关键词: 贝氏体, 沉淀强化, 高强度

Abstract: A high strength steel with the yield strength above 700 MPa is developed successfully with the addition of titanium alloy element based on a low-carbon steel. The results show the strengthening factors of this steel are tiny and crisscross distributed precipitation of bainite and titanium carbide. When the volume fraction of bainite is greater than 70%, the yield strength of steel will be higher than 700 MPa, and simultaneously ratio of tensile to yield strength will be greater than 1.07, and good mechanical performance is obtained. As the bainites in the substrate are all tiny and crisscross lath banites, the plasticity of steel is improved, and the elongation is about 19%. By means of a transmission electron micrograph (TEM), it is observed that there are many tiny TiC precipitations and a few undissolved big TiC on the tiny bainite substrate. The tiny precipitations play the role of precipitation strengthening.

Key words: Bainite, High strength, Precipitation strength