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Aluminum Alloys by Bruce H. Wyma, Aluminum Co. of America, New Kensington, Pa.
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Aluminum alloys are increasing in popularity for processing c hemica Is, petroteu m products, and foods and drugs
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Steady penetration into new markets is shown by construction of more production capacity by U. S. aluminum producers
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F R O M 50 POUNDS A DAY IN 1888, s. aluminum production has expanded to the present rate of about 11 million pounds a day. Figures for 1960 show production at 2,014,499 tons. With confidence in the future, the industry is continuing to expand its capacity. I n the last year the Aluminum Co. of America added 35,000 tons; Reynolds Metals Co., 66,700 tons; Harvey Aluminum Co., 6000 tons; and Anaconda Aluminum Co., 5000 tons. Alcoa's wholly owned Suriname Aluminum Co. has started a project which includes a 60,000 ton-per-year smelter in Suriname. Alcoa also is participating with Aluminio, S. A., in the erection of a smelter in Vera Cruz, Mexico. Reynolds International is planning to build and operate a 25,000 ton-per-year smelter with the Venezuelan government in that country and will participate in the construction of a smelter and alumina plant in Greece. Kaiser is constructing mining, refining, smelting, fabricating, and power facilities with Consolidated Zinc Corp. (London) in Australia, New Zealand, and Tasmania. Kaiser also has invested in new and expanding companies in India and Spain and is negotiating a major project in Ghana. Including Ormet, Inc., the number of domestic producers has increased froin three to six. A future seventh member, Cerro Corp. which gained a prominent position in extruding and fabricating by acquiring Fairmont Aluminum and United Pacific Aluminum, is planning on continuing a 55,000 ton-per-year smelter previously planned by United Pacific. Aluminium, Ltd., of Canada (Alcan) has announced the development of a new process for producing aluminum which is expected to be in pilot plant operation in one or two years. In Europe, Pechiney-Ugine has announced the development of another new process for producing aluminum, also in the pilot plant stage. Residential siding, rigid containers, and automobiles are increasingly largevolume markets for aluminum. In the electrical field, aluminum transmission towers were important news this
year, and the swing to using the light metal in substations, electronics, and automation equipment gained momentum. Developments in military and space-age hardware produced several exotic aluminum applications during the year. Aluminum is continuing to make inroads on many materials of construction in the chemical process and petroleum industries. Low cost and freedom from product discoloration are among aluminum's major advantages in the organic chemical industry. A high resistance to corrosion, light weight, and excellent low-temperature properties have contributed to the growing list of applications of aluminum for the processing and shipping of inorganic chemicals. Resistance to sulfur-bearing gases, COZ, refinery atmospheres, sea coast environments, and cooling waters is responsible for the growing use of aluminum in the petroleum and petrochemical industries. This review covers major published developments from February 1960 through May 1961.
Alloy Development High strength alloys of the 2000 series (principal alloying element copper) and the 7000 series (zinc, with magnesium the second major addition), for many years vital primarily in aircraft construction, are being evaluated and used in nonaircraft applications ( 4 A ) . The 7000 series offers the highest mechanical properties. Favorable characteristics include high strength-weight ratio, excellent machineability, nonmagnetic properties, ease of handling, availability in many forms, and ability to be extruded to the exact shape to obtain required section modulus. Alloys 2014 and 2219, both being considered for fabrication of missile fuel tanks, were evaluated to determine the feasibility of using copper-bearing alloys in fusion-welded and heat-treated pressure vessels ( 7 4 . Results showed solution heat-treated and aged weldmentp of 2014 are inherently low in ductility and toughness and are subject to premature failure under biaxial loads. The 221 9 alloy consistently produced a tough, ductile weldment when heat-treated and
is well suited to pressure vessel applications. Because of their excellent strengthto-cost ratio and resistance to corrosion. aluminum alloys are becoming increasingly popular for processing chemicals, petroleum products, foods and drugs, according to Horst ( 3 4 . A table of wrought alloys most frequently used for processing equipment was presented. Corrosion resistance, galvanic effects with other metals, compatibility with nonmetallics, and cost comparisons also were discussed. Recently, interest has been generated in aluminum powder metallurgy (APM) alloys for use in atomic reactor applications because of their high strength at elevated temperatures and low thermalneutron capture cross section (%). Several have been developed for use in the 400 to 1000" F. range. 'They are dispersion-hardened by either oxide particles or particles of insoluble, intermetallic compounds to give high strength and stability at elevated temperatures. Certain alloying combinations produce desirable corrosion resistance in high temperatu e water. Although APM products of wide variety and complexity have been fabricated, the range is restricted by the amount of oxide or alloying elements present in a particular alloy. Some methods of welding have been developed to join APM alloys. The sharp-notch behavior of some high-strength heat-treatable sheet aluminum alloys and welded joints at 75", -320°, and -423' F. has been discussed ( 2 A ) . Seven alloys were investigated. As-welded joints in each alloy had lower strengths than the parent metal at all temperatures, while heattreated welds in alloy 2219-T62 had strengths equal to those of the parent metal. Sharp-notch sensitivities of welds in some alloys were less than those of the parent metal. Special design precautions may be necessary when using some of these alloys for welded structures or when notch sensitivity is important.
