US3708355A - Castable carbonitride alloys - Google Patents

Castable carbonitride alloys Download PDF

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Publication number
US3708355A
US3708355A US00086622A US3708355DA US3708355A US 3708355 A US3708355 A US 3708355A US 00086622 A US00086622 A US 00086622A US 3708355D A US3708355D A US 3708355DA US 3708355 A US3708355 A US 3708355A
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metal
carbonitride
alloys
nitrogen
group
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US00086622A
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E Rudy
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TDY Industries LLC
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Teledyne Industries Inc
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • 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
    • C22C29/04—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 carbonitrides

Definitions

  • the microstructure of the alloys consist of fine-grained, mechanical mixtures of carbonitride and refractory metal alloys, the fine-grained structure being obtained through solidification of eutectic or near-eutectic melts.
  • the hard carbonitride phase has titanium as its base metal, while the binder phase is a tungsten-rich metal alloy.
  • the present invention relates to carbonitride alloys and more particularly to a new family of carbonitride alloys which, due to their physical characteristics, are particularly useful as machine tools.
  • sintered carbide of one form or another.
  • Commercial sintered carbide tooling material usually consists of a hard carbide alloy, usually tungsten and titanium carbide, dispersed in a matrix or hinder of an iron group metal, usually cobalt or nickel.
  • the binder provides toughness to the brittle carbide and also serves as a sintering aid during fabrication.
  • the iron group metals have relatively low melting temperatures and the loss of strength of the binder alloys based on these metals at relatively low temperatures can cause thermal deformation and thermal wear to become the predominate wear mechanism at high cutting speeds and can cause premature failure of the tools.
  • 'It is accordingly an object of the present invention to provide an improved composition of material for use as machine tooling material.
  • the alloys of the invention are based on group IV metal (titanium, zirconium and hafnium)-rich carbonitride alloys (relative group IV metal content in excess of 60 atomic percent) bonded by group VI metal (molybdenum and tungsten)-rich refractory metal alloys (relative group VI metal content in excess of atomic percent).
  • the desired microstructure of the composition which consists of a fine-grained aggregate of carbonitride and metal phase, is.obtained through rapid solidification of eutectic or near-eutectic alloys formed between the metal and the carbonitride phase.
  • the lamellar, eutectic-type structure consists of the carbonitride phase, which is responsible for the cutting action, and the metal alloy, which contributes toughness and strength to the composite.
  • a hypereutectic composition of the carbonitride-metal is provided in which grains of primary carbonitride are dispersed throughout the lamellar eutectic structure.
  • the carbonitride metal composite comprises a fine-grained lamellar structure consisting of a tungsten-rich metal binder alloy and a carbonitride phase having titanium as its base metal.
  • the carbonitride phase is a solid solution between isomorphous monocarbides and mononitrides.
  • the molar ratio of nitrogen to carbon in the carbonitride phase can be varied at will but as is discussed below, for reasons related to fabricability and performance of the alloys, is usually kept below 0.40.
  • the carbonitride alloys of the invention are made possible by the existence of pseudobinary eutectic equilibria between the metal and the mononitride phases in the boundary systems titanium-tungsten-nitrogen, zirconiumtungsten-nitrogen and hafnium-tungsten-nitrogen, and the existence of nearly isothermally solidifying, eutectic-type equilibria between the carbonitride and the metal solid solutions in the systems titanium-tungsten-carbon-nitrogen, zirconium-tungsten-carbon-nitrogen, and hafniumtungsten-carbon-nitrogen.
  • phase equilibria in the metal-rich regions of the nitride and carbonitride systems are such, that over a wide range of metal-exchanges and temperatures, group IV metal-rich carbonitride, or nitride, solid solutions are in equilibrium with tungsten-rich metal alloys.
  • the products of the eutectic crystallization consist of tungsten-rich binder alloys (relative tungsten content in excess of 80 atomic percent) and a group IV metal-rich carbonitride alloy (relative group IV metal content in excess of 60 atomic percent).
  • the nitrogen dissociation pressures of only nitride-containing alloys located within the range where suitable binder alloys are formed, are too high at melting temperatures to be of practical use.
  • the nitrogen partial pressures as wellas the eutectic temperatures are substantially lowered by alloying the nitrides with carbides.
  • eutectic solidification occurs at approximately 2750 C. along the join metal+carbonitride, at which the metal phase consists of a 94 atomic percent tungsten, 6 atomic percent titanium-alloy, and the interstitial alloy of almost pure titanium carbonitride.
  • TIN in contact with a 10 atomic percent titaniumatomic percent tungsten metal alloy melts at 2970" C. and the mixture has at this temperature a decomposition pressure of approximately 6 atmospheres.
  • the behavior of the other group IV metal nitrides (ZrN, I-IFN) in systems with tungsten are generally similar to the titanium systems, except that the nitrogen decomposition pressures at equivalent temperatures and pressures are somewhat lower than in" the titanium-based alloys.
