CA1036365A - Desulfurization of transition metal alloys - Google Patents
Desulfurization of transition metal alloysInfo
- Publication number
- CA1036365A CA1036365A CA218,514A CA218514A CA1036365A CA 1036365 A CA1036365 A CA 1036365A CA 218514 A CA218514 A CA 218514A CA 1036365 A CA1036365 A CA 1036365A
- Authority
- CA
- Canada
- Prior art keywords
- calcium
- alloy
- nickel
- transition metal
- atmosphere
- 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.)
- Expired
Links
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 25
- 239000000956 alloy Substances 0.000 title claims abstract description 25
- 229910052723 transition metal Inorganic materials 0.000 title claims abstract description 13
- 150000003624 transition metals Chemical class 0.000 title claims abstract description 13
- 238000006477 desulfuration reaction Methods 0.000 title description 4
- 230000023556 desulfurization Effects 0.000 title description 4
- 238000000034 method Methods 0.000 claims abstract description 24
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 22
- 239000011575 calcium Substances 0.000 claims abstract description 22
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000012298 atmosphere Substances 0.000 claims abstract description 13
- 230000003009 desulfurizing effect Effects 0.000 claims abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000001301 oxygen Substances 0.000 claims abstract description 10
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 10
- 229910000882 Ca alloy Inorganic materials 0.000 claims abstract description 8
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 7
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 12
- JEZHBSJTXKKFMV-UHFFFAOYSA-N calcium nickel Chemical compound [Ca].[Ni] JEZHBSJTXKKFMV-UHFFFAOYSA-N 0.000 claims description 12
- 229910000838 Al alloy Inorganic materials 0.000 claims description 8
- ULGYAEQHFNJYML-UHFFFAOYSA-N [AlH3].[Ca] Chemical compound [AlH3].[Ca] ULGYAEQHFNJYML-UHFFFAOYSA-N 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 230000008018 melting Effects 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 3
- 229910017052 cobalt Inorganic materials 0.000 claims 1
- 239000010941 cobalt Substances 0.000 claims 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical group [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 abstract description 22
- 239000002893 slag Substances 0.000 abstract description 6
- 229910052782 aluminium Inorganic materials 0.000 abstract description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 4
- 229910002056 binary alloy Inorganic materials 0.000 abstract 1
- 238000010308 vacuum induction melting process Methods 0.000 abstract 1
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 16
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 16
- 229910052717 sulfur Inorganic materials 0.000 description 16
- 239000011593 sulfur Substances 0.000 description 16
- 229910052786 argon Inorganic materials 0.000 description 8
- 230000006698 induction Effects 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 238000007792 addition Methods 0.000 description 4
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910000601 superalloy Inorganic materials 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 229910001092 metal group alloy Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- JGIATAMCQXIDNZ-UHFFFAOYSA-N calcium sulfide Chemical compound [Ca]=S JGIATAMCQXIDNZ-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000779 depleting effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
ABSTRACT
There is disclosed a process for desulfurizing transition metal alloys, particularly in a vacuum induction melting process where the absence of slag is desirable. The process is effected by adding any dilute calcium bearing binary alloy such as an ally of calcium and nickel or an alloy of calcium and aluminum t o the transition metal alloy while it is in the molten state and in contract with an atmosphere that is substantially free of oxygen.
There is disclosed a process for desulfurizing transition metal alloys, particularly in a vacuum induction melting process where the absence of slag is desirable. The process is effected by adding any dilute calcium bearing binary alloy such as an ally of calcium and nickel or an alloy of calcium and aluminum t o the transition metal alloy while it is in the molten state and in contract with an atmosphere that is substantially free of oxygen.
Description
BACKGR()UND OF THE INVENTION
It is frequently necessary to desulfurize transition metal alloys to very low sulfur levels. Transition metal alloys are those which contain substantial quantities of the elements iron, nickel and cohalt individually or in combination. Many methods for desulfurizing such alloys are known. Alloys prepared by induction vacuum melting present special problems because slag in an induction vacuum furnace is heated only by conduction which is so inadequate that a solid slag phase frequently forms.
