Metal additively versus conventionally manufactured structures – An environmental life cycle assessment

Abstract

The use of wire arc additive manufacturing (WAAM) in conjunction with topology optimisation enables the production of structural components with significantlyhigher strength-to-weight ratios than conventional structural components. How-ever, owing to the additional production stages involved in WAAM (e.g.arc welding), a commonquestion arises regarding the environmental impacts of using WAAM to produce structural componentsrelative to conventional fabrication techniques (e.g.hot-rolling.) Acradle-to-gate life cycleassessment is conducted herein to compare the environmental performance of a conventional hot-rolled I-section steel beam with that of a topologically optimised WAAM beam,the latter having 53% lower mass than the former.With regards to climate change, it is demonstrated that, for a typical deposition rate of 2 kg/h, WAAM can lead to lower CO2-eq. emissions than conventional hot-rollingiftopology optimisationcan offer mass reductions of at least~50%.The contribution of the individual processes in WAAM production is analysed, demonstrating that the use of shielding gas is the greatest contributor to the climate changeimpact of WAAM production.