EP0117932B1 - Warmbearbeitbarkeit einer Nickelbasislegierung mit struktureller Härtung - Google Patents
Warmbearbeitbarkeit einer Nickelbasislegierung mit struktureller Härtung Download PDFInfo
- Publication number
- EP0117932B1 EP0117932B1 EP83301267A EP83301267A EP0117932B1 EP 0117932 B1 EP0117932 B1 EP 0117932B1 EP 83301267 A EP83301267 A EP 83301267A EP 83301267 A EP83301267 A EP 83301267A EP 0117932 B1 EP0117932 B1 EP 0117932B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- percent
- alloy
- raw materials
- magnesium
- lime
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/023—Alloys based on nickel
Definitions
- This invention relates to a method for improving the hot workability of an age hardenable nickel base alloy and to an alloy having such improved hot workability properties.
- One such alloy is commercially known by the designation U-720 and has the following nominal composition: about 18 percent chromium, about 5 percent titanium, about 2.5 percent aluminum, about 14.75 percent cobalt, about 3 percent molybdenum, about 1.25 percent tungsten, about .035 percent boron, about .035 percent carbon, about .037 percent zirconium, up to 0.1 percent niobium, up to 0.1 percent tantalum, up to 0.1 percent vanadium, up to 0.1 percent copper, up to .50 percent iron, up to .15 percent silicon, up to .15 percent manganese, up to 0.1 percent phosphorus, up to .0025 percent silver, up to .01 percent sulfur, and the balance nickel.
- GB-A-1035250 discloses a process wherein an iron-and/or nickel-based alloy is made by adding to a melt of the components with a lime slag cover to absorb and retain calcium and calcium-sulfur compounds, adding elemental calcium to reduce oxygen and sulfur levels and holding the treated melt under the slag cover to allow the calcium to rise into it, then exposing the treated melt to an oxidising atmosphere and/or a vacuum.
- GB-A-1180974 discloses a process in which a nickel-chromium alloy is melted under vacuum to remove impurities and magnesium is added before the alloy is cast, to give an alloy containing up to 0.1 %, preferably 0.015 to 0.05%, of magnesium.
- the present invention is based upon the discovery that significant improvements in the hot workability of certain age hardenable nickel base alloys can be achieved by deliberate additions of lime and magnesium under specified conditions during melting of the alloy.
- the present invention consists in a method for producing an age hardenable nickel base alloy, of a type which would be prone to cracking when subjected to hot working containing sulfur as an impurity, and in which appropriate raw materials for producing an alloy of said composition are melted, refined, and thereafter cast into an ingot, characterised in that the hot workability of the alloy is improved by tying up and/or removing the sulfur present as an impurity in the raw materials by melting the raw materials under a vaccum in the presence of lime and forming a desulfurizing lime slag on the surface of the molten raw material, and thereafter adding a small but significant amount of magnesium thereto just prior to casting the alloy, so that the alloy contains sulfur at a level of no more than 50 parts per million and magnesium from 10 to 100 parts per million.
- This improvement is applicable to the production of the specific class of age hardenable nickel base alloys containing the following basic elements: 17 to 20 percent chromium, 2.9 to 5.3 percent titanium, 1.8 to 2.8 percent aluminium, 11 to 15.5 percent cobalt, 2.5 to 7 percent molybdenum, 0.8 to 1.5 percent tungsten, 0.004 to 0.040 percent boron, 0.02 to 0.06 percent carbon, and about 52 to about 57 percent nickel.
- This class of alloys may also include minor amounts of other elements and incidental impurities including, but not limited to, up to 0.05 percent zirconium, up to 0.1 percent niobium, up to 0.1 percent tantalum, up to 0.1 percent vanadium, up to 0.1 percent copper, up to 2 percent iron, up to 0.15 percent silicon, up to 0.15 percent manganese, up to 0.1 percent phosphorus, up to 0.1 sulfur and up to 0.0025 percent silver.
