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Stainless Steels and Other Ferrous Alloys by W. A. Luce and J. H. Peacock, The Duriron Co., Inc., Dayton 1, Ohio
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Technological advances and new processes in chemical and allied industries continue the demand for large quantities of stainless steel
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Increasing production-scale .vacuum melting of stainless alloys is provid ing hig her q ua lity corrosion-res ist a nt ma t e r ia Is
general uptrend in stainless steel production continued during the past year largely because of increased emphasis on missiles, rockets, and space age equipment. I n addition, application of the various stainless alloys in chemical plants continued to expand. Improved joining and fabrication methods have minimized the problems encountered in field applications, but these advances only emphasize the need for careful handling of stainless equipment during fabrication. The shortage of nickel, which seriously hampered the use of stainless steels a few years ago, is definitely alleviated; the AISI 200-series stainless steels, in which manganese is substituted for some of the nickel in the 1870 chromium - 8% nickel alloys, continue to show promise in specific chemical applications. Vacuum melting and other specialized production techniques are providing alloys with superior properties, and this may greatly increase the range of application in handling severe corrosives. T H E
Oen era1
Noteworthy contributions of a general nature were made in the stainless steel literature during the past year. An interesting review on the properties of various stainless steels and their effect on corrosion resistance and work hardening was provided by Gregory and Simons ( 2 4 ) . The various stainless alloys are categorized according to their structural properties, and the degree of corrosion resistance normally expected from each type material is indicated. Basic information was also provided by Dickerson (18) on the application of various stainless steels in nuclear reactors. H e discussed the dispersion-type fuel element in which uranium oxide is used in conjunction with stainless steel. I t was reported that stainless steel-uranium oxide elements have given excellent service in reactors operating a t fuel element surface temperatures in the range of 1500" F. Stainless steels are among the
few metals having applicability in nuclear reactors where radiation damage can be excessive if incorrect materials are utilized. Recent developments in stainless steel technology as utilized in the chemical industry were discussed by Oppenheim ( 4 2 ) . I n addition to listing all stainless steels available to the corrosion engineer, he pointed out the excellent benefits of extra low carbon contents in minimizing intergranular corrosion difficulties, the cost reduction realized by the substitution of manganese for nickel in the less critical corrosion environments, and the expanded application of the precipitation hardening stainless steels where high strengths, high hardness, and/or wear resistance are desired. I n a general forecast (52) of technical progress currently being made in the stainless steel industry, it was indicated that vacuum melting would increase the range of applicability for stainless steels much beyond present limits. Vacuum melting continues to increase in importance and should soon become a valuable production technique on a relatively standardized basis. Modified stainless steels are becoming extremely important to the future of nuclear power, as these power plants of tomorrow must
be built from inexpensive material to justify their existence. Boron-enriched stainless steels (Type 304 with u p to 2.1% boron) have been supplied for control elements in nuclear power installations. Austenitic Type 304 L stainless steel can also be supplied with a cobalt content controlled to an acceptably low limit for nuclear purposes. I n addition, aircraft, missile, and space vehicle builders have a standing order for better structural grades of stainless steel to handle even higher skin temperatures, and it is for this reason that even higher strength-to-weight ratio stainless steels are being investigated. Corrosion
Data comparing the corrosion resistance of chromium-nickel-manganese stainless steels (AISI Types 201 and 202) with the conventional AISI Type 304 continue to be available. Hamstead and Van Delinder (27) report that these manganese-containing alloys in the annealed condition may be used in numerous services where the Type 304 material is currently being utilized. In fact, where certain organonitrogen compounds or conventional amines are the major corrosives, these newer materials ~
