PSI - Issue 53

R.F. Fernandes et al. / Procedia Structural Integrity 53 (2024) 144–150 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Furthermore, the chosen heat treatment involved stress relief, with a temperature of 250 ºC maintained for 2 h followed by water quenching to the room temperature. The selection of a heating temperature below 260-270 ºC ensures that Si precipitation is avoided, as mentioned above. 3. Results 3.1. Hardness and Monotonic behavior The hardness and monotonic behavior of AlSi10Mg are affected by the post-processing applied treatment, as shown in Table 2. The as-built (AB) series exhibited an average hardness value of 165.6 HV, while the stress relief (SR) was 114.4 HV. This represents a 30% reduction in the hardness.

Table 2. Hardness and monotonic tensile properties. Series HV 0.1 σ UTS (MPa)

σ YS (MPa)

ε f (%)

E (GPa)

AB SR

165.6 114.4

435 380

250 210

4.1 5.6

72 72

As a consequence of this decrease in hardness, there is also a reduction in the monotonic behavior. The SR series exhibited a decrease of 13% and 16% in the ultimate tensile strength and yield strength, respectively. Nevertheless, the ductility of the SR series increased by 37% compared to the AB series. 3.2. Fatigue behavior The fatigue results under variable loading amplitudes are represented in Figure 3 for both the unnotched and notched specimens. It is evident that the SR series demonstrated an overall improvement in fatigue strength in both cases. Upon careful examination, it became clear that the fatigue strength has increased 18% for 10 6 cycles in both cases, when comparing the SR and AB series.

Fig. 2. S-N curves for: a) Unnotched and b) semicircular notch.