采用宏观观察、化学成分分析、力学性能试验、断口分析、金相检验以及硬度试验等方法，分析Q345D钢板冷弯成型开裂的原因。结果表明：钢板的化学成分、基体组织、力学性能均符合技术要求；切割时在钢板侧面形成凹槽，凹槽处为马氏体组织，塑性较差，在弯曲过程中该处产生应力集中，这是Q345D钢板冷弯成型开裂的根本原因。

The reason for cold bending cracking of Q345D steel plate was analyzed by macroscopic observation, chemical composition analysis, mechanical property tests, fracture analysis, gold phase test and hardness test. The results showed that chemical composition, matrix tissue, and mechanical properties of steel plate met technical requirements. During cutting, groove was formed on the side of steel plate, and groove was martensitic structure, the plasticity was poor, stress concentration was generated at this position during bending process, which was the root cause of cold bending cracking of Q345D steel plate.