US2042427A - Apparatus for use at low temperatures - Google Patents

Description

y 1936- A. B. KiNZEL 2,042,

APPARATUS FOR USE AT LOW TEMPERATURES Original Filed March 11, 1933 INVENTOR rash May Augustusnkinsel,

Flushing mesne assignments, to Union gglkion Corporation. a corporation mm'rus ron usi a'r LOW ram-surpass ,n.!.-,uum,w'

arbidc and. of New riginal application M 11, loss, Serial No.

senses. Divided and this application February s, 1934, Serial No. sea-11s lolalm-"(ctm-oi This invention relates to apparatus for use at low temperatures. and particularly to apparatus including containers or vessels for holding liquefied gases, for example liquid air or oxygen, and

to the construction of the same'whereby a metal or alloy is employed that is not embrittled at the low temperatures encountered;

The invention has for its object generally'the provision of improved apparatus of the character indicated which is strong and durable both at atmospheric temperatures and at the temperatures of the liquefied gas being handled, for example at the temperature of liquid air or oxygen.

It is also an object to provide improved apparatus such ascontainers for handling liquefied gases fabricated of an alloy that is characterized by the possession of mechanical strength and ductility and relatively high Izod values when subjected to impact at very low temperatures.

Still another object is to provide improved compositions for alloys for use in apparatus of the character indicated which do ,not have notchbrittleness at very low temperatures, for example at -150 C. or 123 Kelvin (hereinafter denoted degrees K.), and which are free from internal stresses at such 'low temperatures.

Other objects of the invention'will in part be obvious and will in part appear hereinafter.

The invention accordingly comprisesthe features-of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth and thescope of the application of which will'be indicated in the claims.

Serial No. 660,365, filed March 11, 1933. I

For a fuller understanding of the nature and objects of the invention,.reference should be had to the following detailed description taken in connection with the accompanying drawing, in

which: v

'The figure depicts exemplary apparatus in vertical cross-section, particularly a container for liquid oxygen, made in accordance with the invention. v

It is generally impracticable to confine large quantities of liquefied gases of the character indicated in completely closed vessels, though it is possible to confine them within pressure vessels 0 or containers provided with relief valves or other 5 means for preventing the building up of excessive pressures. when this is done, gas pressures of the order of 100 pounds per square inch and above may be safely attained within the apparatus. 5 Considerable difiicul y.

however, is involved in This application is a division of my application.

finding a material suitable for use in the construc- 'tion of such apparatus.

Heretofore, two materials have generally been employed, such as steel and copper. The disadvantage in the use of steel is that it becomes exceedingly brittle at temperatures below about 223 K. (or 50' C.) If there are any locked-up stresses in the articles, due to the conditions of fabrication, the additional stresses set up during the chilling of the article to the temperature of 1 liquid oxygen may be sufiicient to cause the failme of the embrittled steel. For this reason, very careful annealing has been practiced in making such apparatus. Even if such annealing is employedand all locked-up stresses are removed, however, the extreme brittleness of the steel renders it highly sensitive to shock and vibration I 'at these low temperatures. For this reason, the

steel article must be specially supported to minimize the danger of shock vibration. 20

Copper has the advantage of remaining ductile at the temperatures encountered in dealing with liquefied gases of the character indicated. Cop-' per, however, has serious disadvantages, in that, if free from strains, it has practically no plasticfree elasticity andv does not completely return to shape after the removal of an imposed stress.

It gradually stretches with a corresponding reduction in cross-section.- Thus, if a vessel of copper or other article of such'composition becomes deformed, a failure may occur when it is again put under pressure which it could safely have withstood when new. To avoid this sort of failure, it has been proposed to measure the article under stress, but this is not always practical, and in any event a deformed vessel is no longer suitable ,for its original purpose.

In the practice of the present invention, preferably those parts of the apparatus which are subject both to stress and a very low tempera- 4o ture are made of a metal alloy having substantial freedom from internal stress at such temperature. Referring to the drawing, Ill denotes a thick-walled outer vessel of containing apparatus for liquefied gases, which may be made of welded 46 metal sections, and has a spaced inner lining or basket H which hblds a body ll of the liquefied gas, for example, liquid oxygen. The vessel is provided with suitable fluid manipulating connections, for example, a gas-phase withdrawal so connection It and a liquid-phase withdrawal connection l4, together with a filling connection, as shown at l5. v

