43 - Dimensional Growth of Ductile Iron Castings During Heat Treatment

Abstract:

The dimensional changes upon heat treatment were studied in three grades of ductile iron – ferritic, ferritic-pearlitic and pearlitic grades. The amount of growth was measured in five different heat treatment cycles, including subcritical annealing, full annealing, normalizing and quench and tempering. All materials increased in length upon heat treatment. The dimensional change ranged from less than 0.001 inch per inch to greater than 0.004 inch per inch. The maximum growth occurred in annealing, and the amount of growth in annealing was proportional to the amount of pearlite in the starting microstructure.