In situ microscopic observations of low-cycle fatigue-crack propagation in high-Mn austenitic alloys with deformation-induced ε-martensitic transformation
In situ microscopic observations of low-cycle fatigue-crack propagation in high-Mn austenitic alloys with deformation-induced ε-martensitic transformation
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DOI：
10.1016/j.actamat.2016.04.042
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发表时间：
2016-06-15
期刊：
影响因子：
9.4
通讯作者：
Noguchi, Hiroshi
中科院分区：
文献类型：
--
作者：
Ju, Yun-Byum;Koyama, Motomichi;Noguchi, Hiroshi
在这项研究中，显微组织的变化，在Fe-30 Mn-6Al，Fe-30 Mn-4Si-2Al，和Fe-30 Mn-6Si合金进行弯曲疲劳试验，总应变幅为0.7%，原位观察。Fe-30 Mn-4Si-2Al和Fe-30 Mn-6Si合金发生了形变诱发ε马氏体相变，而Fe-30 Mn-6Al合金没有发生形变诱发ε马氏体相变。Fe-30 Mn-4Si-2Al合金的抗疲劳裂纹扩展能力上级其它合金，这是由于ε-马氏体相变的影响。合金中的e-马氏体相变对裂纹扩展有三个积极影响：I）抑制应变局部化; II）锯齿形裂纹扩展，其增强粗糙度引起的裂纹闭合;以及III）亚裂纹形成，其引起裂纹增韧，例如应力再分布。另一方面，e-马氏体相变对裂纹生长具有负面影响，即，它引起亚裂纹萌生，导致亚裂纹与主裂纹合并。然而，Fe-30 Mn-4 Si-2 Al合金中的ε-马氏体相变被优化，使得正面效应最大化并且负面效应最小化，这导致合金对低周疲劳的上级抗性。(C)2016 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
In this study, the microstructural changes in Fe-30Mn-6Al, Fe-30Mn-4Si-2Al, and Fe-30Mn-6Si alloys that were subjected to bending fatigue tests with a total strain amplitude of 0.7% were observed in situ. The Fe-30Mn-4Si-2Al and Fe-30Mn-6Si alloys exhibited deformation-induced epsilon-martensitic transformation, but the Fe-30Mn-6Al alloy did not. The resistance of the Fe-30Mn-4Si-2Al alloy against fatigue-crack growth was superior to that of the other alloys, which is attributed to the effects of the epsilon-martensitic transformation. The e-martensitic transformation in the alloy has three positive effects on crack growth: I) the suppression of strain localization; II) zigzag crack propagation, which enhances roughness-induced crack closure; and III) subcrack formation, which induces crack toughening, such as stress redistribution. On the other hand, the e-martensitic transformation has a negative effect on crack growth, i.e., it causes subcracic initiation, which leads to the subcracks coalescing with the main crack. However, the epsilon-martensitic transformation in the Fe-30Mn-4Si-2Al alloy is optimized so that the positive effects are maximized and the negative effect is minimized, which results in the superior resistance of the alloy against low -cycle fatigue. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.