10 Calcium is known to react strongly with sulfur. However, it reacts more strongly with oxygen. Accordingly, if lime is em~loyed as a desulfurizing agent, a very large amount of lime must be used which becomes a slag phase that is difficult to main-tain molten in a vacuum induction furnace.
Current methods for addition of calcium are inaffective because calcium floats on the molten bath due to its low density and .
. 30 . '~
s '.~
' ~ :
thérefore it partially reacts with residual furnace atmosphere and volatizes rather than perform its desulfurization function. Regardless of density considerations, elemental calcium cannot be used effectively because it is very volatile (boiling point 1487C at atmospheric pressure), and it is therefore tifficult to maintain contact between elemental calc~um and molten iron alloy~ long enough to obtain the desired reaction because the calcium tends to vaporize from the molten metal.
IHE INVENI~ION
~his invention is a process whereby the desirable properties of calcium as a desulfurizing agent can be used while avoiding its undesirable characteristics. ~his invention is a process for desulfurizing tran~ition metal alloys by'treating a molten transition metal alloy while . ln contact with a 8ubstantially oxygen-free atmosphere with either an alloy of calcium and nickel or an alloy of calcium and aluminum.
The process of this invention provides many advantages over prior art processes. Primarily, the calcium in a dilute calcium-nickel alloy or a calcium-aluminum alloy is not extremely volatile so it can be introduced and maintained in contact with a molten transition metal alloy long enough for it to be effective in reacting with sulfur.
When used in metal in contact with a substantially oxygen-free atmosphere, the~e is little competitior. between oxygen and sulfur to react with calcium so that the calcium is used very effecti~rely and sparingly to remove sulfur. The term substantiall~r oxygen-free is used in the - context of this description to define atmospheres obtainable in industry such as those in vacuum induction furnaces or in an inert gas blanketed process. Oxygen and sulfur compete for the available calcium in the , process of this inVentiOD according to the mass action principle. Small, unavoidable residual amounts o oxygen can be tolerated. However, to use the process of this invention most effectively the concentration of o~ygen in the atmosphers over the molten metal should be as 1GW as possible.
The proces~ can be further improved by deoxidizing the molten metal prior to treatment with calcium-nickel or calcium-aluminum alloys, Depleting the oxygen in the molten transition metal alloy and in the atmosphere above it diminishes the total amount of calcium addition and correspondingly decreases the amount of calcium oxide that must be dealt with after the desired desulfurization is accomplished.
Whether a calcium-nickel alloy or a calcium-aluminum alloy -i~ selected will depend upon the character of the metal treated. If small amount~ of aluminum will negatively influence the propertie~ of the metal : being treated, then a calcium-nickel alloy must be used and vice versa.
Since inost transition metal alloys can tolerate nickel, the calcium-nickel alloy is the preferred desulfurizing medium of this invention. The preferred composition for calcium-nickel additions are those which have .
an atomic ratio of nickel to calcium of abo~t 5. This atomic ratio is preferred because of the formation of an intermetalic compound that is quite stable so that vaporization of calcium is greatly retarded. This in turn provides high utilization of the calcium for desulfurization of the transi-tion metal alloys.
Although the process of this ir.vention can be effected at the low pressures obtained in a vacuum induction furnace, it is preferred that an .
.
'.. :. ' ` ; ' :
: ~ .
1036365 ,t~' inert ga~ atmosphere be maintained ~:: the furnace. Argon is the preferret inert gas because of its availability and ease of use although other inert r~ "
gases may be used. Any pressure of inert gas is beneficial in inhibiting calcium volatilization, however pressures of least 100 mm Hg and up to about 760 mm Hg may be used. Pressures of from 300 to 400 mm Hg are preferred.
~he process of thi~ invention is especially useful in making alloys containing iron and nickel by vacuum mduction melting techniques. The nickel added from the calcium-nickel alloy is of little consequence with regard to the total nicke] content of such an alloy, and in any event it can be accommodated for in compositing the alloy to be treated. Ihis invention ; is especially useful in making alloys called Superalloys, which are alloys psedominately niclcel.
