Jj. Gracio, INTERACTION BETWEEN THERMAL RECOVERY AND THE CHANGE IN STRAIN PATH INLOW-CARBON STEEL, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 174(1), 1994, pp. 111-117
Tension experiments were performed on mild steel samples predeformed i
n rolling or predeformed in rolling and recovered. Particular attentio
n was paid to the transient mechanisms produced by a change of the loa
ding mode. In the predeformed and unrecovered specimens just after rel
oading, there occurs a rapid now localization and gradual evolution to
fracture. In the predeformed and recovered specimens, changing the st
rain path produces the abrupt occurrence of a short transient domain o
f plastic instability, characterized by a serrated flow. Transmission
electron microscopy observations showed that the appearance of this do
main is connected with the drastic dissolution of the cell walls creat
ed during the prestraining, as the result of bath latent hardening and
Bauschinger effects. After this short domain of plastic instability,
the dislocations rapidly organize according to the new loading conditi
ons, leading to a renewed increase in the flow stress.