| Two different types of martensite structure of Fe-Ni alloy (20%Ni and 32%Ni), one having retained austenite and the other no retained austenite, were prepared and then the effect of prior deformation applied below Ad point on the austenite start temperature (As) of these martensites was studied. The As of Fe-32%Ni alloy increased appreciably up to about 40% deformation and then showed a nearly constant value above 40% deformation, while As of Fe-20%Ni alloy showed a constant value up to about 40% deformation and decreased gradually with further deformation. The different feature in the effect of plastic deformation on As in two alloys is attributed to whether retained austenite is present or not: in the absence of retained austenite, the reversal reaction is controlled by nucleation of new austenite, and in the presence of retained austenite, it is controlled by its growth. |
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