Abrasive fluidized bed finishing to improve the fatigue behaviour of Ti6Al4V parts fabricated by electron beam melting

Abstract

A study of the abrasive fluidized bed (AFB) finishing process was conducted to quantify the obtainable improvement of the fatigue behaviour of Ti6Al4V parts produced by electron beam melting (EBM). Axial-symmetric EBM samples were rotated at high speed inside a fluidized bed of stainless-steel media. The effects of the treatment time and the rotational speed on morphological features and fatigue life of the EBM samples were investigated. Outcomes showed that the improvement in surface properties induced by the AFB finishing process determined an increase up to 50% in fatigue life and a shift of the S-N curve.

Surface Finishing of Additive Manufactured Ti-6Al-4V Alloy: A Comparison between Abrasive Fluidized Bed and Laser Finishing

“…A pre-heated process chamber and high melting capacity of the EBM system avoid the arising of residual stresses and martensitic structures in the printed parts [ 30 ]. For further details on the printing procedure, reference is made to a previous work dedicated to finishing of additively manufactured Ti6Al4V parts [ 28 , 29 ]. EBM samples were built with an axial-symmetric geometry ( Figure 1 ) typical of fatigue test specimens, in order to systematically investigate the influence of AFB and LF treatments on the fatigue life of parts.…”

“…EBM samples were built with an axial-symmetric geometry ( Figure 1 ) typical of fatigue test specimens, in order to systematically investigate the influence of AFB and LF treatments on the fatigue life of parts. The yield stress of the material is 830 MPa, evaluated by performing static tensile tests in the as-build state [ 29 ].…”

“…The fluidized bed was composed by an air supply system and a vertical fluidization column, 200 mm in height and 500 mm in diameter [ 29 ]. The abrasive media in the bed was uniformly fluidized through a porous plate distributor by supplying a fluidizing gas (purified air).…”

“…Based on preliminary investigations of the effect of process parameters on fatigue performances [ 28 , 29 ], the study provides the description of the main mechanisms causing fatigue failure. Computer tomography (CT) scanning and image analysis were used to evaluate the internal porosity of EBM parts.…”

The technology, economy, and environmental sustainability of isotropic superfinishing applied to electron-beam melted Ti-6Al-4V components

“…However, it is expected that it will allow an accurate evaluation to be made of (i) the material flows, on a per-part basis, through the whole integrated manufacturing approach, as well as of (ii) the dimensional and geometric deviations induced by the finishing process. In this context, the choice of a simple mock-up, when evaluating the performance of post-AM finishing processes, is already established in the literature [27]. The production of the components, by means of electron beam melting (EBM), is described in Section 2.1, together with the post-AM operations.…”