Deformation and fracture behavior in TRIP steels under static and dynamic tensile conditions
Jialei Dai, Jun Yuan, Zixuan Yang, Chaoqun Zhang, Hao Zhang, Shuqin Yu
Abstract
The present study sought to explore the deformation and fracture behavior of Quenching and Partitioning (Q&P) steel at five different strain rates (10−4 s−1, 1 s−1, 10 s−1, 100 s−1 and 1400 s−1). Tensile tests were carried out on Q&P steel at different strain rates, and the deformation and fracture behaviors were explored through digital image correlation (DIC) and scanning electron microscope (SEM). The results indicated that the strength and plasticity of Q&P steel had significant strain rate sensitivity. The yield strength and ultimate strength increases continuously, whereas the elongation first decreased and then increased with increase in strain rate. The dimples gradually became smaller and flatter with increase in strain rate. The dislocation density increased when strain rate was above 100 s−1, indicating that resistance to dislocation slip increases and the slip distance becomes shorter at high strain rates, which inhibits generation of large deformation. The local plastic strain at the fracture significantly decreased from 0.7 to 0.3, resulting in partial brittle fracture characteristics in fracture morphology. These findings provide a basis for further elucidating the deformability and fracture behavior of Q&P steel at different strain rates.