PSI - Issue 53

L.B. Peral et al. / Procedia Structural Integrity 53 (2024) 52–57 L.B. Peral / Structural Integrity Procedia 00 (2019) 000–000

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Since martensite is known to be very sensitive to hydrogen embrittlement [7,8], this can be an important factor explaining the increased hydrogen embrittlement susceptibility of the sample tested at 0.005 mm/min in the presence of hydrogen ( ൎ 37 wt ppm). Thus, in the presence of internal hydrogen, it is important to highlight that the observed fracture micromechanisms near the notched region (Figure 6b) can be promoted by the strain-induced martensite formation. It is well known that hydrogen atoms are driven by the high hydrostatic stress existing in the vicinity of the notch and simultaneously, the strain-induced martensite acts as a diffusion path for hydrogen [7] due to the higher diffusivity through that phase; this short-circuit diffusion induced the formation of quasi-cleavages and secondary cracks. 4. Conclusions Hydrogen ex-situ tensile tests were employed to evaluate hydrogen embrittlement susceptibility in an additively manufactured 316L by selective laser melting. Based on smooth tensile results, significant hydrogen hardening (yield strength and ultimate tensile strength increased) was observed because of the high internal hydrogen ( ൎ 37 wt ppm). Additionally, ductility slightly decreased. On the other hand, in the presence of a notch, the notch tensile strength and especially, the reduction of area were affected by hydrogen. In this case, fracture micromechanism changed from ductile (without hydrogen) to quasi-brittle (with hydrogen) near the notched region. Hydrogen damage is also explained because of the strain-induced martensite formation near the notch tip region. Acknowledgements The authors would like to thank the Spanish Government for the financial support received to perform the research projects PID2021-124768OB-C21 and TED2021-130413B-I00. This work was also supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union Next Generation EU/PRTR (MR4W.P2 and MR5W.P3). References [1] Liverani E, Toschi S, Ceschini L, Fortunato A. Effect of selective laser melting (SLM) process parameters on microstructure and mechanical properties of 316L austenitic stainless steel. J Mater Process Technol 2017;249:255–63. https://doi.org/10.1016/j.jmatprotec.2017.05.042. [2] Lin J, Chen F, Liu F, Xu D, Gao J, Tang X. Hydrogen permeation behavior and hydrogen-induced defects in 316L stainless steels manufactured by additive manufacturing. Mater Chem Phys 2020;250. https://doi.org/10.1016/j.matchemphys.2020.123038. [3] Zhou Z, Zhang K, Hong Y, Zhu H, Zhang W, He Y, et al. The dependence of hydrogen embrittlement on hydrogen transport in selective laser melted 304L stainless steel. Int J Hydrogen Energy 2021;46:16153–63. https://doi.org/10.1016/j.ijhydene.2021.02.035. [4] Claeys L, Depover T, De Graeve I, Verbeken K. First observation by EBSD of martensitic transformations due to hydrogen presence during straining of duplex stainless steel. Mater Charact 2019;156. https://doi.org/10.1016/j.matchar.2019.109843. [5] Matsuo T, Yamabe J, Matsuoka S. Effects of hydrogen on tensile properties and fracture surface morphologies of Type 316L stainless steel. Int J Hydrogen Energy 2014;39:3542–51. https://doi.org/10.1016/j.ijhydene.2013.12.099. [6] Díaz A, Alegre JM, Cuesta II, Zhang Z. Numerical study of hydrogen influence on void growth at low triaxialities considering transient effects. Int J Mech Sci 2019;164. https://doi.org/10.1016/j.ijmecsci.2019.105176. [7] Zhang H yun, Zheng L wei, Wang T, Lv W jie, Shi Q xin, Ma J yao, et al. Interrelationship between hydrogen and α′ -martensite of SUS 304 austenitic stainless steel revealed by tensile tests. Materials Science and Engineering: A 2022;831. https://doi.org/10.1016/j.msea.2021.142169. [8] Fan YH, Zhang B, Yi HL, Hao GS, Sun YY, Wang JQ, et al. The role of reversed austenite in hydrogen embrittlement fracture of S41500 martensitic stainless steel. Acta Mater 2017;139:188–95. https://doi.org/10.1016/j.actamat.2017.08.011.