Abstract The bcc ferritic Fe-Ni steels and in particular the commercial 9Ni alloys were developed and widely used at cryogenic temperatures for liquefied natural gas storage. The excellent thermomechanical properties and cryogenic toughness of these materials are closely related to the presence of metastable fcc austenitic phase whose stability increases in the presence of austenitic components (Ni, Cr, Mn, etc.) and with decreasing fcc grain size. Numerous reports are related to quenching and tempering technological procedures improving the cryogenic performance, however, very little attention has been paid to the structural characterization of austenitic minority species except for a few papers revealing rather contradictory results. Using high-energy X-ray diffraction, small-angle neutron scattering and 57Fe Mossbauer spectroscopy we show that the minority austenitic particles in the commercial X8Ni9 steel are enriched in nickel up to 27 ± 6 at.% Ni and have a characteristic size of 620 ± 25 A. The austenitic phase is highly sensitive to mechanical deformation and stress. Disappearance of the fcc grains during the treatment implies a mechanical failure while mechanically-resistant regions are characterized by a higher intensity of the austenitic reflections probably related to the generated texture. The last finding was never reported previously.

中文翻译：

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使用同步辐射、中子散射和 57 Fe 穆斯堡尔光谱对低温 9Ni 钢进行高级表征

摘要 开发了 bcc 铁素体 Fe-Ni 钢，特别是商用 9Ni 合金，并在低温下广泛用于液化天然气储存。这些材料优异的热机械性能和低温韧性与亚稳态 fcc 奥氏体相的存在密切相关，亚稳态 fcc 奥氏体相的稳定性在奥氏体成分（Ni、Cr、Mn 等）的存在下增加，并且随着 fcc 晶粒尺寸的减小而增加。许多报道都与提高低温性能的淬火和回火技术程序有关，然而，除了一些揭示相当矛盾结果的论文外，很少关注奥氏体少数物种的结构特征。利用高能 X 射线衍射，小角中子散射和 57Fe Mossbauer 光谱表明，商用 X8Ni9 钢中的少数奥氏体颗粒富含镍高达 27 ± 6 at.% Ni，特征尺寸为 620 ± 25 A。奥氏体相高度对机械变形和应力敏感。在处理过程中 fcc 晶粒的消失意味着机械故障，而机械抗性区域的特征在于更高强度的奥氏体反射，这可能与生成的织构有关。最后的发现以前从未报道过。在处理过程中 fcc 晶粒的消失意味着机械故障，而机械抗性区域的特征在于更高强度的奥氏体反射，这可能与生成的织构有关。最后的发现以前从未报道过。在处理过程中 fcc 晶粒的消失意味着机械故障，而机械抗性区域的特征是更高强度的奥氏体反射，可能与生成的织构有关。最后的发现以前从未报道过。