~he proce~ of thi~ invention i9 effective to reduce the sulfur level of a tran~ition metal alloy quickly from a~y rea~onable starting level to less than 0. 005% w.
,, . .
DETAILED DESCRIP'rION OF 'THE INVENl~ION
`~ Following are a number of examples of processes embodying this invention which are presented to illustrate rather than limit the - 20 in;vention. In Example 1 desulfurizing of three similar nickel-iron superalloys was effected in an experimental vacuum inducti~n furnace holdi;lg about lS pounds of material. Each heat was mad~ from virgin materials and in each case an alloy of 10% w calcium in aluminum was employed as the desulfurizing agent. In all cases the alloy was melted in a furnace at a pressure of less than 20 microns, carbon deoxidized ~ - .
10363~5 and the furnace chamber was backfilled with argon at the indicated pressure before the addition of the calcium-aluminum alloy. A sample of the alloy was taken five rrlinutes after the calcium-aluminum alloy was added, and the final product was poured into an ingot mold 18 minutes after the calcium-aluminum alloy was added. Table I reports the results of the~e three heats.
' , ' .
TABLE I
Heat #1 Heat #2 Heat #3 Argon pressure (mm) 600 600 400 Calcium added (~0 w) 0. 015 0. 030 0.015 Snlfur at meltdown (% w) 0. 012 0. 017 0. oi4 .
Sulfur after 5 min. (% ,w) 0. 010 0. 002 0. 003 Sulfur in Ingot (~o w) 0. 001 0. 0005 0. 002 The atditional heats were prepared in an experimental vacuum 15 induction ~urnacc holding 300 pounds of material. Rather than use virgin raw materials to make a virgin heat for experimentation as was done with t~le 15 pound heats reported in Table I, scrap of the same nickel-iron superalloy composition was employed to which about 0. 015% sulfur was added. ~his is the level of sulfur obtained when ordinary, low cost raw 20 materials are used. In each case the desulfurizing medium was an alloy of calcium and nickel containing about 10% w calcium. The desulfurizing - treatment was effected by adding enough of the calcium-nickel alloy to pro~ide 0. 03% w calcium in the furnace. Argon pressures as indicated were maintained in the furnace. In Ingot #1 constant pressure of argon was 25 empioyed; in Ingot ~2 a constant pressure was maintained in the furnace but a small uncontrolled air leak resulted in continuous introduction of ;~;' ~' ~. ' ' ' ';
1 me oxyyen and nitrogen into the furnace atmosphere; and in Ingot #3 a constant argon pressure was maintained for a portion of the heat after which a high vacuum was provided within the furnace.
Table II reports the result of these experiments.
TABLE II
Heat #l Time From Start (min.) Sulfur (~w) Pressure (mm) 0 0.018 400 0.0041 400 1020 0.0023 400 0.0017 400 0.0017 400 56 (ingot) 0.0013 Heat #2 Time From Start (min) . _ .
0 0.014 400*
0.002 400*
0-003 400*
0.0015 400*
48 (ingot) O. 004 Heat #3 Time From Start (min) 0 0.016 600 11 0.005 600 0.004 600 0.003 600 52 0.004 45**
62 0.002 14**
72 0.002 10**
75 (ingot~ 0.002 * air leak ** microns 1Q3~;;~65 1~ is evident from the data reported in Table I and Table IL that .
the process of the present invention is effectivc to reduce the level of sulfur in nickel-iron superalloys to a significant extent and very quickly.
In ~Lll of the heats reported, the vacuum induction furnaces operated without S the formation of a significant liquid slag phase and totally without theformation of solid slzg. Heat #2 reported in Table II illustrates that the proce89 of this invention can be effected in the presence of a small amount o~ oxygen but that oxygen is somewhat detrimental. It may be noted that the sulfur level was initially reduced significantly and then slowly rose.
