在实验室条件下，对一种微合金高强度钢进行热膨胀试验和热轧试验，测定了该试验钢的连续冷却转变动力学(CCT)曲线，并研究了不同温度转变的组织和第二相的体积分数、尺寸对其力学性能的影响。试验结果表明：变形温度的降低，贝氏体转变开始温度与转变结束温度均升高，硬度值也出现不同程度的提高；变形温度的降低，使得不同冷却速度下组织细化程度存在明显差异。利用合理控轧控冷工艺，使得屈服强度均达到690MPa以上，-30℃冲击功均达到230J以上。其中，第二相粒子在整个基体内呈细小弥散分布，起到有效的强化作用并改善钢的冲击韧性。

The high strength microalloyed steel was studied by thermal expansion testing and hot rolling testing under laboratory conditions. CCT diagrams for the tested steel was determined, and effects of the volume fraction and the size of second phases as well as microstructure of different transition temperatures on mechanical properties were investigated. The results showed that: the bainite starting temperature Bs, bainite finish temperature Bf and hardness value increased with decreasing deformation temperature. When high strength microalloyed steels were rolled through the reasonable controlled rolling and controlled cooling (TMCP), meanwhile it exhibited high yield strength (above 690MPa) and high impact energy of the tested steels (above 230J at -30℃). Fine dispersed second phase particles were well distributed in all over of the substrate, which were useful of increasing strength and improving toughness.