PSI - Issue 57

Mathilde Renault et al. / Procedia Structural Integrity 57 (2024) 22–31 Mathilde RENAULT/ Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction In the field of additive manufacturing, the WAAM process is a promising technique that enables the production of complex metal parts with reduced costs and rapid lead times. However, the quality and performance of parts manufactured by WAAM are influenced by many factors, such as the process parameters, the material used and the surface configuration. In this study, we are particularly interested in analyzing the surface of as-built WAAM-manufactured parts. The surface of an as-built WAAM part often has rough and irregular characteristics due to the deposition process. This surface roughness can have a significant impact on the mechanical properties, and we are particularly interested in the area of high-cycle fatigue. In this context, our main objective is to analyze the surface roughness and study the fatigue crack appearance and propagation behavior of surfaces manufactured by WAAM. We will build on the preliminary work carried out by (Bercelli et al. 2022) on raw surfaces taken in the direction of deposition of the layers. The aim is to understand the impact of surface roughness on the fatigue properties of parts manufactured by WAAM. We will also try to assess the effect of anisotropy on the fatigue life. To highlight the effects of the surface condition, 4-point bending tests monitored by infrared camera are carried out. Thermometric measurements are used to detect and monitor cracks. The results obtained will be compared with those presented in (Bercelli et al. 2022) to quantify the effects of surface anisotropy in fatigue. 2. Material and setup In this section, the study material and experimental set-up are presented. They follow on from the publication by (Bercelli et al. 2022). 2.1. As built WAAM surface The material studied is a copper alloy (CuAl9Ni5Fe4) for naval applications. It is produced by Naval Group and supplied in the form of a 450x220x35mm block that has undergone stress-relieving heat treatment. Tensile tests on a servo-hydraulic bench were carried out to determine the mechanical properties of the machined material as described in Table 1 . The results showed little or no anisotropy on macroscopic scale.

Table 1 : Mechanical properties of WAAM bronze aluminum

0.2 ( ) (MPa) 394 852

% (%) 19.0

E (GPa)

112.5

The rough surface was analyzed using a Keyence VHW 5000 optical microscope, as illustrated in Figure1. A 3D analysis was carried out on a 37 mm x 37 mm surface.

Figure1: Keyence optical image of rough surface with chosen convention (transversal or longitudinal) of specimens