Hybrid post-processing effects of magnetic abrasive finishing and heat treatment on surface integrity and mechanical properties of additively manufactured Inconel 718 superalloys

Abstract

• The magnetic abrasive finishing and post heat treatment are hybrid to apply for the additively manufactured In718. • The hybrid effects on the surface integrity and mechanical properties are studied comparatively. • Excellent mechanical properties of the additively manufactured In718 are obtained by the proper post-processing sequence. • The influencing mechanism of the hybrid post-processes provides a promising pathway to improve the mechanical properties. Desired microstructure and surface integrity are critical to achieving the high performance of additively manufactured components. In the present work, the hybrid post-processes of magnetic abrasive finishing (MAF) and post-heat treatment (HT) were applied to the additively manufactured Inconel 718 superalloys. Their hybrid effects and influencing mechanism on the surface quality and mechanical properties of the additively manufactured samples have been studied comparatively. The results show that the MAF process effectively reduces the surface roughness by more than an order of magnitude due to the flexibility and geometric consistency of the magnetic particles and abrasives with the finished surfaces. The proper sequence of MAF and HT obtains enhanced mechanical properties for the homogenized-MAF-aged sample with the yield strength of 1147 MPa, the ultimate tensile strength of 1334 MPa, and the elongation of 22.9%, which exceeds the standard wrought material. The surface integrity, compressive residual stress field, and grain refinement induced by the MAF and subsequent aging heat treatment increase the cracking resistance and delay the fracture failure, which significantly benefits the mechanical properties. The MAF process combined with proper post-heat treatment provides an effective pathway to improve the mechanical properties of additively manufactured materials.