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In this study, the creep performance (at 500 °C) of Ti-6Al-2Sn-4Zr-6Mo wt.% (Ti6246) fabricated from three different laser powder bed fusion (LPBF) processing conditions and heat-treated (HT) at 885 °C were investigated. In the as-built state, all the LPBFed-Ti6246 exhibited columnar microstructures with crystallographic lamellar-like microstructure (CLM), a near single crystal-like microstructure (SCM), and polycrystalline microstructure (PCM) textures, respectively. At low applied stresses (100 - 300 MPa), diffusional creep was the dominant deformation mechanism and its resistance depended on grain size. The β-forged-HT, characterized by large equiaxed grains, exhibited the lowest strain rate compared to the columnar microstructure of SX1 (CLM)-HT, SX2 (SCM)-HT, and SX3 (PCM)-HT. Conversely, dislocation slip governed deformation at high applied stresses (400 - 580 MPa) and its efficacy depended on the α/β interfaces in the microstructures. Compared to SX1 (CLM)-HT, SX2 (SCM)-HT, and SX3 (PCM)-HT, the β-forged-HT contained the lowest volume fraction of the α phase and hence showcased a large accelerated deformation as creep progressed. Disjointed columnar grains in SX1 (CLM)-HT and the deformation of the polycrystalline grains in SX3 (PCM)-HT indicated that the melt pool boundaries were unstable in the LPBFed-Ti6246. SX2 (SCM)-HT exhibited the longest creep life due to the relatively stable melt pool boundaries and the near <001> SCM crystallographic texture parallel to the applied stresses. Shallow dimples, cleavage facets, and the observation of laser scan tracks characterized the fracture surfaces of SX1 (CLM)-HT, SX2 (SCM)-HT, and SX3 (PCM)-HT. These indicated that failure occurred by intergranular fracture resulting from the formation of creep voids at the melt pool boundaries.

権利情報:

• In Copyright
  

  This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s11661-025-07759-8

キーワード: Additive manufacturing, Crystallographic analysis, Heat-resistant titanium alloys, Microstructure, Precipitation, Volumetric energy density

刊行年月日: 2025-04-10

出版者: Springer Science and Business Media LLC

掲載誌:

• Metallurgical and Materials Transactions A (ISSN: 10735623) vol. 56 issue. 6 p. 2057-2073

研究助成金:

• Japan Society for the Promotion of Science JP21H05198 (Science for Super-Titanium Creation in Super Thermal Field)
• Japan Society for the Promotion of Science JP23H00235
• The Light Metal Educational Foundation

原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5520

公開URL: https://doi.org/10.1007/s11661-025-07759-8

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更新時刻: 2025-06-04 17:16:18 +0900

MDRでの公開時刻: 2026-04-10 08:21:29 +0900