|HALFA Hossam||Central Metallurgical R&D Institute|
Over the past 40 years a generic class of ultra- high strength maraging steels has been development mainly for aircraft, aerospace and tooling applications – the ultra – high strength of the most expensive maraging steels is due to the precipitation of intermetallic compounds (high nickel and molybdenum) during ageing process such as Ni3Mo, FeMo and Fe7Mo6. Production of such steels faces many great problems first, a great quantities of strategic elements Co, Ni, Mo second, retention of austenite, third, production methods which need double vacuum process. Due to the sharp increase in the cobalt price the development of a family of a cobalt free maraging steel is promoted. Titanium is used as one of the primary strengthening element replacing cobalt in steels. Furthermore, to overcome the problem of retained austenite, it is supposed that nickel content can be reduced to 12%. Maraging steels are usually produced using double vacuum melting technique. Due to the high cost of the double vacuum technique, electroslag remelting technique (ESR) can be successfully used to remelt the maraging steel and in turn improve its mechanical strength and ductility by selecting the suitable fluxes. The specific objective of this work aims at innovating cobalt free low – nickel maraging steel instead of the costly conventional high cobalt one. Visibility study of this work show that, the local produced steel will cost ≈ 800 L.E./kg comparing with 1100-1400 L.E./kg for the imported one.