通过观察Q345qD钢板冲击性能不合格试样内部组织形貌及断口特征,并回溯该钢种的冶金过程参数,得出了造成该钢种冲击韧性不合格的直接原因是钢板内部严重的带状组织,基本原因是冶金过程质量控制不良,同时轧制过程的稳定性也存在一定影响。通过相应优化措施,使该钢种的-20℃冲击韧性合格率从90%以下提高到100%,且冲击吸收功均值提高了40J以上。 By observing the internal structure and fracture characteristics of Q345qD steel plate with unacceptable impact properties and tracing the metallurgical process parameters of the steel, it is concluded that the direct cause of the unacceptable impact toughness of the steel is the serious band internal structure , The basic reason is poor quality control of metallurgical process, while the stability of the rolling process also has some impact. Through the corresponding optimization measures, the pass rate of -20 ℃ impact toughness of the steel grade is increased from below 90% to 100%, and the average value of impact absorption power is increased more than 40J.