Process flowsheet of test heavy gear steel 18CrNiMo7-6 (/% ： 0.165C

0.59Mn

0.24Si

0.006S

0.008P

1.56Ni

1.71Cr

0.28Mo

0.034Al

0.0129N) is 60 t UHP EAF-LF-VD-12.5 t ingot casting process. The effect of ingot heating process (1200-1220 °C

7-8 〜13-15 h)

forged product complete annealing (900 °C 12 h

with ≤ 80 °C/h slow cooling to 650 °C 50 h

air cooling)

isothermal annealing (900 °C 12 h

air cooling to 650 °C 50 h

air cooling) and normalizing (900 °C 12 h

air cooling) process on banded structure of Φ540 mm forged bar has been tested and studied. Results show that as ingot heating at 1200-1220 °C for 7-8 h

the rating of banded-structure of forged bar by complete annealing

isothermal annealing or normalizing process is respectively 4.0

3.5 and 3.0

while as ingot heating at 1200-1220 °C for 13-15 h

then normalized

the rating of banded-structure of forged bar is 2.5

it is an optimum process.