Abstract
The lower yield stress and flow stress of two kinds of Fe-Si alloys with various grain sizes were measured in the temperature range between 77 and 473°K with strain rates varying from 10-6 sec-1 to 33 sec-1. These data were analyzed using the Hall-Petch relation,
It was found that the addition of Si to iron increased the athermal component of friction stress and decreased the thermal component. This decrease in the thermal component of friction stress caused the solid solution softening phenomena in Fe-Si alloys at low temperatures. The relations between the activation volume or activation energy of both alloys and the effective shear stress were not affected by the amount of Si added, but whole relationship was different from that of the pure iron.
The differences in the low temperature deformation characteristics between iron and Fe-Si alloys were explained from the viewpoint of interaction between moving dislocation and elastic stress field in the lattice around the solute atom, Si.
The strain rate dependences of the lowere yield stress of Fe-Si alloys varied continuously in the range of strain rates from 10-6 sec-1 to 33 sec-1. The relation between the effective component of lower yield stress and strain rate was well approximated by a power function at all temperatures tested.
