Mechanical and microstructural assessment of additive manufacturing parts made up of 18%Ni Maraging 300 steel towards aeronautic application.

Abstract

The aeronautical industry requires a technological maturity from new fabrication processes intended to become part of the productive process of planes. Additive manufacturing (AM) of parts made in steel could offer several solutions in this industry (e.g. structural parts, fundamental parts in engines and turbines), envisioning of parts redesign or creation prioritizing weight reduction. However, a better understanding between microstructural and mechanical properties of AM parts need to be reached. In addition, the search for materials with environmental sustainability is a strategic pillar of the aeronautical industry. Regarding structural applications, the 18%Ni Maraging 300 (18Ni300M) steel stand out among the commercialized steels, providing high mechanical strength (>2000 MPa) and good fracture toughness (80 MPa m0,5). Parts made of 18Ni300M by AM lost toughness and mainly strain capacity when compared to similar steel fabricated by conventional forging. The causes of this behavior are the heterogeneity of the microstructure and segregations presence. Therefore, this project aims to increase fracture toughness and strain capacity without affecting the standard mechanical strength of standard samples made by AM in the 18Ni300M steel. To achieve this objective, solution, intercritical and aging physical-thermal treatments are going to be performed foreseeing a better understanding of the microstructural evolution in each treatment stage. Thus, new routes of thermal treatments will be proposed. The in-situ tests are going to be performed in a physical simulator with an X-ray diffraction facility from a synchrotron source. The microstructure will be studied using microscopy and mechanical properties will be assessed by tensile and fracture toughness tests. Finally, the environmental impacts of the produced samples will be studied by the life cycle assessment (LCA) technique. (AU)