Three-dimensional shear-strain patterns induced by high-pressure torsion and their impact on hardness evolution
Three-dimensional shear-strain patterns induced by high-pressure torsion and their impact on hardness evolution
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DOI：
10.1016/j.actamat.2011.03.015
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发表时间：
2011-06-01
期刊：
影响因子：
9.4
通讯作者：
Zhu, Y. T.
中科院分区：
文献类型：
--
作者：
Cao, Y.;Wang, Y. B.;Zhu, Y. T.
采用光学显微镜和扫描电子显微镜对高压扭转（HPT）过程中不同阶段奥氏体/铁素体双相不锈钢盘的剪切应变进行了平面和截面成像。剪切应变的影响与盘的硬度演变相关。剪切应变模式是复杂的，是不同的顶部和底部表面的光盘。在高压相变初期，顶部出现了双涡结构。随着HPT转数的增加，这两个涡流中心向盘中心移动，最终双涡流演变为单涡流。不太规则的剪切应变模式上观察到的光盘的底部表面。从横截面观察中可以看到在椎间盘中心轴上具有镜像对称性的多个环状图案。对HPT盘的两个表面和横截面的纳米压痕测试表明，硬度对特定的剪切应变模式不敏感，但与奥氏体和铁素体相域的宽度密切相关。在变形过程的后期，HPT盘内部的硬度可能高于盘表面的硬度，这是因为形成了更精细的显微组织相分布。(C)2011 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The shear strain imposed on austenite/ferrite duplex stainless steel discs at different stages of high-pressure torsion (HPT) processing was imaged in plan-view and cross-section using optical microscopy and scanning electron microscopy. The effect of the shear strain was correlated to the hardness evolution of the discs. The shear-strain patterns are complex and are different on the top and bottom surfaces of the discs. A double-swirl pattern emerged on the top surface in the early stages of HPT. These two centres of the swirl moved towards the centre of the disc as the numbers of HPT revolutions was increased and ultimately the double-swirl evolved into a single-swirl. Less regular shear-strain patterns were observed on the bottom surfaces of the discs. Multiple ring-like patterns with mirror symmetry over the central axes of the discs were visible from cross-sectional observations. Nanoindentation testing on the two surfaces and a cross-section of HPT discs showed that the hardness is insensitive to specific shear-strain patterns, but is closely related to the widths of the austenite and ferrite phase domains. Late in the deformation process, the hardness in the interior of an HPT disc may be higher than at either of the disc surfaces because of the development of finer microstructural phase distributions. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.