PSI - Issue 57

Kalle Lipiäinen et al. / Procedia Structural Integrity 57 (2024) 32–41 Lipiäinen et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig 4. Examples of fractography with marked quality-parameter crack lengths. The method could be compared to √ -parameter used by Murakami (Murakami, 2002). The √ -pa ra meter has been proved in assessment of fatigue limit and utilized e.g. in the study by Afkhami, Dabiri, Lipiäinen, et al. (2021) for AM-component fatigue strength assessment. However, using area-based quality parameter would lead to increased complexity when external geometry is considered. In principle, area-based FEA combined with area-based stress averaging would return more detailed analysis but comparable results. Moreover, the linear crack -length based quality parameter advantage is simplicity of modelling and better estimation of typical case withing certain material, structure, and local geometry combination. Table 2. Materials, specimen types and obtained initial crack lengths. Material Specimen ID

Initial crack length ( μ m)

MS1 MS1 MS1 MS1 MS1 MS1 MS1 MS1 MS1

Unnotched

MS1_UN MS1_EV1 MS1_EV2 MS1_EC1 MS1_EC2 MS1_IV1 MS1_IV2 MS1_IC1 MS1_IC2 CX_HTHM CX_HTVM 316L-HM 316L-VM 316L-VA 316L-HFMI CX_VM CX_VA

100

External sharp V-notch External rounded V-notch External circular shallow notch External circular deep notch Internal sharp V-notch Internal rounded V-notch Internal circular shallow notch Internal circular deep notch Vertical print & machined Vertical print & as-build Horizontal print & machined Vertical print & machined Horizontal print & machined Vertical print & machined Vertical print & as-build Horizontal print & HFMI

50 50 50 50 50 50 50 50 70 30 30

CX CX

110

CX-HT CX-HT CX-HT

Horizontal print & as-build surface CX_HTVA

110

316L 316L 316L 316L

80

100 130

70

316L, CX and MS1 Based on previous findings, the results are presented in Figure 5 with critical distances of a = 0.1 mm (Fig 5a) a = 0.04 mm (Fig 5b). Shorter stress averaging length a = 0.04 mm results better estimation especially in cases where equivalent crack is small and external geometry is not present. Therefore, a = 0.04 mm critical distance is utilized in the study.