Industrial Applications Aerospace. Because of aluminum's strength, light weight, and compatibility with fuels and propellants, it is being VOL. 53, NO, 11
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Materials of Construction Review
Aluminum’s light weight gives it an added advantage in ease of handling. This workman has no difficulty in carrying two 8-foot lengths of 8-inch pipe
used extensively throughout U. S.space and missile programs. The Titan ICBM contains about 6000 pounds of aluminum alloy 2014 in the tanks, comprising the bulk of the airframe. Alloy 2219 forms the major structural portion of the Bomarc B long-range missile (IOB). This strong, heat-resistant alloy affords the high strength needed to carry fuel under pressure and serves as a loadcarrying structure for missile wings and power plants. Approximately 11 tons of high-strength Alcoa alloy 5456 sheet are used in the booster for the Saturn, America’s first interplanetary space vehicle. Atomic Energy. Small, precise fin tubes made as APM impacts are being used by Atomics International as containers for uranium oxide fuel pellets in fuel elements. Bundles of the tubes, capable of functioning at temperatures as high as 900’ F., are enclosed in a jacket to comprise a fuel element in organic moderated and cooled reactors. The use of sintered aluminum powder (S.4P or APM) as a fuel bundle cladding material in Canadian General Electric Co., Ltd.’s design for organic-cooled deuterium-moderated reactors was discussed by MacKay (77B). SAP or APM alloys feature better or more uniform properties, such as ductility; insignificant effect on physical properties from prolonged irradiation ; production of tubing to suitable tolerances; and joining by pressure bonding. Improved uranium oxide fuel clad with these alloys is expected to increase allowable fuel surface temperature, increase fuel burnup, and cut the cost of power from the reactor (3B). Radiation effects on reactor metals have been discussed by Leeser ( S B ) .
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Aluminum is only slightly affected by exposure to neutrons and has proved itself in reactors where it is not subjected to appreciable stresses. In a fast flux. the creep rate of high-purity aluminum does not increase significantly during a 50-day radiation. However, cladding creep is enhanced unless a barrier is used to prevent diffusion betrveen cladding and fuel. The first large-scale fluid bed for calcining aluminum-type fuel wastes from test reactors is being built at h c o , Idaho. A discussion of nuclear waste disposal by fluidized calcination of sintered aluminum-type wastes has been published by Jackson and others (7B). Chemical. The W. R. Grace plant in Memphis, Tenn., has been called a “monument to aluminum” (75B). The plant uses the Pechiney-Grace process, a total-recycle method of urea production. A41uminumhas contributed largely to minimizing: economically, corrosion problems which otherwise could result in excessive maintenance and down time. Four 6750-gallon aluminum reactors are used, reducing reactor cleaning time by 69%. Aluminum comprises almost all piping, tanks, and other equipment where processing temperatures permit. -4n aluminum carbamate decomposer is used, as well as aluminum integral steam-traced piping (Unitrace) for handling hot urea. Containerization techniques for handling phosphates have been adapted in the post-treatment operation of the 423 million gallon-per-day Torresdale water treatment plant in Philadelphia; 4000-pound capacity aluminum bins serve as shipping containers, storage bins, and discharge hoppers. Time
INDUSTRIAL AND ENGINEERINGCHEMISTRY
consumed in handling 100-pound bags is avoided. ‘The system utilizes Tote Bins and Tote Tilts (Tote System, Inc.. Beatrice, Neb.). Aluminum Tote tanks, companion to the dry materials containers, have just received Interstate Commerce Commission approval for handling materials having flash points above 20’ E’. and all viscous materials. U p to now, these containers have been used in bulk shipping of liquid adhesives, resins, and various food materials. .4luminum alloy 1060 has been excellent for tanks, piping, and equipment handling €IzOz: and it best meets stringent service requirements involving longtime contact with this chemical ( 7 B ) . It also appears to have the greatest resistance xo pitting in handling peroxide with high chloride concentration. The addition of nitrate ion will control this attack. Alloys ,5652 and 5254, with both copper and manganese contents controlled at less than 0.05yo by weight, could be recommended when higher mechanical strength is required. The Alcoa Research Laboratories have developed an inexpensive easy-to-use solution which removes iron contamination from aluminum surfaces, especially important for equipment handling Hs02 (4B). The solution is nontoxic, noncorrosive to aluminum, and is used at ambient temperatures. I t has been used on field-erected tanks which, after treatment, have passed a ferroxyl test for iron. Cnsymmetrical dimethylhydrazine is finding rapid acceptance as a highenergy, storable liquid propellant. Defense agencies and major