400 MPa级縮微合金化抗震钢的控轧控冷工艺实践

在化学成分合理设计的基础上HRB400E钢(/%:0.21～0.25C,0.40～0.65Si,1.40～1.55Mn,≤0.040P,≤0.040S,0.015～0.025Nb,0.005～0.008N),研究了不同加热温度及控轧控冷温度对力学性能、金相组织和钢筋表面时效锈蚀的影响。提出了最佳的轧制温度参数:加热温度为1140～1170℃、开轧温度为1 040～1 060℃,精轧温度为1000～1030℃,终轧后的冷床温度是870～890℃。结果表明,铌微合金化HRB400E钢屈服强度450-475MPa,其析出物主要为粒径大小为300～600nm的Nb(C,N),分布在网状碳化物上、网状碳化物边缘以及晶界附近的晶粒内部。

Controlled Rolling and Controlled Cooling Process Practice of 400 MPa Grade Nb Microalloyed Seismic Steel

Based on the reasonable design of chemical composition HRB400E steel (/% ：0. 21 ~0. 25C,0. 40 〜 0. 65Si, 1.40 ~ 1. 55Mn, W0. 040P, W0. 0405,0. 015 ~ 0. 025Nb,6. 005 〜0. 008N), the effects of different heating temperature and controlled rolling and controlled cooling temperature on the mechanical properties, metallographic structure and aging corrosion of steel bar surface are studied. The optimum rolling temperature parameters are： the heating temperature 1 140 ~ 1 170 T , the starting rolling temperature 1040 ~ 1060 °C , the finishing rolling temperature 1000 〜 1030 °C , and the cold bed temperature 870 ~890 V. after the final rolling. Results show that the yield strength of niobium microalloyed HRB400E steel is 450 ~475 MPa, the precipitates in steel are mainly Nb( C,N) with a particle size of 300 ~ 600 nm, which are distributed on the network carbide, the edge of the network carbide and the inside of the grain near the grain boundary.