10 - Tensile properties of AlSi7Mg thin specimens manufactured by laser-powder bed fusion

Abstract

Introduction The design of heat exchangers produced by additive manufacturing is a challenge to achieve the objective of net-zero carbon emissions from flying by 2050. A major advantage of additive manufacturing is the construction of complex structures that would be unfeasible using traditional manufacture processes. Within that context, a collaborative project between Sogeclair aerospace, CEA, Addup, and ONERA was initiated to provide a first version of such heat exchanger. ONERA’s scope includes the material characterization of the laser-powder bed fused (LPBF) AlSi7Mg. Moreover, the coming heat exchanger contains massive components, thin-walled tubes, as well as thin-walls. Those parts may have different tensile properties due to the different cooling rates involved during additive manufacturing. This paper presents the tensile properties evolution within the heat exchanger. More specifically, the objective of the present paper is to compare tensile properties of conventional tensile specimens with those of thin-walled tubular and thin-walled sheet specimens manufactured by LPBF using AlSi7Mg powder. Methodology Forty-two tensile tests were performed on conventional tensile specimens, thin-walled tubular specimens, and thin-walled sheet specimens at room temperature. For the thin-walled sheet and tube specimens four thicknesses were studied, namely, 250, 350, 500, and 750 µm. Each group of samples was in an as-built state. In addition, 3 others building techniques were used to manufactured thin-walled sheet specimens. The first technique was a wire electrical discharge (EDM) machining on an as-built sheet. The second technique was an as-built manufacturing with thicker grips sections. The third technique was an as-built manufacturing with thicker grips sections, which were then polished to increase parallelism of the grips sections. Finally, the effect of the tubular profile on the tensile results was also studied using cylindrical, square, and rectangular profiles. Results The results showed that decreasing the thickness reduced the mechanical properties. In addition, results from the tested thin-walled tube specimens showed that the tubular profile had an impact on the tensile properties. Fractographic analyses and tomographic characterizations are on-going to understand the observed variations. Results from the tested thin-walled tube specimens showed that the EDM machining provided higher tensile strength when compared to the others building techniques, as consistently observed by (Wawrzyniak et al., 2023). Finally, complex tensile specimens’ representatives of the heat exchangers are expected to be tested in the next couple of months. Numerical correlation from the complex tensile specimens with those of the elementary tensile specimens previously characterized are also expected.

Speaker

Charles Bianchetti

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ONERA, Châtillon, France

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Conference

10 - Tensile properties of AlSi7Mg thin specimens manufactured by laser-powder bed fusion

Date/Time

21/03/2024

10:45 am -11:05 am

Location

Room 6