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are even superior to Type 304 stainless steel. However, it is pointed out that heat treatment problems with the manganese-containing alloys may be even more severe than with the conventional 18% chromium-8yo nickel stainless steels. For this reason it is recommended that extra low carbon contents be investigated as a means for overcoming the increased susceptibility to intergranular corrosion. Stress corrosion continues to be a major problem in the chemical plant, and while considerable emphasis is being placed on methods for controlling this insidious type of failure, complete success has still not been achieved. Several important articles were available during the past year, and these focus attention on the most important variables which must be controlled. Brooks (8) reviewed the problem in detail and explored the various approaches to the problem which might form a basis for preventive action or fruitful research. Heat exchanger equipment utilizing chloride-containing waters for cooling purposes are extremely prone to this form of attack, and attention is called to the advantages of tube-side rather than shell-side cooling to eliminate stagnation and other factors contributing to stress corrosion problems. I t was found that recirculated water should contain no chromates or other oxidizing compounds, and the equipment in question should be fabricated under ideal conditions to minimize inherent stresses and microstructural problems usually associated with intergranular corrosion. An excellent report by Staehle and others (50) discussed the effects of the relative availability of chloride and oxygen and applied stress on the morphology of stress corrosion cracks in austcnitic stainless steels. Oxygen was found to increase the tendency for stress corrosion cracking of AISI Type 347 stainless steel even a t low chloride concentrations,
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w-hile hydrogen and nitrogen tended to minimize or even eliminate the condition. The authors found no tendency for stress cracking in the vapor phase, providing condensation products were not present. As severe cracking may occur a t low stresses in the liquid phase, it was proposed that the actual crack movement results from electrochemical action with the stress providing a local region of highly stressed metal a t the base of the crack. The effect of inhibitors on stress corrosion of stainless steel was studied by Phillips and Singley (43), who reported that some progress has been made toward controlling failure by inhibition. Under specific test conditions sodium nitrate and sodium sulfite did have an inhibiting
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effect on stress corrosion problems; this is sufficiently interesting to warrant further work on a plant-scale basis. I t was also found that the exclusion of oxygen tends to reduce cracking which probably explains why an oxygen scavenger like sodium sulfite is successful. Although intergranular corrosion problems still exist in chemical plants, the importance of this problem has been greatly minimized by the advent of the extra low carbon grades of stainless steel. Many chemical companies now insist that fabricators observe important details when welding these materials to avert serious failures. Marshall (35) provided a comprehensive discussion on the effect of carbon on the intergranular corrosion resistance of AISI Type 304 and 304 L. He concluded that when a postwelding heat treatment is not feasible: the extra low carbon varieties of the 18-8 stainless steels must be utilized for complete resistance to intergranular corrosion. He also mentioned that some metallurgists are of the opinion that Type 304 stainless steel can be safely used in the as-welded condition, provided that the relationship of carbon content in the 0.04 to 0.06$& carbon range and thickness u p to 1 inch are carefully controlled. I t was concluded that this latter system is no doubt suitable for certain conditions but will not give complete assurance of freedom from intergranular difficulties. I t is the consensus of opinion that many of the most severe environments can exploit an as-welded structure if the carbon content exceeds a 0.037, maximum. A study of the influence of structural factors on corrosion of austenitic stainless steels by intergranular means was made by Nielsen ( 4 1 ) . He concluded that ferrite and sigma phase at the grain boundaries may have a tremendous influence on the corrosion resistance of an austenitic stainless alloy. This excellent revicw considcrcd such other factors as passivity and grain size on the corrosion behavior of these alloys. I n line with further efforts to determine susceptibility to intergranular corrosion, Tisinai and Samans (54)provided data on all-glass multiple-test equipment for the nitric acid testing of stainless steels. They provided further evidence that this multiple testing procedure is feasible and substantiated the fact that location in the test chamber caused no variation in test rates obtained. An interesting discussion of the factors causing pitting corrosion was given by Defranoux (76), who described a technique for investigating this insidious form of attack. The technique was devised to investigate the effect of structural differences of a stainless steel in the corrosive media to which it is subjected. The
