文献类型：期刊文献

英文题名：Hydrogen-assisted decohesion associated with nanosized grain boundary κ-carbides in a high-Mn lightweight steel

作者：Elkot, Mohamed Naguib[1,2];Sun, Binhan[3];Zhou, Xuyang[1];Ponge, Dirk[1];Raabe, Dierk[1]

机构：[1]Max Planck Inst Eisenforsch GmbH, Max Planck Str 1, D-40237 Dusseldorf, Germany;[2]Suez Univ, Dept Met & Mat Engn, Suez 43512, Egypt;[3]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China

年份：2022

卷号：241

外文期刊名：ACTA MATERIALIA

收录：;EI(收录号：20224112857059);WOS:【SCI-EXPANDED(收录号:WOS:000926229900006)】；

基金：Mohamed Elkot acknowledges the funding of DAAD and MoHE of Egypt to his PhD studies within the frame of GERLS scholarship. Xuyang Zhou acknowledges the support from Alexander von Humboldt Foundation. Binhan Sun acknowledges the financial support from the National Natural Science Foundation of China (Grant No. 52275147).

语种：英文

外文关键词：Lightweight steel; kappa-carbides; Hydrogen embrittlement; Intergranular failure; Cryogenic temperature

摘要：While age-hardened austenitic high-Mn and high-Al lightweight steels exhibit excellent strength-ductility combinations, their properties are strongly degraded when mechanically loaded under harsh environments, e.g. with the presence of hydrogen (H). The H embrittlement in this type of materials, especially pertaining to the effect of kappa-carbide precipitation, has been scarcely studied. Here we focus on this subject, using a Fe-28.4Mn-8.3Al-1.3C (wt%) steel in different microstructure conditions, namely, solute solution treated and age-hardened. Contrary to the reports that grain boundary (GB) kappa-carbides precipitate only during overaging, site-specific atom probe tomography and scanning transmission electron microscopy (STEM) reveal the existence of nanosized GB kappa-carbides at early stages of aging. We correlate this observation with the deterioration of H embrittlement resistance in aged samples. While H pre-charged solution-treated samples fail by intergranular fracture at depths consistent with the H ingress depth (similar to 20 mu m), age-hardened samples show intergranular fracture features at a much larger depth of above 500 mu m, despite similar amount of H introduced into the material. This difference is explained in terms of the facile H-induced decohesion of GB kappa-carbides/matrix interfaces where H can be continuously supplied through internal short-distance diffusion to the propagating crack tips. The H-associated decohesion mechanisms are supported by a comparison with the fracture behavior in samples loaded under the cryogenic temperature and can be explained based on dislocation pileups and elastic misfit at the GB kappa-carbide/matrix interfaces. The roles of other plasticity-associated H embrittlement mechanisms are also discussed in this work based on careful investigations of the dislocation activities near the H-induced cracks. Possible alloying and microstructure design strategies for the enhancement of the H embrittlement resistance in this alloy family are also suggested. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.