PSI - Issue 53

João Alves et al. / Procedia Structural Integrity 53 (2024) 236–245 Author name / Structural Integrity Procedia 00 (2019) 000–000 1 shows defects 1, 2, 3, “a” and “b”. According to Murakami, if the distance between the √ defects 1 and 2 are less than the area of the respective defects; then these defects combine to form defect 3. However, Tajiri et al. (2014) proposed that if the distance between “a” in defect 1 and “b” in defect 2 is greater than the area of “a” or “b”, then defects 1 and 2 do not combine. It was observed that the proposed method of accounting for defect area enabled results closer to the experimental values. 239 4

Fig. 1. Illustrative example of defect quantification.

Masuo et al. (2018) studied the influence of defects, roughness, and heat treatment by hot isostatic pressure on the fatigue behaviour of a Ti-6Al-4V alloy produced by DMLS and EBM, using equations 2 and 5 to define the upper and lower limits of its behaviour. The authors concluded that the fatigue behaviour of the specimens treated superficially and by hot isostatic pressure could be effectively predicted by equation 5, with both values being very close to each other, indicating that the effect of defects is not very significant for their behaviour. On the other hand, the fatigue limit stress obtained using equation 2 proved to have a good correlation with the behaviour of the specimens, which were only treated superficially (machined) when the method used for area calculation was adapted to the effective area. Morgado et al. (2022) studied fatigue limit prediction models for an aluminum alloy 6060 manufactured through extrusion. They compared these models with those Murakami, Ueno, and Schönbauer proposed. After thoroughly analyzing the respective equations, the authors (Morgado et al., 2022) concluded that none of the existing models applied to an extruded 6060 aluminum alloy. The errors associated with these models exceeded 5%, a margin the authors deemed unacceptable. Consequently, they introduced their own models, presented as equation 8 and 9, which describes the fatigue behaviour of an aluminum alloy 6060 extruded, heat treated by T1 and T4, respectively. =0.55( +390)/( √ ) 1 6 (8) =1.53( +150)/( √ ) 1 3 (9) 3. Material and Experimental Procedure 3.1. Manufacturing process The material used in the experiment consisted of a titanium alloy powder, specifically Ti-6Al-4V. This powder was spherical , with diameters ranging from 20 to 53 μm, and its chemical composition is outlined in Table 1. The manufacturing process utilized for specimen production was Selective Laser Melting (SLM), with recourse to E-PLUS EP-M150 by SHINING 3D. Detailed parameters and conditions for this process can be found in Tables 2, 3, and 4, respectively. In Fig. 2., the process powder preparation cycle is presented since SLM is a technique that can reuse the powder that hasn’t melted in the previous operation.