Abstract: The steelmaking process of tested steel Q345E (/% ：0.13C,0.23Si, 1.45Mn,0.012P,0. 005S,0.045V, 0.030Nb,0.030Al) is 100 t EAF- LF- VD- Φ500mm bloom casting-Φ140mm bar rolling. By heat treatment test of steel Q345E,it is obtained that the effect of grain size rating on impact energy of tested steel at -40°C is obvious,as the rating of grain size of products is 7.0,the impact energy of steel at -40°C is only 12 ~ 16 J,and as the rating of grain size is 9.0 ~ 10.0,the impact energy of steel at -40°C. is increasing to 80 ~ 198 J. With decreasing finished rolling temperature from 960 °C to 865 ~910 °C,the rating of grain size of steel products increases from 7.0 to 8.5 ~9.0 and the impact energy of steel at -40°C increases from 12 ~ 16 J to 61 ~ 82 J to meet the standard requirement of impact energy 34 J of steel at -40 °C.

摘要： 试验的Q345E钢(/%:0.13C,0.23Si,1.45Mn,0.012P,0.005S,0.045V,0.030Nb,0.030Al)的冶炼工艺为100 t EAF-LF-VD-Φ500 mm坯连铸-Φ140 mm材轧制。通过Q345E钢热处理试验得出晶粒度级别对试验钢-40℃冲击功有显著影响;当钢材晶粒度级别为7.0时,-40℃冲击功仅为12～16 J,当晶粒度级别为9.0～10.0时,-40℃冲击功为80～198 J。通过将终轧温度从960℃降至865～910℃,钢材晶粒度级别由7.0提高至8.5～9.6,-40℃冲击功由12～16 J提高到61～82 J,满足-40℃冲击功34 J的标准要求。

关键词: Q345E钢, Φ140 mm棒材 , -40 °C冲击功, 晶粒度, 控轧控冷