Crystallographic Analysis of Transformation Behavior of Acicular Ferrite from B1-type Compounds in Steels
Crystallographic Analysis of Transformation Behavior of Acicular Ferrite from B1-type Compounds in Steels
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DOI：
10.2355/isijinternational.isijint-2017-017
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发表时间：
2017-07
影响因子：
1.8
通讯作者：
S. Nambu;Y. Takizawa;M. Ojima;J. Inoue;T. Koseki
中科院分区：
文献类型：
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作者：
S. Nambu;Y. Takizawa;M. Ojima;J. Inoue;T. Koseki
晶内铁素体（intraginal ferrite，IGF）是在奥氏体晶粒中的夹杂物处形核的，作为抑制焊接热影响区晶粒粗化导致韧性下降的一种手段，已引起人们的广泛关注。因此，人们对IGF的形成机制进行了大量研究，并对促进铁素体（α）形核的几个因素进行了分析1 -5），如α与夹杂物之间的晶格匹配、γ与夹杂物之间热膨胀差异引起的热应力或应变、γ /夹杂物界面附近化学成分的变化等。关于晶格匹配，已经报道具有NaCl型晶格结构的B1型氧化物和氮化物（B1）对于IGF成核是有效的6，7），因为它们具有与α具有低晶格失配的晶体取向关系，称为贝克-努丁取向关系（B-N OR）; {100}B1//{100}α，B1// α。然而，为了更严格地讨论晶格相干性对IGF形核的影响，应考虑γ-到-α转变行为随转变温度的变化。众所周知，胰岛素样生长因子的形态通常分为两种类型，即多边形和针状。在多边形铁素体（PF）的情况下，铁素体在相对高的温度下通过扩散转变形成，因此，B-N OR可以容易地满足钢中B1型化合物的针状铁素体转变行为的α晶体学分析
Intragranular ferrite (IGF), which nucleates at inclusions dispersed in austenite (γ ) grains, has attracted considerable attention as a means of suppressing the degradation of toughness due to grain-coarsening in the heat-affected zone of steel welds. Thus, many studies have been conducted to clarify the formation mechanisms of IGF, and several factors that promote ferrite (α) nucleation have been reported1–5) such as lattice matching between α and inclusions, thermal stress or strain due to the difference in the thermal expansion between γ and inclusions, and changing the chemical composition in the vicinity of the γ /inclusion interface. Regarding lattice matching, B1-type oxides and nitrides (B1) with the NaCl-type lattice structure have been reported to be effective for IGF nucleation6,7) because they have a crystal orientation relationship with low lattice mismatch with α, called the Baker–Nutting orientation relationship (B-N OR); {100}B1//{100}α, B1// α. However, to rigorously discuss the effect of the lattice coherency on the nucleation of IGF, the change in the γ-to-α transformation behavior with the transformation temperature should be considered. It is well known that the morphology of IGF is usually divided into two types, polygonal type and acicular type. In the case of polygonal ferrite (PF), ferrites form by a diffusional transformation at relatively high temperatures, and thereby, the B-N OR can be easily satisfied between α Crystallographic Analysis of Transformation Behavior of Acicular Ferrite from B1-type Compounds in Steels