An experimental and simulation study on build thickness dependent microstructure for electron beam melted Ti-6Al-4V

JOURNAL OF ALLOYS AND COMPOUNDS

卷:646

Article

Tan, Xipeng¹  Kok, Yihong¹  Tan, Yu Jun¹  Vastola, Guglielmo²  Pei, Qing Xiang²  Zhang, Gang²  Zhang, Yong-Wei²  Tor, Shu Beng¹  Leong, Kah Fai¹  Chua, Chee Kai¹ 

[1] Nanyang Technol Univ, Sch Mech & Aerosp Engn, Singapore Ctr Printing 3D, Singapore 637372, Singapore

[2] ASTAR, Inst High Performance Comp, Singapore 138632, Singapore

关键词: Additive manufacturing;    Electron beam melting;    Titanium alloys;    Martensitic transformations;    Finite element simulations;   

DOI  :  10.1016/j.jallcom.2015.05.178

来源: Elsevier

【 摘 要 】

Build thickness dependent microstructure of electron beam melted (EBM (R)) Ti-6Al-4V has been investigated from both experiment and simulation using four block samples with thicknesses of 1, 5, 10 and 20 mm. We observe a mixed microstructure of alternate alpha/beta with some alpha' martensite inside the 1 mm-thick sample. By contrast, only the alternate a/b microstructure with both colony and basket-weave morphologies occurs inside the 5 mm-, 10 mm-and 20 mm-thick samples. It is found that beta spacing is constantly increased with the build thickness, leading to an obvious decrease in microhardness. Finite element method (FEM) simulations show that cooling rates and thermal profiles during EBM process are favorable for the formation of martensite. Moreover, full-scale FEM simulations reveal that the average temperature inside the samples is higher as the build thickness increases. It suggests that martensitic decomposition is faster in thicker samples, which is in good agreement with the experimental observations. (C) 2015 Elsevier B.V. All rights reserved.

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