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分别采用解剖、总氧分析(T[O])、原位统计分析、金相显微镜统计分析和小样电解实验研究了16.8 t高压锅炉管钢P12铸锭中夹杂物的分布.发现在铸锭的上中部存在夹杂物数量较低的负偏聚区域,而在中心及尾部中心部位存在夹杂物数量较高的正偏聚区域.为了表征夹杂物的偏聚程度,提出了夹杂物偏聚指数的新概念.总氧分析和原位统计分析结果表明铸锭中下部氧化物夹杂物偏聚指数达到1.4～1.6,而在上中部氧化物夹杂物的偏聚指数为0.5～0.7.金相统计分析和小样电解实验可同时分析钢中氧化物和硫化物等夹杂,其分析结果表明铸锭上中部夹杂物的偏聚指数为0.7～0.8,铸锭中下部夹杂物的偏聚指数为1.15～1.35.铸锭中心及锭尾中心区域氧化物夹杂平均尺寸明显大于其他区域,表明大夹杂物在上浮过程中被结晶雨捕获并沉降到底部是铸坯中下部夹杂物偏聚的主要机制.
The distribution of inclusions in P12 ingot of 16.8 t high pressure boiler tube steel was investigated by anatomical, total oxygen analysis (T [O]), in situ statistical analysis, metallographic microscope statistical analysis and sample electrolytic experiment, respectively. There is a negative segregation zone with a lower number of inclusions in the upper middle part and a positive segregation zone with a higher number of inclusions in the central and aft part of the center.In order to characterize the degree of segregation of inclusions, New concept.The results of total oxygen analysis and in-situ statistical analysis show that the segregation index of oxide inclusions in the lower ingot reaches 1.4-1.6, while the segregation index of oxide inclusions in the upper middle reaches 0.5-0.7 Metallographic analysis And the sample electrolysis experiment can simultaneously analyze inclusions of oxides and sulfides in steel. The analysis results show that the segregation index of inclusions in the middle of the ingot is 0.7 ~ 0.8 and the segregation index of the inclusions in the lower ingot is 1.15 ~ 1.35 The average size of oxide inclusions in the center of ingot and in the center of ingot is obviously larger than that of other regions, indicating that the large inclusions are trapped by crystal rain and settle down to the bottom during the ascending process, which is the main mechanism of segregation of inclusions in the middle and lower part of the slab.