Binder jetting 3D printing is an additive manufacturing technique based on the creation of a part through the selective bonding of powder with an adhesive, followed by a sintering process at high temperature to densify the material and produce parts with acceptable properties. Due to the high initial porosity in the material after sintering, which is typically around 5%, post-sintering treatments are often required to increase the material density and enhance the mechanical and fatigue properties of the final component. This paper focuses on the study of the benefits of hot isostatic pressing (HIP) after sintering on the mechanical and fatigue properties of a binder jetting Ti-6Al-4V alloy. Two different HIP processes were considered in this study: one at 920 °C/100 MPa for 4 h, and a second at a higher pressure but lower temperature (HIP-HPLT) at 850 °C/200 MPa for 2 h. The effects of the HIP on the densification, microstructure, mechanical behavior, and fatigue properties were investigated. The results show that the HIP-HPLT process produced a significant increase in the mechanical and fatigue properties of the material compared with the as-sintered parts and even with the conventional HIP process. However, the fatigue and fracture micromechanisms suggest that the oxygen content, which resulted from the decomposition of the binder during the sintering process, played a critical role in the final mechanical properties. Oxygen could reduce the ductility and fatigue life, which deviated from the behavior observed in other additive manufacturing techniques, such as powder bed fusion (PBF).

The development of nuclear fusion as a viable energy source will require the manufacturing of large-scale and complex components capable of withstanding extreme operational conditions. The RODAS project will address this challenge by developing and validating advanced manufacturing technologies, particularly additive manufacturing and Hot Isostatic Pressing, to fabricate demonstrator components representative of those needed in ITER (International Thermonuclear Experimental Reactor) and EU-DEMO (European Demonstration Power Plant) reactors. The project will focus on the production and qualification of fusion-relevant materials such as EUROFER97, CuCrZr, and AISI 316L (ITER-grade), using various additive manufacturing techniques adapted to large-scale applications. Through a coordinated effort among Spanish public research institutions and private technology centers and companies, RODAS will establish specifications, develop hybrid manufacturing routes, and implement non-destructive testing methods to ensure the integrity and performance of the produced components. Additionally, it will explore strategies for future in-service repair using remotely operated systems. The project will significantly strengthen the technological capabilities and international competitiveness of the Spanish industrial sector in the field of nuclear fusion.