Flow Stress and Work Hardening Behavior of 92W-5Co-3Ni Alloy at Different Strain Rates and Elevated Temperatures

The present study is mainly focused on understanding the flow stress and work hardening behavior of the 92W-5Co-3Ni alloy. Initially, the uniaxial compression tests were performed at different strain rates ranging from 1 to 100 s⁻¹ at an interval of 25 s⁻¹ and temperatures from room temperature, RT (32 °C) to 600 °C at an interval of 200 °C. The results demonstrated that the flow stress variation is more sensitive toward temperature change than the strain rates. At room temperature and 200 °C conditions, the nature of flow stress exhibited a gradual decline after reaching a peak strain across all strain rates. Whereas, the flow stress attained a steady state at 400 and 600 °C deformation conditions. Subsequently, the crystallographic texture analysis of the tungsten phase was studied by the electron back-scattered diffraction (EBSD) technique. At a strain rate of 1 s⁻¹, the random poles of (110) planes transform into a fibrous texture within the CD-TD plane when the strain rate was increased to 100 s⁻¹. The four peak poles of the (111) plane were observed along the compression direction at 100 s⁻¹. The plastic deformation was influenced by simultaneous work hardening and thermal softening. The three distinct hardening stages were observed for WHA alloy. Finally, the Hollomon and Ludwigson models were used to predict work hardening behavior. In the lower strain region, the Ludwigson model showed a better prediction capability than the Hollomon model. Whereas in higher strain regions, both models demonstrated their suitability for predicting flow stress behavior. Overall, the Ludwigson model proved the capability for accurate flow stress prediction in various strain rates and temperatures.