Effect of Powder Reuse Times on Additive Manufacturing of Ti-6Al-4V by Selective Electron Beam Melting

Abstract

An advantage of the powder-bed-based metal additive manufacturing (AM) processes is that the powder can be reused. The powder reuse or recycling times directly affect the affordability of the additively manufactured parts, especially for the AM of titanium parts. This study examines the influence of powder reuse times on the characteristics of Ti-6Al-4V powder, including powder composition, particle size distribution (PSD), apparent density, tap density, flowability, and particle morphology. In addition, tensile samples were manufactured and evaluated with respect to powder reuse times and sample locations in the powder bed. The following findings were made from reusing the same batch of powder 21 times for AM by selective electron beam melting: (i) the oxygen (O) content increased progressively with increasing reuse times but both the Al content and the V content remained generally stable (a small decrease only); (ii) the powder became less spherical with increasing reuse times and some particles showed noticeable distortion and rough surfaces after being reused 16 times; (iii) the PSD became narrower and few satellite particles were observed after 11 times of reuse; (iv) reused powder showed improved flowability; and (v) reused powder showed no measurable undesired influence on the AM process and the samples exhibited highly consistent tensile properties, irrespective of their locations in the powder bed. The implications of these findings were discussed.

Modeling the Microstructure Evolution During Additive Manufacturing of Ti6Al4V: A Comparison Between Electron Beam Melting and Selective Laser Melting

“…6 Moreover, even at optimal build conditions, in which the former issues are minimized, a large role is played by the actual metal microstructure, which represents the ultimate factor that dictates the mechanical properties of the part.…”

“…2 In AM, several factors contribute to the ultimate mechanical properties of the part, including the manufacturing technique, 3 the presence of porosity, including incomplete melting, 4 proper thermal control to avoid balling/overmelting, 5 and the quality of the powder feedstock. 6 Moreover, even at optimal build conditions, in which the former issues are minimized, a large role is played by the actual metal microstructure, which represents the ultimate factor that dictates the mechanical properties of the part.…”

Characteristics of Biometallic Alloy to Additive Manufacturing Using Selective Laser Melting Technology

“…The metal powder must present specific characteristics of: size, shape, granulometric distribution and physical properties (flowability and packing). Powder bed fusion methods can be employed with different granulometric powders sizes [4] [5] [6].…”

“…Several authors describe the performance SLM parts using powders alloys at the range of 20 to 50 μm [4] [5]. The system using electron beam source, as know by electron beam melting (EBM) is widely developing with particles of 76 to 106 μm.…”

Characterisation and Monitoring of Ti6al4v (Eli) Powder Used in Different Selective Laser Melting Systems

“…Studies of the reuse of Ti6Al4V powder in both selective laser melting (SLM) and selective electron beam melting (SEBM) systems have been published [4,5]. Each of these studies reports the observed changes in the chemical and physical properties of recycled Ti6Al4V powder, and suggests modifications to the manufacturing process to preserve the powder.…”