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

Abstract

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.

Microstructure and modelling of shear forming

“…Two examples of textures obtained during ECAE are shown in Figure 30 ). [36,39] Simple shear deformation can also be studied using a Split Hopkinson Pressure Bar (SHPB) [40].…”

“…Wong et al [40] used flat Inconel 718 specimens with the shape shown in Figure 32b, and compressed them between two bars to induce shear deformation in the red zone seen in Figure 32a. An example of the textures they obtained is shown in Figure 33, where the presence of adiabatic shear bands (ASB) 1 is very clear in the grain orientation map.…”

Adiabatic shear banding in FCC metallic single and poly-crystals using a micromorphic crystal plasticity approach

“…Meyers et al (2003) studied the microstructural evolution of adiabatic shear localization in stainless steel. Experimental investigations of the effect of strain rates, heat treatments, and grain size on the ASB formation in hat-shaped polycrystalline Inconel 718 specimens using Split-Hopkinson pressure bar test can be found in (Johansson et al, 2016(Johansson et al, , 2017Song et al, 2018). Furthermore, Song et al (2018) observed that the aged top-hat sample with small grain size and fillet radius has the largest tendency to form a shear band compared to the solution treated Inconel 718 specimens.…”

“…Experimental investigations of the effect of strain rates, heat treatments, and grain size on the ASB formation in hat-shaped polycrystalline Inconel 718 specimens using Split-Hopkinson pressure bar test can be found in (Johansson et al, 2016(Johansson et al, , 2017Song et al, 2018). Furthermore, Song et al (2018) observed that the aged top-hat sample with small grain size and fillet radius has the largest tendency to form a shear band compared to the solution treated Inconel 718 specimens. They observed shear bands of 10 µm width in aged Inconel 718 samples of average grain size 28 µm and 10 − 13 µm in solution treated samples of average grain size 18 µm.…”