Classifications

• • 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
  • C22C29/06—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
  • C22C29/067—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 comprising a particular metallic binder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/248—Thermal after-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

• An age hardenable, corrosion and heat resistant nickel-chromium, refractory carbide alloy is provided by powder metallurgy for use at elevated temperatures as high as 2000F (1090C) comprising primary grains of at least one refractory carbide selected from the group consisting of TiC, CbC, VC and TaC dispersed through a matrix of an age hardenable, corrosion and heat resistant nickel-chromium alloy consisting essentially by weight of about 5 to 30 percent chromium, up to about 15 percent iron, about 05 to 5 percent titanium, about 0.2 to 5 percent aluminum, up to about 25 percent cobalt, up to about 0.25 percent carbon and the balance essentially nickel.
• Refractory carbide alloys comprising a non-ferrous matrix metal, such as nickel, having dispersed therethrough primary grains of refractory carbide, such as titanium carbide. While such alloys have been very useful in the manufacture of wear resisting elements, e.g. dies, machine parts, and the like, they generally have been limited in their application to normal environments in which heat and corrosion resistance is a secondary consideration.
• Nickel as a matrix, is relatively soft compared to the refractory carbide dispersed therein and tends to be selectively removed or eroded from between the carbide grains in wear applications involving the rubbing of one metal surface against another. When this occurs, the carbide particles at the surface lose their support and fall out, thus accelerating wear.
• Another disadvantage is that the matrix tends to oxidize easily at elevated temperatures of up to about 2000F. While adding chromium to the nickel improved the heat and corrosion resistance to a large extent, the matrix was still soft relative to the carbide grains, such that it was not sufficiently hard to resist selective wearing between the carbide grains.
• Another object is to provide, as an article of manufacture, a hardened sintered heat, corrosion and wear resistant element of the class including heat resistant dies and machine parts.
• Still another object is to provide a method for producing said refractory carbide alloy.
• the invention resides in the production of a powder metallurgy sintered age hardenable corrosion and heat resistant nickel-chromium refractory carbide alloy comprising primary grains of at least one refractory carbide selected from the group consisting of TiC, CbC, VC and TaC dispersed through a nickel-chromium matrix alloy consisting essentially by weight of about 5 to 30 percent chromium, up to about 15 percent iron, about 0.5 to 5 percent titanium, about 0.2 to 5 percent aluminum, up to about 25 percent cobalt, up to about 0.5 percent carbon and the balance essentially at least about 40 percent nickel.
• a composition range which is particularly advantageous is one in which the amount of refractory carbide by volume ranges from about 30 to percent and the balance essentially the matrix alloy.
• a more advantageous composition is one in which the refractory carbide (e.g. TiC) ranges by volume from about 35 to 55 percent, and wherein the matrix alloy making up substantially the balance consists essentially by weight of about 10 to 25 percent chromium, about 2 to 12 percent iron, about 1 to 3 percent titanium, about 0.5 to 2 percent aluminum, up to about 15 percent cobalt, up to about 0.25 percent carbon and the balance essentially at least about 50 percent nickel.
• the refractory carbide e.g. TiC
• the matrix alloy making up substantially the balance consists essentially by weight of about 10 to 25 percent chromium, about 2 to 12 percent iron, about 1 to 3 percent titanium, about 0.5 to 2 percent aluminum, up to about 15 percent cobalt, up to about 0.25 percent carbon and the balance essentially at least about 50 percent nickel.
• the foregoing refractory carbide alloy is capable of being solution annealed to a hardness as low as 46 R and age hardened to a level of about 54 R
• the alloy resists oxidation at elevated temperatures as high as 2000F (1090C) and is particularly resistant to acid corrosion as evidenced by substantially low rates of corrosion in 10 percent concentratedI'I SO in 50 percent concentrated H SQ, and in pure concentrated H
