通过成分设计和工艺设计开发了大热输入焊接用Q420C钢板，并对其焊接性能进行了试验。结果表明：该Q420C钢板的显微组织细小均匀，力学性能较好，在-80℃下其冲击吸收能量大于200 J。在热输入为250 kJ·cm^-1的情况下，其熔合线处的冲击吸收能量远高于技术要求，焊接性能良好。

Q420C steel plate for high heat input welding was developed by composition design and process design, and its welding performance were tested. The results show that the microstructure of the Q420C steel plate was fine and uniform with good mechanical properties. The impact absorption energy of the Q420C steel plate was more than 200 J at -80 ℃. When the heat input was 250 kJ·cm^-1, the impact absorption energy at the fusion line was much higher than the technical requirements, and the welding performance was good.