It i9 postulated that the increased sulfur in the iDgot over the amount present after 30 minutes of treatment was probably due to the release of ~ulfur caused by the reaction of calcium sulfide with oxygen.
It may be noted from data related to Heat #3 that the presence of an argon atrrlosphere and the presence of a significant vacuum appeared to be about equivalent for maintaining a substantially oxygen-free atmos-phere in contact with the molten metal. It would appear that a slightly better result is obtained when an inert atmosphere of argon is esr.ployed i~stead of a vacuum by comparing the results obtair.ed in Heat #l with the - results obtained in Heat ~3.
A review of all of the data in Table I and Table II indicates that the process of the present invention reduces sulfur levels of nickel-iron super~lloys to very low levels, below 0. 005% w, very guickly whether a calcium-aluminum alloy or a calcium-nickel alloy is employed. The data also indicate that a substantially oxygen-free atmosphere may be 2S maintained either by maintaining a vacuum over the metal or by maintaining an inert gas blanket over the met~ In all cases the problems ; ~
1~)3636S
1 ~,reviously associated with desulfurizing vacuum induction melted heats were avoided; specifically the problems of solid slags and the problem of vaporized calcium were avoided.
.
.
. .
~' ' . ' ' ''' '' ' '
It is frequently necessary to desulfurize transition metal alloys to very low sulfur levels. Transition metal alloys are those which contain substantial quantities of the elements iron, nickel and cohalt individually or in combination. Many methods for desulfurizing such alloys are known. Alloys prepared by induction vacuum melting present special problems because slag in an induction vacuum furnace is heated only by conduction which is so inadequate that a solid slag phase frequently forms.
10 Calcium is known to react strongly with sulfur. However, it reacts more strongly with oxygen. Accordingly, if lime is em~loyed as a desulfurizing agent, a very large amount of lime must be used which becomes a slag phase that is difficult to main-tain molten in a vacuum induction furnace.
Current methods for addition of calcium are inaffective because calcium floats on the molten bath due to its low density and .
. 30 . '~
s '.~
' ~ :
thérefore it partially reacts with residual furnace atmosphere and volatizes rather than perform its desulfurization function. Regardless of density considerations, elemental calcium cannot be used effectively because it is very volatile (boiling point 1487C at atmospheric pressure), and it is therefore tifficult to maintain contact between elemental calc~um and molten iron alloy~ long enough to obtain the desired reaction because the calcium tends to vaporize from the molten metal.
IHE INVENI~ION
~his invention is a process whereby the desirable properties of calcium as a desulfurizing agent can be used while avoiding its undesirable characteristics. ~his invention is a process for desulfurizing tran~ition metal alloys by'treating a molten transition metal alloy while . ln contact with a 8ubstantially oxygen-free atmosphere with either an alloy of calcium and nickel or an alloy of calcium and aluminum.
The process of this invention provides many advantages over prior art processes. Primarily, the calcium in a dilute calcium-nickel alloy or a calcium-aluminum alloy is not extremely volatile so it can be introduced and maintained in contact with a molten transition metal alloy long enough for it to be effective in reacting with sulfur.
When used in metal in contact with a substantially oxygen-free atmosphere, the~e is little competitior. between oxygen and sulfur to react with calcium so that the calcium is used very effecti~rely and sparingly to remove sulfur. The term substantiall~r oxygen-free is used in the - context of this description to define atmospheres obtainable in industry such as those in vacuum induction furnaces or in an inert gas blanketed process. Oxygen and sulfur compete for the available calcium in the , process of this inVentiOD according to the mass action principle. Small, unavoidable residual amounts o oxygen can be tolerated. However, to use the process of this invention most effectively the concentration of o~ygen in the atmosphers over the molten metal should be as 1GW as possible.
The proces~ can be further improved by deoxidizing the molten metal prior to treatment with calcium-nickel or calcium-aluminum alloys, Depleting the oxygen in the molten transition metal alloy and in the atmosphere above it diminishes the total amount of calcium addition and correspondingly decreases the amount of calcium oxide that must be dealt with after the desired desulfurization is accomplished.
