An In Situ Scanning Electron Microscope Study of Void Formation Induced by Typical Inclusions in Low‐Density Steel during Tensile Deformation

Herein, the void nucleation induced by typical inclusions in low-density steel is observed using a scanning electron microscope during the in situ tensile deformations, and the void nucleation mechanism is clarified based on the numerical simulation. The dislocation accumulation and stress concentration are observed around single AlN, MnS, AlN–MnS, aggregated AlN, and aggregated AlN–MnS inclusions. The nucleation and development of the void are through the inclusion cracking or inclusion interface debonding. During the tensile process, the cracking of single AlN and debonding of MnS/matrix induce the void nucleation. For AlN–MnS, the debonding of the internal AlN/MnS interface or external MnS/matrix interface can both induce void formation, which is associated with the relative dimensions of AlN and MnS. Aggregated AlN and aggregated AlN–MnS are suggested to be more harmful to low-density steel. The void nucleation in aggregated AlN and aggregated AlN–MnS is, respectively, owing to the debonding of the AlN/matrix interface or AlN/MnS interface.