EFFECT OF AUSTENITE GRAIN MORPHOLOGY ON VARIANT SELECTION OF MARTENSITE TRANSFORMED FROM ULTRAFINE-GRAINED AUSTENITE

In this research, variant selection of martensite transformed from ultrafine-grained (ufg) austenite fabricated by accumulative roll bonding (arb) process and subsequent annealing was investigated with respect tomorphology of parentaustenitic phase. the results show that the original shape of austenite grain is very effective factor in determiningthe preferred variants of martensite transformed from the elongated ultrafine-grained austenite fabricated by 6-cycles via the arb process. annealing treatment of the austenitic samples subjected to the 6-cycle arb processed at 873 k for 1.8 ks suppressed the variant selection by changing the morphology of austenite grains from elongated ultrafine-grains to fully-recrystallized and equiaxed fine-grains.