Deformation Coordination Mechanism of Dual-Phase Structure Steel Based on Martensite-Ferrite Under Medium-High Strain Rate

Abstract

Under medium (1 s-1, 10 s-1, 100 s-1) and high (500 s-1, 700 s-1, 800 s-1, 1000 s-1) strain rates, deformation coordination mechanism of 1200 MPa grade martensitic-ferrite dual-phase steel is completely opposite to that under quasi static or low strain rate (10-4-1 s-1). When the strain rate exceeds about 700 s-1, the harder phase (martensite) replaces the softer phase (ferrite) as prior deformation phase, and coordination effect of M/F (martensite/ferrite) interface is failed. As strain rate further increases, martensitic deformation amount increase dramatically. When martensitic deformation amount reaches saturation under about 1000 s-1, ferritic deformation amount restarts to increase.