Analysis of the Hot Deformation Behavior and Microstructure of 00Ni18Co8Mo3TiAlB Maraging Steel
摘要
The thermal deformation behavior and microstructural evolution of 00Ni18Co8Mo3TiAlB were systematically investigated under strain rates ranging from 0.005 to 10 s−1 and temperatures between 950 and 1200 °C. A high-precision flow stress model considering strain compensation and a hot processing map of the experimental steel were established, with an analysis of microstructural evolution made. By analyzing the rheological stress–strain curves, it was found that the experimental steel exhibited dynamic recovery characteristics in the flow curve at deformation temperatures of 950-1050 °C. When the deformation temperature exceeds 1100 °C, the flow curve at a low strain rate (≤1.0 s−1) exhibits the characteristics of dynamic recrystallization, which suggests that the experimental steel is more susceptible to dynamic recrystallization (DRX) under conditions of high temperature and low strain rate. Meanwhile, the thermal stability region at true strain 0.1 ~ 0.9 was obtained by building and analyzing the hot processing map, and the optimal processing windows were determined to be 1050-1130 °C/0.005-0.015 s−1 and 1150-1200 °C/0.01-0.2 s−1. The evolution of DRX in experimental steel was obtained through EBSD microstructure characterization, and the dominant DRX regime was confirmed. Due to the relatively high dynamic activation energy Q of the experimental steel, the recrystallization volume fraction is relatively low. Furthermore, the relationship between DRX and grain boundaries was analyzed, and it was found that the occurrence of DRX could promote the generation of large-angle grain boundaries.