Fracture mode transition phenomena in steels as a consequence of the change of operating deformation mode

Correlation between ductile-to-brittle transition behaviour and twinning in ferritic stainless steel

“…The size and dispersion of these (Nb, V, Ti)(C, N) precipitates might be different after two different processes, which will change the twinning behaviour and eventually affect the toughness. 17,22,31 So far, however, the effect of precipitate characteristic on twinning behaviour has not been investigated in a systematic manner. Further work on these aspects relating to the precipitate characteristic after different processes and its effect on twinning behaviour and toughness is needed and will be explored in depth in our future research results for clarifying the effect mechanism of precipitate on twinning and improving the impact toughness.…”

“…A similar sensitivity of cracking to deformation twins has been observed and proved on some steels and alloys by other researchers. [16][17][18][25][26][27][28][29][30] The initiation of microcracks at the tips of deformation twins is most probably associated with the existence of partial dislocations in the interfaces between lenticular twins and matrix. 22,[31][32][33] Because the deformation twin is lenticular, at least part of the boundary must be noncoherent, implying the existence of dislocations at the non-coherent interfaces, especially at the tip of lenticular twin.…”

“…brittle fracture occurs owing to deformation twinning). [16][17][18] As compared with carbon steels having ferritic structure, much less time has been devoted to understanding the physical metallurgy (including the mechanism of ductile-to-brittle transition and brittle fracture) of FSSs containing molybdenum. So far, little systematic work has been carried out on establishing the relationship between ductile-to-brittle transition, microstructural factors (e.g.…”

Twinning-dominated nucleation, propagation and deflection of crack in molybdenum characterized within situtransmission electron microscopy

“…A systematic study in tungsten [2] revealed that micro-cracks are prone to nucleate at the intersections of the deformation twins and free surfaces, grain boundaries (GBs) or other twins, because of both the stress concentration at the intersection point and the ineffective accommodation process in the bcc structure [9][10][11]. Moreover, the twin boundary can be the preferred crack propagation path under certain conditions, further reducing crack resistance [12][13][14]. In previous studies [1,2,15], the links between twins and cracks in bcc structures have been proposed and demonstrated, including the observations that (1) cracks and twins are independently produced, (2) cracks are induced by twins and (3) twins are induced by cracks.…”

A model on twinning-induced crack kinking out of a metal-ceramics interface

“…The rather low stacking fault energy of fcc metals promotes mechanical twinning with a sufficiently high strain concentration. Sufficient dislocation slippage is taken as a precursor for twin development since the lattice rotation needs strong relaxation (Blewitt et al 1957;Narita and Takamura 1992;Smida and Bosansky 2002). In essence, deformation twinning of fcc metals has many important features in competing with dislocation slip to be the dominant carrier of plasticity.…”