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 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
  • C21D8/1227—Warm rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
  • B21B3/02—Rolling special iron alloys, e.g. stainless steel
• • 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
  • 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
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S72/00—Metal deforming
  • Y10S72/70—Deforming specified alloys or uncommon metal or bimetallic work
• • 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
  • Y10T29/00—Metal working
  • Y10T29/30—Foil or other thin sheet-metal making or treating
  • Y10T29/301—Method

Definitions

• This invention relates to normally brittle silicon-iron alloys, and in particular it concerns a method of rolling such alloys to thin gauges.
• Silicon-iron alloys with a silicon content in excess of 4.5 percent are of interest to the electrical industry in view of their reported excellent magnetic properties and very low magnetostriction. To use such material successfully and efliciently it is necessary to be able to fabricate the alloy with sufiicient ease for commercial adaptation to produce the shapes desired for various electrical applications. Fabrication of these alloys, such as the 6.5 percent silicon-iron alloy, to very thin tapm has not been previously accomplished due to its extreme brittleness. The ductility of the alloy as shown by the reduction in area and elongation determined in a tensile test, is zero or nearly zero. Other mechanical properties, such as the tensile strength, also are very poor.
• alloys can be rolled to produce a material having a structure which will permit subsequent cold rolling or other cold forming or deforming without destroying the material.
• This desirable result is achieved by rolling an alloy of an intermediate thickness at a moderately elevated temperature, hereinafter described, to a sheet,
• the resulting sheet is characterized by an elongated microstructure and is duetile; accordingly, it can be cold rolled at room temperature to any desired gauge. In this manner we are able to roll, for example, 6.5 percent silicon-iron to ductile tape of one mil thickness or less.
• an ingot, or slab, of the alloy is first hot rolled to a plate of a thickness on the order of 110 mils or thinner.
• Warm rolling is conducted on the strip resulting from the hot rolling step.
• the warm rolling temperature is materially above room temperature but suitably does not exceed 425 C., because we have found that rolling at higher temperatures, on the order of about 450 0.,
• a temperature range that can be used for this step, with binary silicon-iron, is about 350 to 425 C.
• the alloy is reduced to a thickness at least as low as about 25 mils.
• Warm rolling to the larger thicknesses of, say, 30 to 35 mils has been found to be less desirable from the standpoint of subsequent cold rolling since undue cracking, particularly at the edges, may occur and the material may evidence only marginal ductility.
• the strip obtained from the warm rolling step can then be cold rolled to the desired thickness.
• We have successfully cold rolled this material readily to l and 2 mil thick tapes many times. This result has been achieved Without experiencing edge cracks.
• the resultant cold-rolled tape is very ductile. It may be sheared cold with no cracking and may be sent back on itself without breaking. Heretofore it was not unusual to drop materials of this general nature and find that they shattered as a consequence of their unusual brittleness.
• the rolling steps of our invention can be carried out with any rolling equipment desired.
• any rolling equipment desired For example, twohigh or four-high mills may be used. All thin gauges, particularly below 10 to 15 mils thickness, a Sendzimir mill or its equivalent may be used for cold rolling.
• the reductions per pass during each of the rolling steps is determined by the convenience of the operator and the equipment that is available to him. In our practice we have taken difierent reductions on the same sheet and have changed mills during a rolling procedure without adversely aifecting the results.
• Our invention is primarily concerned with silicon-irons containing about 4.5 to 7.5 or more weight percent or silicon.
• the alloys Preferably contain 6 to 7 weight percent of silicon and the remainder iron.
• the alloys suitably are made from electrolytic iron and commercial grade silicon.
• Other alloying constituents and impurities in conventional amounts may be present as long as they do not deleteriously interfere with the desired end results.
• certain alloying constituents such, for example, as aluminum, can be substituted for small amounts of the silicon with a distinct advantage in spreading the warm rolling temperature.
• the 6.5 weight percent silicon-iron generally is warm rolled within the temperature range of 350 to 425 C.
