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  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
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  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
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  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/38—Non-oxide ceramic constituents or additives
  • C04B2235/3817—Carbides
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  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/40—Metallic constituents or additives not added as binding phase
  • C04B2235/404—Refractory metals
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  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/40—Metallic constituents or additives not added as binding phase
  • C04B2235/405—Iron group metals
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  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/74—Physical characteristics
  • C04B2235/76—Crystal structural characteristics, e.g. symmetry
  • C04B2235/762—Cubic symmetry, e.g. beta-SiC
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  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/74—Physical characteristics
  • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
  • C04B2235/785—Submicron sized grains, i.e. from 0,1 to 1 micron
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  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/74—Physical characteristics
  • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
  • C04B2235/786—Micrometer sized grains, i.e. from 1 to 100 micron

Definitions

• the present invention relates to a sintered, fine grained hard metal alloy having excellent properties for machining cast iron and steel.
• the alloy according to the invention has a superior wear resistance in combination with a very high toughness.
• the alloy has a composition of the known type and contains carbide of tungsten as the main component, together with carbide of titanium and preferably one or more additional carbides such as carbide of tantalum and/or niobium and a bonding metal such as cobalt and/ or nickel.
• the alloy according to the invention contains by volume 60- 80% of WC, -25% of TiC, 020% of TaC, NbC and/or VC, 010% of Cr C ZrC and/or HfC, 05% of Mo and/or carbide of molybdenum, the remainder being in the main Co and/or Ni and possibly also Fe.
• the total quantity of Co, Ni and Fe should not exceed 9.5% and the content of Fe should not exceed 6% by volume.
• the alloy has a certain structure with regard to the phases of the alloy and the grain size of the carbides in order to obtain the unexpected improvement of the properties which is characteristic for the alloy according to the invention.
• the mean (average) grain size of the carbide grains should thus be smaller than 1.6 microns (,u), preferably smaller than 1.5 microns, and at the same time the alloy should be manufactured in such a way that it contains 37.5i7.5% of 'y-phase, 8.5i1% of ,B-phase (bonding metal), the remainder consisting in the main a-phase. Insignificantly amounts of one or more additional phases as -phase can possibly also be present.
• a characteristic property of the alloy according to the invention is that it has a very fine grained structure in relation to the above said phase distribution.
• the 'y-phase is composed of one or more cubic carbides such as TiC, TaC, NbC, VC, ZrC and HfC and which in solid solution contains a not too insignificant amount of WC.
• the fi-phase is a bonding metal phase containing for instance Co, while the OL-PhaSC consists of pure WC, possibly containing a small amount of M0 in solid solution.
• minor quantities of other phases for instance a phase consisting of Mo C may be present.
• the bonding metal should suitably contain a major portion of Co and/or Ni.
• the bonding metal can also contain Fe, the Co and/or Ni being partially substituted by Fe, preferably at the most to such an extent that the bonding metal phase does not lose its above mentioned face centered cubic and/ or hexagonal close packed lattice.
• the alloy should as mentioned have a grain structure which is unusually fine grained With regard to the said phase relation. This is of great importance for obtaining the desired valuable properties in connection with the cutting ability of the alloy for use in machining.
• the grain size should lie within such a range that the coercive force, which is easily measurable, is not less than 200 and preferably not less than 220 oersted, at least when the bonding phase comprises in the main Co.
• the grain size should have such a value that the coercive force is 230-330 oersted.
• the coercive force is related to the grain size of the carbide grains in a sintered hard metal in such a way that a diminishing of the grain size results in an increase of the coercive force and vice versa. It is therefore possible to use the coercive force in defining the grain size. There are certain deviations from this general rule. A large quantity of Fe in the bonding metal phase lowers the coercive force and some complex carbides as n-phase raises the coercive force. Ni also can give deviations from the said rule.
• the alloy according to the invention will have the same superior qualities even if Co is wholly or partly substituted by Ni, or if Co and/or Ni are partly substituted by Fe. This substitution should as mentioned be performed only to such an extent that the fi-phase maintains its face centered cubic and/or hexagonal close packed lattice. Further the grain size should correspond to the grain size of an alloy with Co alone or with Co and up to 0.5% each of Ni and Fe as a bonding metal, the composition and phase structure being in other respects the same, the latter alloy having such a grain size that the coercive force is at least 200 and preferably at least 220 oersted.
