Indentation-Induced Deformation Behavior in Martensitic Steel Observed through In Situ Nanoindentation in a Transmission Electron Microscopy

Abstract:

Deformation behavior in the vicinity of grain boundary in Fe-0.4wt%C tempered martensitic steel were studied through in-situ nanoindentation in a TEM. Two types of boundaries were imaged in the dislocated martensitic structure: a low-angle lath boundary and a high-angle block boundary. In the case of a low-angle grain boundary, the dislocations induced by the indenter piled up against the boundary. As the indenter penetrated further, a critical stress appears to have been reached and a high density of dislocations was suddenly emitted on the far side of the grain boundary into the adjacent grain. In the case of the high-angle grain boundary, the numerous dislocations that were produced by the indentation were simply absorbed into the boundary, with no indication of pile-up or the transmission of strain.

• Periodical: Materials Science Forum (Volumes 503-504)
• Pages: 239-244
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.503-504.239
• Online since: January 2006
• Authors: Takahito Ohmura, Andy Minor, Kaneaki Tsuzaki, John William Morris Jr.
• Keywords: Dislocation, Fe-C Martensite, Grain Boundary, In Situ Nanoindentation, TEM

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