Research on the Nanobainitic Features Formed in the Ultra-low Carbon Steel Non-Containing Nb and Ti Elements

摘要

The XRD analysis, microstructure observation and mechanical test were used to investigate the phase composition, micromorphology and mechanical properties of the intermediate transformation products in an ultra-low carbon steel non-containing Nb and Ti elements. The results showed that even without the presence of Nb and Ti alloy compounds, the experimental steel still exhibited good Rockwell hardness level. When the steels were held for a shorter times at 450°C, its Rockwell hardness under stayed 100s after plastic deformation at 850°C was higher than that under cooled directly because the 100s-stayed process was benefit to the formation of nanobainite. However, when the steels were held over 30min at 450°C, its Rockwell hardness under stayed 100s were close to that of non-stayed steel.Key words: ultra-low carbon steel / stayed process / nanobainite / Rockwell hardness