• the estimation of the grain size in such alloys in which Co has been wholly or partly substituted can be made by comparing the structures of said alloys in a light or electron microscope with the structure of an alloy containing Co or C0 and at the most 0.5% each of Ni and Fe in the bonding metal phase.
• the alloy according to the invention should be unusually fine grained in view of the relatively high content of 'y-phase.
• the mean grain size of the carbide grains should lie below 1.6 microns and preferably below 1.5 microns. As a lower limit can be mentioned 0.5 micron. Normally the mean grain size should lie within the range 0.7-1.4 microns. For certain very tough qualities the range 0.8-1.2 microns has been found especially suitable.
• the stoichiometric composition of the alloy is of course also important for obtaining the desired qualities. Said composition should be chosen within the above-mentioned limits. Thus the content of WC should lie within the range 60-80%. As a rule the narrower range 65-75% has been found especially suitable.
• the alloy should also contain 1025 and preferably 15-25 of TiC.
• the alloy can further contain up to 20% of TaC, NbC and/ or VC. If it contains only TaC and/or NbC the content of these alloy elements should normally not exceed 15%.
• the alloy contains a relatively small quantity, 0.5-10% TaC and/or NbC.
• the alloy can contain up to 10% of Cr C ZrC and/or HfC and up to 5% M0.
• the M0 changes at least partly to carbide as Mo C and MoC during the sintering of the alloy.
• some Mo can form a solid solution in the a-phase, which consists of WC.
• the content of Co and/or Ni should at the most be 9.5%. They can, as mentioned, be partly substituted by 3 Fe but only to such an extent that the bonding metal phase does not lose its face centered cubic and/or hexagonal close packed lattice.
• the Fe-content should at the most be 6% and the total content of Co and/or Ni and Fe 9.5%. Usually the content of Fe is at the most 1 or 0.5%.
• the content of bonding metal which wholly or to a major part consists of Co and/or Ni with or without a certain amount of Fe, should be at least 7.5 and at the most 9.5%. The range 89% has been found especially suitable.
• the alloy has the above defined composition.
• the structure of the alloy with regard to the phase composition and the grain size is of decisive importance, and it is also necessary that the earlier defined conditions in this respect are at the same time fulfilled.
• compositions and the phase relations in said compositions of two alloys according to the invention are examples of compositions and the phase relations in said compositions of two alloys according to the invention:
• the alloys B, C, D and F are examples of alloys which are normally used for machining cast iron while the alloy E is intended for so called universal machining, that is, machining both cast iron and steel, and the alloy G is intended for machining of steel.
• the alloy contents and the phase quantities are given in percents of volume. It can be pointed out that the alloys C and F are fine grained but have a content of 'y-phase which is only 4 and 2% respectively.
• the above mentioned sintered hard metal alloys have been practically tested and compared.
• the following report of said tests comprises Examples l-3 referring to machining of cast iron and Example 4 referring to machining of steel.
• the wear resistance of the alloys has been determined by measuring the wear of the side surface and the top surface of the cutting insert, i.e. the flank wear and the cratering.
• the examples clearly illustrate that the wear resistance of the alloy according to the invention is superior in comparison with the other alloys tested.
• Example 1 Material Grey perlitic cast iron HB 220 (Brinell hardness). Work piece Brake drum. Operation Rough turning (roughing Cutting speed 93 meters/minute. Feed 0.32 mm./turn.
• Cutting speed 148 meters/minute. Feed 0.2 mm./turn. Cutting depth 35 mm. Feed length 40 mm./piece.
• Alloy quality A B D Number of pieces 18 18 18 Flank, wear, mm-" 0.31 1. 34 1. 66 Cratering, microns 111 185 213 Example 3 Material Cast iron SIS 0115 (Swedish standard). Work piece Tube (1 200 mm. Operation External turning. Feed 0.25 mm./turn. Cutting depth 1.5 mm. Feed length 200 mm.
• Sintered fine grained hard metal alloy adapted for machining cast iron and steel and containing by volume 60-80% of WC, 1025% of TiC, 020% of at least one member selected from the group consisting of T aC, NbC and VC, 010% of at least one member selected from the group consisting of Cr C ZrC and HfC, 05% of at least one member selected from the group consisting of Mo and carbide of molybdenum, the remainder consisting essentially of at least one member selected from the group consisting of Co, Ni and Fe, the total amount of Co, Ni and Fe being at the most 9.5%, the amount of Fe being at the most 6%, the mean grain size of the carbide grains being less than 1.6 microns, the alloy containing 37.5i7.5% of y-phase, 8.5:1% of B-phase and the remainder being in the main a-phase.
• Sintered hard metal alloy according to claim 1 characterized in that it contains 0-15 of at least one member selected from the group consisting of TaC and NbC.

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• 1963
  • 1963-07-01 SE SE7258/63A patent/SE301725B/xx unknown
• 1964
  • 1964-06-10 FR FR977697A patent/FR1398360A/fr not_active Expired
  • 1964-06-22 US US377094A patent/US3245763A/en not_active Expired - Lifetime
  • 1964-06-25 DK DK320164AA patent/DK106949C/da active
  • 1964-06-25 GB GB26311/64A patent/GB1061166A/en not_active Expired
  • 1964-06-29 NL NL6407375A patent/NL6407375A/xx unknown
  • 1964-06-30 BE BE649910D patent/BE649910A/xx unknown
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