Stress relaxation in alpha-iron at low temperatures

Relaxation of the applied tensile stress [sgrave] at strains of up to 2% was studied at 77–358°k in vacuum-annealed iron containing 0·1% of carbon. The relaxation was logarithmic, and the slopes of the curves. increased from 19·7 kg/cm2 at 358°k to 313 kg/cm2 at 77°k. The relation previously derived for stress relaxation in copper, in which T m is the melting temperature, [sgrave]y the tensile yield stress and [sgrave]g the temperature independent part of the yield stress, was again found to be applicable, with Qj , the energy associated with the conservative migration of jogs in edge dislocations, equal to 6·4 kcal/g atom.