  • the eutectic temperatures in these systems are higher than in the titanium systems (3070" C. at the join ZrN-tungsten and 3100 C. at the join HfN-tungsten) and remain practically unchanged by alloying with carbon; additionally, the nitride or carbonitride content of the eutectic structure is lower than in the titanium systems, which results in substantially higher wear rates of zirconium and hafnium-based alloys in application as machine tools.
  • phase equilibria in the corresponding systems of group IV metals with molybdenum, nitrogen, and carbon are generally similar to the tungsten systems, although the eutectic temperatures, and hence the nitrogen decomposition pressures, of the alloys in the melting range are substantially lower.
  • the hard alloy content of the eutectics in the molybdenum-containing alloys and the strengths of molybdenum-rich alloy binders are too low, however, in order to be competitive with the tungstenbased alloys as machine tools.
  • the most preferred embodiment of the carbonitride-metal composite in applications as a machine tool is therefore based on the titanium-tungsten-carbon-nitrogen system.
  • certain improvements can be achieved by alloying with other elements, notably by partial substitution of titanium by zirconium or hafnium, and by small additions of group V metals (vanadium, niobium and tantalum). Partial substitution of tungsten by molybdenum and rhenium is also possible.
  • the stoichiometry parameter 2 measures the combined number of moles of interstitial atoms ofcarbon and nitrogen per gram atom of metal titanium+tungsten.
  • Ti W (C,,N of the base alloys of the invention extend between limits of x between 0.28 and 0.60, of y less than 0.50, and of 2 between 0.28 and 0.37. Alloys located outside the preferred range, but inside the boundaries defined by limits of x between 0.25 and 0.70, of y less than 0.50, and of 2 between 0.25 and 0.45, are less suitable for machine tools but are acceptable for some applications.
  • carbonitride-metal composites with low interstitial element contents consist of eutectic only and exhibit somewhat higher wear rates than hypereutectic alloys which contain excess primary carbonitride. Castability, however, becomes poor if the carbon plus nitrogen content of the alloys exceeds about 28 atomic percent (z 0.39).
  • Machine tools fabri- 4 cated from such alloys are also more prone to edge-chipping than tools fabricated from the tougher eutectic, or slightly hypereutectic, alloys.
  • top cratering resistance improves with increasing titanium to tungstenratios (x/l-x) in the alloys, while flank wear is only moderately aifected by the relative metal exchange.
  • Edge stability in heavy roughing applications is optimum at titanium exchanges corresponding to x-0.35 (at 2:034), decreases slightly for alloys with values of x between 0.35 and 0.50, and drops sharply towards higher titanium contents.
  • the alloys of the invention may be prepared by are (skull) melting, for example in a nonconsumable electrode (tungsten) are furnace, and casting of the melt in Water cooled molds, or molds made of refractory materials, preferably graphite.
  • Centrifugal casting of the melt is preferable to casting techniques employing stationary molds, because the former technique minimizes the problems associated with the formation of shrinkage pipes, allows higher casting speeds, and also permits the development of processes by which multiple dies can be used to cast parts closely to shape.
  • Dense bodies can also be prepared by powdermetallurgical techniques, using premelted and then comminuted alloy stock. The performance of sintered alloys as machine tools, however, is inferior to the performance of the cast alloys.
  • the eutectic or near-eutectic melts of the alloys of the invention be solidified under a high temperature gradient (preferably above 20 C./sec.) in order to assure the formation of the fine-grained structure necessary to obtain composites with optimum mechanical properties and performance as machine tools. It has been observed that solidification under higher temperature gradients causes a finer-grained structure and, conversely, solidification under lower temperature gradients causes a coarser-grained structure.
  • the quaternary alloys of the base alloy system can be extensively modified by alloying additions of other metals or interstitials without changing their principal characteristics.
  • a correlation between amount and type of alloying additions, and performance of the resulting composites as machine tools, indicates that noticeable improvements can be achieved by certain low level alloying additions to the base alloys, but that higher level (above atomic percent) alloying is generally unnecessary or even undesirable; addition of selected elements up to certain concentrations proved inert while others resulted, even at low concentrations, in a substantial drop of the cutting performance.
  • the summary of the effect of alloying additions to titaniumtungsten-carbon-nitrogen-based alloys given below is based on the performance of the carbonitride-metal composites in cutting annealed 4340 steel.
  • Molybdenum substituted in amounts up to atomic percent for tungsten in the base alloy system, resulted in no noticeable change in performance, although castability appeared impaired at concentrations higher than 5 atomic percent. Exchanges of 50 atomic percent resulted in nose breakdown and chip welding under the chosen test conditions.
  • Rhenium in amounts up to atomic percent in replacement for tungsten improves the cracking resistance of the composites, but had no measurable effect on cutting performance.
  • Oxygen in amounts up to 4 atomic percent in replacement for carbon or nitrogen results in reduced friction and welding tendency, at some sacrifice in strength and cracking resistance.
