Modelling of ductile fracture in pure iron considering the ductile–brittle transition at very high strain rate

• Published in: Engineering fracture mechanics Vol. 281; p. 109145
• Main Authors: Su, Guosheng, Su, Qian, Sheng, Jialin, Wang, Baolin, Zhang, Hongxia, Du, Jin, Zhang, Peirong, Shen, Xuehui, Liu, Zhanqiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 28.03.2023
• Subjects: Fracture model; High strain rate; Material ductility; Material failure; Pure iron; Material failure; Pure iron; Fracture model; Material ductility; High strain rate
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2023.109145

•An empirical fracture model based on the maximum strain principle is proposed.•The new model takes into account the embrittlement effect of high strain rate, and.•Can predict the ductile fracture of materials in the full range of strain rate. At different deformation rates, a ductile material may fail by isothermal deformation fracture, thermoplastic shear instability, or even brittle fracture. The failure mode transition at sound speed deformation rate has not been well described. This paper aims to establish a new fracture model which considers the strain rate embrittlement effect (SREE) at the sound speed deformation rate, and can be used to predict the failure of the material in a large range of strain rate. Taking pure iron DT 8 as the experimental material, impact tests of pure iron specimens under different stress states, strain rates, and temperatures were carried out. Fracture strains under different stress states, strain rates, and temperatures were obtained. The strain rate was increased to 227450/s (5.36/s in log10) to obtain the ductile–brittle transition point. A new fracture model is proposed to describe the evolution of fracture strain over the wide range of strain rate. The new proposed model is experimentally validated and compared with the J-C failure model. It shows the new proposed fracture model can predict the ductile fracture behavior of a ductile material in the full strain rate range, and capture the failure mode transition at the sound speed deformation rate of a material.