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针对正火态Q345E-Z35特厚板Z向性能不合问题,采用金相检验、扫描电镜等检测手段,对Z向拉伸断口形貌及断口处夹杂物进行了分析。结果发现:导致特厚板Z向性能不合格的主要原因是中心部位存在带状组织偏析,以及长条的硫化锰夹杂、Nb/Ti块状夹杂和Si/Mn球状夹杂。为此,提出控制钢水中S含量,保证合理的板坯浇铸速度,优化加热、控轧和正火工艺等措施,改善了特厚板的Z向性能。
In view of the improper Z-direction performance of the normalized Q345E-Z35 heavy plate, metallographic examination and scanning electron microscopy were used to analyze the morphology and the inclusions in the Z-direction tensile fracture. It is found that the main cause of unacceptable Z-direction behavior is the presence of banded microstructure segregation in the central part, as well as long strips of manganese sulfide inclusions, Nb / Ti bulk inclusions and Si / Mn spherical inclusions. Therefore, measures such as controlling S content in molten steel, ensuring reasonable slab casting speed, optimizing heating, controlling rolling and normalizing process are proposed to improve the Z direction performance of the special thick slab.