Sustainability Assessment of Inconel 718 Turbine Blades Fabricated via Laser Powder Bed Fusion Using Waste-Atomized Powder: Environmental and Lifetime Trade-Offs

Additive Manufacturing (AM), particularly Laser Powder Bed Fusion (L-PBF), has developed into a reliable technique for fabricating components across a wide range of sectors. However, the energy demand and carbon footprint of feedstock and powder production represent a significant share of the cumulative energy demand (CED) and total CO₂ emissions. Consequently, growing interest has been focused on the use of end-of-life components as input material, following appropriate charge preparation prior to powder atomization. Certain number of studies have reported that employing atomized scrap, specifically Inconel 718, can reduce CED and CO₂ emissions by up to 90% while still maintaining mechanical properties close to those of virgin powders. However, for critical applications such as turbine blades operating under high-temperature conditions, even minor variations in mechanical behavior may result in premature failure or a reduction in service life. For this reason, the present work examines the influence of microstructure and mechanical properties of recycled powders and assesses their impact on expected creep rupture time and fatigue life through mathematical scaling. When creep-fatigue interaction is taken into account, the expected lifetime of components manufactured entirely from recycled powder is predicted to be reduced by approximately 34%. This shows the need to evaluate CED and CO₂ reductions on a service-life equivalent basis. Without accounting for lifetime effects, the use of atomized scrap through secondary production shows savings of about 33% in CED and 50% in CO₂ emissions over a cradle-to-grave LCA. Nevertheless, when compared to a reference batch manufactured from virgin powder, a greater number of recycled powder parts is required to achieve the same cumulative service life. Specifically, for a batch of 1000 turbine blades made from virgin feedstock, an equivalent lifetime would require approximately 1500 blades produced from recycled powder. In this case, the overall CED increases slightly by 0.5%, while the CO₂ savings are reduced from 50% to around 25%. These results underline that, while recycled powders can deliver substantial environmental gains, their true benefit must be assessed in relation to part durability and service-life performance. It should also be noted that, in the absence of creep coefficient data for recycled powders, all estimations in this research were scaled on the basis of available mechanical properties. Given the exponential form of the creep and fatigue equations, even minor variations in these coefficients may lead to deviations in the predicted outcomes. Accordingly, further experimental investigations are required to establish accurate coefficient values and to validate the predictive framework employed in this study.