Abstract The orientation of austenite (γ) reverted from lath martensite has been studied using electron backscatter diffraction (EBSD) in Fe-2%Mn-1.5%Si-0.3%C (mass%) alloy. Two morphologies of γ, acicular and globular, are formed during reversion. Nucleation sites for acicular γ are lath, block and sub-block boundaries, while those for globular γ are prior γ grain boundaries, as well as inside packets. Both acicular and globular γ hold a near Kurdjumov-Sachs (K-S) orientation relationship with at least one of its surrounding tempered martensite blocks. Most acicular γ have almost identical orientations with the prior γ, while only a part of acicular γ have a specific twin-related variant with the prior γ. Furthermore, grain boundary globular γ has almost identical orientations with the prior γ into which it does not grow. The formation of acicular and grain-boundary globular γ was attributed to strong variant selection during γ nucleation at lath, block and sub-block boundaries. On the other hand, orientation relationship analyses among intragranular globular γ, tempered martensite and cementite suggest that the nucleation of γ at cementite and tempered martensite interfaces causes weakening of the variant selection for the formation of intragranular globular γ.

中文翻译：

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Fe-2Mn-1.5Si-0.3C合金中马氏体转变为奥氏体的取向

摘要 使用电子背散射衍射 (EBSD) 在 Fe-2%Mn-1.5%Si-0.3%C (mass%) 合金中研究了从板条马氏体转变为奥氏体 (γ) 的取向。γ 的两种形态，针状和球状，在反转过程中形成。针状 γ 的成核位置是板条、块状和子块状边界，而球状 γ 的成核位置是先验 γ 晶界以及内部包。针状和球状 γ 都与其周围的至少一个回火马氏体块保持接近的 Kurdjumov-Sachs (KS) 取向关系。大多数针状γ与先验γ具有几乎相同的取向，而只有一部分针状γ与先验γ具有特定的孪生相关变体。此外，晶界球状 γ 与之前的 γ 具有几乎相同的取向，它不会生长到其中。针状和晶界球状 γ 的形成归因于板条、块状和亚块状边界处 γ 成核过程中的强烈变体选择。另一方面，晶内球状γ、回火马氏体和渗碳体之间的取向关系分析表明，γ在渗碳体和回火马氏体界面处的形核导致晶内球状γ形成的变体选择减弱。