Modelling of Heat Transfer and Phase Transformations in the Rapid Manufacturing of Titanium Components

Ductility improvement due to martensite α′ decomposition in porous Ti–6Al–4V parts produced by selective laser melting for orthopedic implants

“…A basic sequence of decreasing Young's modulus is α4α 0 4β (Crespo, 2011). Hence, the α 0 -αþβ transformation simultaneously produces a phase with lower stiffness (α 0 -β) and a phase with higher stiffness (α 0 -α).…”

Modelling of additive manufacturing processes: a review and classification

“…Welding speed, wire feed rate, arc voltage [96] Microstructure, mechanical properties Pre-heating of substrate, scanning speed, idle time [93] Residual stresses Melt pool geometry, metal powder flow rate, laser power, scanning speed, scanning direction, and deposition layer thickness [97] Microstructure, hardness, residual stresses Deposition parameters [94] Residual stress history, microstructure Phase change [98] Total spread of droplet, solidification front speed, interlamellar spacing Droplet size, speed, superheat [99] Microstructure, hardness Substrate size, idle time [100] Powder-to-solid transition Temperature, porosity-dependent conduction [101] Grain size, grain growth speed, Temperature, deposition over time [115] Thermal history Laser-scan velocities [102] Spreading and shape of the droplet after impact Substrate roughness and temperature, speed of droplet [103] Splashing of droplets Impact velocity, temperature [104] Fingering and splashing of the droplet Droplet velocity, liquid type, temperature of surface, surface roughness, contact angle [105] Desired shape after impact Initial droplet shape [106] Microstructure, temperature field Number of layers, layer height, wire feed rate, travel speed, heat input optimizing the process mechanics can lead to the improvement of such issues. In Table 8, the modelled KPIs and the process parameters used in each study can be seen.…”

“…Modelling of topology and dimensional accuracy takes place in [80][81][82][83][84] using analytical, in [85,86] analytical-numerical, in [17][18][19]32,79,[87][88][89][90][91][92][93][94] numerical, whereas in [95] those issues have been empirically modelled utilizing artificial neural networks (ANN). Modelling of the mechanical properties and microstructure has been conducted in [80,81] using analytical, in [86,96] analyticalnumerical and in [94,[97][98][99][100][101] using numerical approaches. Droplet kinematics and flow phenomena have been modelled in [102,103] using analytical and in [87,98,[104][105][106][107][108][109][110][111][112][113] using numerical approaches.…”

Influence of Heat Treatments on the Microstructure and Tensile Behaviour of Selective Laser Melting-Produced Ti-6al-4v Parts

“…As such, ductility values of post-heat-treated SLM Ti-6Al-4V have been reported in the range of 8 and 10 per cent [7,8] and up to 12 per cent [8]. This is less than its wrought counterpart (16)(17)(18) per cent elongation at break [5]) and below the requirements set by some standards (ASTM F1472-08). Investigation into various tailored heat treatments have been done by various authors [8,11,12]; however, a consistently lower ductility has been reported so far [6].…”

“…Young's Moduli of Ti-6Al-4V phases are compared in magnitude by α>α'>β. In the literature, individual Young's Moduli of α, α', and β are calculated to be 117, 114, and 82 GPa respectively [18]. Martensitic decomposition causes the simultaneous formation of α and β, which in turn causes the elastic stiffness to both increase and decrease; an increase is due to the formation of the α phase and a decrease is due to the formation of the β phase.…”