On the Carburization of Iron

Abstract

THE conditions under which carbon combines with iron have been closely studied, and the observed phenomena fully discussed. Even now, however, it is doubtful whether true chemical combinations of carbon and iron are formed. It has been alternatively assumed that carbon is with difficulty soluble in iron, and that at low temperatures solution may proceed very slowly. In other words, carbon is not easily dissolved except at high temperatures; and it follows that if highly heated iron fully charged with carbon be cooled, a portion of the carbon must be precipitated in this state, existing simply as foreign matter in the metal, but that, on reheating, it may again enter into solution. Low carbon steels may be regarded as dilute solutions of carbon in iron; pig or cast iron as saturated; and intermediate grades may be termed moderately concentrated solutions.