| Original austenite, martensite, reversed austenite, ausformed martensite, and two-phase structure of martensite and austenite were obtained by controlled heat treatment in Fe-32% Ni alloy. The mechanical properties of these structures have been investigated with respect to deformation degree. At all deformation degrees, the tensile strength becomes higher in the order, original austenite. reversed austenite, ausformed martensite, martensite. Undeformed states of original austenite, reversed austenite, and martensite show necking phenomena in tension test, and the strain hardening rate from yield point to necking becomes greater in the order, original austenite, reversed austenite, martensite. Although martensite and reversed austenite ale produced by diffusionless shear transformation, the susbstructure of the former mainly consists of internal twins in lenticular martensite crystal, while that of the latter consists of dislocations in lath type austenite crystal. Cells are formed in original austenite by deformation and their sizes are decreased with increasing deformation degree. However, they are not formed in martensite by deformation and transition bands at higher deformation degrees. |
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