FERRITIC HIGH-SILICON CAST IRONS

摘要

Cast irons contain (1) carbon and silicon at a carbon equivalent of 4.35 to 4.95; (2) transition metals of Groups 5 and 6 in the Periodic Table (Cr, Nb, Mo, Ta, W, and V) of which the total contents are no greater than about 3%; and (3) minor elements such as up to about 0.050% phosphorus (P), and up to about 0.080% total residual of magnesium (Mg) and REM (rare earth metals), and (4) the balance iron (Fe) with inevitable impurities. The graphite nodularity in the microstructures is mixed graphite, preferably from 40 to 80% graphite nodularity, or spheroidal graphite mainly dependent upon the casting geometry and service conditions. The cast irons exhibit higher thermal stability, oxidation resistance, middle temperature ductility, and thermal fatigue resistance than conventional SG or CG high-Si iron or SiMo iron.