{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T05:16:01Z","timestamp":1788412561009,"version":"build-2803163510"},"reference-count":36,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the National Key R&amp;D Program of China","award":["2022YFB4600800"],"award-info":[{"award-number":["2022YFB4600800"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>Laser Powder Bed Fusion (LPBF) has revolutionized high-end manufacturing, particularly in aerospace and biomedical fields. However, internal defects such as pores, cracks, and inclusions compromise the structural integrity and service reliability of LPBF components. Laser ultrasonics, a non-contact, broadband non-destructive testing (NDT) method, offers a promising solution for detecting and characterizing these defects. This study systematically investigated laser ultrasonic testing technology for LPBF-fabricated Ti6Al4V using a combined approach of physics-driven simulation modeling and experimental validation. To accurately model material anisotropy, a finite element model was developed that integrated Voronoi algorithm-generated polycrystalline microstructures with orientation-dependent elastic tensors, providing a comprehensive representation of the material\u2019s microstructural heterogeneity. Simulation results revealed that while sub-100-\u03bcm defects yield weak ultrasonic scattering signals, the Synthetic Aperture Focusing Technique (SAFT) markedly improves the detection and imaging performance for such small-scale defects. Experimental validation using a laser ultrasonic system identified a 90 \u03bcm internal defect in the LPBF Ti6Al4V specimen, though a 75 \u03bcm defect was undetectable. This highlights the need for enhanced sensitivity. A signal processing method combining time-truncation principal component analysis (PCA) with targeted noise reduction and SAFT was proposed to reduce high-frequency noise and improve high-resolution imaging, enhancing defect detection accuracy. This study provides theoretical foundations and technical support for high-precision defect detection in metal additive manufacturing components, with significant implications for quality control in high-end equipment manufacturing.<\/jats:p>","DOI":"10.3390\/mi17091025","type":"journal-article","created":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T18:33:52Z","timestamp":1787942032000},"page":"1025","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Laser Ultrasonic Detection and Signal Enhancement of Internal Microdefects in LPBF Ti6Al4V with Anisotropic Microstructure: Simulations and Experiments"],"prefix":"10.3390","volume":"17","author":[{"given":"Xingyu","family":"Zhou","sequence":"first","affiliation":[{"name":"School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jia","family":"Xie","sequence":"additional","affiliation":[{"name":"Xi\u2019an Aerospace Mechatronics and Intelligent Manufacturing Co., Ltd., Xi\u2019an 710100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yixuan","family":"He","sequence":"additional","affiliation":[{"name":"Xi\u2019an Aerospace Mechatronics and Intelligent Manufacturing Co., Ltd., Xi\u2019an 710100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ping","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1917","DOI":"10.1007\/s11665-014-0958-z","article-title":"Metal Additive Manufacturing: A Review","volume":"23","author":"Frazier","year":"2014","journal-title":"J. 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