The vessel It is preferably enveloped with heat insulating material, asshown at It, and has a 66 a other parts as may be desired are fabricated of supporting casing i'l', supporting connections with the casing being provided in any suitable manner, for example by means of cables or chains il. a relatively poor heat conductivity whichiare anchored at one end to the casing and at the other tearing ll thatembracesthevesseL'Inthe apparatus illustrated, the vessel ll. and such a metal alloy having substantial freedom from internal stress at the temperature of liquidoxys A metal alloy, which has the desired freedom from internal stresses and is suitable for making such vessel and other desired parts, maybe prepared in a variety of ways, for example. by disparsing a small amount of a component in a J main metallic mass possessing thedosired ductility, the dispersion being such as to interfere with the normal slip of the planes of metallic lattice when subject to "This eiiects strengthening of the lattice; When the precipitated partlclesare sufiiciently fine, local stresses produced by temperature changes from room temperature to a temperature of liquid oxygen are notsufiicient to produce brittleness.

If, however, a combination of extremely fine and moderately fine particles is'considered, the local stresses are sufiicient to afiect'seriously the low temperature ductility. Y

A second way of 'accomplishingthe desired strengthening of non-ferrousmaterials without necessarily high internal stress. local or otherwise, is to introduces foreign element into the metallic matrix so that lt is in solid "solution; that is, it either replaces one of the atoms of the matrix material in the lattice or associates itself by means'oi electronic bonds to form a group of one or more metallic atoms whichmay form a secondary lattice, superimposed on the :pri-" mary, lattice. Againinterierence withnormal' slip is afiected and the material is strengthened. In this type, it is most probable that temperature stressu will not be present becauseof the homogeneous distribution or the two or more types'of,

atoms involved. I

It has generally been found in non-ferrous metallurgical practice that when a; given mechanism is relied on for more 7 than a relatively small increase, secondary efiects take place. The embrittlemei' t of duralumin or nickel-silicide-copper when the precipitatimi effect is employed for maximum strength, is a case in point,;as the ductilityisvery .af-

-fected, and it is necessary to limit thestrength to an optimum amount to get the desired ductility. Solid solution phenomena are also inscope, as frequently if an increase in the amoimt oi foreign atoms is introduced, the tendency to compound formation increases with consequent;

with increased strength. i The oldest" method of strengthening metals consists in forming eutectics bymeans of a second component. Eutectics,

rapid falling oil of ductility in general, will not fill the needs of the alloy in the invention because the heterogeneous nature of a lamellar structure tends to'promote local thermal stresses at low temperatures. However, a comparatively small amount of suitable eutectic may be formed withoutdeleterious efiect if the solid solution matrixiis the predominately continuous phase. 1

According to the presentinvention, an alloy is produced in which the strength is higher than that obtained by any one of the above described ways, particularly respect to ductility and amm M with mt elimination arms when thealloy is cooledto Wm"m perature; the alloy here provided comprising elementsso combined that'two others of theaiorementioned desired eilects are simultaneously oh 6 The main metallic component ofthe composit-ionusedinthepresentinventionthusisa metal which has high ductility vthroughout substantlally thewhole range of service tempera- 1o, .tures,.for example from 0. down to and in- 1 eluding that of the liquefied-low boiling point gases. This is particularly true of the rim-ferriticempirical8 mm0fmetalsomiilli'iaiiigcoppositionadaptedtoformasolidsolutionwitb the main metallic component there is employed so a metalloid or metallic element, which forms a solid solution with thefirst in the manner or the well known binaryv systems. a suitable componentoithischaraeterforthecompos'itionsdcsired bechosen from the empirical group 35 consisting of boron, silicon. and beryllium. Bilicon is preferable because it tends to form com pounds with a thirdmetallic wiimoneiii, hoi'einafter described, when taken in relatively smallamounts, for example 3% of silicon begins to 40 form a eutectic with masncsium, 5% with 009-, per and 1.6% with aluminum; Beryllium forms a solid solution with copper up to 2.8%, but more thanthese amounts iormthe A third component may be employed for n45 composition of metal made according to the present invention, such component being oi a=charactersuchthatitremainsindispersionthroughout the metallic mam, either in atomic form or sea compound with the main combination or so:

one or the'v w ndary combinations and'by means oi this dispersion eifects interference with the alipofthemetallieplaneslnthcmetalliclattice as previously described. A suitable component for accomplishing. this is chosen sin-.55

pirical group consisting oi manganese, iron, nickel, andchromium. llanganue is eenerally preferabie because of its acflon in the metallic bath when preparingthealloy. The-manganeseis taken'in relatively small amounts; for example so i in amounts approximating not over 4% by weight of the total mass. which isalso trueforiron and nickel. Chromium, however, should be taken generally in smaller-amounts; for example, in amounts in the neighborhood of of the total mass. 7

