A spectrographic method of analysis is described that allows rapid and accurate quantitative analyses of all metallic constituents in stainless steel stock. A direct current arc and a specially shaped carbon electrode allow chromium and nickel analyses accurate to 2 per cent of the quantity being measured. At the same time, satisfactory silicon, manganese, columbium, molybdenum, and titanium analyses can also be made. Complete analytical details are furnished, including a method of calculating results that takes into consideration the wide variation in iron content likely to be experienced in this type of material.N T H E last five years the spectrograph has been applied I successfully to the analysis of cast iron and low alloy steels (1, 8). I n these fields the great economic advantage of a method so rapid and accurate that it can give analysis in the foundry before the metal is cast, and so convenient that one analyst can do the work of five, was bound to be appreciated. With the advent of the war, such advantages are even more valuable. However, the great need a t the moment is to extend these methods to more and more alloys, so that testing methods can be made to keep step with the tremendous increase of metal production that is being experienced a t this time.The authors' laboratories have attempted to contribute to that need by developing a method of stainless steel analysis that is sufficiently accurate and rapid to be used for the routine analysis of chromium, nickel, manganese, silicon, columbium, molybdenum, titanium, and any other significant element by a single spectrographic procedure. The method represents a distinct step forward, as it allows the analysis of chromium up to 28 per cent and of nickel up to 20 per cent with results precise to f 2 per cent of the quantity being measured. This produces analyses, such as chromium a t 28 f 0.56 per cent, a t 18 =t 0.36 per cent, and a t 12 f 0.24 per cent; and nickel a t 20 * 0.4 per cent, a t 12 * 0.24 per cent, and a t 8 * 0.16 per cent. At first glance, this accuracy may not appear as acceptable as chemical methods, but a careful comparison, using repeat chemical analyses by different laboratories and spectrographic analyses by different operators, indicated that the latter suffer much less from random accidental errors than the former, and hence should be just as acceptable, particularly for routine testing. When the determinations of minor constituents are compared, the spectrographic method proves more accurate than the chemical method. Thus the combination of acceptable consistent analyses a t the higher percentages, and very precise analyses a t the lower percentages for a number of the metallic elements in stainless steel, makes this method of distinct value.In addition to extending the spectrographic method to the determination of alloying constituents a t high percentages, this work, in providing for the analysis of ordinary sheet and wire stock, removes the limitation of specially produced samples which has been found necessary in much previo...
