J. Phys. IV France
Volume 110, September 2003
Page(s) 93 - 98

J. Phys. IV France
110 (2003) 93
DOI: 10.1051/jp4:20020676

Strain rate dependency of dynamic flow stress of iron in wide strain rate range

K. Sakino

College of Engineering, Hosei University, 3-7-2 Kajino-cho, Koganei-shi, Tokyo 184, Japan

In order to clarify a rate controlling mechanism of iron, compressive tests for 0.01wt.%C iron are conducted in a strain rate range from about $1\times 10^{-3}$ to $2\times 10^4$/s and at temperatures ranging from 79 K to 473 K. Furthermore, to evaluate the effect of a strain rate history on the dynamic flow stress, strain rate change tests are performed in the strain rate range from about $1.0\times10^4\sim -1.6\times10^4$/s at temperature of 293 K. The results of measurement are treated on the basis of a theory of thermally activated process. In a high strain rate and low temperature ranges, a dominant rate controlling mechanism is a dislocation motion which surmounts the Peierls potential barriers with a aid of the thermally activated formation of kink pairs. Below the strain rate of 1/sec and at temperature of 293 K, the mechanism may be controlled by the thermally assisted cutting of point obstacles with moving dislocations.

© EDP Sciences 2003