高强度低合金钢Q420N轧制工艺优化实践

试验高强度低合金钢Q420N(/%:0.16C,0.28Si,1.39Mn,0.015P,0.003S,0.11Cr,0.009N)的生产流程为120 t转炉-LF精炼-RH真空脱气-连铸300 mm×340 mm方坯-热连轧成Φ90 mm棒材。试验研究了普通轧制工艺(开轧1100~1150℃,终轧950~1000℃,上冷床900~950℃,冷却速度0.5~1.0℃/s)和控轧控冷工艺(开轧1100~1150℃,终轧800~850℃,上冷床700~750℃,冷却速度5.0~15℃/s)对Q420N钢热轧显微组织和力学性能的影响。结果表明,随着终轧温度的降低和冷却速度的增大,Q420N钢材的显微组织得到改善,屈服强度明显增加;普通工艺轧制Q420N钢材屈服强度为325~340 MPa,晶粒度为6.0级,控轧控冷工艺轧制Q420N钢材屈服强度为495~515 MPa,晶粒度为9.0级,满足了标准要求,降低了生产成本。