采用光学显微镜、扫描电镜、能谱仪和拉伸试验机等对HRB500热轧带肋钢筋力学性能不合格的原因进行了分析;针对力学性能不合格的原因给出了改进的工艺措施,并对改进后HRB500热轧带肋钢筋的组织和力学性能进行了分析。结果表明:较严重的带状组织、硫化锰和硅酸盐类夹杂物的存在以及较低的氮含量是该钢筋力学性能不合格的重要原因;采用提高钢中氮含量、炼钢过程中采取渣洗工艺、延长吹氩时间以及优化控制连铸拉速等工艺措施后,HRB500热轧带肋钢筋中的带状组织明显减轻,且未发现明显的夹杂物存在,各项力学性能均能满足国标要求。

The causes of disqualified mechanical properties of HRB500 hot rolled ribbed bar were analyzed by optical microscopy, scanning electron microscopy, energy disperse spectroscopy and tensile testing. For the causes of mechanical properties disqualification, some improved process measures were given, and the microstructure and mechanical properties of the ribbed bar after improving also were analyzed. The results show that the important reasons for disqualification tensile strength of the ribbed bar are the serious banded structure, manganese sulfide and silicate inclusions and low concentration of N element. After the improvement measures, such as increasing the N content, adopting slag washing process in steel making, prolonging the time of blowing argon and controlling the speed in continuous casting process, are adopted, the banded structure in the HRB500 hot rolled ribbed bars dramatically reduce and the inclusion is not found, the mechanical properties of the ribbed bar can satisfy the requirements of Chinese standard.