The study focuses on the measurement of microstrain and the assessment of damage during tensile loading of intercritical austempered ductile iron by using digital image correlation technique and in situ observations. The results show that the first stages of damage involve the initiation and propagation of cracks along the matrix‐nodule interface. By comparing the strain maps retrieved from digital image correlation analysis with the microstructure, plastic deformations were observed to be located preferentially in the ferritic internodular areas. However, for a more advanced stage of damage, cracks are seen to initiate in the metallic matrix at the boundary between ausferrite sheaves and propagate preferentially following the direction of the ausferrite plates. The final fracture shows a mix of quasi‐cleavage and ductile morphology. The quasi‐cleavage is produced by the nucleation and growth of multiple quasi‐cleavage cracks formed on the ausferrite sheaves, while the overloaded ferritic zones are fractured by ductile tearing.

中文翻译：

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临界奥氏体球墨铸铁拉伸载荷过程中的微应变测量和损伤分析

这项研究的重点是使用数字图像相关技术和原位观察来测量临界奥氏体球墨铸铁的拉伸应变过程中的微应变和损伤评估。结果表明，损伤的第一阶段涉及沿基体-结节界面的裂纹萌生和扩展。通过比较从数字图像相关性分析获得的应变图和微观结构，观察到塑性变形优先位于铁素体结节区域。然而，对于更高级的破坏，可以看到裂纹在奥氏体滑轮之间的边界处的金属基体中萌生，并优先沿着奥氏体板的方向传播。最终的断裂显示出准裂解和韧性形态的混合。