贝氏体铁素体取向关系及残留奥氏体膜

Bainitic Ferritic Orientation Relationships and Retained Austenitic Films

使用高分辨电子显微镜 (TRTEM)观察分析了中碳和中高碳贝氏体钢贝氏体铁素体 -奥氏体取向关系及贝氏体铁素体条束内残留奥氏体。贝氏体钢中上贝氏体 -奥氏体界面同时存在K S关系和N W关系或单独存在K S关系。标定结果证明 ,[1 0 0 ]α1 [1 1 0 ]γ [1 1 1 ]α2 ,( 0 1 1 ) α1 ( 1 1 1 ) γ ( 1 1 0 ) α2 ,以及 [1 1 1 ]α [1 1 0 ]γ,( 1 1 0 ) α ( 1 1 1 ) γ。透射电镜观察发现 ,贝氏体铁素体内有形貌及尺度不同的残留奥氏体膜存在 ,它们把贝氏体铁素体分割或包围成不同层次的结构单元 ,以残留奥氏体膜为分界面确定了贝氏体铁素体不同层次的精细结构单元及其尺度。贝氏体铁素体条束由亚片条、亚单元和基本单元 (或称为超亚单元 )组成。多数亚片条 ,亚单元和基本单元尺度分别在 2 5～ 80nm、2 5～ 80nm和 50～ 30nm不等。

The orientation relationship between bainitic ferritic and austenite and retained austenitic films in bainitic ferritic laths in middle and middle\|high carbon bainitic steels were observed and analyzed with high resolution electronic microscope. There are K\|S and N\|W orientation relationships between interface of upper bainite\|austenite and there is alone K\|S orientation relationship in bainitic ferrite. The indexing results of electronic diffraction pattern proved [100] α1 //[110] γ //[111] α2 ,(011) α1 //(111) γ //(110) α2 , and [111] α //[110] γ ,(110) α //(111) γ . The investigation results discovered that there are retained austenitic films of different appearance and size in bainitic ferritic laths. The boundaries of the different structural levels are separated and encircled by retained austenitic films. The fine structural units and their size of different structural levels in the bainitic ferrite were determined by retained austenitic films. The bainitic ferritic laths are composed of different structural level sublats, subunits and elementary units (or so called sub\|subunits). The dimensions of mostly sublaths, subunits and elementary units are between 25～80nm,25～80nm,5 0～30nm respectively.