Fine equiaxed β grains and superior tensile property in Ti–6Al–4V alloy deposited by coaxial electron beam wire feeding additive manufacturing

Jiahua Zhang¹，Yi Yang¹，Sheng Cao²，Zhiqiang Cao¹，Songquan Wu¹，Enquan Liang⁴，Xi Zhang⁴，Wei Chen⁵，Fan Wu⁵，Aijun Huang⁶

1. School of Materials Science and Engineering,University of Shanghai for Science and Technology2. School of Materials,University of Manchester4. Shanghai Aircraft Design and Research Institute5. Key Laboratory of Power Beam Processing,AVIC Manufacturing Technology Institute6. Department of Materials Science and Engineering,Monash University

摘 要：Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti–6Al–4V alloy fabricated by coaxial electron beam wire feeding additive manufacturing presents a weak anisotropy, high strength and ductility. The superior tensile property arises from a microstructure with fine equiaxed β grains(EGβ), discontinuous grain boundary α phase and short intragranular α lamellae. A large region of fine EGβ arises from a special combination of the temperature gradient and solidification rate, and attractive α morphology is caused by solid phase transformations during interpass thermal cycling and post heat treatments.

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