liquid rocket engine companies have developed information on compatibility of metals and elastomers with this fuel; aluminum is among the recommended materials, although experimental results are not given. Corrosion studies of aluminum and other materials widely used in ground support equipment and airborne hardware handling this fuel have been reported by Raleigh and Derr ( 7 3 8 ) . Cryogenics. The generation, transportation, and storage of liquefied gases have, until recently, involved temperatures down to -3320’ F. Increasing need for liquid hydrogen, which boils at -422.9’ F., and liquid helium, which boils at -453.8’ F., has created new demands for materials of construction ( S B ) . Aluminum has become the accepted material for inner vessels in large field-erected storage equipment for liquid oxygen, nitrogen, and hydrogen. Aluminum alloy 5456 is presently in service handling liquid helium. Eight 70-inch aluminum alloy 5456 tanks are used for storing liquid oxygen in the Saturn. Eleven tons of this alloy will be used in the superbooster, which
anb4 is 22 feet in diameter and stands 80 feet high. The new Torrance, Calif., plant of Linde will provide up to 3.3 million pounds per year of liquid hydrogen to NASA on a commercial basis (74B). A double-wall sphere, with a 13-ton capacity, 23-foot-diameter aluminum inner tank, stores the liquefied gas at -423' F. Another double-wall cylindrical tank, internally constructed of aluminum, stores liquid nitrogen at -320' F. I t is 15.5 feet in diameter and 14.75 feet high. I n Sacramento, modification of two Thor test stands and installation of two 90,000-gallon liquid hydrogen tanks are under way for the Saturn S-IV vehicle test program. The tanks, believed to be the largest spherical liquid hydrogen tanks in the country, are constructed with a '/,-inch-thick aluminum internal sphere. An application of great potential is in liquefying and storing natural gas for "peak shaving" (6B). Oil companies and utilities indicate that a cubic foot of the liquid gas at approximately -260' F. corresponds to 610 or 624 cubic feet of gas. Greatly reduced volume under liquid storage conditions is quite attractive. New data on aluminum alloys for cryogenic applications have been reviewed (823). Moduli, fatigue strengths, and those properties related to toughness, such as notch sensitivity and tear resistance, were considered. Conclusions support previous indications that the alloys tested, particularly the aluminum-magnesium alloys, are well suited for cryogenic service. Their strengthr, fatigue properties, and elastic moduli are as high or higher at low temperatures as at room temperature. As indicated by elongation, reduction of area, notch-tensile strength, and tear resistance, resistance to fracture is at least as good at low temperatures as at room temperature. Alloy 5083-HI13 was tested to gather data on the effect of low temperature on fatigue properties of aluminum-magnesium-manganese alloys and, in particular, information on fatigue of weldments at low temperatures (5B). Results showed the fatigue strengths of the three materials tested, 3/,-inch plate and plate with 5183 weldments with bead on and bead off, are significantly higher at -300' F. than a t room temperature. The bead off material almost doubled its fatigue strength at the lower temperature, meaning that fatigue strength data for room temperatures are very conservative for designing low temperature vessels. Packaging and Shipping Containers. Last year an estimated 161,000 tons of aluminum went into packaging. Industry shipments to the can industry,
only about 3 million pounds in 1958, shot up to over 50 million pounds in 1960. Already motor oil, beer, frozen citrus concentrates, and many aerosol products are being sold in aluminum cans. Cargo shippers now are rapidly converting to the relatively new concept of carrier boxes, known as freight-carrying, shipping, or cargo containers. Initial experience has demonstrated that the best way to ship many small packages or units is to pack them into single containers which are essentially truck trailers without wheels. The list of aluminum's advantages includes high strength, light weight, ease of forming and repairing, and corrosion resistance. Most containers measure 8 feet wide by 8 feet high by IO, 20,30, or even 40 feet in length. Kaiser Industries Corp. has introduced its candidate to the fast-growing bulk shipping container market. Nest-A-Bin containers are of two types, a liquid-containing model with capacities of 440, 550, and 660 gallons and one for granular materials with product capacities of 54 and 70 cubic feet. The bins nest together for compact return shipment. Pulp a n d Paper. Development work and service experience in recent years have demonstrated that aluminum alloys are resistant to many corrosive chemicals and vapors found in pulp and paper operations. Aluminum industrial products are being used for buildings, sheds, ducts, hoods, ventilation systems, and other architectural applications. Tests carried out over a period of years in British Columbia pulp mills have