- the improvement provided in accordance with the present invention is particularly applicable to the age hardenable nickel base alloy known commercially as U-720, the specification of which calls for a composition as follows: 17.5 to 18.5 percent chromium, 4.75 to 5.25 percent titanium, 2.25 to 2.75 percent atuminium,14to 15.5 percent cobalt, 2.75 to 3.25 percent molybdenum, 1 to 1.5 percent tungsten, .03 to .04 percent boron, .03 to .04 percent carbon, .02 to .05 percent zirconium, up to 0.1 percent niobium, up to 0.1 percent tantalum, up to 0.1 percent vanadium, up to 0.1 percent copper, up to .5 percent iron, up to .15 percent silicon, up to .15 percent manganese, up to 0.1 percent phosphorous, up to .0025 percent silver, up to .01 percent sulfur, balance nickel.
- the improved hot workability and other desirable characteristics achieved in accordance with the present invention are believed to be attributable, at least in part, to the critical combination of magnesium and sulfur content provided in the alloy by the combined use of lime and magnesium addition in the melting operation.
- Melting of the raw materials in the presence of lime, together with the addition of magnesium just prior to casting of the molten alloy, are believed to contribute to the hot workability of the alloy by removing and/or tying up sulfur present as an impurity in the raw materials.
- the addition of lime to the molten raw materials is believed to result in removal of major quantities of the sulfur impurity.
- the subsequent addition of magnesium is believed to further contribute to the hot workability properties by tying up significant amounts of sulfur which may remain in the alloy following the lime treatment.
- magnesium be added to the molten raw materials under an inert gas back pressure and that the molten materials then be promptly poured from the furnace to form ingots.
- alloys exhibiting improvements in hot workability pursuant to the lime and magnesium practice of this invention are characterized by a magnesium content within critical limits of from 10 to 100 parts per million and a sulfur content of no more than 50 parts per million.
- the lime and magnesium practice is carried out in such a manner that the magnesium content is within the range of 10 to 60 parts per million and the sulfur content no more than 30 parts per million.
- an age hardenable nickel base alloy which is characterized by excellent hot workability and which consists of 17 to 20 percent chromium, 2.9 to 5.3 percent titanium, 1.8 to 2.8 percent aluminum, 11 to 15.5 percent cobalt, 2.5 to 7 percent molybdenum,.8 to 1.5 percent tungsten, .004 to .040 percent boron, .02 to .06 percent carbon, up to .05 percent zirconium, up to 0.1 percent niobium, up to 0.1 percent tantalum, up to 0.1 percent vanadium, up to 0.1 percent copper, up to 2 percent iron, up to .15 percent silicon, up to .15 percent manganese, up to 0.1 percent phosphorus, up to .025 percent silver, no more than 50 parts per million sulfur, from 10 to 100 parts per million magnesium, and the balance essentially nickel.
- the improved alloy of this invention is further characterized by having excellent hot workability, as evidenced by a rapid strain rate hot ductility significantly greater than that of similar alloys without the lime and magnesium practice.
- Hot workable alloys in accordance with this invention exhibit a rapid strain rate hot ductility at 1700°F (927°C) greater than 50 percent RA, and generally 60 percent RA or greater.
- magnesium was added to the lime desulfurized heat under inert gas back pressure at the end of the refine cycle, just prior to pouring from the vacuum furnace. A very significant improvement in hot workability was observed.
- the hot workability of the above-noted alloys was quantitatively measured by rapid strain rate hot tensile testing.
- the specimens are first annealed at 2000°F (1093°C) for one hour and air cooled.
- Tensile specimens, machined from the material being studied, are heated to a series of test temperatures approximating the range normally employed in hot working.
- the specimens are broken in tension, at a strain rate of approximately .05 inches (1.27 m. per second.
- the hot ductility is expressed as the percentage of reduction of area (%RA) of the broken bars, and this has been found to be a good indication of hot workability and to correlate well with actual results in hot rolling.
- %RA percentage of reduction of area
- Rapid strain rate hot ductility results from the above tests are displayed graphically in the figure.
- the asterisk ( * ) represents the mean value of %RA and the shaded bar area indicates the range or spread of %RA, based on the standard deviation.
