Influence of Powder Production Process and Properties on Material Properties of Ti 6Al 4V Manufactured by L-PBF

Abstract

Besides process parameters, powder properties such as grain size, morphology and chemical composition have the highest impact on material properties of parts produced by powder based additive manufacturing. These properties are strongly influenced by the production process of the powder and its feedstock. In scope of this work this influence of three different powder producers of Ti6Al4V, on density, chemical composition, and mechanical properties of build samples are investigated. Further the effects of the varying atomization process on morphology, particle size distribution, chemical composition and oxide layers are studied. Particle size distribution and flowability seem to have minor influence on the production process while density depends highly on the surface topology, sphericity and nature of the oxide layer, which affect energy intake. Tensile properties are highly influenced by chemical composition, mainly dissolved oxygen and polluting satellites, while notched bar impact strength is additionally influenced by the oxide layer and suspected TiO 2 precipitations caused by it.

Influences of Surface, Heat Treatment, and Print Orientation on the Anisotropy of the Mechanical Properties and the Impact Strength of Ti 6Al 4V Processed by Laser Powder Bed Fusion

“…After SR (Figure 3a), the microstructure was finer with a partially decomposed martensitic phase and a small β phase due to the low temperature of the treatment, which is way below the β transus temperature. Similar findings were discovered by Baitimerov et al [17] using conditions of 3 h and 650 • C. When the material was heat-treated at 800 • C and cooled in the furnace, stabilized and coarser α laths were observed in the β phase (Figure 3b).…”

“…Ti6Al4V Grade 23 extra-low interstitial (ELI), which has lower oxygen levels, shows higher ductility, as oxygen is an α stabilizer. Even the range of oxygen found in Grade 5 powder is quite large, and therefore, results may vary [17].…”

“…Finally, all tests were performed using only virgin powder from a single production batch to rule out any influence of changing powder properties [11,12,17], as such effects can be greater than the effects of parameters, orientation, and post-process treatments. This enabled the comparability of post-process treatments and orientation, which is not the case for previous studies.…”