Banding structure of φ100 mm rolled products produced by 300 mm X 340 mm cast bloom of gear steel SAE8620H (0. 19C
0. 48Cr
0. 48Ni
0. 18Mo
0.32 Al) with 3 process conditions- hot rolled
completed annealed treatment-heating at 930 °C 1 h furnace cooling to 650 °C 1 h air cooling
and isothermal annealed treatment-heating at 930 °C 1 h outside furnace quick cooling to 650 °C 1 h air cooling has been tested. Results showed that the rating of banding structure of completed annealed rolled-products was higher than that of hot rolled ; and the rating of banding structure of isothermal annealed rolled-products was lower than that of hot rolled by 1. 0 ~ 1. 5
due to quick cooling from 930 °C to 650 °C to inhibit proeutectoid ferrite precipitation that obviously improved the banding structure of steel.