ON THE PRODUCTION OF PIG IRONS FOR NODULAR CAST IRON AND EFFECTS OF MINOR SPECIAL ELEMENTS IN THEM

Pig irons for nodular cast iron have been produced since 1953 by the blast furnace in Kamaishi Iron Works. But sometimes, it took place that inadequate pig irons for nodular cast iron were produced, although these contents of primary (C, Si, Mn, P, S) and secondary (Ti, As, Sn etc.) elements were within specification of pig iron for nodular cast iron.In order to inspect these accidents, the authors investigated the practical producing conditions of these irons. And the following results were obtained:The special elements such as Sn, As, Sb and etc. which came in pig iron from ore materials used in blast furnace had the harmful influence for the formation of nodular graphite, and the influence was emphasized by the presence of 0.05-0.1% titanium which was always contained in pig irons.Thus the authors were able to produce superior pig iron for nodular cast iron by using raw materials which contained the harmless amount of the above elements.