US2948604A - Nickel-free austenitic elevated temperature alloy - Google Patents

Nickel-free austenitic elevated temperature alloy Download PDF

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Publication number
US2948604A
US2948604A US802485A US80248559A US2948604A US 2948604 A US2948604 A US 2948604A US 802485 A US802485 A US 802485A US 80248559 A US80248559 A US 80248559A US 2948604 A US2948604 A US 2948604A
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alloy
alloys
manganese
nickel
boron
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US802485A
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Macfarlane Richard Reed
Richard K Pitler
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Allegheny Ludlum Steel Corp
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Allegheny Ludlum Steel Corp
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Priority to BE589052A priority patent/BE589052A/fr
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    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese

Definitions

  • This invention relates to austenitic iron base nickelfree alloys which are suitable for use at elevated temperatures of up to about 1500 F. and higher.
  • alloys have been made and used as turbine parts and the like where it is necessary that the alloys possess sufiicient hardness, strength and corrosion resistance to withstand the stresses and corrosive condi tions encountered under the operating conditions at elevated temperatures of up to about 1500 'F. and higher.
  • Some available prior art alloys have been made and used which possess suitable mechanical properties for use at, these elevated temperatures, but these same alloys are not adequate from the standpoint of either their chemical properties, for example, corrosion resistance, or their physical properties, for example, dimensional stability.
  • Other alloys have been made which compromise between chemical, physical and mechanical properties, but usual- 1y such alloys contain high amounts of nickel or other strategic alloying elements.
  • the alloy of this invention is characterized by having an optimum combination of chemical, physical and mechanical properties, freedom from costly and strategic alloying elements, and economical from the standpoint of material and fabrication costs.
  • An object of this invention is to provide an austenitic iron base nickel-free alloy which is capable of withstanding high stresses at temperatures of up to 1500 F. and higher.
  • Another object of this invention is to provide an austenitic iron base nickel-free alloy having optimum amounts of manganese and chromium with small amounts of carbon, silicon, molybdenum, vanadium, nitrogen and boron as essential alloying elements and which is suitable for use at high stresses at temperatures of up to about 1500 F. and higher.
  • a more specific object of this invention is to produce 2,948,604 Patented Aug. 9, 1960 about 2.0% which are usually found the manufacture of steel such as copper, cobalt, nickel, phosphorus, sulfur and the like, and which 'do not detrimentally alfect the an iron base nickel-free alloy containing critical amounts 1 mium contents greatly affect the formation of both alpha apparent when taken in conjunction with the following;
  • Figure 1 is a graph, the curve. of which illustrates the eifect of manganese on the, rupture properties of the alloy, and
  • Fig. 2 is a graph, the curves of which illustrate the effect of boron on the rupture properties of the alloy.
  • the alloy of this invention comprises between about 0.20% and about 0.35% carbon, between about 10.0% and about 15.0% manganese, up to about 0.75% silicon, between about 11.5% and about 13.5% chromium, between about 2.0% and about 3.5% molybdenum, between about 0.7% and 1.2% vanadium, between about 0.1% and about 0.3% nitrogen, between alloy.
  • Table I sets forth the general range and the optimum range of the composition of the alloy of this invention. It is to be noted that where the balance is reported as iron, such balance includes the incidental impurities as setforth hereinbefore.
  • the carbon content will not exceed a maximum of about 0.35%, because it has been found that higher carbon contents lower the ductility of the alloy of this invention. Carbon also contributes to the strength and hardness of the alloy. While carbon is a strong austenitizing element, the predominant austenitizing element of this alloy is manganese, it being found that atleast 10.0% is needed to insure a completely austenitic structure. Manganese contents in excess of about 15.0% do not contribute to thestability of the austenite and may detract from the attainable mechanical properies. The optimum combination between austenitic stability commensurate with good mechanical properties is obtained when the manganese content is maintained within the range between about 11.0% and about 14.0%.
  • chromium is needed in order to impart sufiicient corrosion resistance to the alloy, es- I and delta ferrite.
  • Molybdenum and vanadium within the ranges givenhereinbefore in Table I function to impart additional strength to the alloy of this invention by strengthening the solid solution of the matrix.
  • vanadium also contributes to the precipitation hardening phenomenon of the alloy and thereby materially contributes to the V strength.
  • Nitrogen within. the range given has a strengthening effect upon the alloy of this invention and materiall-y contributes to the austenitic stability of the alloy.
