Effect of Coaxial Beam Wire Source Mode on Microstructure and Mechanical Properties of TC11 Titanium Alloy Fabricated by Wire-Fed Electron Beam Additive Manufacturing
The presence of needle-like α'martensite within the coarse columnar β grains is the primary reason for the poor ductility of TC11 titanium alloys produced by wire-fed electron beam additive manufacturing(EBAM).To enable the engineering fabrication of high-strength and high-ductile TC11 titanium alloys,a novel coaxial beam wire-EBAM(C-EBAM)process was developed,which could enhance the interaction between the electron beam,wire,and substrate,thereby improving the thermal distribution within the melt pool.Comparison between EBAM and C-EBAM samples was conducted,in terms of microstructures,grain morphologies,and mechanical properties.The impact of wire transition states on process stability,martensitic transformation,and the anisotropy of tensile properties was explored.The results reveal that C-EBAM facilitates the formation of strong lamellar α+β microstructure with minimal evaporation of Al elements,which is achieved through slow cooling within the β phase field and in situ martensite decomposition.Compared with EBAM,the enhanced ductility by C-EBAM is attributed to the development of the bi-lamellar microstructure and discontinuous α grain boundaries.
wire-fed electron beam additive manufacturingcoaxial beam wireTC11 titanium alloymicrostructuremechanical property
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