Effects of different heat treatments on the dynamic shear response and shear localization in Inconel 718 alloy

The effects of different heat treatments on the dynamic shear response and the adiabatic shear localization characteristic of Inconel 718 alloy (Inconel 718) are studied by the flat hat-shaped sample subjected to the Split Hopkinson Pressure Bar (SHPB) loading. The microstructures of the concentrated shear zone are examined by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), and Vickers micro-hardness tests, respectively. The results indicate that the aged Inconel 718 with higher yield strength and lower strain hardening rate is easier to form an adiabatic shear band (ASB) than that of the solution treated Inconel 718 under dynamic shear loadings. Meanwhile, it has been found that the δ phase plays an important role in inhibiting the shear localization of the solution treated Inconel 718. Little plastic deformation occurs in the region adjacent to the ASB in the aged Inconel 718, whereas significant plastic deformation occurs in a certain width area around the ASB in the solution treated Inconel 718.