PSI - Issue 68

Adam Ståhlkrantz et al. / Procedia Structural Integrity 68 (2025) 1051–1058 Ståhlkrantz et al./ Structural Integrity Procedia 00 (2025) 000–000

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4. Conclusion For AHSS steels with RA, trapped hydrogen was shown to severely limit the capability for sustained strain hardening and to alter their mechanical properties significantly. This could lead to severe consequences in for example shock absorbing crash box component in an automotive or other critical applications where a certain material behavior is expected. From the work conducted within this study the following have been concluded: • Hydrogen reduced the local formability of AHSS. • Hydrogen also reduced the global formability of the steel, with the severity of the drop correlating with the fraction of retained austenite. • The observed changes can be rationalized on the hypothesis that trapped hydrogen reduces the mechanical stability of retained austenite, leading to a more rapid TRIP effect and smaller uniform elongations. Hai, C., Zhu, Y., Du, C., Cheng, X., & Li, X. (2024). Optimization of the hydrogen embrittlement resistance in ultra-high-strength multi-alloyed steel via controlling the reversed austenite fraction and stability. International Journal of Hydrogen Energy, 71, 59-69. Hance B, Advanced High Strength Steel: Deciphering Local and Global Formability, Proc. International Automotive Body Congress, Dearborn, MI 2016. Li, S., Li, K., Zhang, L., Feng, Y., Liu, Z., Cao, P., ... & Dong, J. (2023). Characterization of Retained Austenite in Advanced High‐Strength Steel. Scanning, 2023(1), 9565903. Malitckii, E., Yagodzinskyy, Y., & Vilaҫa, P. (2019). Role of retained austenite in hydrogen trapping and hydrogen-assisted fatigue fracture of high-strength steels. Materials Science and Engineering: A, 760, 68-75. Smith, A. (2021, February). Hydrogen embrittlement and hydrogen trapping behaviour in advanced high strength steels. In Materials Science Forum (Vol. 1016, pp. 1344-1349). Trans Tech Publications Ltd. Takashima, K., Nishimura, T., Yokoyama, K. I., & Funakawa, Y. (2024). Delayed fracture enhanced by martensite transformed from retained austenite in ultra-high strength steel sheet. ISIJ International, 64(4), 742-750. Vennet S, Leitner S, Razumovskiy V, Ecker W, Depover T, Verbeken K. Mechanical load induced hydrogen charging of retained austenite in quenching and partitioning (Q&P) steel, International Journal of Hydrogen Energy 2023; 48(6):2428-2441. Wagner L, Larour P. Influence of specimen geometry on measures of local fracture strain obtained from uniaxial tensile tests of AHSS sheets, Materials Science and Engineering 2018; 418. References