Deformation behavior of Fe-3% Si steel at high temperatures

Deformation behavior of a Fe-3% Si steel with ultrafine MnS inhibitors was studied in the temperature range 500-1000°C. The steel exhibits a threshold behavior. Analysis in terms of threshold stress shown that there were two characteristic modes of deformation behavior in the power-law creep regime. At temperatures 500-700°C the value of the stress exponent. n, is equal to 6, and the true activation energy for plastic deformation. Q, linearly increases from 170 kJ mol to value closed to 239 kJ/mol with temperature rise. A temperatures above 700°C the stress exponent is about 4, and the true activation energy for plastic deformation is about 240 kJ/mol. Two temperature dependencies of normalized threshold stress differed by a value of the energy term, Q0, were found in these two temperature intervals. The value Q0 is about 55 and 39 kJ/mol in an intermediate and high temperature range, respectively. Operating deformation mechanisms in two temperature regions are discussed.