Mn含量对热轧超低碳钛低合金钢组织与力学性能的影响

Effect of Mn Content on Microstructures and Mechanical Properties of Hot-rolled Ultra-low Carbon Ti Low Alloyed Steel

实验钢在传统C-Mn钢的基础上添加低合金元素Ti,通过调整钢中Mn元素含量,同时采用简便的控制轧制与控制冷却工艺,获得了良好的组织形态及纳米尺度析出物,从而在保证优良延伸性能的前提下大幅度提高了钢板的强度,显著降低了钢材成本。使用金相显微镜(OM)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对微观组织进行观察。结果表明:当实验钢Mn含量从1.05%(质量分数,下同)提高至1.5%,平均晶粒尺寸从6.4μm细化至5.2μm;基体中纳米尺度TiC的析出量明显增加;屈服强度、抗拉强度和断后伸长率分别提高了56.7,42.2MPa和1.2%,达到了558.7,662.2MPa和22.4%。

Based on conventional C-Mn steel, low alloyed element Ti was appropriately added to the experimental steels, and the content of Mn was adjusted. Meanwhile, the simple thermo mechanical control process （TMCP） was adopted. As a result, the good microstructural morphology and nanoscale precipitates were obtained. Therefore, the strength of steel plate obviously increased under the premise of guaranteed good elongation, and the cost of steel was reduced significantly. The microstructures were observed by OM, SEM, and TEM. The results show that when Mn content in the experimental steels increases from 1.05% （mass fraction） to 1. 5%, the average grain size is refined from 6.4μm to 5.2μm, the nano-scale precipitates of TiC increase evidently. At the same time, the yield strength, the tensile strength and elongation increase by 56.7, 42.2MPa and 1.2%, and reach 558.7, 662.2MPa and 22.4%.