Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
  • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
  • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
  • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
• • 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
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • 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
  • H01F1/032—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 hard-magnetic materials
  • H01F1/04—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 hard-magnetic materials metals or alloys
  • H01F1/06—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 hard-magnetic materials metals or alloys in the form of particles, e.g. powder
  • H01F1/08—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 hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
  • H01F1/086—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 hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together sintered

Definitions

• ABSTRACT Semi-hard magnetic Fe-Mn system alloys prepared by powder metallurgical methods, are subjected to cold working and subsequent heat treatment to obtain a product of superior magnetic properties and relatively constant magnetic characteristics, as compared to those products prepared by conventional casting methods.
• the properties of these magnetic alloys render them suitable for use in hysteresis motors, mechanical channel elements employed in electrical communication systems and the like.
• This invention relates generally to a method for manufacturing semi-hard magnetic alloys,and more particularly to a method for manufacturing Fe-Mn system magnetic materials of the quench hardening type,which are suitable for hysteresis motors and mechanical channel e1ements,such as are used in electrical communication systems.
• Fe-Mn system magnetic materials refers herein to magnetic materials consisting of less than 20 percent by weight of manganese, less than several percent by weight of additives,such as titanium- ,copper,chromium,vanadium and the like,with the balance being substantially iron.
• Such magnetic materials may further contain less than 20 percent by weight of cobalt for the purpose of increasing the coercive force and the residual magnetic flux density of the product.
• Magnetic materials to be useful in hysteresis motors and the like should have a coercive force of about 50 to 200 Oersteds,and a residual magnetic flux density of about 8,000 to 17,000 Gausses.
• Alnico alloy systems have been used in an attempt to satisfy this need.
• the Alnico system has several inherent drawbacks which have inhibited their full utilization in the art; particularly:
• the magnet is so hard (more than 600 in Vickers hardness) that machinability is poor,thereby resulting in high manufacturing costs,due to the necessity of abrasive working,
• Fe-Mn system magnets instead of Alnico,because of its lower hardness,lower cost and more easily controllable coercive force.
• Fe-Mn systems are characterized by:
• Fe-Mn system magnets have been only prepared by casting techniques in which Fe and Mn are co-melted with other additives,such as Co, in vacuum or in an inert atmosphere, cast into a mold and then subjected to hot rolling and cold rolling. The products are then lathe machined,and heat-treated to obtain the desired magnetic characteristics.
• the cast magnets are frequently subject to blowholes,caused by the casting of molten materials into a mold. As a result, the magnets are frequently characterized by uneven magnetic characteristics.
• Still another disadvantage is that in order to obtain a useable configuratiori,the cast material must be lathed extensively,thereby resulting in wasted material. Of course,lathing is still easier than abrasive machining.
• a further disadvantage is the great extent of cold working necessary to obtain the desirable magnetic characteristics.
• a mixture of iron and manganese powders is prepared in amounts of 5-14 wt percent Mn, with the balance being Fe.
• Other additive powders such as cobalt, titanium, copper, vanadium, chromium, silicon, or the like, may be added to the mixture.
• tita nium may be used in amounts of 0.6-6 wt percent and copper, chromium, silicon or the like, may be used in amounts of 0 to 0.3 wt percent with the balance being Fe.
• titanium when Mn is used, in preferable amounts of 10-13 percent, titanium may be used in amounts of 2-4 wt percent, Cn, Cr, Si or the like may be used in amounts of 0-3 wt percent, with the balance being Fe. Moreover, when Mn is used in amounts of less than 30 wt percent, Ti in amounts of less than 5 wt percent with the balance being Fe, and preferably, when Mn is used amounts of 24 wt percent with the balance being Fe.
• the powder mixture is then compacted under high pressure of from -10 ton/cm", and is subjected to sintering temperatures of higher than 1,200" C, but lower than the melting point in an inert atmosphere or in vacuo.
• sintering is effected at temperatures of from l,250 C to l,330 C.
