Effect of Post Heat Treatment on Tensile Strength of Dissimilar Aluminum Alloy Joints Manufactured through Powder Bed Fusion Process

Toko Miura, Kenji Omori and Koichi Kitazono
Graduate School of Systems Design, Tokyo Metropolitan University

Al-10Si-0.3Mg alloy has been additively manufactured (AM) on a commercial A5083 aluminum alloy bar through powder bed fusion (PBF) process. EOS M280 selective laser melting system was used in this study. Post heat treatment at 813 K for 2 h in air was carried out after the building.

Figure 1 shows the microstructure of the bonding interface. A part of the A5083 alloy melted by laser irradiation. No crack was observed at the bonding interface.

Energy-dispersive X-ray spectroscopy [Fig. 2] reveals the diffusion of Mg atoms from A5083 aluminum alloy to Al-10Si-0.3Mg alloy after the post heat treatment.

Tensile tests were carried out with the crosshead speed of 1 mm/min. The shape of the specimen is 6 mm in diameter and 34 mm gage length. Results of the tensile tests were shown in Fig. 3. The bonding strength before the heat treatment was higher than the tensile strength of A5083 alloy. The bonding strength after the heat treatment was higher than the tensile strength of Al-10Si-0.3Mg alloy.

Experimental results indicate that the PBF process has a potential to manufacture dissimilar aluminum alloy joints. In addition, Al-10Si-0.3Mg alloy possesses good bonding potential to A5083 aluminum alloy even after post heat treatments. A5083 alloy can be used as an interface part between AM Al-10Si-0.3 Mg alloy and conventional aluminum alloys.

[Published in Journal of the Japan Institute of Light Metals, Vol. 69, No. 6 (2019), pp. 309-311]

Fig. 1 SEM micrographs of (a) as-built and (b) post heat treated specimens. SEM/EBSD inverse pole figure maps of (c) as-built and (d) post heat treated specimens.
Fig. 2 Result of SEM/EDS analysis at the bonding interface. Mg atoms diffused from A5083 alloy region to Al-10Si-0.3Mg alloy region.

Fig. 3 Tensile test specimens after fracture. (a) As-built, (b) Post heat treated specimens. (c) Tensile stress-strain curves of as-built and post heat treated A5083/Al-10Si-0.3Mg specimens. Results of PBF Al-10Si-0.3Mg alloys are plotted for comparison.