Model of metal fracture in cold deformation and ductility restoration by annealing

Grain refinement versus voids accumulation during severe plastic deformations of polycrystals: mathematical simulation

“…5 (a). This was observed before experimentally (see Kolmogorov, 1997). This effect is captured by our model since as the loading direction changes, the number of sites where nucleation of micropores can take place decreases.…”

“…The smallest value of deformation before fracture is typically obtained in simple shear experiments (Kolmogorov, 1997).…”

“…There are a number of models allowing one to track changes in structural characteristics of metals during metal forming processes (e.g., Tvergaard, 1992;Raabe, 1998;Kolmogorov, 1997;Beygelzimer et al, 1994). None of them, however, takes into account the relation between grain refinement and ductile failure.…”

Improved ductile fracture criterion for cold forming of spheroidised steel

“…Continuum damage mechanics techniques have also been used to predict ductile fracture [17,18]. Kolmogorov and coworkers have introduced a phenomenological metal fracture model, which is used in practice of the metal forming in Russia [19][20][21][22][23][24][25][26][27][28][29][30]. Shabara et al [31] have assessed six widely recognised ductile fracture criteria utilising the experimental data from the cold upsetting of spheroidised steel specimens.…”

“…for the axial failure strain (ε zf ), we get the effective failure strain,ε f . Substituting the value ofε f in Eq (20),. the value of I 1 is obtained.…”