Influence of alloying elements on the strain rate and temperature dependence of the flow stress of steels

After a short introduction to the theoretical background of thermally activ ated glide of dislocations, a constitutive model is presented, which descri bes the temperature and strain-rate dependence of the flow stress. The prop erties of this constitutive equation were estimated for several plain carbo n steels in normalized conditions, for quenched and tempered low-alloy stee ls, as well as for some high-strength low-alloy (HSLA) steels based on the temperature dependence and strain-rate sensitivity of the flow stress at te mperatures 81 K less than or equal to T less than or equal to 398 K and str ain rates 5 . 10(-5) s(-1) less than or equal to epsilon less than or equal to 1 . 10(-2) s(-1). The constitutive equation enables the extrapolation o f flow-stress data to higher strain rates (epsilon less than or similar to 10(+4) s(-1)), which are in good agreement with the results obtained from h igh strain-rate deformation tests. The influence of solute-alloying element s on the thermal stress, the activation enthalpy, and the constitutive para meters will be discussed.