a n m d Materials of Construction Review stainless steel specimen is polarized, first anodically and then cathodically, in the corrosive medium in question, and the corrosion rates are calculated from the point of intersection of the two polarization curves. The author considers it to be an introduction to a potentially good technique for evaluating susceptibility to this type of corrosion. The use of cathodic protection techniques for preventing or a t least minimizing corrosion in chemical plant applications has come in for discussion in recent years. This technique has been widely applied in the protection of underground pipe lines, buried cables, and docks and piers, but only in rare instances has it been employed to protect materials other than steel and then only in relatively mild corrosives. There is no reason to limit the application of cathodic protection in chemical plants except where a suitable anode material is not available or a very complex piece of equipment is involved. The application of cathodic protection to increase the usefulness of certain stainless steels was discussed in a report ( 7 3 ) summarizing the work of NACE Task Group T-3T-3 on cathodic protection of process equipment. This report discusses the protection of an AISI Type 316 cooling coil which had failed in two or three months in a sodium hypochlorite solution, but the replacement pipe in the same alloy cathodically protected with a n impressed current system provided over five years service. A similar benefit occurred when a Type 302 tank was found to be corroding intergranularly in a severe manner after a short exposure time, but failure was averted when the tank was put under cathodic protection. This latter case illustrates that a cathodically protected piece can provide many years of successful service life when it would otherwise fail in a few months. A general review on the potentialities of cathodic protection was provided by Luce and Peacock (36) who outlined some of the areas where this method for preventing corrosion can be utilized. Stainless steel equipment is as adaptable to these techniques as other materials. Plesset (44)stated that increased service life was received from a precipitationhardened 17-7 P H stainless steel propeller in an aqueous sodium chloride environment where cavitation damage was involved. I t is predicted that cathodic protection will be considered a more important method for corrosion control in future years. A new technique for determining the weight loss of a metal used as a heat transfer surface and immersed in a corrosive solution was described by Groves and Eisenbrown (25). This procedure pre-
dicts the actual corrosion rate of a metal surface when at a considerably higher temperature than the corrodant. Data were provided on the use of Carpenter 20 - C b stainless as a heat transfer surface in sulfuric acid solutions. I t was found that the temperature and acid concentration were interdependent and, as expected, the rate of corrosion increases rapidly with increase in temperature. Therefore, when utilizing a metal or alloy for heat transfer operation the "corroding temperature" is invariably higher than the temperature of the solution being handled and may more closely approximate the temperature of the heating medium involved. Mechanical Properties and Structure
Considerable data continue to be obtained on the mechanical properties of the various stainless steels, but the most vital information concerns some of the newer, hardenable grades. Kasak and others (30) described the tensile and creep properties of various manganesecontaining stainless alloys varying from 0.09 to O.82Yc carbon, 10.3 to 15.7% manganese, 12.2 to 28.0%) chromium, and 0.1 to O.87? nitrogen. A definite relationship between the composition and properties of these various materials was established. Data on the mechanical properties of a 17-7 P H stainless steel containing 1% aluminum were obtained by Furukawa and Sat0 (27) who considered the effect of various heat treatment times and temperatures on important properties. I t was found that this material showed better mechanical properties by aging subsequent to a solutionizing heat treatment. The 17-7 PH alloy was also studied by another investigator (19) who tested the material in tension and fatigue after various heat treatments. Brisbane (7) provided tensile stressstrain results from room temperature to 1000" F. on both the 17-7 P H and PH 15-7 Mo stainless steels. I t was found that the PH 15-7 Mo alloy provided the best elevated temperature ultimate strength through 1000" F., although both materials displayed approximately the same degree of elongation u p to 800" F. An investigation to determine changes in dimensions and mechanical properties in stainless steel control rods exposed in reactors was described by Schaffnit (47). After irradiation the specimens were subjected to tensile and hardness tests, and it was found that an 18-8 stainless steel containing 1yo boron became extremely brittle after a relatively short irradiation period. Upon etching it was found that samples subjected to 25y0 burn-up and above were subject to pitting.
