Electron-beam powder-bed-fusion additive manufacturing was used to build Ti6Al4V blocks. Postfabrication thermal treatments were applied to modify the mechanical properties. The postfabrication treatments included hot isostatic pressing and solution treatment and ageing. The microstructure and mechanical properties of the as-built and postthermally treated material were characterised. The postfabrication treatments were found to be effective in homogenising the microstructure and reducing the number of defects/pores, which improved the material Charpy impact toughness and fatigue life with some reduction in the material's strength. Based on the present results, as well as data from previous literature studies, the reduction in material strength after the postthermal treatment is likely to be caused by the combined effect of α-lath coarsening and the low oxygen content of the powder feedstock.

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Laser powder bed fusion (L-PBF) is one of the most widely used additive manufacturing techniques for fabrication of components with complex geometries for various industrial applications including aerospace, medical and automotive. The unconsumed powder after part manufacturing is often recovered and recycled to improve process efficiency. However, some of the particles in the recycled powder can have different physical and chemical properties from those in the virgin powder owing to their exposure to the complex environment during the manufacturing process. In addition, some contaminants can be introduced in the recycled powder due to poor process control. A number of studies have been published in the past few years revealing the effects of powder recycling on the build properties. The present work aims to highlight the key phenomena during the manufacturing process that caused degradation to the recycled powder. Further to this, some comments, gaps and areas that deserve further detailed studies are also highlighted. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.