Effect of grain boundary Widmanst?tten α colony on the anisotropic tensile properties of directed energy deposited Ti-6Al-4V alloy

Wei Fan ¹Yijie Peng ¹Yongxia Wang ¹Yang Qi ²Zhe Feng ¹Hua Tan ¹Fengying Zhang ³Xin Lin¹

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作者信息

1. State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China;Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design,MIIT China,Northwestern Polytechnical University,Xi'an 710072,China
2. Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Wuhan 430074,China
3. School of Material Science and Engineering,Chang'an University,Xi'an 710064,China
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Abstract

Columnar grain structure caused anisotropy in mechanical properties,especially in elongation,is an im-portant concern for Ti-6Al-4 V alloy fabricated by directed energy deposition(DED).Several strategies have been proposed to reduce anisotropy by globularizing the grains,but these conventional approaches are costly and inefficient due to challenges faced during producing the columnar β-grain structures.How-ever,understanding the impact of columnar grain-related microstructures on the anisotropic deformation behavior is still necessary.Despite the recognition of the importance of grain boundary Widmannstättenα colony(αWGB)as a grain-related microstructure,it has received limited attention in available literature on anisotropy in mechanical properties.This study employed in-situ induction heating during DED to control αWGB formation,yielding three Ti-6Al-4 V samples with varying αWGB sizes.Anisotropic deforma-tion of αWGB and its impact on elongation in build and transverse directions were analyzed.αWGB width grew from 0.5 μm to 32.4 μm via diffusion-controlled growth due to reduced cooling rate.Transverse deformation led to dislocation movement and accumulation,causing early failure and worsened ductile anisotropy within αWGB.Notably,larger αWGB size significantly exacerbated anisotropy in ductility.This work underscores αWGB's role in anisotropic deformation and offers insights for optimizing mechanical properties in DED-fabricated titanium alloys.

Key words

Additive manufacturing/Directed energy deposition/Anisotropic mechanical properties/Titanium alloy/Microstructure

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基金项目

National Key Research and Development Program of China(2022YFB4600300)

National Key Research and Development Program of China(2022YFB4600301)

National Natural Science Foundation of China(52175364)

ND Basic Research Funds(G2022WD)

Shenzhen Science and Technology Plan Project(JCYJ20180508151903646)

Key Research and Development Program of Shaanxi(2023-YBGY-359)

Science and Technology Plan of Xi'an City(21ZCZZHXJS-QCY6-0001)

出版年

2024

材料科学技术(英文版)

中国金属学会中国材料研究学会中国科学院金属研究所

材料科学技术(英文版)

CSTPCD

影响因子：0.657

ISSN：1005-0302

参考文献量35

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