296 



National Resources Planning Board 



not be developed. Alclad aluminum, a similar product 

 consisting of a strong aluminum alloy base carrying a 

 pure aluminum surface had previously been developed 

 and found wide use in aircraft. 



The cost of the cladding process proved so high with 

 18:8 that the expected margin of saving was difficult 

 to attain, but effort is being continued with signs that 

 ultimate success may be in sight. 



Hydrogen In Steel 



Failure through transverse fissures of rails in railway 

 service has caused bad wrecks and given railroad exe- 

 cutives much cause for worry. Means were developed 

 for detecting fissured rails in track and removing 

 them before failure, but this was cure rather than pre- 

 vention. The source of fissures was long in dispute 

 but is now regarded as preexistent internal shatter 

 cracks formed as the rail cools after hot-rolling. Cer- 

 tain slow cooling schedules have been found to prevent 

 cracking and are applied commercially to almost all 

 rails. It is now evident that the presence of hydrogen 

 fosters cracking and means to insure its absence are 

 being sought. 



The Rare Elements Put to Use 



Even in the limited number of cases mentioned 

 above, from the hundreds of equal import that could 

 be cited, the elements molybdenum, tantalum, selenium, 

 tellurium, beryllium, titanium, and columbium have 

 been mentioned as alloying elements commercially 

 utilized in steel, each of which does a specific job ex- 

 cellently. There is also hydrogen which is, in the case 

 cited, harmful. Ten years ago a book on metallurgy 

 written from the point of view of commercial practice 

 would have omitted all these elements save molyb- 

 denimi, and one of 15 years ago would very likely have 

 omitted that. The metallurgist of today recognizes 

 that there doubtless are no useless or meffective ele- 

 ments, and that, as in the instances cited of phos- 

 phorus and lead in steel, even the familiar ones may 

 at any time turn up in a new role. 



Nonferrous Examples 



While one naturally picks the steel industry to sup- 

 ply outstanding examples of successful research, case 

 histories are not lacking in the nonferrous industries. 



Zinc 



Zinc is a cheap metal. On a volume basis, it is a 

 vcrj' cheap metal. Its low melting point allows it to 

 be die-cast readily, with high production,, low cost of 

 operation, and remarkable precision of dimensions. In 

 the early days there were two chief grades of zinc, one 

 rather high in impurities but acceptable for galvanizing, 

 the other a high-purity 99.95 percent product smelted 



from naturally pure ores. Even using this high-purity 

 zinc as a material for alloys to be die-cast, the castings 

 were not stable and were prone to crack in time. Such 

 zinc die-castings had small commercial utility. In the 

 search for methods of utilizing some complex ores con- 

 taining zinc, electrolytic refining was tried and after 

 painstaking research was made both successful and 

 economical. When the solutions used were purified as 

 the process itself demanded the product was zinc of 

 99.99 percent purity. Coincidentally with this de- 

 velopment research had shown how to make and handle 

 the die-casting alloys to insure stability and it had 

 become clear that high purity was essential. Not only 

 was the pure electrolytic metal at hand, but an electro- 

 thermic process was also developed which produced 

 99.99 percent zinc. From here the zinc-base die- 

 casting industry progressed by leaps and bounds. Not 

 only the decorative grilles on motorcars, which could 

 be made from other materials, though not so cheaply 

 for equal decorative appearance, but more vital parts 

 such as fuel pumps for motorcars and many parts of 

 other industrial machines are now zinc die-castings 

 which serve adequately and cut costs materially. 



Magnesium 



A sizeable magnesium industry is being built up Ln 

 the United States based on the use, as a raw material, 

 of byproducts of the chemical utilization of natural 

 brines and, in a plant now being constructed, on the 

 utilization of sea water. These are very cheap sources 

 of supply. Though it is occurring more slowly, the 

 development of magnesiiun is following the pattern of 

 that of the aliuninuin industry, in spite of the handicap 

 of lack of corrosion resistance in some environments. 

 Research has steadily improved the corrosion resistance 

 and the mechanical properties of the magnesium alloys 

 so that they are finding extended use. Due to special 

 economic and political factors, the production and use 

 of magnesium has advanced faster in Germany than in 

 the United States, since some of the applications do not 

 meet the same competition there from other materials 

 of construction that they do here. Extension of our 

 use of magnesium on a purely engineering basis is 

 certain, because much research has already been done 

 and the producers have a definite program for continued 

 research that will inevitably result in still better mate- 

 rials. The price has already been progressively lowered 

 so that the costs of magnesium and aluminum are 

 practically equal on a volume basis. 



Aluminum and Precipitation Hardening 



About 30 years ago, Wilm, working in a Govern- 

 ment research laboratory in Germany, discovered the 

 heat-treatable strong aluminum alloy duralumin. Its 

 heat treatment was on an empirical basis and its use 



