Hybrid additive manufacturing with MIG-deposit of aluminium alloy enhanced by friction stir processing

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Journal Title
Journal ISSN
Volume Title
Insinööritieteiden korkeakoulu | Master's thesis
Date
2017-06-12
Department
Major/Subject
Production Engineering
Mcode
IA3027
Degree programme
Master’s Programme in Mechanical Engineering
Language
en
Pages
76+6
Series
Abstract
Hybrid additive manufacturing (HAM) is an additive manufacturing (AM) process that integrates multiple metal processing/shaping techniques. This thesis work focuses on the development of a HAM process that combines the MIG welding technique, to produce the initial AM via multi-layer deposit, with friction stir processing (FSP) technique, to enhance the properties of the deposited layers. In order to validate this hybrid concept, filler wire of aluminium alloy AA5183, with diameter of 1.2 mm was deposited on a base plate of aluminium alloy AA5083, with thickness of 6 mm. The initial AM component was produced with three overlapped layers, resulting in a plate of about 400 x 130 x 9 mm, over the base plate. Each layer was produced with parallel and partially overlapping string passes with MIG. The resulting AM component was then processed by FSP, in parallel passes aligned with the initial MIG passes. The effect of the HAM process on the strength and microstructure of the final component was then investigated. It was observed that the initial AM microstructure was refined, with evident dynamic recrystallization in the stirred region by the probe of the FSP tool. There are evidences that the porosities produced by MIG were removed by the FSP. In terms of mechanical properties, the ductility increased in comparison to the initial AM material, in both transversal and longitudinal directions. Concerning the strength, the ultimate tensile (UTS) and yield strength 〖(σ〗_y) are higher than the initial AM material in the longitudinal direction, but lower than the initial AM material in the transversal direction. This fact is mainly due to the overlap ratio between the FSP passes, along the transversal direction, which did not reach continuous overlapping of the stirred zones. Based on a global analysis, encompassing several mechanical properties, the overall quality of the HAM sample improved in comparison to the initial AM.
Description
Supervisor
Vilaҫa, Pedro
Thesis advisor
Vilaҫa, Pedro
Keywords
metal-based additive manufacturing, hybrid additive manufacturing, arc-based additive manufacturing, friction stir processing, MIG
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