Ad Hoc Heat Treatments for Selective Laser Melted Alsi10mg Alloy Aimed at Stress-Relieving and Enhancing Mechanical Performances

Tuning of Static and Dynamic Mechanical Response of Laser Powder Bed Fused AlSi10Mg Lattice Structures through Heat Treatments

“…The microstructure evolution of such microstructure upon heat treatment is shown in Figure 6. It may be appreciated that the results are consistent with the ones previously reported by the authors for bulk samples [14] and, furthermore, that no bending or warping of the lattice structures could be noted after heat treatments. The well-known cellular structure, which characterizes the as-built sample, is retained after direct ageing at 170 C and even after the stress relieving treatment carried out at 263 C (Figure 6b,c).…”

Production Strategy for Manufacturing Large-Scale AlSi10Mg Components by Laser Powder Bed Fusion

“…This weakening was ascribed to the former Si diffusion from the a-Al supersaturated solid solution that contributed to the formation of fine precipitates within Si cells and the concurrent low-temperature stress relieving, as recently reported in Refs. 31,32 by Fiocchi et al In this case, a remedy to the over-aging phenomenon can be applied by using post-process heat treatment. 26,33,34 When the T6 heat treatment was applied, the current work witnessed a remarkable increase of hardness up to 115 HV, which is comparable to that of die-cast A360-T6 counterparts.…”

Heat Treatments for Stress Relieving AlSi9Cu3 Alloy Produced by Laser Powder Bed Fusion

“…In fact, 8 h (480 min) was chosen as a reference time for full stabilization in the present work: further characterizations will address as-built samples and parts treated at 250 °C for 8 h (141.4 HV) and 64 h (128.1 HV). The decrement of hardness between as-built and stabilized samples amounts to 10.1%, which is somehow smaller than the one revealed in the well-known AlSi10Mg alloy treated at a similar temperature (244 °C, 23.9% decrement) [ 9 ]. On the contrary, the time-dependency of the trends in the two alloys appears extremely similar, suggesting that the main underlying process might still be the relaxation of residual stresses.…”

“…However, few alloys have driven considerable attention: among these the well-known AlSi10Mg alloy has been widely studied and its properties are now relatively deeply assessed under many different perspectives, including processability [ 1 , 2 ], microstructure [ 3 ], static [ 4 ] and dynamic [ 5 ] mechanical properties and fatigue life [ 6 , 7 ]. Moreover, it has been widely demonstrated that LPBF-built aluminum parts require post-processing heat treatments [ 8 ] in order to remove residual stresses [ 9 ] and, potentially, homogenize the microstructure and the mechanical behaviour [ 10 ]. In this respect, owing to the arising fine microstructure and large supersaturation, it has been recognized by numerous authors that temperatures and durations of the aforementioned treatments need to be properly tuned according to the specific features of the LPBF-ed alloys [ 11 , 12 ].…”

“…Their reduction or removal is usually obtained by means of annealing treatments, which are performed in a temperature range, which lies between the one used for ageing treatment (usually from 140 °C to 180 °C) and the one able to induce a proper solubilization of the material (above 480 °C). Inside this temperature interval, two different ranges can be identified, which differently affect the microstructure of LPBFed Al-Si alloys [ 29 ]: the lower one (up to 270 °C) is able to reduce residual stresses without affecting the eutectic cellular Si network; the upper one on the contrary also induces the spheroisation of the Si network, leading to a sharp decrease in mechanical resistance [ 9 ].…”