Implications of post-processing induced microstructural changes on the deformation and fracture response of additively manufactured Ti-6Al-4V

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:795

Article

Draelos, Lara¹  Nandwana, Peeyush²  Srivastava, Ankit¹ 

[1] Texas A&M Univ, Dept Mat Sci & Engn, College Stn, TX 77843 USA

[2] Oak Ridge Natl Lab, Mat Sci & Technol Div, Knoxville, TN USA

关键词: Characterization;    Additive manufacturing;    Titanium alloys;    In situ tension test;    Digital image correlation;    Fracture behavior;   

DOI  :  10.1016/j.msea.2020.139986

来源: Elsevier

【 摘 要 】

Ti-6Al-4V parts fabricated via electron beam melting (EBM) powder bed fusion are often subjected to hot isostatic pressing below the beta-transus temperature to mitigate defects. During which the pressure aids in pore closure and the thermal exposure results in coarsening of alpha phase while retaining the columnar prior-beta phase grain morphology present in the as-fabricated condition. The same post-processing treatment can also be carried out above beta-transus temperature which is an effective way to modify both the grain morphology and the associated a textures. The objective of this work is to correlate thermally induced microstructural changes to the deformation and fracture response of the EBM processed Ti-6Al-4V. To this end, we have carried out both subtransus and super-transus heat-treatments of the as-fabricated material. The mechanical response of the asfabricated and all heat-treated materials are characterized by in-situ tensile tests under a high-resolution digital optical microscope. This enabled us to capture large-scale panoramic images of the deforming microstructure, and overcome the trade-off between the image resolution and the field of view during in-situ experiments. The series of images captured throughout the imposed deformation are subsequently used to perform microstructure-based digital image correlation to measure microstructural-scale strains over a large area. The results of the insitu tests together with detailed fractographic analyses are then used to elucidate how the heterogeneous deformation spanning over multiple microstructural length-scales, for example, at the scale of lamellae, colonies of lamellae and grain boundaries, affect the overall deformation and fracture response of the post-processed materials.

【 授权许可】

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