  • test condition A the annealed 4340 steel having a Rockwell hardness of 22 to 23 was cut at a speed of 530 surface feet per minute using a depth or cut of 0.125 inch and a feed rate of 0.020 inch per revolution.
  • test condition B The other test condition, indicated as being test condition B, using the 4340 steel having a Rockwell hardness value of 28 to 30 and was cut at a speed of 410 surface feet per minute while maintaining a cutting depth of 0.075 inch and a feed rate of 0.020 inch per revolution. In each case, tool life was empirically established at 0.016" total flank wear.
  • the comparison tools selected for the test were tools of identical dimension made from the best tooling materials known in the prior art.
  • the first tool indicated as comparison tool 1 in Table 2 below, was constructed from the highest grade sintered carbide material available. This top grade sintered carbide material, known as grade C-50 in the trade, is sold by the General Electric Company under the t-radename Carboloy 370.
  • the second comparison test tool in Table 2 below, indicated as comparison tool 2 was constructed from the recently developed cast carbide alloys mentioned above, evaluated under identical test conditions. This material had the composition Ti Zr W C using the convention described above. An attempt was also made to obtain comparable data on commercial C2 grade sintered carbide material, but tools constructed from this material under the chosen test conditions failed almost immediately after initiation of the cutting test.
  • Example IV A metal-carbide alloy with the initial composition Ti Zr W C was arc melted in a graphite skull and nitrided in the melted state by a 2 minute exposure to nitrogen at atmospheric pressure prior to casting. The nitrogen content of the alloy was atomic percent, resulting in an approximate overall composition of the cast part corresponding to Ti Zr W C N
  • a carbonitride-metal alloy composition comprising a base alloy composition of a Group IV metal, a Group VI metal, carbon and nitrogen having a fine-grained lamellar microstructure derived from a eutectic solidification reaction, said lamellar microstructure consisting of a refractory, hard carbonitride phase and a metal phase, with the metal phase being rich in said Group VI metal and contributing toughness to the composite and said carbonitride phase having said Group IV metal as its base metal, said alloy having the composition Group IV metal) (Group VI metal) [N C in which said Group IV metal is comprised of at least 85 atomic percent titanium, said Group VI metal is comprised of at least 90 atomic percent tungsten, and in which the mole fraction x is variable between the limits 0.25 and 0.70, the mole fraction y is less than 0.50, and the stoicniometry parameter z, which measured the combined 8 number of moles of nitrogen and carbon per gram atom metal alloy, is variable between the limits 0.25 and 0.45
  • a carbonitride-metal alloy composition comprising a base alloy composition of a group V metal, group IV metal, a group VI metal, carbon and nitrogen having a fine-grained lamellar microstructure derived from a eutectic solidification reaction, said lamellar microstructure consisting of a refractory, hard carbonitride phase and a metal phase, with the metal phase being rich in said group VI metal and contributing toughness to the composite and said carbonitride phase having said group IV metal as its base metal, said alloy having the composition [(group V metal),,(group IV metal) (group VI metal) [N C in which said group V metal is selected from the group consisting of vanadium, niobium and tantalum, said group IV metal is comprised of at least 85 atomic percent titanium, said group VI metal is comprised of at least atomic percent tungsten, and in which the mole fraction v is less than 0.05, the mole fraction x is variable between the limits 0.25 and 0.70, the mole fraction y is less
  • a borocarbonitride-metal alloy composition comprising a base alloy composition of a group IV metal, a group VI metal, boron, carbon and nitrogen having a fine-grained lamellar microstructure derived from a eutectic solidification reaction, said lamellar microstructure consisting of a refractory, hard borocarbonitride phase and a metal phase, with the metal phase being rich in said group VI metal and contributing toughness to the composite and said borocarbonitride phase having said group IV metal as its base metal, said alloy having the composition [(group IV metal) (group VI metal) [B N C in which said group IV metal is comprised of at least 85 atomic percent titanium, said group VI metal is comprised of at least 90 atomic percent tungsten, and in which the mole fraction u is less than 0.03, the mole fraction x is variable between the limits 0.25 and 0.70, the mole fraction y is less than 0.50, and the stoichiometry parameter z, which measured the combined number of mo
  • An oxycarbonitride-metal alloy composition comprising a base alloy composition of a group IV metal, a group VI metal, oxygen, carbon and nitrogen having a fine-grained lamellar microstructure derived from a eutectic solidification reaction, said lamellar microstructure consisting of a refractory, hard oxycarbonitride phase and a metal phase, with the metal phase being rich in said group IV metal and contributing toughness to the composite and said oxycarbonitride phase having said group IV metal as its base metal, said alloy having the composition [(group IV metal) (group VI metal) [O N C in which said group IV metal is comprised of a least 85 atomic percent titanium, said group VI metal is comprised of at least 90 atomic percent tungsten, and in which the mole fraction t is less than 0.04, the mole fraction x is variable between the limits 0.25 and 0.70, the mole fraction y is less than 0.50, and the stoichiometry parameter 2, which measured the combined number of moles of oxygen

