{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T17:01:42Z","timestamp":1790010102404,"version":"4.0.1"},"reference-count":35,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key R&D Program of China","doi-asserted-by":"publisher","award":["2023YFB4606401"],"award-info":[{"award-number":["2023YFB4606401"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Multi-laser powder bed fusion (PBF-ML) enables efficient fabrication of large components but introduces spatially heterogeneous thermal histories near inter-laser overlap zones. However, how global thermal-input variables and local thermal-path variations jointly affect defect evolution, microstructure, and mechanical response in geometrically constrained Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) structures remains unclear. Here, TC11 arch structures were fabricated by varying laser power, scanning speed, overlap-zone position, and interlayer rotation and characterized by tensile testing, optical metallography, Scanning Electron Microscope (SEM), and fractography. Increasing laser power from 170 to 290 W increased Yield Strength (YS) and Ultimate Tensile Strength (UTS) from 955 and 1228 MPa to 1259 and 1463 MPa, respectively, while Elongation (EL) decreased from 14.7% to 3.1%. Increasing the scanning speed from 1050 to 1450 mm\/s produced the opposite strength\u2013ductility trend, whereas overlap-zone position had limited influence on strength and 67\u00b0 interlayer rotation produced moderate improvements. Defect count and area fraction did not always vary synchronously, while semi-quantitative SEM analysis revealed microstructural coarsening with increasing laser power and refinement with increasing scanning speed. These results show that global thermal-input variables primarily govern the overall strength\u2013ductility and microstructural-scale responses, whereas local thermal-path variables mainly regulate spatial defects and microstructural heterogeneity.<\/jats:p>","DOI":"10.3390\/ma19183956","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T16:06:51Z","timestamp":1790006811000},"page":"3956","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Thermal-History-Mediated Defect\u2013Microstructure\u2013Property Evolution in Multi-Laser Powder Bed Fusion of TC11 Titanium Alloy Structures"],"prefix":"10.3390","volume":"19","author":[{"given":"Liubaixiang","family":"He","sequence":"first","affiliation":[{"name":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi\u2019an 710072, China"},{"name":"MIIT Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design, Northwestern Polytechnical University, Xi\u2019an 710072, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"}]},{"given":"Junfeng","family":"He","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi\u2019an 710072, China"},{"name":"MIIT Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design, Northwestern Polytechnical University, Xi\u2019an 710072, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"Jiamin","family":"Zhang","sequence":"additional","affiliation":[{"name":"International Centre for Numerical Methods in Engineering, Universidad Polit\u00e9cnica de Catalu\u00f1a, 08034 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]},{"given":"Xin","family":"Lin","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi\u2019an 710072, China"},{"name":"MIIT Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design, Northwestern Polytechnical University, Xi\u2019an 710072, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"supervision","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5829-385X","authenticated-orcid":false,"given":"Xufei","family":"Lu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi\u2019an 710072, China"},{"name":"MIIT Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design, Northwestern Polytechnical University, Xi\u2019an 710072, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1016\/j.actamat.2016.07.019","article-title":"Additive manufacturing of metals","volume":"117","author":"Herzog","year":"2016","journal-title":"Acta Mater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"150085","DOI":"10.1016\/j.msea.2026.150085","article-title":"Crack elimination and mechanical performance enhancement of selective laser melted CM247LC superalloy","volume":"959","author":"Xu","year":"2026","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_3","first-page":"103149","article-title":"Crack-free laser powder bed fusion by substrate design","volume":"59","author":"Lu","year":"2022","journal-title":"Addit. Manuf."