Cyclic deformation behavior of austenitic Cr-Ni-steels in the VHCF regime: Part I - Experimental study
Cyclic deformation behavior of austenitic Cr-Ni-steels in the VHCF regime: Part I - Experimental study
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DOI：
10.1016/j.ijfatigue.2016.05.005
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发表时间：
2016-12-01
影响因子：
6
通讯作者：
Christ, H. -J.
中科院分区：
文献类型：
--
作者：
Grigorescu, A. C.;Hilgendorff, P. -M.;Christ, H. -J.
研究了稳定（AISI 316L）和亚稳定（AISI 304 L）奥氏体不锈钢的VHCF行为。本文的重点在于研究这两种材料在极低应力幅下的循环变形行为。304 L钢的特征在于在其循环变形的初始阶段具有显著的循环软化。在随后的加载循环过程中，伴随着体积膨胀的相变（γ-奥氏体-> α '-马氏体）与全局塑性应变幅度的减小相关联，并在近表面层中引起压应力。因此，材料在240 MPa下进行10（9）次循环后未出现失效。相比之下，316L型钢具有更高的堆垛层错能，并且当通过磁感应方法分析时，在循环变形期间微观结构保持完全奥氏体。在这种情况下，发生非常局部化的塑性剪切，滑动带形貌显示出明显的侵入体的形成。微裂纹从VHCF状态下的这些侵入中开始，并且样本在超过10（7）个周期后也失效。这项研究提出了一个比较调查的损伤演化-包括位错形态和相变-在循环加载过程中的两种材料。在本研究的第二部分中讨论的微观结构敏感的模拟的背景下，这两种材料的个别变形机制的综合效果进行了研究。(C)2016由Elsevier Ltd.出版
A stable (AISI 316L) and a metastable (AISI 304L) austenitic stainless steel were investigated with respect to their VHCF behavior. The focus of the paper lies on the investigation of the cyclic deformation behavior of the two materials at very low stress amplitudes. The 304L steel is characterized by a pronounced cyclic softening during its initial stage of cyclic deformation. In the course of the following loading cycles, a phase transformation (gamma-austenite -> alpha'-martensite), accompanied by volume expansion is associated with the reduction of the global plastic strain amplitude and induces compressive stresses in the near surface layer. As a consequence, the material shows no failure up to 10(9) cycles at 240 MPa. In contrast, the type 316L steel has a higher stacking fault energy and the microstructure remains fully austenitic during cyclic deformation when analyzed by means of magneto-inductive methods. In this case, very localized plastic shear occurs and the slip band topography reveals the formation of pronounced intrusions. Microcracks initiate from these intrusions in the VHCF regime and samples failed also beyond 10(7) cycles. This study presents a comparative investigation of the damage evolution - including dislocation morphology and phase transformations - during cyclic loading for both materials. The combined effect of the individual deformation mechanisms is investigated for both materials in the context of a microstructure-sensitive simulation discussed in Part II of this study. (C) 2016 Published by Elsevier Ltd.