Experimental study of microstructure changes due to low cycle fatigue of a steel nanocrystallised by Surface Mechanical Attrition Treatment (SMAT)
Experimental study of microstructure changes due to low cycle fatigue of a steel nanocrystallised by Surface Mechanical Attrition Treatment (SMAT)
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DOI：
10.1016/j.matchar.2016.12.017
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发表时间：
2017-02-01
影响因子：
4.7
通讯作者：
Kanoute, P.
中科院分区：
文献类型：
--
作者：
Sun, Z.;Retraint, D.;Kanoute, P.
采用电子背散射衍射技术对316L钢表面机械雾化处理（SMAT）后低周疲劳试验前后的显微组织进行了表征。在SMAT之后，从样品的顶部表面到内部产生粒度梯度，使得在处理表面下方可以区分三个主要区域：（i）在顶面下5 μ m内的超细晶粒区域，具有优选取向的晶粒，（ii）原始晶粒部分转化的中间区域，以及（iii）边缘周边区域，在该区域中，原始晶粒在塑性滑移的存在下仅机械变形。疲劳试验表明，循环加载不会改变晶粒取向扩展，不会激活SMAT诱导的超细晶粒顶面区域的任何塑性滑移。相反，在塑性SMAT影响区，包括中间区域和边缘周边区域，新的滑移系统被激活的低周疲劳，而晶粒取向扩展增加。这些结果代表了第一个非常有趣的步骤，对表征和理解的机械机制，在疲劳过程中涉及的晶粒尺寸梯度材料。(C)2016 Elsevier Inc. All rights reserved.
Electron Backscatter Diffraction technique is used to characterize the microstructure of 316L steel generated by Surface Mechanical Attrition Treatment (SMAT) before and after low cycle fatigue tests. A grain size gradient is generated from the top surface to the interior of the samples after SMAT so that three main regions can be distinguished below the treated surface: (i) the ultra-fine grain area within 5 mu m under the top surface with preferably oriented grains, (ii) the intermediate area where the original grains are partially transformed, and (iii) the edge periphery area where the original grains are just mechanically deformed with the presence of plastic slips. Fatigue tests show that cyclic loading does not change the grain orientation spread and does not activate any plastic slip in the ultra-fine grain top surface area induced by SMAT. On the opposite, in the plastically SMAT affected region including the intermediate area and the edge periphery area, new slip systems are activated by low cycle fatigue while the grain orientation spread is increased. These results represent a first very interesting step towards the characterization and understanding of mechanical mechanisms involved during the fatigue of a grain size gradient material. (C) 2016 Elsevier Inc. All rights reserved.