EH36船板钢生产过程中夹杂物成分的变化

Changes of inclusions composition in the EH36 ship plate steel during production process

对采用"BOF→LF→RH→CC"工艺生产EH36船板钢过程中的夹杂物进行了研究。用SEM-EDS分析了试样中的夹杂物形貌和成分,用FactSage软件计算了夹杂物的析出情况。研究表明:LF进站钢液中夹杂物主要为SiO_(2),试样中的MnS是在试样凝固过程中形成的。Ca处理后,液态夹杂物数量增多。经过RH处理后,夹杂物中Al_(2)O_(3)含量升高,CaO和MgO含量降低。中间包钢液中夹杂物的Al_(2)O_(3)含量降低,CaO含量升高,夹杂物与渣发生反应,使夹杂物成分向低熔点区靠近。中间包渣中SiO_(2)含量较高,与钢中Al发生反应,使钢液中Si含量升高,Al含量降低。钢液凝固过程中发生成分偏析,使铸坯中夹杂物的S含量明显升高,Al_(2)O_(3)含量升高,CaO含量降低。在铸坯中形成了CaO和Al_(2)O_(3)比例不同的钙铝酸盐夹杂物以及Al_(2)O_(3)夹杂物,且部分钙铝酸盐表面形成CaS。

The inclusions of EH36 ship plate steel produced by "BOF→LF→RH→CC" process were studied. The morphology and composition of inclusions in the sample were analyzed by SEM-EDS,and the precipitation of inclusions were calculated by Factsage software. The research showed that inclusions were mainly SiO_(2) when the molten steel was hoisted into LF furnace, and MnS of the sample was formed during solidification of the sample. The number of liquid inclusions was increased after calcium treatment. Al_(2)O_(3) content of inclusions was increased and the content of CaO and MgO were decreased after RH refining. Al_(2)O_(3) content of inclusions was decreased and CaO content of inclusions was increased in tundish. The composition of inclusions was close to the low melting point zone due to the inclusions reacting with slag. SiO_(2) content of slag was high and it reacted with Al of molten steel, which caused to increase Si content and reduce Al content in the molten steel. Because composition segregation occurred during solidification of molten steel, S content of inclusions was significantly increased, Al_(2)O_(3) content of inclusions was increased and CaO content of inclusions was decreased. Calcium aluminate inclusions with different ratios of CaO and Al_(2)O_(3) and Al_(2)O_(3) inclusions were formed in the billet, and CaS was formed on the surface of some calcium aluminate.