图a、b和c为DZ（连铸）钢边部、1/2半径和心部的EBSD反极图，图中黑色线表示取向差大于15°的大角度界面。由图可知，在马氏体中有大量的马氏体板条，这些马氏体板条之间界面基本上是有由大角度界面构成，导致在马氏体结构中有大量大角度界面。这些大角度界面能够有效的阻碍裂纹的扩展，从而提高试验钢的低温韧性。

Figures A, B and C are EBSD inverse polar diagrams of DZ (continuous casting) steel edge, 1/2 radius and center. The black lines in the figure represent large Angle interfaces with orientations greater than 15°. It can be seen from the figure that there are a large number of martensite lath in martensite, and the interfaces between these martensite lath are basically composed of large Angle interfaces, resulting in a large number of large Angle interfaces in martensite structure. These large Angle interfaces can effectively hinder the crack propagation and improve the low temperature toughness of the test steel.