Engineering Mechanics

Proceedings Vol. 9 (2003)

ENGINEERING MECHANICS 2003

Copyright © 2003 Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, v.v.i., Prague

 

Polák K., Bošanský J.
pages 268 - +5p., full text

The occurrence of deformation twins in the ductile-to-brittle transition (DBT) temperature region were observed under different testing conditions. Mechanical twinning could play a significant role in the DBT of polycrystalline ferritic structural steels. Frequent presence of nuclei of pre-cleavage micro-cracks (PCMC) which presumably related to deformation twins was revealed in close vicinity of cleavage facets or cleavage part of fractured surfaces. It was assumed that deformation twinning represent an integral part of deformation processes in the region of propagating cleavage crack tip and the deformation twins which nucleate in front of the crack tip act as nucleation areas for cleavage fracture nuclei. The assumed (re) initiation of cleavage fracture on deformation twins nucleating in front of propagating cleavage crack tip eliminates the contradiction between the results of recent brittle/cleavage fracture theory and the results of experiments.

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