Extraction of slag and oxide inclusions in iron or steel: Electrolytic method

Abstract

ANY methods of ext r a c t i o n other than electrolytic have been devised for the determination of non-metallics in iron and steel, but none have been satisfactory for all t y p e s of oxides. The outstanding method a t the prese n t t i m e is t h e Dickenson method (2) which will extract silicon dioxide and aluminum oxide from "killed" steels with varying degrees of accuracy. However, this m e t h o d will n o t give a quantitative extraction of inclusions which contain ferrous and manganous oxide from ''rimming" steels (4). In fact, after a detailed study of .extraction methods proposed to date and outlined by C. H. Herty, Jr., and others (4), and by Westcott, Eckert, and Einert ( 7 ) , it is seen that none are satisfactory for use upon steel. A l a r g e s a m p l e must be used, as it is absolutely necessary, in a study of inclusions, to have enough non-metallics extracted for the determination A f i ELECTROLYTIC method, rapid, simple T h e o u t e r cell is a l a r g ein operation, and inexpensive, for the determouth reagent Of about 3 liter capacity, with a cork to mination of oxides found in plain carbon steel fit. The inner cell is a and iron as inclusions, has been successfully r e a g e n t bottle with the b o tdeveloped. Magnesium iodide is used as the tom cut off. The cork of the electrolyte and is found to be superior to a n y outer cell has a hole cut in it to used heretofore.fit the neck of the inner cell, and these are fastened together so The sulfides are not determined, but only the as to support the inner cell. oxides of manganese, silicon, and iron. I n theThe cork f i t t i n g t h e s m a l l e r "killed" steels where the principal inclusion is bottle has a hole punched in manganous silicate, the recovery is practically it for the platinum wire to pass 100per cent; in the "rimmed" steels, slighfly less. through* The cathode is made of the The accuracy of the method has been deterordinary copper Screen used in mined through the use of slaggy material containwindow screens. A piece is ing various percentages of ferrous, manganous, cut as long as the circumference silicon, and aluminum oxides. This material and as wide as the straight sides was actually formed in the rimmed ingot of steel, of the large bottle. Two strips of screen are f a s t e n e d as conand was collected for the study. It is believed tacts to the screen It is that such material is a definite improvement overthen rolled up and inserted into the use of synthetically prepared compounds, as the bottle, where it unrolls and it is the same physically and chemically as the forms a cylinder. The contact inclusions dispersed throughout the steel itself. s t r i p s a r e b e n t d o w n on the outside of the bottle neck and fastened together with a third of their physicaland chemi-band of wire screen. Figures 1 and 2 show the cell in detail. cal properties. Also the extraction must b e fairly rapid and must not require from 2 to 6 weeks as does the Dickenson method.As regards previous work on electrolytic methods, nothing was found...