• the alloy exhibits high strength at elevated temperatures.
• the alloy is easily machinable in the annealed state and can be precisely machined or ground to any desired shape and thereafter hardened by age hardening without affecting the precise dimensions.
• the matrix had the following nominal composition by weight:
• the balance nickel may include optionally other ingredients in amounts which do not adversely affect the basic characteristics of the alloy.
• TiC powder about 45 vol. percent of average particle size of about 5 to 7 microns are mixed with 1000 grams of powdered alloy-forming ingredients which include 180 grams of minus mesh high purity electrolytic chromium powder, 80 grams of iron powder of approximately 20 microns average size, 20 grams of titanium added as TiH powder, 3L8 grams of NiAl powder (contains grams aluminum) and the balance (688.2 grams) carbonyl nickel powder of about 5 to 8 microns average size.
• the aluminum is added as NiAl in order to assure take-up of the aluminum by the liquid melt, otherwise, the aluminum added alone tends to be lost by vaporization in vacuum.
• the powder mixture also contains l gram of paraffin (1 percent) for each 100 grams of mix. The mix is placed in a stainless steel ball mill half filled with stainless steel balls, using hexane as the vehicle. The milling is conducted for about 40 hours.
• the mix is removed and vacuum dried.
• a proportion of the mixed product is compressed in a die at tons/sq. in. to the desired shape.
• the shape is liquid phase sintered at a temperature of about l350C for one-half hour (after reaching the temperature) at a vacuum corresponding to microns or better.
• the shape is cooled at a rate through the liquidus solidus region such as to prevent hot tearing during solidification from the liquid phase.
• a rate should not exceed 35C per hour as the liquidus-solidus region is quite narrow and should not be traversed too quickly during solidification. For example, a compact of 2 inches in diameter and 2 inches high is cooled at a rate not exceeding about C per hour.
• the sintered compact is subjected to a solution heat treatment by heating to l232C for minutes to provide a hardness of about 46 R
• the sintered shape is machined and/or ground into a tool element, e.g. a hot extrusion die, and thereafter age hardened in a two-step hardening treatment by heating at 900C(l600F) for 8 hours, followed by heating at 800C (1400F) for 4 hours and then air cooled.
• the hardness obtained is in the neighborhood of about 54 R EXAMPLE 2 about 30 vol.% CbC Primary carbide about 70 vol.%
• Alloy Matrix The nominal composition by weight of the matrix is as follows:
• the nominal composition of the matrix by weight is as follows:
• the nominal composition of the matrix by weight is as follows:
• the nominal composition of the matrix by weight is as follows:
• the non-ferrous alloy matrix should contain at least about 40 percent and, more preferably, at least about 50 percent nickel by weight.
• Other elements may be present in the alloy matrix, such as up to about 10 percent molybdenum, up to about 6 percent tungsten, up to about 5 percent columbium and/or tantalum, up to about 2 percent zirconium, up to about 2 percent hafnium, up to about 2 percent manganese, up to about 2 percent silicon, and the like, the total amount of the other elements not exceeding about 15 percent by weight of the total composition of the alloy matrix.
• the appropriate amount of alloyforming ingredients is mixed with an appropriate amount of primary carbide in a ball mill.
• the mixture may be shaped a variety of ways. It is preferred to press the mixture to a density of at least about 50 percent of true density by pressing over the range of about 10 t.s.i. to t.s.i., preferably 15 t.s.i. to 50 t.s.i., followed by sintering under substantially inert conditions, e.g. in a vacuum or an inert atmosphere.
• the temperature employed is above the melting point of the chromium steel matrix, for example, at a temperature up to about 100C above the melting point for a time sufficient for the primary carbide and the matrix to reach equilibrium and to obtain substantially complete densification, for example, for about 1 minute to 6 hours.
• the product When the liquid phase sintering is completed, the product is allowed to furnace cool to room temperature, the rate through the liquidus phase not exceeding about 35C per hour. If necessary, the as-sintered product is subjected to mechanical cleaning. 1f the assintered product requires solution annealing, it is heated to a temperature of about 1900F(1038C) to 2300F (1260C) for about 30 minutes to 5 hours followed by air cooling.
