Refinement of Low Carbon Bainite Structure by Deformation in Un-recrystallized Austenite Region
Refinement of Low Carbon Bainite Structure by Deformation in Un-recrystallized Austenite Region
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未再结晶奥氏体区变形细化低碳贝氏体组织
DOI：
10.2355/tetsutohagane1955.80.10_771
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发表时间：
1994
影响因子：
0.3
通讯作者：
S. Okaguchi
中科院分区：
文献类型：
--
作者：
K. Fujiwara;S. Okaguchi
摘要：研究了低碳Nb-B轴承钢非再结晶奥氏体区变形对等温转变贝氏体组织的影响。SEM观察表明，在不变形的情况下，大量板条状贝氏体铁素体板从奥氏体晶界平行形成，表现为典型的上贝氏体组织。30%的变形对贝氏体铁素体板的长度影响不大，尽管它使它们的形状像一束弓。相比之下，50%的变形显著减少了它们的长度。然而，这些贝氏体铁素体板也被靠近{451}a的两组习惯面所包围，这表明由严重变形的奥氏体转变而来的贝氏体铁素体具有与典型上贝氏体相同的晶体学特征。贝氏体铁素体板的细化使其微观组织的外观变得复杂。定量分析表明，75%变形后的贝氏体铁素体板的长度与先前在低碳钢中估计的亚晶粒尺寸一致。因此，大变形引入的亚晶界被认为对贝氏体组织的细化起着重要的作用，即它们会抑制贝氏体铁素体板的生长，并为它们提供进一步的形核位置。
Synopsis : Effects of deformation in unrecrystallized austenite region on isothermally transformed bainite structure were investigated in low carbon Nb-B bearing steels. SEM observation shows, in a case of non-deformation, a number of lath-like bainitic ferrite plates form in parallel from austenite grain boundaries, showing a typical upper bainite structure. A 30%-deformation has little influence on the length of bainitic ferrite plates, although it shapes them like a sheaf of bows. In contrast, a 50%-deformation significantly decreases their length. However, it is confirmed that those bainitic ferrite plates are also surrounded by two sets of habit planes close to {451}a, which suggests the bainitic ferrite transformed from heavily deformed austenite has the same crystallographic characteristic as the typical upper bainite has. Those refinement of bainitic ferrite plates leads to complicate an appearance of the microstructure. A quantitative analysis reveals the length of bainitic ferrite plates, after 75%-deformation, is consistent with the subgrain size estimated from previous study in low carbon steels. Therefore, subgrain boundaries introduced by heavy deformation are considered to play an important role in refinement of bainite structure, namely they will stifle the growth of bainitic ferrite plates and also supply further nucleation sites of them.