Abstract: The φ10~25 mm reinforced bars of Nb microalloying 400 MPa Ⅲ Grade steel - 0.17~0.25C,1.20~1.45Mn,0.02～0.04Nb have been developed by 40 t EBT are furnace- 40 t LF- 150 mm×150 mm billet concasting process. The mechanical properties of reinforced bars were σ_s 420~490 MPa,σ_b 590~680 MPa,δ₅ 24%～30%,and the yield strength decreasing was minor after nature aging for 8 weeks. The produced Nb microalloying 400 MPa Ⅲ grade steel reinforced bars were up to the requirement of CB 1499- 1998 standard and the production cost was obviously decreasing by 0.02%～0.04%& Nb to replace 0.05%～0.10% V.

Key words: Nb Microalloying, 400 MPa Ⅲ Grade Reinforced Bar, Development

摘要： 采用40 t EBT电弧炉40 t LF 150mm × 150mm方坯连铸工艺 ,开发了成分(%)为: 0.17～0.25C，1.20～1.45Mn，0.02～0.04Nb的400 MPaⅢ级Φ10～25mm铌微合金化钢筋。钢筋的力学性能为σ_s 420～490 MPa ,σ_b 590～680 MPa ;δ₅ 24%～30% ,自然时效8周后屈服强度下降较少。生产的Nb微合金化400 MPa Ⅲ级钢筋符合GB1499-1998标准要求。用0.02 %～0.04%Nb取代0.05%～0.10%V时，吨钢成本显著降低。

关键词: 铌微合金化, 400 MPa Ⅲ级钢筋, 开发