Abstract
With the advent of disruptive additive manufacturing (AM), there is an increasing interest and demand of high mechanical property aluminium parts built directly by these technologies. This has led to the need for continuous improvement of AM technologies and processes to obtain the best properties in aluminium samples and develop new alloys. This study has demonstrated that porosity can be reduced below 0.035% in area in Al-Mg samples manufactured by CMT-based WAAM with commercial filler metal wires by selecting the correct shielding gas, gas flow rate, and deposition strategy (hatching or circling). Three phase Ar+O2+N2O mixtures (Stargold®) are favourable when the hatching deposition strategy is applied leading to wall thickness around 6 mm. The application of circling strategy (torch movement with overlapped circles along the welding direction) enables the even build-up of layers with slightly thicker thickness (8 mm). In this case, Ar shielding gas can effectively reduce porosity if proper flow is provided through the torch. Reduced gas flows (lower than 30 Lmin) enhance porosity, especially in long tracks (longer than 90 mm) due to local heat accumulation. Surprisingly, rather high porosity levels (up to 2.86 area %) obtained in the worst conditions, had a reduced impact on the static tensile test mechanical properties, and yield stress over 110 MPa, tensile strength over 270 MPa, and elongation larger than 27% were achieved either for Ar circling, Ar hatching, or Stargold® hatching building conditions. In all cases anisotropy was lower than 11%, and this was reduced to 9% for the most appropriate shielding conditions. Current results show that due to the selected layer height and deposition parameters there was a complete re-melting of the previous layer and a thermal treatment on the prior bottom layer that refined the grain size removing the original dendritic and elongated structure. Under these conditions, the minimum reported anisotropy levels can be achieved.
Highlights
Wire-arc additive manufacturing (WAAM) is offering a new building perspective to the industry, enabling higher depositions rates than other additive manufacturing techniques despite having lower dimensional precision in as-built state
Four mm thickness AA6082-T6 substrate was used. This material only has an influence in the initial layers, while the study has been focused in the analysis of soundness and porosity of additively manufactured components built
Both hatching (H) and circling (C) strategies were applied with 130 A of intensity
Summary
Wire-arc additive manufacturing (WAAM) is offering a new building perspective to the industry, enabling higher depositions rates than other additive manufacturing techniques despite having lower dimensional precision in as-built state. Compared with other additive manufacturing (AM) technologies, WAAM uses simple equipment and obtains higher deposition rates [1]. Since this technology is based on arc welding processes with wire raw material in either robots or computer numerical control (CNC) systems, it is considered appropriate for medium-large part manufacturing. Industry has been interested in this manufacturing alternative for different applications, such as aeronautical, automotive, defence, naval, and nuclear energy industry [2,3] Another beneficial aspect of this technology is the reduction of material waste, and overall process cost, especially in metallic alloys with high added value. The buy-to-fly (BTF) ratio of many aeronautical parts can be usually higher than 30 when machining from billets, 4.0/)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