Materials of Construction Review proved aluminum to be an excellent material of construction. A sulfate pulp mill of the Crofton Pulp Division, British Columbia Forest Products, has recently installed over 4500 feet of 3- to 24-inchdiameter aluminum piping to handle its water supply (72B). The 24-inch main supply line was manufactured and installed on the j o b a t an estimated savings of over 35% compared with the cost of stainless steel or other suitable materials. Over 60,000 pounds of aluminum sheet were used for the entire ventilating and air conditioning system and over 65,000 pounds of aluminum industrial sheet to house the conveyor and mechanical handling system. All runners and gratings, as well as ladders leading to the machines with their guardrails and handrails, are of aluminum. All machinery safety guards are being replaced by aluminum. Petroleum. I n prospecting new uses for aluminum, major producers have been actively engaged in basic research and product development pointed toward new applications in the petroleum industry (2B). Transportation. Major aluminum producers are actively investigating the potential for aluminum river barges in a concerted drive to supplant steel in transporting chemicals by water and rail. The first aluminum barge to be biiilt in the United States is being assembled for Reynolds; 98 feet long, 35 feet wide, and weighing over 86 tons, the barge will be used along the Mississippi-Ohio River system transporting perchloroethylene made by Diamond Alkali at its Deer Park, Tex., plant. Lighter weight allows greater payloads,
This welded 4-inch aluminum gas flow line i s being dragged down U. S. mountain terrain. Aluminum's flexibility minimized prebending VOL. 53, NO. 1 1
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maintenance costs are negligible, and a wide variety of chemicals can be handled without contamination or need for special liners. Alcan has introduced an all-aluminum railway hopper car with the shape of a tank car and the loading principles of a hopper for bulk solids, specifically chemicals, foodstuffs. and refined ores. Based on increased payload (3000 cubic feet, 88 tons), nine of these new cars reportedly do the work of 10 steel cars. No cars of this latest design have yet been built in the United States. Aluminum is fast becoming the preferred material for highwa) vehicles hauling such diverse bulk commodities as corrosive rock salt. red fuming " 0 3 , liquefied nitrogen. tarlike creosote, and high-purity water. Aluminum is receiving increasing attention from cost conscious truck operators because of its ability to contain a wide variety of materials, maximum payload capabilities. and ease of cleaning. Corrosion A detailed discussion of the inhibition of corrosion of commercial aluminum in alkaline solutions has been published ( E ) . Corrosion rates for commercial aluminum containing 47, manganese and 376 iron have been determined in NaOH solutions under different conditions, and the inhibition efficiencies for
agar-agar, gum acacia, dextrin, gelatin, and glue have been calculated, Information on aluminum pitting in 17 Canadian waters, sea water, and oil field brine, along with a discussion of the corrosion behavior of aluminum in natural waters, has been presented by Godard ( 3 C ) . A statistical treatment of pitting data was presented. and support \vas given to the existence of a cube root rate curve for aluminum pitting in water. Aluminum pipe can be safely installed in neutral soils, sandy dry soils. and dry rock areas (7C). It can be installed bare in underground service if protection by zinc or magnesium anodes is provided for any local "hot spots" which develop. Results are drawn from a case history on a bare 6063-T5 aluminum pipe used in a sour gas gathering system buried in a primarily sandy loam and broken caliche soil. There has been growing interest in aluminum corrosion in high-temperature water with increasing use of aluminum in water-cooled nuclear power reactors. Examination of corrosion product from alloys exposed to 300' C. high-purity water showed that corrosion resistance is associated with distribution of secondphase particles in the alloys; best corrosion resistance was associated with alloys containing the most uniform distribution of cathodic second-phase particles (5C). The corrosion behavior of aluminum
alloys containing nickel and iron such as X8001, has been described by Geske (2C). These show very good corrosion resistance under operating conditions for water-cooled reactors (distilled waier at 290' C.). He also reported that these alloys also can be used with a current of high-temperature water: which was found more aggressive than static water, through the use of inhibitors such as HsPO? or Si02 with a low pH value. Further evidence of aluminum's serviceability in severe sea coast atmospheres has been demonstrated in a test exposure of aluminum, aluminized steel, and galvanized steel pole-line hardware Rear Kahuka Point, Oahu, Hawaii (42). The test was of three years' duration. Results indicated superior performance of all-aluminum hardware, improved corrosion resistance of aluminized steel to that of galvanized steel, and the relationship between thickness of aluxninum coatings and service life of aluminized steel hardware. Fabrication and Equipment Ultrasonic \velding engineering, manufacturing, and quality control problems, together with suggested solutions and related process potentials, have been surveyed by Koziarski ( I D ) . There are many advantages associated with this relatibely new method of joining metals, and it is n o t strictly limited to
