Towards densification of multi-track multi-layer friction surfacing deposition of 7075 aluminium alloy

Details

Supervisors

Simar, Aude

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil mécanicien, à finalité spécialisée

Abstract

Friction surfacing is a solid-state based process that is beginning to emerge in the field of additive manufacturing (AM). It offers an interesting alternative because it is not limited by the constraints associated with fusion. However, FS struggles with several constraints that limit its industrial applications. While depositing layers one on top of the other using FS is feasible, creating dense defect-free metallurgical joints between multiple adjacent deposits (multi-track FS) represents a completely different challenge. This study explores the use of FS to produce multi-track single-layer (MTSL) and multi-track multi-layer (MTML) structures in Al7075 on a substrate plate of the same material. The effects of different parameters on the formation of volumetric defects in both inter-track and layer-to-substrate interfaces are studied. Also, the use of friction stir processing (FSP) in combination with multi-track multi-layer friction surfacing (MTMLFS) to obtain dense bonding is analysed using X-ray tomography, tensile tests, bending tests and microhardness tests. The combined use of FS and FSP has made it possible to obtain dense inter-track and LTS interfaces in MTML structures. However, the mechanical properties of MTML samples are lower than those of BM (UTS = 613 MPa) with the highest UTS being 502 MPa.