Industrial Research 



295 



allurgical advances violate established concepts so 

 grossly as to appear, at first sight, to run counter to 

 fundamental laws. He says that really fundamental 

 advances are likely to come when someone pulls his 

 mind out of the rut that every other mind is following 

 and goes ofT in an entirely different direction. The 

 research-minded man is far more likely to jump out of 

 the rut than is the production-minded man. 



An example of this is the shift in the classification of 

 phosphorus in steel from the category of a poison, to 

 that of a tonic, as Sauveur ^ phrased it. In the very 

 early days of steel, high-phosphorus steels, in which 

 experience dictated that the carbon must be low, were 

 in use, because it was not known how to remove 

 phosphorus. But as advancing teclmology made it 

 more feasible to lower the phosphorus content, and 

 since high phosphorus causes cmbrittlement in the 

 presence of too much carbon, practice and specifica- 

 tions changed to limit that element to the lowest 

 practical level.* 



Copper and Phosphorus in Steels 



Some 25 years ago a committee of the American 

 Society for Testing Materials undertook research on 

 the resistance to atmospheric corrosion of steels of 

 varying copper content. This was done because of a 

 controversy between two factions of metallurgists, one 

 advocating a copper content of some 0.20 percent, the 

 other advocating "extreme purity," i. e., avoiding all 

 copper as nearly as possible. The experimental method 

 was adopted of exposing a large number of sheets of 

 known composition at a number of different locations 

 and observuig their resistance to the elements year by 

 year. The experiment took years for completion. 

 Not only was it made evident long before all the sheets 

 had rusted through that copper was a help, in resisting 

 the effects of such exposure, but Storey,' taking the 

 phosphorus content into consideration as well, pointed 

 out that it also was helpful. 



Much later in the search by research men for still 

 better corrosion resistance of bare steel in the atmosphere, 

 primarily from the point of view of roofing materials, 

 it was found that a low-carbon steel with the phosphorus 

 shockingly high according to ideas then prevalent, plus 

 copper and small amoimts of other alloying elements, 

 not only had somewhat improved corrosion resistance, 

 but a yield strength double that of ordinary structural 

 steel, plus satisfactory formabUity and weldability.^ 



• Sauveur. A. A review of progress in lerrous metallurgy. Steel, 99, 38 (July 6, 

 1936). 



• Gillett, H. W. Phosphorus as an alloying element in steel. MetaU and Alloyt, 6, 

 280, 307 (1935). 



'Storey, O. W. Discussion (Corrosion resistance of steel). Transaclicms oj the 

 American EUclwchemkal Socieli/, S9, 121 (1921). 



' Epstein, S. J., Nead, J,, and Halley, J. W. Choosing a composition for low-alloy 

 high-strength steel. Transactions of the American Institute of Mining and Metallurgical 

 Engineers, tiO, 309 (1936). 



Furthermore this was all accomplished at a very low 

 cost for alloying elements and without any need for 

 heat treatment. The suitability of such steel for 

 bridges, ships, railway cars, truck bodies, and so on was 

 obvious. A score of other steels of equal yield strength 

 and good corrosion resistance, some containing more 

 expensive alloying elements without phosphorus, others 

 containing phosphorus and still cheaper ingredients as 

 alloying materials came on the market in quick succes- 

 sion to fill a real need and form a brand new class of 

 structural steels." 



Once an erroneous belief is wiped out by some bold 

 research worker, a long train of industrial consequences 

 is likely to result, involving many other experimenters. 



Stainless Steels 



Another case of a long train of experiment is the 

 recent, but well-known stainless steel, 18:8, containing 

 18 percent of chromium and 8 percent of nickel, the 

 research development of which, along with that of the 

 plain chromium stainless steels, it would be interesting 

 to trace in detail were space available, since their cor- 

 rosion resistance and mechanical properties make them 

 extremely serviceable for a wide range of corrosive 

 conditions. It is commercially too expensive to make 

 18:8 with a very low carbon content i. e. less than about 

 0.06 percent. In welding 18:8 containing even this 

 small proportion of carbon, an embrittling separation 

 of carbides occurs as the metal cools from the welding 

 temperature by a precipitation phenomenon akin to 

 that which occurs in the heat treatment of duralumin. 

 To prevent this an element is added that will form a 

 more stable carbide and one less prone to dissolve and 

 precipitate in this fashion; molybdenum (the presence 

 of which is also helpful in resisting some special condi- 

 tions of corrosion) is useful and titanium and colum- 

 bium are especially potent. The addition of titanium 

 or columbium was the direct result of logical thinking 

 about the phenomena concerned, but their effective- 

 ness had to be proved by exhaustive experiment. In 

 the case of columbium, the world had to be scoured 

 for ores of this then rare metal to make sure that an 

 adequate commercial supply would be available. 

 This was no task for an individual researcher not backed 

 by ample funds. 



Clad Metals 



Once the technical value of the 18:8 type of steel 

 became established, the economic angle appeared. 

 On the basis of "save the surface, you save aU," many 

 began to ask whether a thin skin of stainless would 

 not suffice and whether a "clad" material, ordinary 

 steel with a mere fUm of stainless on the surface, could 



• Lorig, C. H., and Krause, D. E. Phosphorus as an alloying element In low 

 carbon, low alloy steels. Metals and Alloys, 7, 9, 61, 69 (1936). 