A general study on the precipitation of phases in austenitic stainless steels containing manganese was made by Andrews and Huges ( 2 ) . Their work provided excellent information on the precipitation of various phases, their stability, and identity. Bungardt and others ( 9 ) compared the degree of stabilization of several niobium-containing austenitic stainless steels with the precipitation reactions which occurred. Their work was designed to determine the precipitation reactions occurring during creep testing and included data on the influence of creep on the formation and stability of precipitatng phases. Sigma phase and niobium carbide were the predominant constituents involved. I n the welding of various austenitic stainless steels, it is usually desirable to include a controlled amount of ferrite in the deposited metal to minimize cracking during cooling, and considerable attention has been given in the past to controlling the extent to which ferrite is formed. Schaffler's diagram has been used to predict the true ferrite content in stainless steel welds, but DeLong (77) proposed a modified version of that diagram to give a n even closer approximation particularly when nitrogen is involved. High Temperature
Stainless alloys having good high temperature properties and oxidation resistance continue to be in demand. A relatively new precipitation hardening alloy designated Unitemp 212 reportedly meets these basic requirements. An article (39) describing the nominal properties of this 23 to 27oj, nickel, 15 to 17% chromium, and 3.70 to 4.30y0 titanium alloy a t various temperatures also provides detailed information on five heat treatments used to obtain various combinations of mechanical properties. Unitemp 212 has good formability and is easily machined and welded. The high temperature properties of practically nickel-free austenitic stainless steel were compared by Brady and Boughner (6) to standard 18-8 type alloys. Their work shows this 18yo chromium-1 5% manganese-0.50% nickel alloy has rupture strengths comparable to AISI Types 316 and 347 and superior to Types 304 and 321 in the 900" to 1350" F. temperature range. Previous work established the room temperature strengths of low nickel-containing Type 201 and 202 alloys, but this recent study emphasized that the newer alloy can compete with the 18-8 type stainless steels for high temperature applications. An interesting article by Lula (37) presents typical room and high temperaVOL. 52, NO. 10
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ture properties of AM 350 and AM 355. These alloys are very similar in composition except for a slightly higher carbon and lower chromium content of AIM 355, but differences in structure and mechanical properties are significant. Recommendations are made on preferred heat treatments for both alloys to provide the most desirable properties in Ivrought and cast form. The high temperature oxidation characteristics of AIS1 Types 302. 309, and 330 stainless steels w-ere investigated by Caplan and Cohen ( 7 0 ) ; they thoroughly examined and analyzed scale removed from test specimens. Weightgain ZJS. time in the 1600" to 2000' F. range was studied, and it was observed that two types of breaks occur in the scale formation. Factors influencing this formation and breakdown are discussed, and photomicrographs illustrating the scale are presented. Radavich (45) studied the effect of various silicon levels on high temperature oxidation of 1670 chromium-1 07, nickel stainless steel. His results show that as the silicon content increases from 0.17 to 3.5570, the oxidation resistance increases rapidly for the temperatures studied. The article is well illustrated, and the mechanism by which silicon imparts oxidation resistance is explained. The H series stainless steels are considered by Schoefer (48)in his presentation on the application of cast materials in the temperature range of 1200' to 2200' F. Surface stability, structural stability, mechanical properties, physical properties, and design are five factors taken into consideration in governing the selection of the most suitable alloy for a specific application. Illustrations provide a very suitable means of comparing the alloys from various aspects Included in the work by Garofalo ( Z Z ) , pertaining to the influence of environment on creep characteristics a t 1000' to 1200' F., were two 18-8 type austenitic stainless steels. Within the limits of the test program, the results showed that environment had no effect on the minimum creep rate or rupture life of the materials studied. A detailed investigation of austenitic stainless steels and other alloys by Clark (72) and others provided an evaluation of superheater tubes after long-time exposure to steam a t temperatures of 1100' to 1500' F. Factors studied were resistance to creep, corrosion, and thermal shock, metallurgical stability, and the effects of oxide films on thermal conductivity. Welding
Advancing technology in many fields has directed more efforts toward welding of stainless steels and related alloys.
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Structures involving dissimilar alloys, more severe corrosives, missiles, rockets, and nuclear equipment emphasize the need for extremely high quality welds that are equal or superior to the base metal. Table I summarizes recent developments.
