Abstrait

Test of elaboration protocols for obtaining highly Co- or Ni -alloyed spheroidal cast irons from an industrial SGcast iron. Part B: second protocol. subpart 1: obtainedmicrostructures

KamelMeridja, Patrice Berthod, Elodie Conrath

{Co, Fe}-based and {Ni, Fe}-based cast irons with spheroidal graphite may be interesting alloys, simultaneously easy to cast, displaying highmechanical properties including tensile strength, chromium-free corrosion-resistantÂ… A first protocol tested to obtain such cast irons at a laboratory scale without the liquid metal treatment facilities of industry, did not succeed in obtaining a nodular shape for graphite. In this new work, an elaboration in two steps involving the preparation then the use of mother alloys, was imagined and applied. Graphite spheroids were successfully obtained in the cobalt-rich cast iron, but together with flake graphite. Since the same protocol applied to the elaboration of similar cast iron but with only Fe, in parallel for comparison, allowed recovering the total nodular character of graphite, it seems that nickel, and maybe partially cobalt too, are intrinsically unfavourable to the spheroidal growth of graphite during solidification.