Determination of Limiting Dome Height (LDH) values for Inconel 718 alloy sheet using FEA and Hemispherical Punch Method

Abstract

In this work, initially the chemical composition of Inconel 718 alloy sheet was obtained using X-ray fluorescence technique (XRF). The material properties such as yield strength, ultimate tensile strength, percentage of elongation, normal anisotropy, planar anisotropy, strain hardening exponent, and the strength coefficient were determined in longitudinal, diagonal, and transverse rolling direction using a uniaxial tensile test. The Limiting Dome Height (LDH) values are obtained by simulation and experimentation based on the hemispherical punch method. In simulation work, Barlat-89 yield criterion was used to obtain the Limiting Dome Height (LDH) values and strain distribution along with the specimen in Abaqus 6.1 software. The experimental LDH values of Inconel 718 alloy sheet and simulated results obtained from Abaqus 6.1 software were in close agreement. The approach presented in this work can be applied to obtain the LDH test values of interesting material focused by researchers. With the help of experiments, a limit curve was established which ensures the safe working region of Inconel 718 sheet.  Scanning Electron Microscope (SEM) analysis of 100 &120 mm width specimens indicated smooth surface and ductile fracture. The examination of 140 &160 mm width specimens showed rough surface and shear-ductile failure. Energy Dispersive Spectrum (EDS) analysis of a fractured surface confirms the constituents of the sheet present before failure.