PSI - Issue 34

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Ramesh Babu et al. / Procedia Structural Integrity 34 (2021) 20–25 Ramesh babu/ Structural Integrity Procedia 00 (2019) 000 – 000

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There are no significant differences in microstructure and mechanical properties on the horizontal (W1 and W3) and the vertical specimens (W2 and W4) on the base to tip of the propeller since each layer undergoes a heat treatment caused by the following weld pass. A coarse microstructure is present in the Heat Affected Zone (HAZ) close to the fusion line between each single weld pass, see Figure 4 – 7. It is most likely originated by the WAAM process ’ re heating of previous deposited and solidified weld metal. Furthermore, in Figure 4 – 7 one can see that the bright contracts regions are p rimary α -dendrites and the dark etched are interdendritic. Microstructure at the interface of melt pool boundary revealed no defects, and microstructure were same as in literature by Eva et al.(2019)W.Ya et al (2017)Kiakidis et al.(2017). The chemical composition of the WAAM material complies with the Ship classification rule requirements for sand casting and weld joints given by IACS W24(2020) and the mechanical properties of the WAAM material exceed the ship rule requirements, see Table 2 and 3. Furthermore, impact toughness was tested on specimens from the high stress area, and the results exceeds 27 J; that is a general minimum requirement for quality weld joint applications, see Table 3. Demonstrating that WAAM components with acceptable toughness quality can be produced. For the sake of increased understanding and future research to meet DNV-CG-0039(2021) and DNV Pt.2 Ch.2 Sec.14(2021), the hardness values of the CU3 WAAM material were collected and compared toward existing CU3 cast material data. The generic identification of a WAAM process is DED-Arc/wire • Propellers are appealing to be additive manufactured: • WAAM is well-established an mature technology at manufacturing and repair of ship hulls, marine machinery • Existing Ship classification rules and standards intended for conventional manufacturing served as basis for assessment of the WAAM propeller • Tensile strength, ductility, toughness of the as printed was found to be isotropic along the build and deposition direction • WAAM components with acceptable toughness quality can be produced • Strict temperature controls of the WAAM process preheat and interpass temperature is the main contributor to the achieved WAAM material’s mechanical properties. • The Ni-Al-bronze (CU3) WAAM marine propeller was found to meet and exceed the Ship rule´s chemical and mechanical requirements of cast propeller • Based on the results of this benchmark study DNV has accepted WAAM as a manufacturing method • To prove the WAAM marine propeller concept’s seaworthiness; additional experimental data is necessary • This benchmark study has been a successful Industrial-Academic research project 5.0 ACKNOWLEDGEMENT The authors gratitude’s Det Norske Veritas maritime classification society; Hyundai Heavy Industries; Korea Evaluation Institute of Industrial Technology; and SY Metal Co., Ltd. for financing this research study. As well as the following individuals for valuable advises and information from DNV-Deinboll,Oddvar; Amini, Hamid; Sames, Pierre C; Norheim, Marit Haugen; Laumann, Marit; Lohman, Thorsten; Kim,Su Cheol and from Ramlab-Wei Ya, Vignesh. 4.0 CONCLUSIONS •

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