一种新型含钛高强度钢

New Ti-bearing High Strength Steel

通过成分设计,成功开发一种以低碳钢为基础添加合金元素钛,屈服强度达到700 MPa以上的高强度钢。研究结果表明,该钢的强化相为细小而交错分布的贝氏体及钛碳化物的沉淀析出相。当贝氏体的体积分数大于70%时,钢材的屈服强度将高于700MPa,同时强屈比大于1.07,具有较好的力学性能。由于基体中的贝氏体都为细小而交错的贝氏体束,改善钢材塑性,使钢材的断后伸长率为19%左右。同时在透射电镜下观察到,在细小的贝氏体基体上存在相对较多的细小的TiC的析出及少量未溶解的大块的TiC,细小的析出起到沉淀强化作用。

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.