PSI - Issue 83

Sze Pei Tan et al. / Procedia Structural Integrity 83 (2026) 28–40

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Table 1. The processing parameters that are applied to fabricate the specimens.

Laser Power, W

Focal Diameter, µm

Scanning Speed, m/s

Layer Thickness, µm

Power Supply, A

400

100

7.0

30

32

Post-processing was applied to the specimen for enhancing mechanical performance. To minimize the residual stress that produces during DMLS process, all samples were stress relieved at 300 °C for 2 h. In this study T6 heat treatment was used for further post processing of the prepared specimen. Heat treatment was performed in a temperature-controlled VECSTAR furnace adjacent to the quenching facility to ensure rapid cooling. However, T6 heat treatment contains total three steps: (i) solution heat treatment, (ii) water quenching, and (iii) artificial aging, The samples were quenched in water after the heat treatment at room temperature. Artificial aging was performed on the heat-treated specimen sample at 165 °C for 7 hours, that is followed by the air-cooling temperature to room temperature. During quenching, the samples are rapidly cooled in water at room temperature to retain a supersaturated solid solution formed during the high-temperature treatment. Then artificial aging is performed to achieve maximum hardening. The overall post-processing route follows the T6 method illustrated in Fig. 3 [21] . Mechanical performances were evaluated for some as-built selected specimen samples while other samples were tested after the T6 heat treatment process to evaluate the effect of heat treatment process in the material’s structural integrity. In this regard mechanical tests like tensile test, fatigue propagation test and after that fractographic tests were performed on failed specimens to correlate fracture properties with mechanical behavior under monotonic and cyclic loading.

Fig. 3. T6 solution heat treatment.

3. Material Characterization Test This section discusses the material characterization test of the DMLS fabricated specimen using AlSi10Mg as the built material. The material characterization test includes tensile testing and fatigue life testing. 3.1. Tensile test The tensile test was performed to determine the structural behavior of the materials when it is subjected to the loading. The stress strain diagram derived from the experiment is observed for the ultimate tensile strength, UTS and Young’s modulus, E . Several other results also acquired such as maximum strain and yield stress. Fig. 4 (a) shows the geometry for the tensile test specimen and it is fabricated vertically using the DMLS parallel to Z axis. Six samples are produced by AM, half of them are heat treated to T6 condition and the rest are as-built. All the specimens are grinded and polished to reduce the possibility for the crack to occur due to the surface roughness. However, the ASTM E8 standard was followed in the testing processes. The crosshead speed and strain rate is set to be 1.8 mm/m and 1x10 -3 s -1 as reported by Rosenthal et al. [22]. Fig. 4 (b) shows the testing that is performed using the Zwick 100 kN universal testing machine . The UTS is used to design the fatigue loading for the fatigue life test. Further explanation regarding the fatigue life experiment is presented subsequently.