Whether a calcium-nickel alloy or a calcium-aluminum alloy -i~ selected will depend upon the character of the metal treated. If small amount~ of aluminum will negatively influence the propertie~ of the metal : being treated, then a calcium-nickel alloy must be used and vice versa.
Since inost transition metal alloys can tolerate nickel, the calcium-nickel alloy is the preferred desulfurizing medium of this invention. The preferred composition for calcium-nickel additions are those which have .
an atomic ratio of nickel to calcium of abo~t 5. This atomic ratio is preferred because of the formation of an intermetalic compound that is quite stable so that vaporization of calcium is greatly retarded. This in turn provides high utilization of the calcium for desulfurization of the transi-tion metal alloys.
Although the process of this ir.vention can be effected at the low pressures obtained in a vacuum induction furnace, it is preferred that an .
.
'.. :. ' ` ; ' :
: ~ .
1036365 ,t~' inert ga~ atmosphere be maintained ~:: the furnace. Argon is the preferret inert gas because of its availability and ease of use although other inert r~ "
gases may be used. Any pressure of inert gas is beneficial in inhibiting calcium volatilization, however pressures of least 100 mm Hg and up to about 760 mm Hg may be used. Pressures of from 300 to 400 mm Hg are preferred.
~he process of thi~ invention is especially useful in making alloys containing iron and nickel by vacuum mduction melting techniques. The nickel added from the calcium-nickel alloy is of little consequence with regard to the total nicke] content of such an alloy, and in any event it can be accommodated for in compositing the alloy to be treated. Ihis invention ; is especially useful in making alloys called Superalloys, which are alloys psedominately niclcel.
~he proce~ of thi~ invention i9 effective to reduce the sulfur level of a tran~ition metal alloy quickly from a~y rea~onable starting level to less than 0. 005% w.
,, . .
DETAILED DESCRIP'rION OF 'THE INVENl~ION
`~ Following are a number of examples of processes embodying this invention which are presented to illustrate rather than limit the - 20 in;vention. In Example 1 desulfurizing of three similar nickel-iron superalloys was effected in an experimental vacuum inducti~n furnace holdi;lg about lS pounds of material. Each heat was mad~ from virgin materials and in each case an alloy of 10% w calcium in aluminum was employed as the desulfurizing agent. In all cases the alloy was melted in a furnace at a pressure of less than 20 microns, carbon deoxidized ~ - .
10363~5 and the furnace chamber was backfilled with argon at the indicated pressure before the addition of the calcium-aluminum alloy. A sample of the alloy was taken five rrlinutes after the calcium-aluminum alloy was added, and the final product was poured into an ingot mold 18 minutes after the calcium-aluminum alloy was added. Table I reports the results of the~e three heats.
' , ' .
TABLE I
Heat #1 Heat #2 Heat #3 Argon pressure (mm) 600 600 400 Calcium added (~0 w) 0. 015 0. 030 0.015 Snlfur at meltdown (% w) 0. 012 0. 017 0. oi4 .
Sulfur after 5 min. (% ,w) 0. 010 0. 002 0. 003 Sulfur in Ingot (~o w) 0. 001 0. 0005 0. 002 The atditional heats were prepared in an experimental vacuum 15 induction ~urnacc holding 300 pounds of material. Rather than use virgin raw materials to make a virgin heat for experimentation as was done with t~le 15 pound heats reported in Table I, scrap of the same nickel-iron superalloy composition was employed to which about 0. 015% sulfur was added. ~his is the level of sulfur obtained when ordinary, low cost raw 20 materials are used. In each case the desulfurizing medium was an alloy of calcium and nickel containing about 10% w calcium. The desulfurizing - treatment was effected by adding enough of the calcium-nickel alloy to pro~ide 0. 03% w calcium in the furnace. Argon pressures as indicated were maintained in the furnace. In Ingot #1 constant pressure of argon was 25 empioyed; in Ingot ~2 a constant pressure was maintained in the furnace but a small uncontrolled air leak resulted in continuous introduction of ;~;' ~' ~. ' ' ' ';
1 me oxyyen and nitrogen into the furnace atmosphere; and in Ingot #3 a constant argon pressure was maintained for a portion of the heat after which a high vacuum was provided within the furnace.