Manufacture, Metal Working, and Surface Treatmenf
A digest (20) of a report presented at the 1959 \Vestern Metal Congress discussed vacuum melting of stainless steels and superalloys by the induction and consumable electrode arc melting processes. A list of alloys being produced by vacuum melting since this process has reached production status is given. I t is pointrd out that quality improvements over air melting fall into the following categories : decreased gas content, improved cleanliness, better hot and cold workability, better mechanical properties, improved magnetic properties, improved soundness, and production of new metals and alloys which cannot be economically produced by conventional methods. A new induction unit utilizing a static device for frequency conversion is described in a brief article (28). This unit is reported as capable of reclaiming stainless steel chips, turnings, and bor-
Table I. Subject Welding stainless steel to low alloy or carbon steel
ings into usable ingots for less than 7.5 cents a pound for metal at the spout. With all the advantages of induction melting such as being fast and clean. having little time for oxidation, little metal and heat loss, and uniformity of ingots, the unit should be of particular interest to companies engaged in a considerable amount of metalworking. The largest type of unit has a melting rate of 2 tons per hour. The need for an alloy to withstand 3000 p.s.i. at 700' F in petrochemical operations has led to tlie development of a new stainless alloy. A summary by Hall (26) follows the d r velopment of this niobium-containing 17.5 to 18.57, chromium, 12.0 to 13.07, nickel, and 2.0 to 3.07, molybdenum alloy into centrifugally cast heat exchanger tubes. The need for controlling the formation of ferrite to produce the desired properties was realized and thus resulted in the development of a magnetic permeability indicator that is used before tapping to ensure the desired ferrite content. Mechanical properties of the alloy are listrd, and inspection of the tubes after being in service revealed them to be in very satisfactory condition. An excellent review by Angstadt ( 3 ) points out trouble areas to avoid in the melting, heat treating, and fabricating of Type 431 stainless steels. The author points out delta ferrite as the primary
Welding Stainless Steels Remarks Special emphasis on Nb-containing 187cCr-8 Ni ; recommendations for welding austenitic to ferritic steels Nuclear plants require many stainWelding copper to stainless steel less-copper combinations Use of Ni-Cr-Fe welding rods Welding dissimilar metals, including stainless steels (Inco-Weld A) Evaluation of brittle failure of Filler material for welding stainless multiple-alloy, high-strength arc steels and other alloys in fabricatwelded joints ing shipboard missile launching systems Details of components, electrodes, Welding nuclear power equipment, and welding processes including 300-ton reactor vessel Type 347 weld exposed to tank Welding pressure vessel of Type 347 interior, weld backing of Type stainless steel 307 stainless Search continues for weld metal to Developments in welding stainless steels replace Type 347 stainless Braze bonding preferred; best sysBonding 18% Cr-8% Ni stainless steel fuel elements for nuclear retern uses Electroless Xi-I' alloy deposited on stainless, followed by actors heating contacted parts at 1850 O1875 n F. Ag-Li alloy used for joining material Brazing 17-7 PH stainless steel sandwich panels for B-58 aircraft Preliminary tests determined weldFusion welding of 17-7 PH and 17-4 ing techniques for welding alloys PH stainless steels used in fabricatin hardened condition ing large, liquid-tight missile assemblies
