针对厚度为85 mm海上风电用S355G10+N钢板心部冲击功低且离散性大的问题，结合夹杂物生成理论，采用金相检验、扫描电镜及能谱分析研究了钢板不同厚度处的微观组织。结果表明，钢板的组织主要为粒状贝氏体、少量铁素体和少量珠光体。钢板表面与1/4厚度处组织均匀，在钢板心部发现了严重偏析和板条贝氏体。冲击断口形貌表明，中心偏析导致生成的MnS和(Nb，Ti)C夹杂物为断裂源，其附近断裂方式为沿晶断裂。钢板中心偏析处的板条贝氏体加剧了裂纹的扩展，夹杂物与板条贝氏体的综合作用显著降低了钢板心部的冲击韧性。

To address the issues of low impact energy and high variability in the core of 85 mm thick S355G10+N steel plates used in offshore wind power, the microstructure of steel plates with different thickness was investigated through metallographic examination, scanning electron microscope, and energy spectrum analysis, combined with theoretical calculations of inclusion formation. The results show that the microstructure of the steel is predominantly granular bainite, with minor amounts of ferrite and pearlite. While the surface and the 1/4 thickness region of the plate exhibit homogeneity, significant segregation and lath bainite are observed in the core. Impact fracture morphology shows that MnS and (Nb,Ti)C inclusions generated by center segregation act as fracture initiation points, with intergranular fracture occurring around these inclusions. The presence of lath bainite in the center segregation zone increases crack propagation, and the combined effect of inclusions and lath bainite significantly reduces the impact toughness of the steel plate core.

U441.8