J. Phys. IV France
Volume 112, October 2003
Page(s) 319 - 322

J. Phys. IV France
112 (2003) 319
DOI: 10.1051/jp4:2003892

Interphase boundary structures of lath martensite and bainite in steel

T. Furuhara, N. Miyajima, T. Moritani and T. Maki

Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan

Interphase boundary structures of lath martensite and bainite formed in austenite were examined by means of conventional and high-resolution transmission electron microscopy. Orientation relationships of the isothermal lath martensite in Fe-20Ni-5.5Mn and of the bainitic ferrite in Fe-2Si-IMn-O.6C are both slightly scattered in the vicinity of K-S, N and G-T relationships with respect to austenite. The broad face of martensite lath contains transformation dislocations (monoatomic steps with the (111) $_{\rm fcc}$//(011) $_{\rm bcc}$ terrace). Two kinds of accommodation dislocations exist alternately on every three layers of the parallel close packed planes, in a glissile arrangement. Such dislocations can fully accommodate the shear component of transformation strain. It is found that the atomic structure of bainitic ferrite/austenite interphase boundary is similar to that of lath martensite.

© EDP Sciences 2003