• the compacted and sintered product is then cold worked by conventional means, at a working ratio of greater than 40 percent, with no upper limit, but preferably at a low cold working ratio of from 40 to 65 percent, to provide sufficient magnetic characteristics of the magnetic materials suitable for hysteresis motors.
• the working processes can be reduced by carrying out sizing" concurrently with cold working. This expedient can lead to reduction in manufacturing costs.
• the Fe-Mn system magnets are quench hardening type, which is subject to austenite-martensite transformation, the cold working will contribute to improvements in magnetic characteristics by creating strains in the structure of the magnets. The strains promote the transformation to the fullest extent and increases the density of the sintered compact.
• the material is subjected to heat treatment of 450 C to 530 C.
• the following table compares the residual magnetic flux density Br (Gauss) and coercive force He (Oersted) of (A) Fe-Mn system magnets sintered and subjected to cold working according to the present invention, (B) Fe-Mn system magnets sintered according to the present invention but not cold worked, and (C) Fe-Mn system magnets manufactured according to the conventional casting method.
• the superiority of the magnets according to the present invention will be clearly understood from this table.
• magnets can be prepared which are highly uniform and which are characterized by good component consistency and stable magnetic characteristics,since only a small amount of the Mn will be vaporized during the sintering process as low as 0.1 percent if sintering is conducted at l,300 C. for 5 hours).
• the process of the present invention provides a high mass productivity,as compared with conventional casting methods,especially where small size magnets,as used in hysteresis motors, are prepared.
• EXAMPLE 1 A mixture of materials,consisting of 87 wt. percent Fe and 13 wt. percent Mn, was compacted under pressure and then sintered at l,300 C.for 5 hours in an inert atmosphere. The product was then subjected to cold working at a working ratio of 50 percent and heat treated at 500 C.for 10 hours. The magnetic characteristics of the magnets thus prepared were found to have a residual magnetic flux density of 9,500 Gauss and a coercive force of 60 Oersted. By way of comparison, the magnetic characteristics of the magnet prepared without cold working,but under the same treatment conditions werezresidual magnetic flux density of 2,300 and coercive force of 20 Oersted.
• the amount of evaporation of Mn in the course of sintering was about 0.1 percent of the prepared amount of Mn and is considerably less than the 10 percent amount for magnets having the same constituents but prepared by conventional casting methods.
• EXAMPLE 2 A powder mixture of materials,consisting of 84.5 wt. percent Fe, 12.5 wt. percent Mn,and the balance being additives such as Ti, Cu, V, Cr, Si and the like was compacted and then sintered at l,250 C.for 5 hours in an inert atmosphere. The compact was then subjected to cold working, at a working ratio of 65 percent and heat treated at 500 C.for 8 hours.
• the magnetic characteristics of the magnets thus prepared were: residual magnetic flux density of 9,700 Gauss,and coercive force of 55 Oersted.
• EXAMPLE 3 A powder mixture of materials,consisting of 77 wt. percent Fe, 10 wt. percent Mn,10 wt. percent Co and 3 wt. percent Ti was compacted under pressure and sintered at 1,300 C.for 10 hours in an inert atmosphere. The compact was cold worked at a working ratio of 65 percent,and then subjected to heat treatment at 500 C.for 10 hours. The magnetic characteristics of the magnets thus manufactured were: residual magnetic flux density of 14,000 Gauss,and coercive force of 35 Oersted.
• EXAMPLE 4 A powder mixture of materials,consisting of wt. percent Fe, 10 wt. percent Mn, 10 wt. percent Co, 3 wt. percent Ti and 2 wt. percent additives such as Cu, V, Cr and Si,was compacted under pressure and sintered at l,300 C.for 10 hours in an inert atmosphere. The compact was cold worked at a working ratio of 65 percent and heat treated at 550 C.for 8 hours. The magnetic characteristics of the magnets thus prepared were: residual magnetic flux density of 12,000 Gauss- ,and coercive force of 55 Oersted.
• a method of preparing a semi-hard Fe-Mn system magnetic material which comprises:
• said powder mixture contains at least one additive powder selected from the group consisting of: Ti, Cu, V, Cr, Si and Co.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Power Engineering (AREA)
• Hard Magnetic Materials (AREA)
• Powder Metallurgy (AREA)

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• 1971
  • 1971-09-06 DE DE2144560A patent/DE2144560C2/de not_active Expired
  • 1971-09-08 GB GB4198971A patent/GB1369509A/en not_active Expired
  • 1971-09-08 NL NLAANVRAGE7112378,A patent/NL173575C/xx not_active IP Right Cessation
  • 1971-09-10 US US00179550A patent/US3769100A/en not_active Expired - Lifetime
  • 1971-09-10 FR FR7132653A patent/FR2112946A5/fr not_active Expired
  • 1971-09-10 CA CA122552A patent/CA932992A/en not_active Expired

Patent Citations (4)

Non-Patent Citations (1)

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