铌微合金化控冷工艺生产HRB500抗震钢筋强韧化机理

Strengthening and toughening mechanism of HRB500 anti-seismic rebars with Nb microalloyed and controlled cooling process

采用Nb微合金化和控冷工艺开发HRB500抗震钢筋,通过金相显微镜、扫描电镜、透射电镜、X线衍射仪及拉力试验机对钢筋取样金相显微组织、析出相、力学性能及强韧化机理进行分析研究。研究结果表明：采用Nb微合金化和控轧控冷工艺生产HRB500抗震钢筋,最主要的强化机制为细晶强化,其对强度贡献超过40%;采用该工艺,钢筋铁素体晶粒度达11.0级以上,晶粒细化效果明显;铁素体基体、晶界及位错线上形成和分布着尺寸为10~20 nm的大量细小弥散的Nb（CN）析出相,起到了较好的沉淀强化及细化晶粒作用;晶粒细化使冲击转折温度下降150℃,使钢筋在获得较高强度的同时,仍具有较好的塑韧性。

Development of HRB500 anti-seismic rebars by Nb microalloyed and controlled cooling process was introduced.The microstructure,educt,mechanical properties,strengthening and toughening mechanism were researched and analyzed by means of metallographic microscopy,scanning electron microcopy,transmission electron microscopy,X-ray diffraction apparatus and tensile testing machine.The results show that fine-grain strengthening is the primary mechanism of strengthening and toughening for HRB500 rebars produced by Nb microalloyed and controlled cooling process,contribution of its strength is more than 40% of total strength;ferrite grain grade of rebars is more than 11.0,obvious effect of grain refinement is obtained.A large number of small and diffuse of Nb（CN） educts sized 10-20 nm are formed and distributed on ferrite matrix,grain boundary and dislocation lines,good effect of precipitation strengthening and grain refinement are received;impact transition of temperature reduces by 150 ℃ by grain refinement,and higher strength for rebars is acquired.Meanwhile,rebars still have good plasticity and toughness.