The Effect of Ti and Mo Microalloying on Hydrogen Embrittlement Resistance of Ultra-High Strength Medium Mn Steel

The Effect of Ti and Mo Microalloying on Hydrogen Embrittlement Resistance of Ultra-High Strength Medium Mn Steel

This study elucidated the effect of Ti–Mo microalloying on the hydrogen embrittlement (HE) resistance and fracture behavior of warm-rolled Fe-5.6Mn-0.16C-1Al (wt%) steel. After intercritical annealing, both steels, i.e., without and with Ti–Mo microalloying, showed ultrafine ferrite (<i>α</...

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Bibliographic Details
Main Authors: Pujunhuan Zhang, Yang Zhao, Jianglong Pan, Weizhuo Hao, Shuyi Wang, Minghui Cai
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Metals
Subjects:
medium Mn steel
Ti–Mo microalloying
precipitation strengthening
hydrogen embrittlement
<i>γ</i><sub>R</sub> stability
Online Access:https://www.mdpi.com/2075-4701/15/4/397
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Summary:This study elucidated the effect of Ti–Mo microalloying on the hydrogen embrittlement (HE) resistance and fracture behavior of warm-rolled Fe-5.6Mn-0.16C-1Al (wt%) steel. After intercritical annealing, both steels, i.e., without and with Ti–Mo microalloying, showed ultrafine ferrite (<i>α</i>) and austenite (<i>γ</i><sub>R</sub>) duplex microstructure. The addition of Ti–Mo to 5.6Mn steel reduces the volume fraction of <i>γ</i><sub>R</sub>, facilitating the formation of (Ti, Mo)C carbides in <i>α</i> phase and further refining the final microstructure. The product of ultimate tensile strength (UTS) and total elongation (TEL) of 5.6MnTiMo can be as high as 35 GPa·% with an ultra-high yield strength of above 1.2 GPa. Furthermore, the addition of Ti–Mo also had a significant effect on the resistance to HE of medium Mn steels. Firstly, the limited (Ti, Mo)C carbides precipitated in <i>γ</i><sub>R</sub> could act as irreversibly trap sites to capture a considerable amount of H, effectively increasing the C<sub>H</sub> (Diffusible Hydrogen Content). Additionally, 5.6MnTiMo displayed higher <i>γ</i><sub>R</sub> stability, resulting in a reduced susceptibility to HE. The H-assisted microcracks mainly formed inside <i>γ</i>(<i>α</i>′) and extended along <i>γ</i>(<i>α</i>′) grain boundaries, leading to intergranular cracking and premature fracture.
ISSN:2075-4701

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