Effect of solution treatment on grain boundary structure of Inconel 617 alloy bar

The grain-boundary microstructure of Inconel 617 alloy hot-rolled rods during cold drawing and subsequent solution treatment is investigated using the electron backscattering diffraction （EBSD） technique. The results reveal that the microstructure of the hot-rolled rods contains a substantial number of coincidence site lattice （CSL） grain boundaries， predominantly Σ3 grain boundaries. Following cold drawing， the proportion of CSL grain boundaries decreases significantly， while the proportion of low-angle grain boundaries experiences a sharp increase. After solution treatment at 1120 ℃， low-angle grain boundaries are almost entirely replaced by high-angle and CSL grain boundaries. As the solution temperature rises， the proportion of Σ3 grain boundaries increases， whereas the proportions of Σ9 and Σ27 grain boundaries decline. Within a specific grain-size range， the proportion of Σ3 grain boundaries rises with an increase in grain size. During the solution treatment process， annealing twin boundaries with “cluster” and “island” morphologies emerge， and there exists a Σ3 n orientation relationship between adjacent grains.