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
δ
5
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%