• the range of rolling temperature becomes extended at least to the lower temperature of 275 C. It may be expected that other ternary additions will produce a similar result.
• the alloys can be prepared for use in this invention in any manner desired. Vacuum and controlled atmosphere procedures have been found of use, in making materials to be used for electrical applications, to prevent the uncontrolled introduction of impurities into the melts.
• Example 7 An ingot was prepared from electrolytic iron and commercial silicon. A typical chemical analysis of these raw materials was within the following ranges:
• the raw materials in a weight ratio of 93.5 parts of iron for each 6.5 parts of silicon, were charged to a vacuum induction melting furnace. The temperature of the furnace was raised and as the charge started to melt helium was admitted to prevent excessive evaporation of the silicon.
• An ingot having dimensions of l x 2 x 6 inches was poured under a helium atmosphere, was stripped hot and then was placed in a furnace containing a hydrogen atmosphere at 800 C'.
• the ingot was hot rolled at 800 C. with a two-high mill.
• a box furnace was located about 10 to 12 feet from the mill and the material fed thereto when required. The drop in temperature occurring upon transfer of the alloy from the furnace to the mill did not materially alter the rolling temperature. This hot rolling was performed at reductions of 50 to 75 mils per pass to a thickness of 100 mils.
• the temperature of the sheet was then reduced to 400 C. [for warm rolling below the recrystallization temperature. Visual examination of the sheet at this point showed no edge cracks; it had a fine grain size which was nearly equiaxed.
• Warm rolling was conducted at 400 C., the temperature being maintained by a strip furnace 12 feet long .placed adjacent the entry end of the rolling mill. Since the furnace temperature was set at 400 C., the strip was rolled at almost exactly this temperature because it was pushed directly from the furnace through the rolls. Warm rolling continued at reductions of about 15 to milsper pass until the resulting material had a thickness of 20 mils, that is, about one fifth the original thickness. The reduction in thickness was 80%. This rolling procedure produced an elongated structure in the resulting strip. The strip was quite ductile and showed no significant edge cracking.
• the 20 mil strip was then permitted to cool to room temperat-ure whereupon it was cold rolled to a thickness of 1 to 2 mils.
• edges of the strip may be slit; in that manner nuclei that may cause edge crackings will be eliminated.
• hot rolling is used in its usual sense of rolling at a temperature above the recrystallization temperature.
• Warm rolling indicates rolling at a temperature below the recrystallization temperature but above room temperature.
• Cold rolling indicates rolling at about room temperature.
• the binary alloys of the present invention which contain from 4.5% to 7.5% by weight of silicon are characterized by high electrical resistivity. In the range of from 6% to 7% by Weight of silicon the magnetostriction is zero or nearly zero and therefore electrical apparatus made therefrom will be exceptionally quiet.
• a method of producing thin gauge silicon-iron sheets of a thickness of the order of from 2 to 1 mils and less comprising hot rolling an alloy plate consisting essentially of from at least 4.5 Weight percent to 7.5 weight percent of silicon and the remainder iron, to a thickness at least as thin as 110 mils, then Warm rolling the resulting material at an elevated temperature of above about 275 C. but below 425 C. to effect a reduction of about and the resulting material is at least as thin as about 25 mils to produce an elongated microstructure therein, and then, without annealing, rolling the resulting thin gauge material at about room temperature to effect a reduction of the order of to so that the cold rolled sheets are of the desired iinal thickness.
• a method of producing a relatively thick silicon-iron sheet that is ductile and capable of being directly cold rolled without annealing to a reduction of from 90% to 95 at about room temperature to thicknesses of the order of 2 to l mils and less which comprises warm rolling an alloy plate of a thickness of not over about mils and consisting essentially of at least 4.5 and not exceeding 7 .5 weight percent of silicon and the remainder iron, to at least as thin as 25 mils at an elevated temperature of above 275 C. but below 425 C.

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

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Citations (11)

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  • BE BE572663D patent/BE572663A/xx unknown
• 1957
  • 1957-11-06 US US694709A patent/US3099176A/en not_active Expired - Lifetime
• 1958
  • 1958-10-07 DE DEW24225A patent/DE1173116B/de active Pending
  • 1958-10-30 GB GB34820/58A patent/GB870870A/en not_active Expired
  • 1958-11-05 FR FR1207243D patent/FR1207243A/fr not_active Expired

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