PSI - Issue 53

S. Senol et al. / Procedia Structural Integrity 53 (2024) 12–28 Author name / Structural Integrity Procedia 00 (2019) 000–000

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continuous wave laser. Compared to the AB condition, the in-process dL-PBF treated surface (R) had a 73% lower surface roughness (Ra) and a 63% lower stress concentration factor (k t ).  It is shown that although compressive stresses are introduced during the first step of dL-PBF, subsequent to the re-melting step, tensile stresses are re-introduced and the surface residual stress state of dL-PBF processed surface condition is comparable to AB surface condition for this aluminium-based metal matrix composite.  The run-out level in as-built condition is realized at 124 MPa for high-strength (Ti+B 4 C)/Al-Cu-Mg metal matrix composite, similar to the 3PBF fatigue performance reported for AM205 and almost doubling the one for AlSi10Mg, despite the lower surface roughness recorded for the latter Al-Si alloy.  The fatigue life of the in-process dL-PBF treated surface (R) is significantly improved as compared to the AB condition, approaching to a comparable fatigue life level as conventionally machined (milled) surfaces. The lower surface roughness and concomitant stress concentration factor are distinguished as the main influencing factors for this improvement. Acknowledgements This project was funded by an FWO-SBO project: Hi-Pas (FWO reference number: S00931N). The FWO large infrastructure project (I013518N) is acknowledged for their financial support of the X-ray infrastructure and the KU Leuven XCT Core facility is acknowledged for the 3D image acquisition and quantitative post-processing tools (https://xct.kuleuven.be). The research at Yale University was supported by the United States National Science Foundation (Grant No. NSF CMMI-1901959). Authors would also like to thank to Shuhan Zhang from Yale University for SEM imaging of nanoindentations, as well as, from KU Leuven, Dr. Jitka Metelkova for the knowledge transfer on the dual laser processing and Yannis Kinds for his support on the dL-PBF experiments using 3D Systems ProX320 DMP machine with the integrated pulsed wave laser. Appendix A. Supplementary data on the microstructure of hybrid particle reinforced (Ti+B 4 C)/Al-Cu-Mg metal matrix composite

Fig. A. (a) Optical microscopy image displaying crack-free dense cross section, (b) SEM-BSE image displaying the as-built microstructure, c) zoomed in SEM-BSE image, white arrows indicating reinforcing Ti (bright) and B 4 C (dark) particles, while yellow arrow shows a spherical pore. Appendix B. Supplementary data on the full stress tensor for each surface condition Table B. The average surface roughness parameters (Ra and Rv) and the critical stress concentration factor (k t ) calculated from the surface profiles measured by tactile method for five surface conditions: as-built (AB), dL-PBF processed (R), wire electric-discharge machined (EDM), milled (M), and pulsed wave (PW) laser processed.