Development of a Hot-rolled Low Carbon Steel with High Yield Strength

摘要

A high strength steel with yield strength on the order of 700 MPa had been developed successfully with the addition of titanium alloy element based on a low-carbon steel. The results show the hot deformation accelerates ferrite and pearlite transformation and retards bainite transformation under continuous cooling condition. The strengthening factors of this steel are attributed to the tiny interlocked distribution of bainite laths and titanium carbide precipitation. When the amount of bainite is more than 70%, the yield strength of steel is higher than 700 MPa, and simultaneously ratio of tensile of yield is more than 1.07, and good mechanical performances are obtained. As a result of the presence of finely dispersed cementite particles which improve the work hardening capacity, the ductility of steel is improved, with the steel's elongation being about 19%. Many tiny TiC precipitates are observed under transmission electron micrograph (TEM), and these particles result in precipitation strengthening.