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3303","DOI":"10.1016\/j.actamat.2010.02.004","article-title":"A study of the microstructural evolution during selective laser melting of Ti\u20136Al\u20134V","volume":"58","author":"Thijs","year":"2010","journal-title":"Acta Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/j.jallcom.2012.07.022","article-title":"Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties","volume":"541","author":"Vrancken","year":"2012","journal-title":"J. Alloys Compd."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"186754","DOI":"10.1016\/j.jallcom.2026.186754","article-title":"Quantitative prediction of microstructure and mechanical properties of additively manufactured titanium alloys using machine learning","volume":"1057","author":"Zhang","year":"2026","journal-title":"J. Alloys Compd."},{"key":"ref_7","first-page":"102915","article-title":"Effect of processing parameters on pore structures, grain features, and mechanical properties in Ti-6Al-4V by laser powder bed fusion","volume":"56","author":"Luo","year":"2022","journal-title":"Addit. Manuf."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"144202","DOI":"10.1016\/j.msea.2022.144202","article-title":"Discovering the role of the defect morphology and microstructure on the deformation behavior of additive manufactured Ti-6Al-4V","volume":"859","author":"Liu","year":"2022","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.matdes.2018.08.004","article-title":"Defects-dictated tensile properties of selective laser melted Ti-6Al-4V","volume":"158","author":"Voisin","year":"2018","journal-title":"Mater. Des."},{"key":"ref_10","first-page":"334","article-title":"The effect of multi-beam strategies on selective laser melting of stainless steel 316L","volume":"22","author":"Heeling","year":"2018","journal-title":"Addit. Manuf."},{"key":"ref_11","first-page":"102178","article-title":"Dual-beam laser-matter interaction at overlap region during multi-laser powder bed fusion manufacturing","volume":"46","author":"Yin","year":"2021","journal-title":"Addit. Manuf."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"899","DOI":"10.1016\/j.phpro.2016.08.094","article-title":"Computational Investigation of Synchronized Multibeam Strategies for the Selective Laser Melting Process","volume":"83","author":"Heeling","year":"2016","journal-title":"Phys. Procedia"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"140644","DOI":"10.1016\/j.msea.2020.140644","article-title":"Multi-laser powder bed fusion of Ti\u20136Al\u20134V alloy: Defect, microstructure, and mechanical property of overlap region","volume":"802","author":"Wei","year":"2021","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1016\/j.jmst.2020.08.061","article-title":"Influences of residual stress and micro-deformation on microstructures and mechanical properties for Ti-6.5 Al-3.5 Mo-1.5 Zr-0.3 Si alloy produced by laser powder bed fusion","volume":"75","author":"Zhang","year":"2021","journal-title":"J. Mater. Sci. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1007\/s40195-021-01297-z","article-title":"In situ elimination of pores during laser powder bed fusion of Ti-6.5 Al-3.5 Mo-1.5Zr-0.3 Si titanium alloy","volume":"35","author":"Zhang","year":"2022","journal-title":"Acta Metall. Sin. (Engl. Lett.)"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1186\/s10033-023-00863-z","article-title":"Investigation of the Laser Powder Bed Fusion Process of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy","volume":"36","author":"Zhang","year":"2023","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"032015","DOI":"10.2351\/7.0000932","article-title":"Response surface analysis, tensile properties, and microstructure of Ti\u20136.5Al\u20133.5Mo\u20131.5Zr\u20130.3Si fabricated by laser powder bed fusion","volume":"35","author":"Ou","year":"2023","journal-title":"J. Laser Appl."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Lu, X., Shu, C., Zheng, Z., Shu, X., Chen, S., Essa, K., Li, Z., and Xu, H. (2023). Effects of L-PBF Scanning Strategy and Sloping Angle on the Process Properties of TC11 Titanium Alloy. Metals, 13.","DOI":"10.3390\/met13050983"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2714","DOI":"10.1016\/j.jmrt.2023.12.173","article-title":"Influences of island size on the forming quality, microstructure, and tensile properties of laser powder bed fusion Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy","volume":"28","author":"Zhang","year":"2023","journal-title":"J. Mater. Res. Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"558","DOI":"10.1016\/j.matdes.2016.08.036","article-title":"Role of molten pool mode on formability, microstructure and mechanical properties of selective laser melted Ti-6Al-4V alloy","volume":"110","author":"Yang","year":"2016","journal-title":"Mater. Des."