• the temperature may range in a first hardening step from about 1350F (732C) to 1800F (982C) for about 4 to 30 hours followed by air cooling, and then further age hardened at a temperature ranging from about 1200F (649C) to 1650F (899C) for about 2 to 25 hours.
• the hardness after aging may range from about 49 R to 66 R Corrosion studies have indicated that the alloy compositions of the invention exhibit good resistance to corrosion in such acid media as sulfuric acid, nitric acid and hydrochloric acid (boiling).
• heat resistant dies and machine parts are hot pressing dies, hot extrusion punches, rolls for ironing welded tubing to flatten out the weld bead, hot forging dies, corrosion resistant rotating seals, mold inserts for aluminum and zinc die casting molds, and the like.
• a powder metallurgy sintered age hardenable corrosion and heat resistant nickel-chromium refractory carbide alloy comprising by volume about 30 to 75 percent of primary grains of at least one refractory carbide selected from the group consisting of TiC, CbC, VC and TaC dispersed through a nickel-chromium matrix alloy making up the balance, said matrix alloy consisting essentially by weight of about 5 to 30 percent chromium, up to about 15 percent iron, about 0.5 to 5 percent titanium, about 0.2 to 5 percent aluminum, up to about 25 percent cobalt, up to about 0.5 percent carbon and the balance essentially at least about 40 percent nickel.
• a heat resistant element of the class including heat resistant dies and machine parts formed of an age hardened powder metallurgy sintered corrosion and heat resistant nickelchromium refractory carbide alloy comprising by volume about 30 to 75 percent of primary grains of at least one refractory carbide selected from the group consisting of TiC, CbC, VC and TaC dispersed through an age hardened nickel-chromium matrix alloy making up the balance, the matrix alloy consistingessentially by weight about 5 to 30 percent chromium, up to about 15 percent iron, about 0.5 to 5 percent titanium, about 0.2 to 5 percent aluminum, up to about 25 percent cobalt, up to about 0.5 percent carbon and the balance essentially at least about 40 percent nickel.
• a method of producing bypowder metallurgy a sintered, age hardenable, corrosion and heat resistant nickel-chromium refractory carbide alloy which comprises, providing a powder composition containing about 30 to percent by volume of at least one refractory carbide selected from the group consisting of TiC, CbC, VC and TaC mixed with a powder formulation of alloy-forming ingredients to form an alloy matrix making up the balance containing about 5 to 30 percent chromium, up to about 15 percent iron, about 0.5 to 5 percent titanium, about 0.2 to 5 percent aluminum, up to about 25 percent cobalt, up to about 0.5 percent carbon and the balance essentially at least about 40 percent nickel, the aluminum in the powder mixture being in the form of MA] to assure recoveryof the aluminum in the alloy matrix, forming the powder mixture into a compact, heating said compact to a liquid phase sintering temperature in vacuum ranging up to about C above the melting point of the alloy matrix, cooling said sintered refractory carbide alloy through the liquidussolidus region of the alloy at
• the refractory carbide ranges by volume from about 35 to 55 percent TiC and wherein the alloy matrix making up substantially the balance consists essentially by weight of about 10 to 25 percent chromium, about 2 to 12 percent iron,

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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)
• Drilling Tools (AREA)
• Heat Treatment Of Nonferrous Metals Or Alloys (AREA)

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Cited By (10)

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Citations (7)

• 1970
  • 1970-10-21 US US00082785A patent/US3713788A/en not_active Expired - Lifetime
  • 1970-12-09 DE DE2060605A patent/DE2060605C3/de not_active Expired
• 1971
  • 1971-09-09 CA CA122,476A patent/CA944975A/en not_active Expired
  • 1971-10-06 GB GB4649171A patent/GB1330218A/en not_active Expired
  • 1971-10-20 FR FR7137605A patent/FR2111569A5/fr not_active Expired
  • 1971-10-21 JP JP46082912A patent/JPS5016288B1/ja active Pending

Patent Citations (8)

Non-Patent Citations (2)

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