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观测和分析了40MnB钢铸坯断面不同位置的枝晶偏析形貌,并对枝晶和枝晶间成分偏析进行微观检测;研究了不同热轧压下量时显微组织的偏析形态;借助扩散方程讨论了枝晶间距和热轧显微组织对带状组织的影响。结果表明：40MnB钢铸坯由表面到中心偏析逐渐加重,C、Mn元素在枝晶间偏析,铸坯中心处Mn元素偏析严重;偏析间距决定着消除带状组织的难易;减轻铸坯枝晶偏析和热轧组织偏析有利于消除带状组织。

Research on Mechanism of Forming Banded Structure for Segregation of 40MnB Steel

Dendritic segregation morphology locating at different areas on the strand of casting billet was observed and analyzed, and segregation microcontent of dendrite and interdendrite were examined in 40MnB steel; Segregation microstructure was researched at different hot rolling reductions; The effect of dendritic distribute and hot rolling microstructure with banded structure was discussed by diffused equation. The results show: Segregation becomes bad gradually from exterior to center in casting billet of 40MnB steel, the element C and Mn segregate in interdendrite, and especially the element Mn is very seriously at the center of casting billet; The difficulty and easiness eliminating banded structure are decided by segregation distribute; It's advantaged to eliminate banded structure that dendritic segregation is lightened in casting billet and hot rolling reduction is increased.