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S¢Ptf 2, 1947»
G. R. BURKHARDT
A2,426,814
METHOD FOR TREATING METALS WITH NOBLE GASES y
Ä Filed Feb. 24„ 1944
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INVÍENTOR
GEORGE R BURKHARDT
FIG. 2
AITY
Sept. 2, 1947.
G. R. BURKHARDT
ì
y2,426,814 ,
METHOD FOR TREATING METALS WITH mSBLFV GASES
Filed Feb. 24, 1944
s sheezsLsheet 2
O ,
INVENTon
H
GEORGE R. BURK HAR or
.ATTY
[email protected] 2, 1947.
vG. »RÍBURKHARDT'
2,426,814
METHOD FOR TREATING METALS WITH NOBLE GrÁSESv
a
INVENIOR
2,8
GEORGE R. BURKHARDT
BWM
.ATTY
Patented Sept. 2, 1947
2,426,814
"
@UNI rec
l >@nsw.ice Y
:Merece-»feos reaATmc‘MerAts »wire
»NOBLE GASES
‘ George lIt: `Burkhardt,eGhioa-go, ' Il-l.
êhplicaitioniäebruary 24, 1,944,.'SerialrNooäZäßüä
(cimas-te)
`.This Vinvention relates to an improvement in
metallurgy _resulting in .a more compactv .and mi
nutre-.crystalline structure of the metal, as welles,
inf-a `_removal-of dissolved em-brittling gases,.sla_g
inclusions and other stress raisers.
'
The usual’practioe in .the »manufacture of .mete
vals,_,partioularly _in themanufacture of the iron
_carbonalloys _known .assteeL result_sin a struc
practical. means .o'f reducing, if. not entirely elim
inating, some `of ¿the imperfections in 'the linished
metal :discussed above. .More specifically, Vin Vthis
part „of .the .invention these .results .are „ obtained
by working the molten metal with noble .gas un
Aderhigh.pressure `eitherin a compression cham
.ber adjoining .thefurnaceßin which the metal is
made, or 'in Lthe mold in which 'the Ymetal is
poured.
'".The .effect .of this „pressure is to control
10
,thesize of the crystals O'f grains o'f the metal
ically active gases, thereby reducing the >strength
.whi1e.,it.is.stil1 in semifliquid or pasty form,
of the metal. Furthermore, usualmethods of
i. e. .during the period whenifreezing.takesplace,
manufacturing steel make diliicult the control'of
ture of »cmetal havingslag inclusions, dissolved
_gases »such as hydrogen, oxygen and other chem
is .110.. improve the ,physical properties .of _the vrfinal
grain size. Also, themetal poured Vinto moulds
or ingots contracts _during freezing, resultingiin A15 product. `If..metal `is-.placed under compression
during .this period, .the shrinkage .cavitiesexperi
the formation of cavities _known as pipes. These
.enced .under usual methods will'be avoided .and
pipes Voften .extend‘so far down into the ingot
the crystalline ,structure .of .the .metal .will `.be
that they are _not removed when top of the ingot
made more .compact and minute. .The .impor
is cut 01T during the rolling operations.
>One object .of the invention is to Vprovide a 20 tance .of subjecting. _metal Yin `the semiffluidstate
toV pressure vof anoble „gas is seen from ,examina
quiescent period in the manufacturing of certain
tion `withthe. microscope. .Thecrystals of lmetals
metals such as carbon-iron alloys whereby the
subjectedto .the said pressure are all the l.same
size, .whereas .the .crystals Aof steel made „by the
25 ,usual _methods varyin size, Accordingly, vthe
metal treated as abovedescribed. is much stronger
than metal .notsubjectedtd pressure because the
uniform size of crystals in the metalresultsin
AThis `is impossiblein >the usual openfhearth
uniform distribution of stress. This consolidation
method :ofmanufacturing steel becauseof _oxidiz
of .the structure .and _prevention of formation. of
ing conditions’always present. The electric fur
.large fcrîystals .have a beneñcial „effect .on _the
nace or crucible permits-this quiescent _period but
strength and otherqualities ofthe metal.
not under the ideal .or inexpensiveconditions per.
mitted ,bythe improved method.