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troublemaker from various aspects; it cannot be removed by any known metallurgical process after forming in cast ingots. However, by maintaining nickel and carbon on the high side of the allowable range and chromium on the low side it is possible to produce the alloy free of ferrite. Machining and heat treating characteristics and quenching procedures are also included in this summary. A new bonding process described by Davis (75) uses high vacuum, heat, and atmospheric pressure to produce a fluxfree metallurgical union of stainless steels and other alloys used in cladding. Details of the process, corrosion tests used, and fabrication and special applications of the cladding are included in the discussion. Information on hot machining high strength heat-resistant stainless alloys used in missiles and aircraft was presented by Scott (49). Plastic deformation, work hardening, and abrasive tendencies made these alloys extremely difficult to machine a t room temperature. Although investigational work concerning machining at temperatures u p to 1200’ F. is continuing, results thus far indicate that metal can be removed faster, work-hardening is eliminated, and tool life is increased by hot machining. A report (57) on metalworking by explosive forming illustrates stainless steel parts formed in this manner. Based on experience, it is recommended that explosive forming be considered for single shot forming, size finishing, improved mating of parts, and hardening of austenitic steels. The advantages and limitations of this relatively new process are cited, and further research could very likely result in more widespread use of this method of metalworking. The increasing demand for special stainless steel shapes available from warehouse stock created a need for a method t o cut the stainless to the customer’s specification. Wait and Resk (55) describe the procedure and equipment selected for tungsten-arc cutting of stainless alloys to satisfy the demand for special shapes. An investigation by Lowry and Thompson (35) concerned cleaning and passivating stainless steels. They studied ,existing methods of removing surface contaminants, dimensional changes as the result of pickling and/or passivating, and evaluated methods for determining surface iron contamination. For all types of stainless steels the authors considered exposure to 1 0 0 ~ ohumidity a t 100’ F. and alternate wetting in tap water and drying to be the two most satisfactory methods for determining iron contamination. A discussion (29) on a blast descaling machine for descaling the 300 and 400 series stainless steels
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prior to pickling is reported as reducing cost and increasing production rate. Line speed and blast stream control are among the unique features of the machine. Miscellaneous Iron-Base Alloys
A detailed report (74) on the application of high silicon iron as a material for impressed-current cathodic protection anodes presents factual data pertaining to the suitability of this material for anodes. I n addition to the discussion, which is divided into ground bed, fresh water, and salt water categories, extensive tables are included in each category outlining specific conditions under which various anode installations are operating. An article by Charmeau (77) considered the 16% silicon alloys with regard to their behavior in various organic and inorganic corrosives. Nickel steels containing 2.5 to 9% nickel were reviewed by Gill and Swales (23) for application in the petroleum industry where temperatures down to -321’ F. are encountered. The first part concerns the characteristics which render the steel suitable for sub-zero applications, and the second part deals with the low-temperature characteristics of the wrought, welded, and cast forms. Six grades of nickel-containing austenitic cast irons are covered in a specification (7) pertaining to various aspects of these alloys. Requirements as to manufacture, composition, mechanical and magnetic properties, and testing of these materials are outlined. Literature Cited
