Layered fracture prediction of QStE700 medium-thickness steel plate under tensile loading

Abstract

Layered fracture frequently occurs in the deforming process of QStE700 medium-thickness steel plates under tensile loading. In this study, the morphology of a layered fracture was observed via scanning electron microscopy, and the mechanism of the layered fracture was also analyzed. Based on the three-dimensional digital image correlation technique, a section analysis method was adopted for determining the true stress–strain curve including the necking process. A modified Bridgeman’s equation was adopted to transform the true stress–strain curve into the equivalent stress–strain curve. At the time of layered fracture occurrence, the equivalent strain and stress triaxiality of differently shaped specimens were obtained and fitted to a linear exponential relationship equation. The equation was the layered fracture criterion function and combined with the finite element method (FEM) simulations for determining the damage criterion of the layered fracture of a certain specimen. The FEM-simulated equivalent strain was consistent with the experimental equivalent strain of the layered fracture. Summarizing, the proposed method to predict the layered fracture of a QStE700 medium-thickness steel plate is effective and can be adopted in the study and control of layered fracture.