been added to the melt, producing a metal sheet of about 14 to 100 mils thickness from said melt, rolling the thus pro-duced metal sheet to a thin sheet having a thickness of less than 7 mils, and annealing the thus produced thin metal sheet to refine the same and to develop grain-orientation therein.

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

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Cited By (5)

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Citations (2)

• 0
  • BE BE563545D patent/BE563545A/xx unknown
• 1956
  • 1956-12-31 US US631447A patent/US2913361A/en not_active Expired - Lifetime
• 1957
  • 1957-12-26 FR FR1189013D patent/FR1189013A/fr not_active Expired

Patent Citations (2)

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