Investigating the Portevin-Le Chatelier effect in strain rate and stress rate controlled tests by the acoustic emission and laser extensometry techniques
Investigating the Portevin-Le Chatelier effect in strain rate and stress rate controlled tests by the acoustic emission and laser extensometry techniques
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DOI：
10.1016/j.msea.2006.01.169
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发表时间：
2007-07-25
期刊：
影响因子：
6.4
通讯作者：
Lukac, Pavel
中科院分区：
文献类型：
--
作者：
Chmelik, Frantisek;Klose, Frank B.;Lukac, Pavel
Portevin-Le Chatelier（PLC）效应是许多合金在一定的应变速率和温度间隔下变形时的动态应变时效效应。PLC效应的主要特征是应力的负应变率敏感性，其与应力波动、塑性变形的宏观时空局部化（变形带的成核和传播）和强烈的声发射相关联。最近的理论和实验研究指出，位错的协同运动是负应变率敏感条件下发生塑性失稳的必要条件。在这项工作中的潜力声发射和激光拉伸监测原位合作位错运动由于PLC效应是重新审视和检查在Al-3.5重量%镁合金。该合金进行了两种拉伸模式，即在一个恒定的十字头速度和在一个恒定的应力速率。对于每种测试模式，合金表现出特定的PLC变形行为和独特的声发射特性。结果表明，这两种拉伸模式的位错动力学的功能。(C)2006 Elsevier B. V.保留所有权利。
The Portevin-Le Chatelier (PLC) effect is a spectacular effect of dynamic strain aging in many alloys deformed in certain intervals of strain rates and temperatures. The main feature of the PLC effect is a negative strain rate sensitivity of stress, which is associated with stress fluctuations, a macroscopic spatio-temporal localization of plastic deformation (nucleation and propagation of deformation bands) and an intense acoustic emission. Recent theoretical and experimental studies have pointed out that cooperative dislocation motion is a necessary condition for plastic instabilities to occur under conditions of negative strain rate sensitivity. In this work the potential of acoustic emission and laser extensometry to monitor in situ cooperative dislocation motion due to the PLC effect is revisited and examined in an Al-3.5 wt.% Mg alloy. The alloy was tested for two tensile modes, i.e. at a constant cross-head speed and at a constant stress rate. For each testing mode, the alloy exhibits specific PLC deformation behavior and unique characteristics of acoustic emission. The results demonstrate features of dislocation dynamics for both of these tensile modes. (C) 2006 Elsevier B.V. All rights reserved.