In-situ shelling via selective laser melting: modelling and microstructural characterisation

This study focuses on the use of selective laser melting (SLM) to produce tooling (a shell) that is filled with powder and subsequently consolidated via hot isostatic pressing (HIPing) so that the tooling, rather than being removed, becomes part of the sample. The microstructures of HIPed samples were studied using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) to assess the bond between the shell and the consolidated powders. The columnar grains in the SLM-built tooling bonded with the powder although the grains in the tooling were found to be much coarser than those in the HIPed powder, leading to preferential failure in the tooling. However, failure occurred in a fairly ductile mode and reasonable tensile strengths and ductility were obtained. Finite element models were developed to define the required initial shape of the shell in order to obtain the correct geometry after HIPing. It was found that the final shapes predicted are consistent with the observations on HIPed samples.