A study on the relationship between microstructure and mechanical properties of acicular ferrite and upper bainite
A study on the relationship between microstructure and mechanical properties of acicular ferrite and upper bainite
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DOI：
10.1016/j.msea.2016.03.103
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发表时间：
2016-04-29
期刊：
影响因子：
6.4
通讯作者：
Kotousov, Andrei
中科院分区：
文献类型：
--
作者：
Costin, Walter L.;Lavigne, Olivier;Kotousov, Andrei
针状铁素体和贝氏体是铁素体焊缝金属以及许多其他黑色合金中常见的微观结构组成部分。这些往往高度局部化的微观结构区域已知对它们所构成的块状材料的力学性能有重大影响。众所周知，针状铁素体和贝氏体具有明显不同的形态和特征，这些形态和特征可直接与其内在力学性能相关联。然而，在块状材料中，它们通常与其他微观结构组成部分和特征共存并相互作用。因此，针状铁素体和贝氏体各自的贡献仍然不明确。这项工作利用微观测试技术来评估和比较这两种微观组成部分的力学性能，最终目的是了解它们对黑色合金块状性能的影响。首先选择由针状铁素体或上贝氏体组成的微观区域，然后使用高分辨率扫描电子显微镜（SEM）和电子背散射衍射（EBSD）对其进行表征。采用常规纳米压痕和一种先进的表征方法来评估这两种微观组成部分的弹性模量、屈服强度、硬度和应变硬化指数。通过在所选区域内进行的微观断裂试验来估算抗断裂性能。实验研究表明，在微观尺度上，尽管针状铁素体和上贝氏体的微观结构不同，但它们具有非常相似的力学性能。然而，上贝氏体的抗断裂性能更多地受塑性变形的贡献所主导。（C）2016爱思唯尔有限公司。保留所有权利。
Acicular ferrite and bainite are microstructural constituents commonly found in ferritic weld metal and many other ferrous alloys. These often highly localised microstructural volumes are known to have a significant impact on the mechanical properties of the bulk material they constitute. It is well established that acicular ferrite and bainite have substantially different morphologies and features that can be directly linked to their intrinsic mechanical properties. However, in the bulk material they usually co-exist and interact with other microstructural constituents and features. Therefore, the individual contributions of acicular ferrite and bainite still remain unclear. This work utilises micro-testing techniques to evaluate and compare the mechanical properties of these two micro-constituents with an ultimate objective to understand their impact on bulk properties of ferrous alloys. Microscopic regions consisting of either acicular ferrite or upper bainite were first selected and then characterised using a high resolution Scanning Electron Microscope (SEM) and Electron Backscattered Diffraction (EBSD). Conventional nano indentation and an advanced characterisation procedure were implemented to evaluate elastic modulus, yield strength, hardness and strain hardening exponent of both micro-constituents. The fracture resistance was estimated from micro-fracture tests that were conducted within the selected regions. The experimental studies have indicated that, at the micro-scale, despite their different microstructures, acicular ferrite and upper bainite have very similar mechanical properties. Nevertheless, the fracture resistance of upper bainite was more dominated by the contribution of plastic deformations. (C) 2016 Elsevier B.V. All rights reserved.