  • the balance of the alloy is predominantly all iron with not more than 2% of incidental impurities as set forth hereinbefore.
  • the alloy of this invention is an age harden-able alloy.
  • the alloy is preferably solution heat treated at a temperature in the range between about 2000" F. and about 2100 F. for a time period ranging between about 10 minutes and 6 hours. Thereafter, the solution heat treated alloy is rapidly quenched, usually in water, although in some instances either oil or air will suifice. As quenched the alloy is usually soft and rnachinable. Following the quench, the alloy is aged at a temperature in the range between about 1250 F and about 1400 F. for a time period ranging between about 8 and 30 hours. Thereafter, the alloy is air cooled. V
  • Table II contains the chemical analysis of a series of alloys which were made and tested to illustrate the effect of some of the alloying elements on the rupture life of the alloy. It is to be noted that the alloys set forth in Table II are both within and outside the general range as set forth hereinbefore in Table I.
  • Table III illustrates the effect of manganese upon the stress rupture properties of a portion of the alloys set forth hereinbefore in Table II. It is to be noted that these alloys have been subjected to heat treatment consisting of a solution heat treatment at a temperature of 2050 F. for one hour followed by a rapid quench in water and thereafter an aging treatment at the temperature of 1300 F. for a time period of 16 hours followed by air cooling. The test bars of the alloys were stressed at their respective levels and temperatures indicated, and the time required to produce rupture was measured. I
  • Table IV illustrates the effect of boron on the stress rupture properties of the alloy of this invention.
  • the alloys, as set forth hereinafter in Table IV were first subjected to a solution heat treatment at 2050 F. for a time period of 1 hour followed by a rapid quench in water and thereafter aged at a temperature of 1325 F. for a time period of about 32 hours and thereafter air cooled.
  • the stress rupture tests were made both at 1200 F. and 1500 F. and at stresses of 65,000 p.s.i. and 20,000 p.s.i., respectively.
  • curve 14 illustrates the effect of boron on the 100-hour rupture stress at 1500 F. It is immediately seen from curves 12 and 14 of Fig. 2 that at least 0.01% boron is necessary in order to show any significant increase in the IOO-hour rupture stress. Optimum results appear to be obtained when the boron content is maintained within the range between 0.02% and about 0.20%. From the foregoing, it is apparent that it is necessary to maintain a critical balance between the alloying elements in order to obtain outstanding properties capable of being produced within the alloy of this invention.
  • This alloy is efiective for use in engine parts of gas turbines and other high temperature applications where an outstanding combination of strength, corrosion resistance and ductility is required at elevated temperatures of up to 1500 F. and higher. No particular skills nor equipment are necessary in practicing this invention since the alloy can be produced by ordinary air melting techniques which are commercially employed in the metal industry.
  • An austenitic iron base nickel-free alloy suitable for use at temperatures of up to 1500 F. and having a composition including from about 0.20% to about 0.35% carbon, from about 10.0% to about 15.0% manganese, to about 0.75% silicon, from about 11.5% to about 13.5% chromium, from about 2.0% to about 3.5% molybdenum, from about 0.7% to about 1.2% vanadium, from about 0.10% to about 0.30% nitrogen, from about 0.01% to about 0.40% boron and the balance substantially iron with incidental impurities.
  • An austenitic iron base nickel-free alloy suitable for use at temperatures of up to 1500 F. and having a composition including from about 0.22% to about 0.32% carbon, from about 11.0% to about 14.0% manganese, to about 0.40% silicon, from about 12.0% to about 13.0% chromium, from about 2.5% to about 3.25% molybdenum, from about 018% to about 1.1% vanadium, from about 0.15% to about 0.25% nitrogen, from about 0.02% to about 0.20% boron and the balance substantially iron with incidental impurities.
  • An austenitic iron base nickel-free alloy suitable for use at temperatures of up to about 1500 F. and having a composition including about 0.23% carbon, about 12.3% manganese, about 0.12% silicon, about 12.8% chromium, about 1.0% vanadium, about 3.2% molybdenum, about 0.2% nitrogen, about 0.05% boron and the balance substantially iron 'With incidental impurities.
  • An age hardened article of manufacture suitable for use under high stresses and at elevated temperatures of up to 1500'F. comprising an alloy having a composition within the range between about 0.20% and about 0.35% carbon, between about 10.0% and about 15.0% manganese, about 0.75 silicon, between about 11.5% and about 13.5% chromium, between about 2.0% and about 3.5% molybdenum, between about 0.9% and about 1.2% vanadium, between about 0.10% and about 0.30% nitrogen, between about 0.01% and about 0.40% boron and the balance substantially iron with incidental impurities, the alloy beingcharacterized by having a hour rupture stress of at least 20,000 p.s.i. at 1500 F.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
US802485A 1959-03-27 1959-03-27 Nickel-free austenitic elevated temperature alloy Expired - Lifetime US2948604A (en)

