Modeling and measurement of residual stresses in a forged IN718 superalloy disc

The residual stresses present in a quenched IN718 aero-engine compressor disc forging have been characterized using neutron diffraction and the results compared to those obtained from a finite element (FE) model for the quenching process. The ∼40 kg forging had a diameter of ∼400 mm and a maximum thickness of ∼45mm. Neutron path lengths of up to 60 mm were required to record strain components at the deepest points within the material. The residual hoop and radial stresses measured are generally compressive at the surface, up to 600 MPa and tensile at depth, up to 400 MPa, whilst the radial stresses are generally small. The deviatoric stresses are generally <150 MPa. FE model predictions of the residual stress are reasonable agreement with the measured values.