Numerical, Mechanical, and Metallurgical analyses of an innovative lightweight titanium conrod additively manufactured

This study presents findings of an investigation on the reduction of the weight of a critical engine component manufactured by means of additive manufacturing technologies. The component under examination is a Ti6Al4V connecting rod (conrod) having a non-conventional optimized structure produced with SLM. Thanks to the capabilities of the AM technologies, the innovative near net shape design allows: the manufacturing of a lightweighted part, the reduction of some difficult machining operations, and the integration of conformed cooling channels into the part. To take full advantage of these potential benefits, a careful work is necessary to carefully consider all the aspects connected with the product development to ensure the feasibility of replacing the traditional and consolidated manufacturing methods for serial production in the automotive field. In this work we present a summary of the research activities carried out and in progress to assess the innovative conrod design, including selection of heat treatment after experimental characterization of mechanical properties, finite element analyses of the component and fatigue tests on a full-scale prototype, integrated with metallurgical investigations and fracture surface analyses. These activities helped to identify critical locations for fatigue performance, which could pave the way to potential future improvements (i.e. post-processing and re-designing specific component regions based on local methods for fatigue prediction).There is currently very limited literature about the development and testing of actual SLM Ti6Al4V parts and the results of the present work are also a first test bench toward the definition of procedures for the fatigue assessment of real additively manufactured full-scale components.