},{"key":"ref_21","first-page":"102605","article-title":"On the role of volumetric energy density in the microstructure and mechanical properties of laser powder bed fusion Ti-6Al-4V alloy","volume":"51","author":"Zhao","year":"2022","journal-title":"Addit. Manuf."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"117366","DOI":"10.1016\/j.jmatprotec.2021.117366","article-title":"Understanding the effect of scanning strategies on the microstructure and crystallographic texture of Ti-6Al-4V alloy manufactured by laser powder bed fusion","volume":"299","author":"Liu","year":"2022","journal-title":"J. Mater. Process. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Bartolomeu, F., Gasik, M., Silva, F.S., and Miranda, G. (2022). Mechanical Properties of Ti6Al4V Fabricated by Laser Powder Bed Fusion: A Review Focused on the Processing and Microstructural Parameters Influence on the Final Properties. Metals, 12.","DOI":"10.3390\/met12060986"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1080\/17452759.2021.1942077","article-title":"Simulation-assisted investigation on the formation of layer bands and the microstructural evolution in directed energy deposition of Ti6Al4V blocks","volume":"16","author":"Lu","year":"2021","journal-title":"Virtual Phys. Prototyp."},{"key":"ref_25","first-page":"102865","article-title":"In-situ grain structure control in directed energy deposition of Ti6Al4V","volume":"55","author":"Zhang","year":"2022","journal-title":"Addit. Manuf."},{"key":"ref_26","first-page":"166","article-title":"Residual stress and distortion of rectangular and S-shaped Ti-6Al-4V parts by Directed Energy Deposition: Modelling and experimental calibration","volume":"26","author":"Lu","year":"2019","journal-title":"Addit. Manuf."},{"key":"ref_27","first-page":"101507","article-title":"Scanning strategies effect on temperature, residual stress and deformation by multi-laser beam powder bed fusion manufacturing","volume":"36","author":"Zhang","year":"2020","journal-title":"Addit. Manuf."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.powtec.2021.02.010","article-title":"Multi-laser powder bed fusion of Ti-6.5Al-2Zr-Mo-V alloy powder: Defect formation mechanism and microstructural evolution","volume":"384","author":"Li","year":"2021","journal-title":"Powder Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"108249","DOI":"10.1016\/j.optlastec.2022.108249","article-title":"Difference-extent of microstructure and mechanical properties: Simulating multi-laser selective melting Ti6Al4V","volume":"153","author":"Li","year":"2022","journal-title":"Opt. Laser Technol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/j.matlet.2017.04.050","article-title":"Microstructures and mechanical properties of Ti6Al4V alloy fabricated by multi-laser beam selective laser melting","volume":"199","author":"Li","year":"2017","journal-title":"Mater. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"e2142802","DOI":"10.1080\/17452759.2022.2142802","article-title":"The role of overlap region width in multi-laser powder bed fusion of Hastelloy X superalloy","volume":"18","author":"Xie","year":"2022","journal-title":"Virtual Phys. Prototyp."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1016\/j.jallcom.2018.02.111","article-title":"Role of martensite decomposition in tensile properties of selective laser melted Ti-6Al-4V","volume":"744","author":"Cao","year":"2018","journal-title":"J. Alloys Compd."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.msea.2017.03.035","article-title":"Formation mechanism of the \u03b1 variant and its influence on the tensile properties of laser solid formed Ti-6Al-4V titanium alloy","volume":"691","author":"Zhao","year":"2017","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_34","unstructured":"(2024). Standard Test Methods for Tension Testing of Metallic Materials (Standard No. ASTM E8\/E8M-24)."},{"key":"ref_35","unstructured":"(2019). Metallic Materials\u2014Tensile Testing\u2014Part 1: Method of Test at Room Temperature (Standard No. ISO 6892-1)."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/18\/3956\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T16:09:01Z","timestamp":1790006941000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/18\/3956"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,17]]},"references-count":35,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["ma19183956"],"URL":"https:\/\/doi.org\/10.3390\/ma19183956","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,17]]}}}