(1) Am. SOC.Testing Materials Preprint No. 2, 4-8 (1959). (2) Andrews, K. W., Huges, H., “Precipitation Processes in Steels,” Iron Steel Inst. (London) Spec. Rept. No. 64, 124-6 (1959). (3) Angst‘adt, C. C., Metal Progr. 75, 86-91 IJunr 1959). - (4) Bain, A.‘M., Clark, A. H., Lavigne, M. J., Zbid., 77, 96-100 (January 1960). (5) B., Weldinp ~, Bott, H. - J . (.N . Y .,) 38, 236-8 (March 1959). (6) Bradv, R. R., Boughner, D. T., Iron Age 184,90-2 (Aug. 11, 1959). (7) Brisbane, A., WADC (Wright Air Develop. Center) Tech. Rept. No. 58400 (January 1959). (8) Brooks, W. B., Corrosion 15, 103, 106, 108, 110 (September 1959). (9) Bungardt, K., Lennartz, G., Wetzlar, K., Arch. Eisenhiittenw. 30, 429-34 (July 1959) ____ (10) Ciplan, D., Cohen, M., Corrosion 15, 141t-6t (March 1959). (11) Charmeau, A., Metallurgie (Paris) 91, 441-57 (June 1959). (12) Clark, C. L., Rutherford, J. J. B., others, Am. SOC.Mech. Engrs., Preprint 59-Pwr-1 (1959). 13) Corrosion 15, 123t-4t (March 1959). 14) Ibid., 16, 65t-9t (February 1960). 15) Davis, R. A., Zbid., 15,88-90 (October 1959). \-
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(16) Defranoux, J. M., Werkstoffe u. Korrosion 10, 425-9 (July 1959). (17) DeLonp, W. T., Metal Propr. 77, . 98-100, 16OB (February 1960). (18) Dickerson, R. F., Battelle Tech. Review 8, 3-6 (April 1959). 19) Draht 10,222-4 (May 1959). 20) Dyrkacz, W. W., Metal Progr. 75, 138, 140-2, 144 (May 1959). (21) Furukawa, T., Sato, T., Nippon Kingoku Gakkaishi 23, 281-4 (May 1959). (22) Garofalo, F., Am. SOC. Testing Materials Preprint No. 78 (1959). (23) Gill, E. T., Swales, G. L., Brit. Petrol. Equip. News 7, 60-4 (Spring 1959). (24) Gregory, E., Simons, E. N., Edgar Allen News 38, 156-7 (July 1959); 177-9 (August 1959). (25) Groves, N. D., Eisenbrown, C. M., Metal Progr. 75, 78-81 (May 1959). (26) Hall, E. R., Iron Age 185, 100-1 (Jan. 28, 1960). (27) Hamstead, A. C., Van Delinder, L. S., Corrosion 15, 147t-57t (March 1959). (28) Iron Age 184, 50 (Dec. 31, 1959). (29) Iron Steal Engr. 36, 142 (December 1959). (30) Kasak, A., Hsiao, C. N., Dulis, E. J., Am. SOC. Testing Materials Preprint No. 74. . (1959). (3i)-King, P. P., McGeary, R. K., Welding J.38,241s-6s (June 1959). (32) Kobler, J. S., J . A m . Soe. Naval ’ Engrs. 71, 543-51 (August 1959). (33) Lanzara, A. A., Setapen, A. M., Welding J . 38, 118-24 (February 1959). 134) Linnert. G. E.. Metal Proer. 75, 127-8 ’ (June 1959). (35) Lowry, L., Thompson, J., U. S. Offic~ of Tech. Services. Naval Gun ~. Factory Tech. Rept. NGF-T-28-57, PB 131964 (1959). (36) Luce, W. A., Peacock, H., IND. ENG. CHEM. 51, 69A-70A (October 1959). (37) Lula, R. A., Metal Progr. 75, 116-20 (March 1959). (38) Marshall, M. W., Welding J . 38, 237s-50s (June 1959). (39) Materials in Design Eng. 49, 120-2, 124 (January 1959). (40) Meredith, R., Welding J . 38, 963-8 (October 1959). (41) Nielsen, N. A,, Werkstoffe u. Korrosion 10, 429-42 (1959). (42) Oppenheim, R., Znd.-Anr. 81, 191-8 r e b . 17, 1959). (43 Phillips, J. H., Singley, W. J., orrosion 15,450t-4t (September 1959). (44) Plesset, M. S., Am. SOC. Mech. Engrs., Paper No. 59-A-170 (1959). (45) Radavich, J. F., Corrosion 15, 613t-17t (November 1959). (46) Rutherford, J. J. B., Welding J . 38, 19s-25s January 1959). ;47) SchaAnit, W. O., U. S. Atomic Enerev Comm. Rept. IDO-16502 (Jan. 28,1559). (48) Schoefer, E. A., Machine Design 31, 119-25 (April 2, 1959). (49) Scott, R. A., A m . Machinist 103, 88-9 (Nov. 30, 1959). (50) Staehle, R. W., Beck, F. H., Fontana, M. G., Corrosion 15, 373t-80t 381t (July 1959). (51) Steel 145, 74-6 (Nov. 23, 1959). (52) Ibid., 146, 228-34 (Jan. 4, 1960). (53) Sutton, R., Metal Progr. jr5, 124-6 ’ (June 1959). (54) Tisinai, G. F., Samans, C . H., A S T M Bull. No. 238, 64 (1959). (55) Wait, J. D., Resh, S. H., Welding J. 38, 576-81 (June 1959). (56) Weldiug Eng. 44, 5-10, 12-13 (MidJune 1959).
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