Hot formability of inconel $718$ using constitutive equations

Hot deformation behavior of an Inconel $718$ superalloy was investigated by hot torsion tests over wide ranges of strain rate and temperature. In this study, the effects of hot deformation parameters (deformation temperature and strain rate) on flow stress are analyzed. The flow stress of the solution treated superalloy was significantly affected by deformation temperature and strain rate, the samples were then deformed in the temperature range $1050$–$1100^{\circ}$C, under strain rates of $0.01{,}~0.1{,}$ and $1$ s$^{-1}$. The flow stress decreased with strain rate or the increase of deformation temperature. Based on the experimental results, a constitutive model was developed to describe the hot deformation behavior. The microstructural analysis of the testing samples were performed, in order to correlate the microstructural state with the mechanical properties of the Inconel $718$.