Coal chutes fabricated from aluminum have resisted corrosion and erosion from continuous passage of coal. This experimental unit has been ir. service over five years
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This i s the prototype of Linde's portable machine pipewelder. Machines like it, for "on the job" welding, are built to butt weld pipe in sizes from 2 to 12 inches in 1 to 3 minutes
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Courtesy Alcan Industries, Lid.
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a n v w Materials of Construction Review certain gage thicknesses. Aluminum foil 0.0002 inch and thicker can be welded to itself or to any thickness of aluminum or other metal. Sound ductile joints have been produced between aluminum and copper. A number of helium-tight joints between aluminum and stainless steel were necessary for a direct conversion of nuclear energy to electrical energy for space applications (SNAP-1A, Systems for Nuclear Auxiliary Power). The connections between 6061-T6 aluminum and AIS1 321 stainless steel defied conventional joining methods. Ultrasonic welding was successful. It is expected that ultrasonic welding’s main application will be in joining dissimilar and refractory metals in space aircraft. The process also may find application in joining such materials as sintered aluminum powder. It also provides for joining metals of widely spread melting temperatures such as tungsten and aluminum. Linde has recently developed a technique called “square butt” welding. I t eliminates vee-joint preparation, all preheating, back chipping, and stringerbead pass, needing only a clean, square, end-to-end joint. The new high-current welding method uses shielded inert-gas metal-arc equipment at about 600 amperes. Heavy wall aluminum cylinders can now be welded more economically, in fewer passes, at increased speed, and with less total heat input. National Steel and Shipbuilding Co. is using the method to construct 1.5-inchthick aluminum cylinders for nuclear applications. Changes in the extent of the heataffected zone and in the strength of the joint resulting from repeated weld repairs in plates of two tempered aluminum alloys, one strain-hardenable and one heat-treatable, have been discussed by Nelson (20). For each alloy, four panels of two 3/8-inch-thick plates were groove welded in three passes by the semiautomatic inert-gas consumableelectrode process. The 5456-H321 plates were welded with 5456 wire and the 6061-T6 plates with 5356. Tensile and Rockwell hardness tests on repair welding (up to six repair welds) showed that the tensile properties across the welds are not significantly affected by the number of times the panels are rewelded, nor is the width of the heataffected zone significantly increased. The effect of welding heat extends not more than 1.5 inches from the centerline of the weld. NASA’s Marshall Center has developed a unique method of explosive forming in the manufacture of LOX manifolds for the big Saturn booster. The cylindrical manifold blanks are welded together from four drop-forged
pieces of 5052-H32 alloy a t Redstone Arsenal. Olin-Mathieson cuts the holes, then a plastic bag of water containing the explosive charge at the center is put inside and set off. The first explosion improves the cylindrical shape. Smaller bags with smaller charges are then set off, two in each hole. Before this process was developed, explosive forming usually took place with both the explosive charge and the object to be formed under water. I n the last two or three years there has been a great increase in interest in aircooled heat exchangers. Rubin has discussed the experience of many people in designing exchangers of this type (30). Though economics generally limited aluminum tube temperatures to about 450” F., aluminum fins are considered most economical for process design temperatures up to 750’ F. The least expensive finned tubing has aluminum fins mechanically wrapped under tension onto the outside surface of the tube. Fin ends are soldered or held by a collar to prevent loosening or unraveling. Often a bimetallic tube is used. A complete mechanical bond is made between an inner liner tube of some material required for the process conditions and an aluminum outer tube from which most of the metal has been cold extruded into high fins. The process design temperature is limited to 550’ F. I n another type of tube, aluminum fins are mechanically wrapped under tension and inserted into a groove about 0.0008 inch deep in the tube wall. Recent developments for fin insertion to a depth of 0.050 inch increases fin strength. These types of tubes are adequate for service u p to 750’ F. Fan blades in these units are often made of aluminum.
