PSI - Issue 75

Ninian Sing Kok Ho et al. / Procedia Structural Integrity 75 (2025) 35–42 Author name / Structural Integrity Procedia (2025)

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Figure 5: a) Typical surface defect observed on the milled face of a sample and b) example of a defect on the face opposite to the milled bottom surface, both from the 210 mm, H, HT, milled batch. 4. Conclusion Horizontal surface characterization for S-N performance involves asymmetrical surface finishing on the four sides of prismatic E466 fatigue samples. Removal of support structures can leave surface defects. Precision grinding to eliminate them improves S-N curve performance, similar to milling of the support structure surface. Meanwhile, the top surface is smooth in the central portion being almost flat. Heat treatment further raises the S-N curve, likely due to the alleviation of residual stresses and part distortion. Even so, the majority of samples failed on the milled face, with 2 samples that failed elsewhere falling away from the linear S-N trend. This study shows the importance of addressing the non-uniform surface textures in horizontally built parts, shows how fatigue failure can favour the support structure surface, and discusses the scatter in relation to vertically built parts with no such surface texture differences around the gauge section. Acknowledgements The authors would like to acknowledge that this research work is supported by The RIE2025 Manufacturing, Trade and Connectivity (MTC) Industry Alignment fund Pre-Positioning (MTC-IAF-PP) Grant No. M24N2a0018.