Wire-Based Additive Manufacturing of Ti-6Al-4V Using Electron Beam Technique

被引:41
作者
Pixner, Florian [1 ]
Warchomicka, Fernando [1 ]
Peter, Patrick [1 ,2 ]
Steuwer, Axel [3 ,4 ]
Colliander, Magnus Hornqvist [5 ]
Pederson, Robert [6 ]
Enzinger, Norbert [1 ]
机构
[1] Graz Univ Technol, Inst Mat Sci Joining & Forming, Kopernikusgasse 24, A-8010 Graz, Austria
[2] Liebherr Werk Telfs GmbH, A-6410 Telfes, Austria
[3] Nelson Mandela Univ, ZA-6031 Port Elizabeth, South Africa
[4] Univ Malta, Res Support Serv, Msida 2080, Malta
[5] Chalmers Univ Technol, Dept Appl Phys, S-41296 Gothenburg, Sweden
[6] Univ West, Dept Engn Sci, S-46132 Trollhattan, Sweden
关键词
additive manufacturing; titanium alloys; electron beam; wire feed process; residual stresses; mechanical properties; MECHANICAL-PROPERTIES; FREEFORM FABRICATION; OVERLAPPING MODEL; HEAT-TRANSFER; ROBOTIC WIRE; MELT POOL; MICROSTRUCTURE; DEPOSITION; REFINEMENT; PARAMETERS;
D O I
10.3390/ma13153310
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
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 alpha + beta-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 beta-grains, with some randomly scattered macro and micropores. The developed microstructure consists of a mixture of martensitic and finer alpha-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 alpha-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.
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页数:23
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