design stresses previously limited to sheet and plate thicknesses under 0.750 inch
Codes
Corrosion (IC) Flournoy, R. W., Corrosion 16, 91 (September 1960). (2C) Geskc, H. J., Aluminum M a g . 36, 454 (August 1960). (3C) dodird, H. P., Can. J . Chem. Eng. 167, (1960). (4C) Lowe, T A., Corrosion 17, 101 (April
The case for the second aluminum casting alloy approved for use in construction of unfired pressure vessels was published in February 1961 (3E). Case 1291 permits the use of aluminum casting alloy 356 (ASTM SG70A), meeting the requirements of ASTM B26-59T. Two tempers, -T6 (temperatures to 250’ F. permitted) and -T71 (temperatures to 400’ F. permitted), are included. Case 1265, permitting the use of S5A (casting alloy 43) appeared in June 1960 (ZE). Welded construction is not permitted with either approved casting alloy. The approval of these materials will now permit greater use of aluminum in the petroleum and processing industries. Under a new ruling, Specification SB209 now permits GM41A (5083) in thicknesses from 0.750 to 2.000 inches to use the higher maximum allowable
(7G. literature Cited Alloy Development (1A) Crane, C. H., Smith, W. G., Welding J . 40, 33-s (January 1961). (2A). Hanson, M. R., Stickley, G. LV., Richards. H. T., ASTM Soec. Tech. Pub. No.’ 287. 1960. (3A) Horst, R. L,, Materials in Design Eng 51, 130 (May 1960). (4A) Peckner, D., Zbid., 53, 133 (April 1061\ -,--
(5A) ?&mer, R. J., Natl. Metal Congr., Philadelphia, Pa., October 1960. Industrial Applications (1B) Bloom, R., Jr., Weeks, L. E., Raleigh, C. W., Corrosion 16, 100 (April 1960). (2B) Brandt, P. E., Flournoy, R. W.: Petrol. Mech. Eng. Conf., New Orleans, La.. SeDtember 1960. (3B) Bra$mer, D., Elec. World 153, 63 (May 16, 1960). (4B) Brown, M. H. (to Aluminum Co. of America), U. S. Patent 2.901.344 (Aug. 25, 1959). (5B) DeMonev. F. W.. Wnlfer. G. C.. in “Advances in Cryogenic Engineering,” K. D. Timmerhaus, ed., Vol. 6 , Chap. 5-4, p. 590, Plenum, New York, 1961. (6B) Fellom, Roy, Jr., Light Metals Age 18, 6 (February 1960). (7B) Jackson, J. D., Sorgenti, H. A., others, IND.ENC. CHEM.52, 795 (1960). (8B) Kaufman, J. G., Johnson, E. W., in “Advances in Cryogenic Engineering,” K. D. Timmerhaus, ed. Vol. 6, Chap J-8, p. 637, Plenum, New York, 1961. (9B) Leeser, D. O., Nucleonics 18, 68 (September 1960). (10B) Light Metals Age 18, 5 (October 1960). (11B) MacKay, Ian, Nucleonics 18, 78 (October 1960). (12R) Pafier Ind. 42, 28 (April 1960). (13B) Raleigh, C. W., Derr, P. F., Corrosion 16,115 (October 1960). (14B) W a f e r Tower 47, 6 (January 1961). (15B) Weyermuller, G., Smiley, W., Chem. Processing 23, 122 (May 1960). ,
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(5C) MacLennan, D. F., Zbid., 17, 105 (April 1961). (6C) Sundararaian, J.. Rama Char. T. L:, Zbid., 17, l i l (January 1961). Fabrication and Equipment (1D) Koziarski, J., Welding J . 40, 349 (April 1961). (2D) Nelson, F. G., Zbid., 40, 166-s (.4pril 1961). (3D) Rubin, F. L., Chem. Eng. 67, 91 (October 31, 1960). Codes (1E) Lockwood, J. S., Aluminum Co. of America, New Kensington, Pa., private communication, May 20. 1961. (2E Mech. Eng. 82 (June 1960). (3E1 Ibid., 83 (February 1961). VOL. 53. NO. 11
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