The effect of inter-layer cold working and post-deposition heat treatment on porosity in additively manufactured aluminum alloys

Wire + Arc Additive Manufacture (WAAM) has been shown to be suitable for manufacturing large-scale metallic parts. However porosity in the deposited aluminum material restricts the application of WAAM for aluminum alloys. In this study inter-layer rolling process was employed during the deposition of aluminum alloys and its influence on porosity was investigated. Samples of straight walls were prepared with both the 2319 aluminum alloy wire and the 5087 aluminum alloy wire. Inter-layer rolling was employed between each and every deposited layer. Different rolling loads of 15 kN, 30 kN and 45 kN were applied, greatly reducing the quantity of the pores for both alloys. With a rolling load of 45 kN the pores larger than 5 μm in diameter were eliminated. In additional, the influence of post-deposition heat treatment on porosity was investigated on the as-deposited samples as well as on the samples built with inter-layer rolling of 45 kN load. A different behavior of pores’ formation and growth was found between 2319 alloy and 5087 alloy, both for as-deposited status and heat-treated status. Post-deposition heat treatment increased the area of the pores for both alloys. After the post-rolling heat treatment, no pores larger than 5 μm in diameter was found re-initiated for both alloys.