Sa. Moir et al., EVOLUTION OF MICROSTRUCTURES RESULTING FROM DENDRITE GROWTH IN UNDERCOOLED FE-CR-NI MELTS, Acta materialia, 46(11), 1998, pp. 4029-4036
Citations number
28
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
Experiments have been carried out For two alloys Fe69Cr1Ni30 and Fe69C
r7Ni24 to investigate the evolution of microstructures of steels grown
from undercooled melts. The microstructures undergo several critical
transitions as the undercooling at which solidification starts is incr
eased. Firstly, grain size can change by up to an order of magnitude f
rom small to large and back to small at critical undercoolings. Second
ly, the segregation pattern changes from dendrilic/equiaxed to dendrit
ic and finally to equiaxed with increasing undercooling. Measurements
from the segregation patterns indicate that the primary dendrites had
undergone considerable Ostwald ripening depending on the processing co
nditions (heat-extraction rate). Relating the measured trunk sizes to
an original trunk size through ripening and then applying this value t
o a recent model for grain refinement, which is based on dendrite frag
mentation, yields a rough approximation to the critical transitions of
the grain size. (C) 1998 Acta Metallurgica Inc.