Nb microalloying high strength ship plate was produced by 100 t converter-100 t LF-200 mm x 1 500 mm caster-2800 mm medium plate mill flow sheet at Anyang Steel. Production data statistic results showed that with precisely controlling chemical composition of steel ( % : 0. 13 ~0. 16C

0. 33 ~0. 43Si

1. 31 ~ 1.42Mn

0. 007 〜0. 014P

0. 005 〜 0. 018S

0. 021 ~0. 039Al

0. 018 -0. 022Nb)

beginning finish rolling at 950 °C

total reducing ≥50% in finish rolling

and end finish rolling at 780 ~ 850 °C

the grain size rating of 6 〜25 mm steel plate of grade AH36 was 9 ~ 9. 5

yield strength 360 ~475 MPa

tensile strength 490 〜610 MPa

85 elongation 18% 〜36% and impact energy at 0°C 110 〜221 J.