The functions of the metals chosen for first and second additionsmay overlap,- that is, the main solid solution alloying element may tend to give precipitation when taken in certain 0.

amounts and under certain conditions of heat treatment. Beryllium is an illustration when.

used with copper. Amounts in excess of the solid; solution saturation content at room may be used in dispersion strengthermzg.

2% by w s 65 Example I Percent Copper 96 Si1icon 3 Manganese 1 Example 11 Percent Copper 58 Zinc 38 Silicon 3 Manganese I 1 Example III Percent Magnesium--. 98. 4 Si i I 1.2 Manganese ,4

Example IV Percent Copper 97. 1 Silicon .4 Nickel 2.5

Example V Percent Copper- 98.7 Silicon ,3 Chromium 1.0

Example VI Percent Aluminum 92.5 Beryllium 1.5 Iron 3.0 Manganese 3.0

Example VII Percent Copper 94 Beryllium 8 groups to promote strengthening to a limited degree by taking them in such amounts as to cause the presence of eutectics, the relative proportion being. substantially small when compared to the amount of base metal matrix used. Generally, however, this is not desirable, as eutectics are conducive to the production of thermal stresses at low temperatures. 1

The following are examples of compositions made in accordance with the invention:

tained, together with the elongation and the re-- duction in area. When a standard specimen of an alloy of the composition of Example I is made comparatively with one of steel having the composition: carbon 0.40%; manganese 0.68%: silicon 0.28%: Phosphorous 0.01%: sulphur 0.30%: the remainder being iron; typical values or these tests are obtained which are comparatively set forth in the following table:-

Steel Typical alloy Physical r0 p ppm Room At Room At tamp. 90 K. temp. 90" K.

Ultimate strength 1b./sq. in 94. 360 142, 800 58, 200 83, 300 Yield point lb./sq. in 00, 210 136, 000 26, 000 33, 500 Percent elongation 28. 5 7. 6 00. 0 84. 0 Percent reduction in area... 52.0 8. 2 77. 0 70. 0

Tests on an alloy of the composition of Example I when subject to Izod impact tests show values at room temperatures of from 58 to 64 root-pounds, while at the low temperature of 90 K. values of from '10 to '78 toot-pounds are obtained. Similar tests with steel of the above composition show Izod ,values of from 35 to footpounds at room temperature, while at 90 K. it gave substantially zero values and shattered easily.

Besides high Izod test values, an alloy of the composition of Example I has additionally the desirable properties of great ductility and workability, weldability with great strength and toughness of welds, and relatively low heat conductivity as compared with copper;,this latter being in general a property in common with all the alloys proposed in accordance with the invention.

Izod values of the order of 40 foot-pounds are had from standard specimens of an alloy of the composition of Example II at temperatures in the neighborhood of that of liquid air, the alloys of the other examples giving similar substantial values at temperatures in the neighborhood of that of liquid air.

From the above, it will be seen that the criterion of strength is the usual tensile test and that the criterion for ductility which postulates the absence of internal stresses at low temperature is the Izod value obtained at such tempera-,

tures. Hence, 'it is seen from the above that the alloys here proposed for use iii-apparatus which is subjected to stress and very low temperatures provide safe apparatus that is substantially free from internalstresses in the metal composing it when subject to a low temperature such as that of liquid air or oxygen. I since certain changes maybe made in the 'above construction and different embodiments oi. the invention could be made without depart" ing from the scope thereof, it is intendedthat all mattercontained inthe above description or shown in the, accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

Apparatus for use in storing, transporting and dispensing liquid oxygen comprising a relatively thick-walled pressure vessel having a heat insulating envelope and support therefor, and subject to a temperature in the neighborhood 01 90 K., said vessel being made of sections joined together in a fabricated whole and of an alloy which consists of coppertaken in 'an amount in excess of 90% by weight of the whole, the balance being beryllium; thecopper and beryllium being so combined and .compounded as to impart to the alloy relatively great mechanical strength, substantial absence of internal stress, and a relatively high Izod value when at said low temperature in comparison with such properties at room temperature.

auousrus B. kmzan

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