Effects of Alloying Elements on the Mechanical Properties of Steels at Low Temperatures

Abstract

AbstractThe low-temperature tensile properties of dilute Fe–C, Fe–Nb–C, Fe–V–C, Fe–N, Fe–Nb–V–N, and Fe–V–N steels have been analysed. The major differences in the plastic behaviour of the alloys arise from their athermal stress/strain behaviour. The lower yield strength vs. temperature relations correspond qualitatively with the Peierls mechanism for thermally activated deformation. The activation volumes also agree well with expectations based only on the Peierls mechanism. The results suggest that the Peierls stress, kink energy, and shapes of the Peierls hills are insensitive to alloy composition and heat-treatment. The fact that higher yield stresses at 298° K also gave higher values of Tc , the temperature at which plastic behaviour becomes athermal, has been interpreted to mean that the product, ρL, of the density of mobile dislocations times the dislocation length swept out by a pair of kinks decreased as the athermal component of stress increased.