My Y. experiments. have shown .that .the gas .used
in the refining operation .of molten steel ydiscussed
Another object of the invention is to iDu-riiy
above must have the following properties:
metals manufactured by other processes rsuch-as
(l) It mustclosely approacha perfect gas, that
the Bessemer converter. vIn .this ?application,zthe
is, the volume must vary as the temperature.
`
.atmosphere permit.
'(2) The composition of atoms of the gas must
ting the .use ofzany suitable temperature~ Itßalso
be such that electricityand heat will .bereadily
provides 'the possibility of working in a non-oxi
dizing atmosphere.
The electric process fur
nishes .the‘last two conditions, however, only at
ICi'mducted.
40
much greater expense.
(3) The 'gas'inust ‘be‘inert `or 'chemically in
different.
(4) The gas must be insoluble in molten'metal.
Accordingly, one phase ofthe .purification @of
carbon-iron’metals consists of tapping the'metal
Furthermore, 'my 'experiments demonstrater that
thevgases that have all’ofthese properties and
45 composition of atoms are only the noble “gases
to be »found in rgroup zero -of the Mendeleef
metal in fluid condition for any-suitable period
of time. ’This -permits the metal _to lie quietly
under -non-oxidizing conditions at V'atmospheric
pressures and permitsfsuspended particles to rise 50
byf gravity vand thus clarify the bath. The-slag
is-then carefully removed from the ‘top ofthe
metal and the metal is ladled into a'mold.
periodic table. In `this table V'the -elements'are
grouped so that‘the v,groups v‘are 'periodic functions
of the atomic number. Also `my experiments
showedthat gases such asnitrogen did not'have
the atomic composition resulting in suitable ther
mal “and >electrical conductivity. :Other gases
such as hydrogen were goodconductors `of‘heat
#Another object of the inventioniis vto 'provide 55 but werenot inert. iAlsofrny»v experiments showed
that the' cost Off-raming steeity use» of a gas/such
2,426,814
4
3
Figure 3 is a sectional view of an ingot mold,
as nitrogen would be seven times as much as if
illustrative of another application of the inven
hehum were used. This will be seen from the
tion.
followìng comparison of the thermal coefñcients,
Figure 4 is a plan view or diagram illustrative
KX 10
of the use of the invention in connection with
ingots on the conventional ingot car.
For nitrogen at 100° C., K=.0718
Figure 5 is‘a sectional view illustrative of the
For helium at 100° C., K=A994
application of the invention in connection with
The gases in the group zero of the periodic table
an ingot mold of the bottom poured type.
are the noble gases helium, neon, argon, krypton
Referring to the several drawings illustrative of
10
and xenon. The use of helium is entirely prac
V different applications of the invention the pro
tical and eilicient for the purpose of the present
cedure under the new method in connection with
Fig. 1 of the drawings
invention.
- the apparatus shown in
The method is very practical and metal so Y' is that the steel is tapped from the open hearth
processed is shown to be superior by means of
furnace A at I by raising the door 2 and the door
the microscope and physical tests. The chem 15 is secured in position 3. The metal ilows into
istry of the metal is no way different -from thatY
an enclosure bounded by a Wall of the incandes
of the chemistry of metal produced by usual
cent furnace B, the open hearth furnace and the
method, yet the microscope shows a liner grained
enclosure sides `Il, the said enclosure being cov
structure and the physical tests show substantial
ered at its top by the opened door 2. When the
20
improvement in strength. Furthermore, all fa
metal has risen to a height greater than the
tigue- tests made to date show complete absence
inlet opening 5 of the incandescent furnace, the
of stress raisers such as dissolved gases. Accord
valve 6 is- opened allowing the metal to flow into
ingly, railroad rail manufactured from steel made
the gas filled chamber 'I of the furnace B which
under this method should be free from fissures.
is heated by the tungsten rods 8. The temper
In addition toattaining the objectives men 25 ature in this chamber may be as high as 2190o C.
tioned above, the invention also improves the
or 4000” F. The metal lies in a quiescent con
condition of metal in the ingot next to the sides
dition for about an hour to allow the enclosed
of theY ingot mold. As molten metal is poured
gases and slag to become freed from the ‘bath
into a mold, the metal next to the sides and
by gravity. The slag is then carefully skimmed
30
bottom of the mold are chilled by contact with
oiî and the furnace is tapped at 9 and the metal
the cold surfaces and this chilling forms a “skln.”
run olf into ladles.
This skin grows in thickness as the interior of
The procedure in connection with a ladle shown
the lingot becomes cooler.
