PSI - Issue 38

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D. Rigon et al. / Procedia Structural Integrity 38 (2022) 70–76 D. Rigon and G. Meneghetti / Structural Integrity Procedia 00 (2021) 000 – 000

74

a)

Red marker: broken specimens before N A Black marker: unbroken/broken specimens after N A

R = -1

1

estimated ALM model MS 300 NT (a) MS 300 NT (a) MS 300 T (b)

Série1 Série2 Série3 Série4 Série5 Série6 Série7 Série8 Série9 Série10 Série11 Série12 Série13 Série14 Série15 Série16 Série17 Série19 Série20 Série18

Rigon Meneghetti 2020 N A = 2∙10 6 cycles

Δσ g,th / Δσ 0,est

Ti6Al4V (EBM) Ti6Al4V (DMLS)

Masuo et al 2018 N A = 10 7 cycles

Ti6Al4V surface defects Ti6Al4V internal defects Ti6Al4V internal defects - Qian et al. 2020 N A = 10 17-4PH steel - Romano et al. 2020 N A = 10 7 cycles H13 tool steel - Pellizzari et al. 2020 N A = 10 Liu et al 2020 N A = 10

7 cycles

7 cycles

7 cycles

0,1

0,01

0,1

1

10

100

a eff /a 0,est

b)

R = 0.1

1

Red marker: broken specimens before N A Black marker: unbroken/broken specimens after N A

Δσ g,th / Δσ 0,est

Série1 Série2 Série4 Série8 Série9 estimated ALM model Ti6Al4V - Hu et al. (2020) N A = 10 7 cycles Ti6Al V - Wycisk et al (2014) N A = 10 7 cycles AISI 316L surface defects - Andreau et al (2021) N A = 10 AISI 316L internal defects - Andreau et al (2021) N A = 10

7 cycles

6 cycles

0,1

0,01

0,1

1

10

100

a eff /a 0,est

Fig. 1. Comparison between the experimental fatigue test results taken from dataset of Table 2 and fatigue thresholds according to the ALM model (Eq. 4) for (a) R=-1 and (b) R=0.1.

Interestingly, data relevant to AM 316L steel (Andreau et al. 2021) resulted in good agreement with the theoretical predictions in case of failure relevant to the surfaces defects, whereas estimations relevant to the large artificial internal defects are highly conservative. It is interesting to note that the authors of the original paper (Andreau et al. 2021) underline that the different fatigue behaviour of internal as opposed to surface defects can be explained by the different gaseous environment to which they are exposed.