Theoretical Study for Dynamic Strain Aging in Niobium: Effect of Temperature and Strain Rate on the Flow Stress

A constitutive model for niobium with the effect of dynamic strain aging is proposed. The crystal structure of metals hugely influences the dynamic strain aging phenomenon and causes considerable alterations in the material’s macroscopic mechanical responses. Dynamic strain aging needs to be accounted for in a constitutive model to obtain accurate predictions of material’s thermo-mechanical behaviors during deformation. The proposed constitutive model attempts to describe the material’s flow stress responses during deformation by separating the flow stress contributions into the athermal component, thermal component, and dynamic strain aging component. Two different mathematical equations are proposed to model the dynamic strain aging component. The proposed model attempts to describe the mechanical response of niobium for a wide range of strain rates: from quasi-static loading ( $$\dot{\varepsilon } = 0.001\,{\text{s}}^{ - 1}$$ ) to dynamic loading ( $$\dot{\varepsilon } = 3300\, {\text{s}}^{ - 1}$$ ) across the temperature ranges 77 K–800 K.