This causes a contrac
tion of the ingot and results in a space between
the ingot and the side of the mold. This space
is about sie” all around the periphery of an ingot
20” square, and in the usual methods is ñlled with
air.
This air causes the metal, around small
blowholes just beneath the skin of the ingot, to
become oxidized; in which case the oxidized
metal is not welded up in the rolling and a seam
is formed in the rolled shape. The space between
the ingot and the sides of the mold in the im
proved method is ñlled with noble gas under high
pressure, so that oxidation is absent and the
metal in the rolled shape is free- from seams due
to blowholes.
l
_
The gas used may be helium, neon, argon,
krypton or xenon. ' The use of helium is entirely
practical and efûcient. Helium has the following
properties important in metallurgy:
I
in Fig. 2 is that the molten metal is run into the
ladle I0, and an incandescent furnace unit or
head II is then wedged into the ladle. Fireclay
I2 may beused to seal the joint between the two.
The furnace unitA il contains noble gas heated
to a temperature of 2190" C. >by the tungsten
rods I3. The heated gas is pumped by suitable
means> into the ladle through a valved gas :feed
ing port I4. The atmosphere in the ladle is
displaced Vthrough a vent opening I5 until the
spectrosco-pe shows the discharge to be pure
helium. The said valved feeding port is then
closed and the molten metal allowed to lie in the
the slag floats on the top
of the metal. The slag is then carefully skimmed
\ hot noble gas until
off andthe metal is poured into the ingot mold.
The procedure inV connection with the ingot
mold is illustrated by Fig. 3 of the drawings. As
here shown the ingot mold is designated by the
reference letter I and to carry out the present
invention there is associated with this mold a
(l) It is an excellent conductor of heat. Its
thermal conductivity, K><10“6 is 339 as compared
with 56.8 for air and 56.3 for oxygen.
55 gas-feeding head i6 designed to be properly fitted
over and into the upper end of the mold and
(2) It is insoluble inmolten metal.
provided with a noble gas intake I1, a suitably op
(3) It is entirely chemically indiñerent or in
erated
intake valve I8, a combined feeding and
ert.
'
exhaust neck' I9 snugly fitting within the upper
(4) It diffuses very rapidly.
Moreover, helium is easily separated or puriñed 60 open end of the ingot mold, an exhaust outlet
20 opposite the gas intake I1 and a suitably de
from chemically active gases such as hydrogen
signed and suitably controlled valve 2l for open
or nitrogen.
ingand closing the gas exhaust outlet 20. In
The practical application of the invention is
explanation of the invention as carried out in
exemplified by the accompanying drawings, in
which:
65 connection with an ingot mold and a gas feeding
head I6, such as suggested in Figi?, of the draw
, Figure 1 is a sectional view of an incandescent
furnace associated with an open-hearth furnace,
designated in dotted lines, illustrative of one ap
plication of the present invention.
,
Figure 2 is a sectional view of a metal pouring 70
ladleî associated with an incandescent furnace
unit or head, illustrative of another application
of the present invention.
Figure 2Ais anelevational view of the furnace
.unit or head associated with the pouring ladle. ,
ings, it'is to be noted that the noble gas is con
tained in suitable supply tanks or tank cars, under
high pressure, and the maintained pressure there
in is suñicient to pump out the atmosphere in the
moldl or supplemental pumping means can be
used. In practice the molten metal is poured
into the ingot mold I Vand the gas feeding head
I6 is then inserted into the open top of _the mold.>
The
valves are then opened and the air' in the
75,
2,426,814
t
mold is displaced by the incoming noble gas,
after which the valve 2i of the exhaust outlet 20
is closed and the pressure of the noble gas is
built up until the metal cooled to a pasty con
sistency is thoroughly compressed by pressure on
top and sides of the ingot. Then, after a pre
determined period of soaking the ingot in the
heated noble gas the exhaust valve is opened
to permit the noble gas to be collected for reuse.
In the illustration of Fig. 4 it is to be> noted
that the ingots on the ingot car 22 are followed
by a gas tank 23 mounted on the car.
In Fig. 5 of the drawings is shown a bottom
fed type of ingot mold designated generally by
the letter A and which type of mold lends itself
very effectively to the carrying out of the process
of the present invention.