Table II reports the result of these experiments.
TABLE II
Heat #l Time From Start (min.) Sulfur (~w) Pressure (mm) 0 0.018 400 0.0041 400 1020 0.0023 400 0.0017 400 0.0017 400 56 (ingot) 0.0013 Heat #2 Time From Start (min) . _ .
0 0.014 400*
0.002 400*
0-003 400*
0.0015 400*
48 (ingot) O. 004 Heat #3 Time From Start (min) 0 0.016 600 11 0.005 600 0.004 600 0.003 600 52 0.004 45**
62 0.002 14**
72 0.002 10**
75 (ingot~ 0.002 * air leak ** microns 1Q3~;;~65 1~ is evident from the data reported in Table I and Table IL that .
the process of the present invention is effectivc to reduce the level of sulfur in nickel-iron superalloys to a significant extent and very quickly.
In ~Lll of the heats reported, the vacuum induction furnaces operated without S the formation of a significant liquid slag phase and totally without theformation of solid slzg. Heat #2 reported in Table II illustrates that the proce89 of this invention can be effected in the presence of a small amount o~ oxygen but that oxygen is somewhat detrimental. It may be noted that the sulfur level was initially reduced significantly and then slowly rose.
It i9 postulated that the increased sulfur in the iDgot over the amount present after 30 minutes of treatment was probably due to the release of ~ulfur caused by the reaction of calcium sulfide with oxygen.
It may be noted from data related to Heat #3 that the presence of an argon atrrlosphere and the presence of a significant vacuum appeared to be about equivalent for maintaining a substantially oxygen-free atmos-phere in contact with the molten metal. It would appear that a slightly better result is obtained when an inert atmosphere of argon is esr.ployed i~stead of a vacuum by comparing the results obtair.ed in Heat #l with the - results obtained in Heat ~3.
A review of all of the data in Table I and Table II indicates that the process of the present invention reduces sulfur levels of nickel-iron super~lloys to very low levels, below 0. 005% w, very guickly whether a calcium-aluminum alloy or a calcium-nickel alloy is employed. The data also indicate that a substantially oxygen-free atmosphere may be 2S maintained either by maintaining a vacuum over the metal or by maintaining an inert gas blanket over the met~ In all cases the problems ; ~
1~)3636S
1 ~,reviously associated with desulfurizing vacuum induction melted heats were avoided; specifically the problems of solid slags and the problem of vaporized calcium were avoided.
.
.
. .
~' ' . ' ' ''' '' ' '
Claims (7)
1. A process for desulfurizing a transition metal alloy comprising maintaining said alloy in a molten state, substantially in the absence of an oxygen-containing atmosphere and in contact with a calcium alloy selected from a calcium-nickel alloy and a calcium-aluminum alloy.
2. The process of Claim 1 wherein the calcium alloy is a calcium-nickel alloy having a nickel-to-calcium atomic ratio of about 5 or greater.
3. The process of Claim 1 wherein the transition metal alloy is deoxidized prior to treating it with said calcium alloy.
4. The process of Claim 1 wherein said transition metal alloy is an alloy containing at least one of nickel, iron, and cobalt and said calcium alloy is a calcium-nickel alloy.
5. The process of Claim 1 wherein treatment is effected in a vacuum melting furnace.
6. The process of Claim 5 wherein said furnace contains an atmosphere of inert gas at a pressure of from about 100 mm Hg to about 760 mm Hg.
