The heat-affected-zone microstructure, its microhardness and the redistribution of the carbon concentration of the ductile cast iron irradiated by a CO_2 laser are described, and the process of dissolution of the spheroidal graphite and the structural changes in the vicinity of it on rapid heating is discussed. The partial melting phenomenon around the spheroidal graphite and the reabsorption of carbon atoms in the graphite, which have already diffused into the matrix, are explained qualitatively.
Transactions of JWRI 17 (2), 381-384, 1988-12
Osaka University
