Texture and microstructure characterization in laser additive manufactured Ti–6Al–2Zr–2Sn–3Mo–1.5Cr–2Nb titanium alloy

• Published in: Materials & design 2015-12, Vol.88, p.550-557
• Main Authors: Zhang, Qiang, Chen, Jing, Guo, Pengfei, Tan, Hua, Lin, Xin, Huang, Weidong
• Format: Article
• Language: English
• Subjects: Additives; Construction; Laser additive manufacturing; Lasers; Microstructure; Microstructure characterization; Morphology; Surface layer; Texture; Thermal history; Titanium base alloys
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2015.09.053

Laser additive manufacturing (LAM) is a novel manufacturing technique in which metal components can be fabricated layer by layer. In this study, a recently developed damage tolerance titanium alloy TC21 (Ti–6Al–2Zr–2Sn–3Mo–1.5Cr–2Nb) was deposited by LAM process. Texture and microstructure characterization have been investigated by XRD, SEM and EBSD. Prior β grains texture analysis indicates that the (100) poles concentrate in build direction with a texture intensity about 18.7. During cooling down from β phase field, the β to α phase transformation follows the Burger orientation relationship and a pronounced variant selection occurred. Besides, morphology and scale of α phase are quite different along the build direction due to different thermal history. Very fine rib-like α phase with the length less than 2μm and acicular martensite α' can be obtained at the bottom and the top of the sample, respectively. In the middle position, distribution and morphology of α phase is quite uneven and the precipitation sequence of α phase is αGB→αWGB→αWM→αS. The reasons by which they formed are discussed. [Display omitted] •The laser additive manufactured TC21 alloy is dominated by columnar β grains and exhibit strong fiber texture.•Variant morphology of α phase related to the deposited positions are caused by different thermal history they experienced.•The possible correlation between variant selection and temperature history is discussed.