INCREASED quality, which is reflected through higher valve-seat hardness and improved microstructure, can be obtained by additions of nickel and chromium to automobile-cylinder iron. Different combinations of these alloys were used, and it was found that a ratio of three parts of nickel to one of chromium gives the greatest improvement in structure in conjunction with maximum hardness. The effect of prolonged heating on three representative plain irons, as well as on three nickel-chromium-alloyed irons of the same base composition, is also shown. A marked difference is revealed in these cases in favor of alloyed irons. A method is given of producing chilled roller wheels by additions of chromium in the ladle instead of using special cupola charges. This is capable of better control and results in a superior product.
