In order to study the morphology transition behavior of deformation-induced lenticular and thin plate martensites, tensile tests have been carried out at various strain and different temperatures between Ms and Md for Fe-30Ni、Fe-30Ni-0.11C and Fe-30Ni-0.34C alloys austenitized at different temperatures. For the first two alloys, the morphology of thermally transformed martensite is lenticular and for the third one is thin plate. However, the morphology of deformation-induced martensites transites with in creasing temperature or strain. The results obtained by means of optical and transmission electron microscopy are as follows: (1) From lenticular to butterfly and then to mass martensite in Fe-30Ni alloy deformed at temperatures above Ms (Ms: -62 ℃、-57 ℃) and in Fe-30Ni-0.11C alloy above Ms+34℃ (Ms: -68 ℃). (2) From lenticular to small butterfly martensite in Fe-30Ni-0.11C alloy deformed at Ms+15 ℃ (Ms: -49 ℃). (3) From thin plate to couple-plate an then to lenticular couple-plate martensite in Fe-30Ni-0.34C alloy deformed at Ms+12 ℃ (Ms: -208 ℃). (4) From thin plate to lenticular martensite in Fe-30Ni-0.34C alloy deformed at Ms+48 ℃ (Ms: -208 ℃) and above the Ms temperature (Ms: -180 ℃, -170 ℃). The deformation-induced mass、 couple-plate and lenticular couple-plate martensites have not been reported before. Crystallographic and substructural features of these martensites have been investigated using TEM. The factors affecting the morphology of deformation-induced martensite and the mechanism of transition are discussed.
修改评论