Hot deformation behavior and dynamic recrystallization of ultra high strength steel

Abstract

In this paper, in order to improve the microstructure uniformity of an ultra-high strength martensitic steel with a strength greater than 2500 MPa developed by multi-directional forging in the laboratory, a single-pass hot compression experiment with the strain rate of 0.01 to 1 s−1 and a temperature of 800 to 1150 °C was conducted. Based on the experimental data, the material parameters were determined, the constitutive model considering the influence of work hardening, the re-crystallization softening on the dislocation density, and the recrystallized grain size model were established. After introducing the model into the finite element software DEFORM-3D, the thermal compression experiment was simulated, and the results were consistent with the experimental re-sults. The rule for obtaining forging stock with a uniform and refinement microstructure was ac-quired by comparing the simulation and the experimental results, which are helpful to formulate an appropriate forging process.