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US802485A US2948604A (en) 1959-03-27 1959-03-27 Nickel-free austenitic elevated temperature alloy
BE589052A BE589052A (fr) 1959-03-27 1960-03-25 Alliages austénitiques à base de fer et exempts de nickel.

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3020152A (en) * 1960-05-02 1962-02-06 Gen Motors Corp Exhaust valve steel
US3836406A (en) * 1973-01-22 1974-09-17 Director Of Nat Res Inst For M PERMANENT MAGNETIC Fe-Mn-Cr ALLOY CONTAINING NITROGEN
EP0087975A1 (fr) * 1982-03-02 1983-09-07 United Engineering Steels Limited Aciers austénitiques amagnétiques
US4533406A (en) * 1983-07-26 1985-08-06 The United States Of America As Represented By The United States Department Of Energy Minimum activation martensitic alloys for surface disposal after exposure to neutron flux

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2562854A (en) * 1949-04-22 1951-07-31 Union Carbide & Carbon Corp Method of improving the high-temperature strength of austenitic steels
US2814563A (en) * 1955-07-27 1957-11-26 Allegheny Ludlum Steel High temperature alloys
US2876096A (en) * 1957-12-27 1959-03-03 Crucible Steel Co America Non-magnetic austenitic steel

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2562854A (en) * 1949-04-22 1951-07-31 Union Carbide & Carbon Corp Method of improving the high-temperature strength of austenitic steels
US2814563A (en) * 1955-07-27 1957-11-26 Allegheny Ludlum Steel High temperature alloys
US2876096A (en) * 1957-12-27 1959-03-03 Crucible Steel Co America Non-magnetic austenitic steel

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3020152A (en) * 1960-05-02 1962-02-06 Gen Motors Corp Exhaust valve steel
US3836406A (en) * 1973-01-22 1974-09-17 Director Of Nat Res Inst For M PERMANENT MAGNETIC Fe-Mn-Cr ALLOY CONTAINING NITROGEN
EP0087975A1 (fr) * 1982-03-02 1983-09-07 United Engineering Steels Limited Aciers austénitiques amagnétiques
US4533406A (en) * 1983-07-26 1985-08-06 The United States Of America As Represented By The United States Department Of Energy Minimum activation martensitic alloys for surface disposal after exposure to neutron flux

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