CORROSION RESISTANCE OF CAST IRON WITH AND WITHOUT ADDITIVE TREATMENT.

Treatment with FTsM-5 produces a compact graphite form and halves the room temperature corrosion rate; in this case, the difference between the matrix microstructures is 2 per cent in favour of pearlite. At the higher testing temperatures, the corrosion rates increase by factors of 3 and 7 and the differences increase to 15 and 12 percent respectively. Mg-treated nodular iron is 2. 5 times more corrosion-resistant at room temperature than untreated flake graphite iron. Once again, the pearlitic matrix is the better, by 20 percent. At the higher test temperatures the corrosion rates increase by factors of 4. 5 and 8 and the differences are 14 and 9 percent, respectively in favor of pearlite. Experimental results demonstrate that the corrosion resistance of plain gray cast irons is largely determined by the graphite flake size.