The 300 mm slab of tested steel EH460 (/% : 0.06~0.08C

0.20~0.33Si

1.51~1.52Mn

0.003〜0.013P

0.002S

0 〜0.18Mo

0.34~0.36Ni

0.04~0.05Nb

0.05~0.06V

0.013~0.015Ti

0.006~0.026Als) is rolled to 60 mm plate by Φ550 mm mill

end rolling temperature at 798~817 °C. and cooling rate 5~20 °C/s. The effect of no-bearing Mo and bearing 0.18% Mo on structure and mechanical properties of the steel has been studied. Test results show that with cooling rate 15 ℃/s

of no-adding Mo steel the tensile strength is 645~655 MPa

-40 ℃ impact energy is 168~200 J

and of 0.18% Mo steel the tensile strength is 677~679 MPa

-40℃ impact energy is 48~64 J. For the high strength hull steel EH460

the strength of plate shall be increased by adding Mo in steel to meet the ships' classification society standard requirement for strength of steel ( yield strength ≥460 MPa

tensile strength 570~720MPa and impact energy at -40 ℃ ≥46 J)

but the impact energy of higher Mo content steel decreases more

therefore in real production the Mo content in high strength bull steel EH460 should be ≤0.15%.