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Cutting Tools, Boring Holders, And Turrets (AREA)
US00086622A 1970-11-03 1970-11-03 Castable carbonitride alloys Expired - Lifetime US3708355A (en)

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US (1) US3708355A (enrdf_load_stackoverflow)
JP (1) JPS5312883B1 (enrdf_load_stackoverflow)
CA (1) CA948888A (enrdf_load_stackoverflow)
FR (1) FR2112987A5 (enrdf_load_stackoverflow)
GB (1) GB1356302A (enrdf_load_stackoverflow)
SE (1) SE384531B (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046517A (en) * 1975-02-14 1977-09-06 Ltd. Dijet Industrial Co Cemented carbide material for cutting operation
US4277283A (en) * 1977-12-23 1981-07-07 Sumitomo Electric Industries, Ltd. Sintered hard metal and the method for producing the same
US4279651A (en) * 1977-12-29 1981-07-21 Sumitomo Electric Industries, Ltd. Sintered hard metal and the method for producing the same
US4290807A (en) * 1977-09-20 1981-09-22 Sumitomo Electric Industries, Ltd. Hard alloy and a process for the production of the same
US4417922A (en) * 1979-11-20 1983-11-29 Hall Fred W Sintered hard metals
DE3346873A1 (de) * 1982-12-24 1984-06-28 Mitsubishi Kinzoku K.K., Tokyo Metallkeramik fuer schneidwerkzeuge und daraus hergestellte schneidplaettchen
US4961780A (en) * 1988-06-29 1990-10-09 Vermont American Corporation Boron-treated hard metal
US5116416A (en) * 1988-03-11 1992-05-26 Vermont American Corporation Boron-treated hard metal

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2420768A1 (de) * 1973-06-18 1975-01-09 Teledyne Ind Karbonitridlegierungen fuer schneidwerkzeuge und verschleissteile
GB2006264B (en) * 1977-09-20 1982-03-10 Sumitomo Electric Industries Hard alloy and a process for the production thereof
GB2235145B (en) * 1988-12-23 1992-11-18 Royal Ordnance Plc Metal matrix composite materials
RU2270736C1 (ru) * 2004-07-26 2006-02-27 Государственное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный технологический институт (технический университет)" Способ изготовления твердого сплава на основе карбида вольфрама и сложного карбонитрида титана-вольфрама

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB478016A (en) * 1936-10-05 1938-01-11 Paul Marth Improvements in a process for producing very hard substances of high mechanical resistance
AT193141B (de) * 1953-09-01 1957-11-25 Metallwerke Plansee Ges M B H Werkstoff für Tiegel, Kokillen, Ofenfutter od. dgl. zum Niederschmelzen von Titan und Zirkon

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4046517A (en) * 1975-02-14 1977-09-06 Ltd. Dijet Industrial Co Cemented carbide material for cutting operation
US4290807A (en) * 1977-09-20 1981-09-22 Sumitomo Electric Industries, Ltd. Hard alloy and a process for the production of the same
US4277283A (en) * 1977-12-23 1981-07-07 Sumitomo Electric Industries, Ltd. Sintered hard metal and the method for producing the same
US4279651A (en) * 1977-12-29 1981-07-21 Sumitomo Electric Industries, Ltd. Sintered hard metal and the method for producing the same
US4417922A (en) * 1979-11-20 1983-11-29 Hall Fred W Sintered hard metals
DE3346873A1 (de) * 1982-12-24 1984-06-28 Mitsubishi Kinzoku K.K., Tokyo Metallkeramik fuer schneidwerkzeuge und daraus hergestellte schneidplaettchen
US5116416A (en) * 1988-03-11 1992-05-26 Vermont American Corporation Boron-treated hard metal
US4961780A (en) * 1988-06-29 1990-10-09 Vermont American Corporation Boron-treated hard metal

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CA948888A (en) 1974-06-11
JPS5312883B1 (enrdf_load_stackoverflow) 1978-05-06
GB1356302A (en) 1974-06-12
FR2112987A5 (enrdf_load_stackoverflow) 1972-06-23
SE384531B (sv) 1976-05-10

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