KEI SAITO
(Center for Basic Research on Materials/Data-driven Materials Research Field/Materials Modeling Group, National Institute for Materials Science)
;
MASAHIKO DEMURA
(Center for Basic Research on Materials/Data-driven Materials Research Field/Materials Modeling Group, National Institute for Materials Science)
;
KENICHI TAKAI
(Sophia University)
コレクション
引用
説明:
(abstract)Advanced-high strength steels (AHSS) have been attracting attention in recent years for application to structure parts of automobile to secure both crashworthiness and weight reductions. Developing AHSS with excellent resistance to hydrogen embrittlement (HE) is an urgent issue since the risk of HE increases with increase in a tensile strength of steel due to hydrogen uptake under vehicle manufacturing process and market service. The present study aimed to elucidate the effect of microstructural hardness on resistance to hydrogen embrittlement in ferrite-martensite dual-phase (DP) steel sheet with a tensile strength of approximately 1180 MPa. Two kinds of DP specimens with similar tensile strength, but different microstructural hardness between ferrite and martensite, were prepared: as-quenched DP (DP-AQ) and tempered DP (DP-TM) specimens with a high and low difference in microstructural hardness, respectively. The resistance to HE of two types of specimens was evaluated by using slow strain rate tensile test (SSRT) in-situ a specific electrochemical charging with hydrogen, based on the change in the maximum fracture strength and uniform elongation obtained by stress-strain curves, and fracture strain calculated by the amount of reduction in area. The maximum fracture strength was similar among hydrogen-charged two types of specimens. The orders of uniform elongation and fracture strain for the hydrogen-charged two types of specimens were DP-TM > DP-AQ. The fracture surface of hydrogen-charged DP-AQ specimen was mainly quasi-cleavage over the entire fracture surface, however that of DP-TM specimen was quasi-cleavage only around the crack initiation site and dimple patterns was observed apart from crack initiation area. These results indicate that reduction in microstructural hardness between ferrite and martensite improves the HE resistance in terms of global and local ductility due to presumably suppressing the hydrogen-related crack initiation and crack propagation in brittle mode.
権利情報:
キーワード: hydrogen embrittlement, dual phase steel, hardness, ductility
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出版者:
掲載誌:
会議: 5th International Conference on Metals & Hydrogen (2025-10-14 - 2025-10-16)
研究助成金:
- JSPS JP24K21211 (水素脆化破面の局所領域における格子欠陥検出技術の開拓と新たな水素脆化理論への展開)
原稿種別: 論文以外のデータ
MDR DOI: https://doi.org/10.48505/nims.6110
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更新時刻: 2026-01-07 11:05:00 +0900
MDRでの公開時刻: 2026-01-07 12:22:01 +0900