Wire-Based Additive Manufacturing of Ti-6Al-4V Using Electron Beam Technique
Journal article, 2020

Electron beam freeform fabrication is a wire feed direct energy deposition additive manufacturing process, where the vacuum condition ensures excellent shielding against the atmosphere and enables processing of highly reactive materials. In this work, this technique is applied for the α + β-titanium alloy Ti-6Al-4V to determine suitable process parameter for robust building. The correlation between dimensions and the dilution of single beads based on selected process parameters, leads to an overlapping distance in the range of 70-75% of the bead width, resulting in a multi-bead layer with a uniform height and with a linear build-up rate. Moreover, the stacking of layers with different numbers of tracks using an alternating symmetric welding sequence allows the manufacturing of simple structures like walls and blocks. Microscopy investigations reveal that the primary structure consists of epitaxial grown columnar prior β-grains, with some randomly scattered macro and micropores. The developed microstructure consists of a mixture of martensitic and finer α-lamellar structure with a moderate and uniform hardness of 334 HV, an ultimate tensile strength of 953 MPa and rather low fracture elongation of 4.5%. A subsequent stress relief heat treatment leads to a uniform hardness distribution and an extended fracture elongation of 9.5%, with a decrease of the ultimate strength to 881 MPa due to the fine α-lamellar structure produced during the heat treatment. Residual stresses measured by energy dispersive X-ray diffraction shows after deposition 200-450 MPa in tension in the longitudinal direction, while the stresses reach almost zero when the stress relief treatment is carried out.

titanium alloys

mechanical properties

additive manufacturing

wire feed process

electron beam

residual stresses

Author

Florian Pixner

Technische Universität Graz

Fernando Warchomicka

Technische Universität Graz

Patrick Peter

Technische Universität Graz

Liebherr Werk Telfs GmbH

Axel Steuwer

Nelson Mandela University

University of Malta

Magnus Hörnqvist Colliander

Chalmers, Physics, Microstructure Physics

R. Pederson

University West

Norbert Enzinger

Technische Universität Graz

Materials

1996-1944 (ISSN)

Vol. 13 15 3310

Subject Categories

Other Materials Engineering

Metallurgy and Metallic Materials

Areas of Advance

Materials Science

DOI

10.3390/ma13153310

PubMed

32722303

More information

Latest update

12/3/2020