7. The process of Claim 6 wherein said furnace contains an atmosphere of inert gas and a pressure of about 400 mm Hg.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US446447A US3891425A (en) | 1974-02-27 | 1974-02-27 | Desulfurization of transition metal alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1036365A true CA1036365A (en) | 1978-08-15 |
Family
ID=23772621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA218,514A Expired CA1036365A (en) | 1974-02-27 | 1975-01-23 | Desulfurization of transition metal alloys |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US3891425A (en) |
| JP (1) | JPS50120415A (en) |
| CA (1) | CA1036365A (en) |
| FR (1) | FR2262120B1 (en) |
| GB (1) | GB1462007A (en) |
| SE (1) | SE7500648L (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4049470A (en) * | 1976-04-29 | 1977-09-20 | Special Metals Corporation | Refining nickel base superalloys |
| US4456481A (en) * | 1981-09-08 | 1984-06-26 | Teledyne Industries, Inc. | Hot workability of age hardenable nickel base alloys |
| ATE28668T1 (en) * | 1983-03-08 | 1987-08-15 | Teledyne Ind | HOT WORKABILITY OF A NICKEL-BASED ALLOY WITH STRUCTURAL HARDENING. |
| US4612164A (en) * | 1984-11-01 | 1986-09-16 | Inco Alloys International, Inc. | Nickel copper alloys with enhanced malleability and improved sulfide distribution |
| GB2174716B (en) * | 1985-04-26 | 1989-11-15 | Mitsui Shipbuilding Eng | Method of producing an iron-cobalt-and nickel-base alloy having low contents of sulphur, oxygen and nitrogen |
| JPH0699737B2 (en) * | 1989-02-01 | 1994-12-07 | 株式会社メタル・リサーチ・コーポレーション | Method for producing clean steel |
| US5346563A (en) * | 1991-11-25 | 1994-09-13 | United Technologies Corporation | Method for removing sulfur from superalloy articles to improve their oxidation resistance |
| JPH0594193U (en) * | 1992-05-26 | 1993-12-21 | 松下電工株式会社 | Cushioning material, cushioning material, and packaging structure for vanity using the same |
| US5344510A (en) * | 1993-04-14 | 1994-09-06 | United Technologies Corporation | Method for removing sulfur from superalloy articles to improve their oxidation resistance |
| JPH09225623A (en) * | 1995-12-12 | 1997-09-02 | General Electric Co <Ge> | Method for improving environmental resistance of investment cast cemented carbide article |
| US5922148A (en) * | 1997-02-25 | 1999-07-13 | Howmet Research Corporation | Ultra low sulfur superalloy castings and method of making |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3467167A (en) * | 1966-09-19 | 1969-09-16 | Kaiser Ind Corp | Process for continuously casting oxidizable metals |
| GB1206062A (en) * | 1967-10-18 | 1970-09-23 | Nippon Kokan Kk | Deoxidation method |
| DE1907512A1 (en) * | 1968-02-15 | 1972-03-09 | Kobe Steel Ltd | Process for removing arsenic from metals or metal alloys |
| AT327265B (en) * | 1970-05-29 | 1976-01-26 | Lenin Kohaszati Muvek | PROCESS WITH SPECIAL DEOXIDATION FOR THE PRODUCTION OF GOOD MACHINABLE CARBON STEELS |
| US3695946A (en) * | 1971-11-24 | 1972-10-03 | Forges De La Loire Comp D Atel | Method of manufacturing oriented grain magnetic steel sheets |
-
1974
- 1974-02-27 US US446447A patent/US3891425A/en not_active Expired - Lifetime
-
1975
- 1975-01-21 SE SE7500648A patent/SE7500648L/xx unknown
- 1975-01-22 FR FR7501992A patent/FR2262120B1/fr not_active Expired
- 1975-01-23 CA CA218,514A patent/CA1036365A/en not_active Expired
- 1975-02-08 JP JP50016794A patent/JPS50120415A/ja active Pending
- 1975-02-17 GB GB660275A patent/GB1462007A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2262120A1 (en) | 1975-09-19 |
| US3891425A (en) | 1975-06-24 |
| SE7500648L (en) | 1975-08-28 |
| GB1462007A (en) | 1977-01-19 |
| JPS50120415A (en) | 1975-09-20 |
| FR2262120B1 (en) | 1978-07-13 |
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