25CrMo钢锭点状偏析区微观组织特点
发布时间：2019-07-02 13:46
【摘要】：为了研究钢锭点状偏析区微观组织特点,对CrMo钢锻坯中的斑点偏析区域进行了分析研究。研究表明,钢坯中的元素偏析区沿锻造方向拉伸且尺寸较小,可判断原铸锭中的偏析为3个维度方向尺寸相近的点状偏析。偏析区中铬、钼元素质量分数相对较高,在冷却后点状偏聚区形成贝氏体组织,与基体的铁素体、珠光体组织呈交错分布的特征,且夹杂物在偏析区富集比较明显,局部偏析区还存在气孔。钢中的点状偏析的出现主要原因是钢液凝固前沿过冷度降低,在成分过冷条件下,高熔点铬、钼组元在枝晶表面局部富集,随温度的下降,钢液中Mn S夹杂物同时受枝晶表面的物理吸附作用聚集,同时增加了枝晶区域液相的黏度,导致气体溢出困难,在凝固后局部形成气孔。通过提高钢液凝固速度,降低钢液在固液两相区的停留时间,将有效缓解钢锭中斑点偏析的形成。
[Abstract]:In order to study the microstructure of spot segregation zone of ingot, the spot segregation region in CrMo steel forging billet was analyzed and studied. The results show that the element segregation zone in the billet is stretched along the forging direction and the size is small, so it can be judged that the segregation in the original ingot is a point segregation with similar dimensions in three dimensions. The mass fraction of chromium and Mo in the segregation region is relatively high. The bainitic structure is formed in the punctate segregation zone after cooling, which is crisscrossed with the Ferrite and pearlite structure of the matrix, and the inclusions are enriched obviously in the segregation zone, and there are still pores in the local segregation zone. The main reason for the occurrence of point segregation in steel is the decrease of undercooling at the solidification front of molten steel. under the condition of composition undercooling, the high melting point chromium and Mo components are locally enriched on the dendritic surface. With the decrease of temperature, the Mn S inclusions in molten steel are aggregated by the physical adsorption of dendritic surface at the same time, the viscosity of liquid phase in dendritic region is increased, which leads to the difficulty of gas overflow and the local formation of pores after solidification. By increasing the solidification rate of molten steel and reducing the residence time of molten steel in the solid-liquid two-phase region, the formation of spot segregation in ingots will be effectively alleviated.
【作者单位】： 贵州大学材料与冶金学院;贵州省材料结构与强度重点实验室;首钢贵阳特殊钢有限责任公司;
【基金】：国家自然科学基金资助项目(51461007) 贵州省重大应用基础研究资助项目(黔科合JZ字[2014]2003)
【分类号】：TG142.1
本文编号：2508979
[Abstract]:In order to study the microstructure of spot segregation zone of ingot, the spot segregation region in CrMo steel forging billet was analyzed and studied. The results show that the element segregation zone in the billet is stretched along the forging direction and the size is small, so it can be judged that the segregation in the original ingot is a point segregation with similar dimensions in three dimensions. The mass fraction of chromium and Mo in the segregation region is relatively high. The bainitic structure is formed in the punctate segregation zone after cooling, which is crisscrossed with the Ferrite and pearlite structure of the matrix, and the inclusions are enriched obviously in the segregation zone, and there are still pores in the local segregation zone. The main reason for the occurrence of point segregation in steel is the decrease of undercooling at the solidification front of molten steel. under the condition of composition undercooling, the high melting point chromium and Mo components are locally enriched on the dendritic surface. With the decrease of temperature, the Mn S inclusions in molten steel are aggregated by the physical adsorption of dendritic surface at the same time, the viscosity of liquid phase in dendritic region is increased, which leads to the difficulty of gas overflow and the local formation of pores after solidification. By increasing the solidification rate of molten steel and reducing the residence time of molten steel in the solid-liquid two-phase region, the formation of spot segregation in ingots will be effectively alleviated.
【作者单位】： 贵州大学材料与冶金学院;贵州省材料结构与强度重点实验室;首钢贵阳特殊钢有限责任公司;
【基金】：国家自然科学基金资助项目(51461007) 贵州省重大应用基础研究资助项目(黔科合JZ字[2014]2003)
【分类号】：TG142.1
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