DUCTILE IRON AND METHOD FOR MANUFACTURING DUCTILE IRON FOR ENGINEERING COMPONENTS REQUIRING STRENGTH AND TOUGHNESS

摘要

The invention relates to ductile iron for engineering components requiring strength and toughness. This ductile iron is fine grain ductile iron. Fine grain ductile iron (FGDI) comprises as weight percentages: C 3.6-2.8, Si 1.3-2.6, Mg 0.065-0.025, Mn 0.8-0.1 and Cu 0.1-1.6, Ni 0.2-2.0, P 0.03-0.005 and S 0.003-0.01. The graphite sphere density of fine grain ductile iron (FGDI) is 150-400 spheres/mm2. The object of the invention is also a method for manufacturing ductile iron for engineering components requiring strength and toughness. In the method, raw materials are melted with induction melting (21), in the melt-treatment phases, the melt is spheroidised (22), inoculated (23) and cast (24), and after the shake-out phase of castings (25), the secondary operations of castings are performed (26). For manufacturing fine grain ductile iron (FGDI), the pieces are heat-treated in a URVA 850 heat treatment (28).