Experimental analysis of additively manufactured component and design guidelines for lightweight structures: A case study using electron beam melting

Powder bed fusion additive manufacturing (AM) technology, such as electron beam melting (EBM) and selective laser melting, has attracted tremendous academic and industrial interests because of its capacity to fabricate components with greater complexity compared with traditional processes, without significantly increasing the cost. It provides significantly higher design freedom to the designers and can make the built components closer to the optimum design in theory when compared with traditional processes. However, the mechanical performance of the new design fabricated by AM has not been clarified yet. Here, we report the fabrication and tensile deformation behavior of the EBM-built lightweight car suspension double wishbone for both conventional and optimized designs. EBM process is an effective method to produce a highly-dense Ti-6Al-4V lightweight design component with good reproducibility and fine alpha/beta duplex microstructure. A poor mechanical performance in the optimized design is observed, which results from the build thickness-dependent mechanical performance that is caused by both various microstructures and rough surfaces in the Ti-6Al-4V parts. Notably, the rough surface plays a dominant role in premature failure when the build thickness is below 2 mm. Based on these findings, the degraded mechanical performance in the optimized design is discussed. The experimental results and analyses provide a guideline for the design of lightweight structures that are mainly comprised of thin walls and/or struts.