- a significant improvement in %RA is apparent in the lime plus Mg practice of the present invention as compared to the non-lime/non-Mg practice and the lime/non-Mg practice.
- the hot ductility of the lime plus Mg heats is actually better at 927°C than the non-Mg heats are at 982°C, a 55°C or greater improvement which is of tremendous significance in hot working.
- yield Another measure of the improvement in hot workability observed for the lime plus Mg composition is yield. This is a measure of the amount of final bar product shipped expressed as a percentage of the amount of the starting material. Yield figures accumulated on lime plus Mg heats show a 34 percent increase over lime/non-Mg heats.
- lime plus Mg composition over the lime/non-Mg composition was a dramatic reduction in the frequency of sonic indications found in finish centerless ground bar product.
- Lime plus Mg heats average slightly less than one (1) sonic defect per ingot while lime/non-Mg heats had more than four (4) sonic defects per ingot.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Materials For Medical Uses (AREA)
- Adornments (AREA)
- Laminated Bodies (AREA)
Claims (5)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT83301267T ATE28668T1 (de) | 1983-03-08 | 1983-03-08 | Warmbearbeitbarkeit einer nickelbasislegierung mit struktureller haertung. |
DE8383301267T DE3372789D1 (en) | 1983-03-08 | 1983-03-08 | Improving the hot workability of an age hardenable nickel base alloy |
EP83301267A EP0117932B1 (de) | 1983-03-08 | 1983-03-08 | Warmbearbeitbarkeit einer Nickelbasislegierung mit struktureller Härtung |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP83301267A EP0117932B1 (de) | 1983-03-08 | 1983-03-08 | Warmbearbeitbarkeit einer Nickelbasislegierung mit struktureller Härtung |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0117932A1 EP0117932A1 (de) | 1984-09-12 |
EP0117932B1 true EP0117932B1 (de) | 1987-07-29 |
Family
ID=8191079
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83301267A Expired EP0117932B1 (de) | 1983-03-08 | 1983-03-08 | Warmbearbeitbarkeit einer Nickelbasislegierung mit struktureller Härtung |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0117932B1 (de) |
AT (1) | ATE28668T1 (de) |
DE (1) | DE3372789D1 (de) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7713743B2 (en) | 2006-09-21 | 2010-05-11 | Kci Licensing, Inc. | Method for quantitation of collagen in tissue |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3212881A (en) * | 1962-12-04 | 1965-10-19 | Westinghouse Electric Corp | Purification of alloys |
US3512963A (en) * | 1966-07-25 | 1970-05-19 | Int Nickel Co | Process for improving elevated temperature strength and ductility of nickel-base alloys |
US3575734A (en) * | 1968-07-26 | 1971-04-20 | Carpenter Technology Corp | Process for making nickel base precipitation hardenable alloys |
US3907552A (en) * | 1971-10-12 | 1975-09-23 | Teledyne Inc | Nickel base alloys of improved properties |
US3850624A (en) * | 1973-03-06 | 1974-11-26 | Howmet Corp | Method of making superalloys |
US3891425A (en) * | 1974-02-27 | 1975-06-24 | Special Metals Corp | Desulfurization of transition metal alloys |
US4376650A (en) * | 1981-09-08 | 1983-03-15 | Teledyne Industries, Inc. | Hot workability of an age hardenable nickle base alloy |
-
1983
- 1983-03-08 EP EP83301267A patent/EP0117932B1/de not_active Expired
- 1983-03-08 DE DE8383301267T patent/DE3372789D1/de not_active Expired
- 1983-03-08 AT AT83301267T patent/ATE28668T1/de not_active IP Right Cessation
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7713743B2 (en) | 2006-09-21 | 2010-05-11 | Kci Licensing, Inc. | Method for quantitation of collagen in tissue |
Also Published As
Publication number | Publication date |
---|---|
EP0117932A1 (de) | 1984-09-12 |
DE3372789D1 (en) | 1987-09-03 |
ATE28668T1 (de) | 1987-08-15 |
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