Exploring the use of switchback for mitigating homoepitaxial unidirectional grain growth and porosity in WAAM of aluminium alloys
2019 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 104, no 1-4, p. 1581-1592Article in journal (Refereed) Published
Abstract [en]
In this work, an alternative approach to prevent unidirectional grain growth in wire + arc additive manufacturing (WAAM) is proposed and assessed, by moving cyclically the torch forward and backward, likewise the welding technique known as switchback. A series of tests were planned with CMT (cold metal transfer) process to compare three wall-like build-ups, which uses different deposition patterns, namely, in one-way direction, reverse direction, and switchback. The same equivalent travel speed and number of deposited layers were kept among them. Longitudinal sections were taken to identify the grain growth behaviour. Finally, samples were removed from the walls for porosity evaluation. The results confirmed the characteristics of unidirectional grain growth, when one-way direction condition was employed, and the break of growth direction between layers, when reverse direction was used, yet a zig-zag pattern became present. Differently, the application of switchback showed no preferential or unidirectional grain growth, suggesting less anisotropy of mechanical properties. In addition, switchback reduced porosity. © 2019, The Author(s).
Place, publisher, year, edition, pages
2019. Vol. 104, no 1-4, p. 1581-1592
Keywords [en]
Aluminum; Anisotropy; Gas metal arc welding; Porosity, Anisotropy of mechanical properties; Cold metal transfers; Deposition patterns; Forward-and-backward; Growth directions; Longitudinal section; Switchback; WAAM, Grain growth
National Category
Condensed Matter Physics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
URN: urn:nbn:se:hv:diva-14460DOI: 10.1007/s00170-019-03959-wScopus ID: 2-s2.0-85068187211OAI: oai:DiVA.org:hv-14460DiVA, id: diva2:1357082
2019-10-022019-10-022020-01-14