关键词: 超级钢, 控轧控冷, 系列冲击实验, 脆性转变温度, 低温韧性

Abstract: Series impact tests were carried out to measure a 400 MPa-class super-steel using the series impact work. The brittle transition temperature curve was obtained. The brittle transition temperature or ductile-brittle transition temperature (DBTT) of the steel was determined as-80°C according to the integrated energy consumption and fracture morphology of the tested samples. Compared with that of other steel sheets of the same composition but rolled in different ways, the reasons of such a lower temperature were analyzed. A conclusion was thus drawn that the decreased DBTT and the improvement of low-temperature ductility can be attributed to the combination of composition and rolling technique with microstructure and other factors. Low contents of S, P and Si in tasted samples are beneficial to the decreasing of DBTT as well as the microalloying element Nb. In addition, refined grain and subgrain strengthening play an important role in decreasing DBTT, and TMCP technique can refine ferrite grain so as to benefit DBTT decreasing.