The steelmaking process of 700 MPa microalloying steel (/% : 0.05C

0.18Si

1.80Mn

0.010P

0.003S

0.15Mo

0.l0Ti

0.075Nb

0.035V

0.030Al

0.0020Ca) is 240 t BOF-LF-2150 mm slab casting. The structure and mechanical properties of hot-rolled 10 mm strip of 700 MPa microalloying high strength steel air-cooling processcoiling at 600℃. and direct sampling air-cooling for 3.7 h to ambient (25℃ ) and slow-cooling process-coiling at 600℃ and coils stacked slow-cooling for 36.2 h to ambient (25℃)are observed and tested by using optical microscope

scanning electron microscope

energy spectrometer and tensile tester. Results are obtained that with slow-cooling process the amount of bainite in steel strip is relatively less

the steel strip has higher yield strength (732~740 MPa)

lower tensile strength (793~799 MPa) and larger elongation (21.0% 〜23.0% ) ； and with air-cooling process the amount of bainite in steel strip is rather more

the steel strip has lower yield strength (647〜654 MPa)

higher tensile strength (811〜831 MPa) and rather lower elongation (15.0%~17.0% ). Comprehensive consideration

the mechanical properties of steel strip with slow-cooling process are better than that with air-cooling process.