The procedure in con
nection with the bottom-fed mold shown in Fig. 5
of the drawings is that the metal is iirst poured
in the gate 2d at the top and rear of the mold.
The sides 25 of the riser 2li are made of refrac
tory material to hold in the heat. The refrac
tory material is encased by a cast iron portion 2ï
phere for a substantial period of time, permitting
the said alloy to solidify, and thereafter remov
ing the gas therefrom.
3. A method for the treatment of steel which
comprises subjecting the said steel at a tempera
ture at which it is at least semi-molten to an at
mosphere of a noble gas under a high pressure
suñicient to render the crystalline structure of
the metal more compact and minute, heating the
io said gas extraneously to maintain said steel in
said state for a suiiicient period of time to pro
vide a quiescent condition for eliminating im
puritìes from the said steel, permitting the steel
to solidify, and thereafter removing the gas
therefrom.
Ll. A method for the treatment of steel which
comprises subjecting the said steel at a tempera
ture at which it is at least semi-molten to an at
mosphere of a noble gas under` a pressure ap
20 proximating 2000 pounds per square inch in an
ingot mold, permitting the said steel in said state
to remain quiescent in said atmosphere for sub
stantially an hour to allow the enclosed gases and
integral with the ingot mold A which rests on
slag to become freed by gravity, skimming 01T any
the usual pouring plate 23. The metal runs into
the ingot mold through the opening 29 until 25 supernatent slag, permitting the steel to solidify
and removing the said gas after the steel has
the molten metal is at the proper height in the
solidified.
ingot mold. The top B is made integral with the
bottom by threading or by welding. The top
5. An improvement in the art »of metallurgy
which comprises subjecting a metal at a tempera
contains the inlet valve 30 and exhaust valve
3|. The heated helium under pressure of about 30 ture at which the metal is at least semi-molten to
an atmosphere of a noble gas under a high super
2000 pounds pe-r square inch crushes the ingot
atmospheric pressure, permitting the metal to
from all sides. After the ingot has solidified the
remain in said atmosphere in a quiescent condi
gas is pumped off and the mold lifted olf the ingot
by grabbing the mold through the hole at the top.
tion in said state for a substantial period of time,
The gate is burned off. This type of ingot mold 35 thereafter solidifying the metal and then remov
ing the said gas from the metal.
prevents slag getting into the molds, prevents
metal from spattering up the side of the mold
6. A method for the treatment of steel which
comprises tapping steel from an open hearth fur
and forming co-ld shuts, and is more practical
in the improved method than in the usual mill
nace, running the said steel into a chamber con
method because the hot gas prevents the top of 40 taining noble gas at a high temperature, permit
the ingot from cooling before the bottom.
ting the said steel to remain quiescent at a tem
From the foregoing it is thought that the char
perature at which the said steel is at least semi
acter and scope of the invention and its many
molten, subjecting the said gas during the period
advantages will now be apparent to those skilled
of quiescence to a high pressure to form crystals
in the art without further description.
-^
of substantially the same size while the steel is
I claim:
still in the pasty form, thereafter solidifying the
l. A method for the treatment of ferrous metal
steel and then removing the said gas from the
said steel.
which comprises subjecting the metal at a tem
perature at which the metal is at least semi 50
GEORGE R. BURKHARDT.
molten to an atmosphere of a noble gas under a
high pressure, permitting the metal to remain in
REFERENCES CITED
said atmosphere in said state in a quiescent con
The following references are of record in the
ñle of this patent:
dition for a substantial period of time, permitting
the metal to solidify and thereafter removing the
UNITED STATES PATENTS
said gas therefrom.
‘2. A method fo-r the treatment of carbon-iron
Number
alloys which comprises subjecting the said alloy
at a temperature at which the alloy is at least
semi-,molten to an atmosphere of a noble gas un
der a super-atmospheric pressure not exceeding
about 2,000 pounds per square inch, permitting
the said alloy to remain quiescent in said atmos
60
Name
Date
282,041
Bennett _________ ___ July 31, 1883
2,290,961 '
Heuer ____________ __ July 28, 1942
1,792,967
1,845,694
1,978,222
1,627,269
Clark ____________ __ Feb. 17,
Wood ____________ __ Feb. 16,
Otte _____________ __ Oct, 23,
Browne ___________ __ May 3,
1,663,916
Mittasch et al ..... __ Mar, 27, 1928
1931
1932
1934
1927
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