Orientation gradients and geometrically necessary dislocations in ultrafine grained dual-phase steels studied by 2D and 3D EBSD
Orientation gradients and geometrically necessary dislocations in ultrafine grained dual-phase steels studied by 2D and 3D EBSD
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DOI：
10.1016/j.msea.2010.01.004
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发表时间：
2010-04-25
期刊：
影响因子：
6.4
通讯作者：
Raabe, Dierk
中科院分区：
文献类型：
--
作者：
Calcagnotto, Marion;Ponge, Dirk;Raabe, Dierk
研究了两种不同马氏体粒度和体积分数的超细晶粒双相钢的取向梯度和几何必要位错。马氏体量越高的钢，其弹性极限越低，屈服强度越高，抗拉强度越高。这些效应归因于铁素体中较高的第二相含量和不均匀的相变应变调节。利用高分辨电子背散射衍射(EBSD)对后一种假设进行了分析。我们量化了铁素体-铁素体和铁素体-马氏体界面处的取向梯度、图案质量和GND密度变化。利用3DEBSD，获得了关于颗粒体积和马氏体分布对应变调节的影响的附加信息。给出了基于核平均位错测量和基于位错密度张量的两种从EBSD数据计算GND密度的方法。结果表明，随着总马氏体量的增加、晶粒体积的减小以及铁素体附近马氏体量的增加，GND的总体密度增加。(C)2010爱思唯尔B.V.保留所有权利。
We study orientation gradients and geometrically necessary dislocations (GNDs) in two ultrafine grained dual-phase steels with different martensite particle size and volume fraction (24 vol.% and 38 vol.%). The steel with higher martensite fraction has a lower elastic limit, a higher yield strength and a higher tensile strength. These effects are attributed to the higher second phase fraction and the inhomogeneous transformation strain accommodation in ferrite. The latter assumption is analyzed using high-resolution electron backscatter diffraction (EBSD). We quantify orientation gradients, pattern quality and GND density variations at ferrite-ferrite and ferrite-martensite interfaces. Using 3D EBSD, additional information is obtained about the effect of grain volume and of martensite distribution on strain accommodation. Two methods are demonstrated to calculate the GND density from the EBSD data based on the kernel average misorientation measure and on the dislocation density tensor, respectively. The overall GND density is shown to increase with increasing total martensite fraction, decreasing grain volume, and increasing martensite fraction in the vicinity of ferrite. (C) 2010 Elsevier B.V. All rights reserved.