稀土处理对高牌号无取向硅钢中夹杂物的影响

Influence of rare earth treatment on the inclusions in high-grade non-oriented silicon steel

通过工业试验研究了不同稀土含量对高牌号无取向硅钢中夹杂物的影响。研究结果表明,当稀土质量分数为0.0021%时,稀土元素主要形成(La,Ce)AlO_(3)夹杂物,从而进行脱氧、变质钢中Al_(2)O_(3)夹杂物;随着钢中稀土含量的增加,稀土主要形成以(La,Ce)AlO_(3)-(La,Ce)_(2)O_(2)S类和(La,Ce)_(2)O_(2)S类稀土夹杂物,主要降低了钢中硫化物的析出量,但是此时生成的稀土夹杂物对钢中大量温降过程析出和二次氧化产生的Al2O3类夹杂物的改性作用较弱,这导致稀土含量高时钢中Al_(2)O_(3)夹杂物的数密度明显增加。此外,夹杂物长宽比的统计结果表明,稀土处理使铸坯中夹杂物发生明显球化,但在随后的热轧工序中,常规处理与稀土处理的热轧板中夹杂物的平均长宽比差异较小。即在工业生产实际中,稀土处理对成品组织中的夹杂物的长宽比影响很小,影响夹杂物长宽比的主要因素主要是轧制过程的相关工艺参数。

The present study aimed to investigate the effect of different rare earth contents on inclusions in high-grade non-oriented silicon steel through industrial experiment.The results revealed that at a compound rare earth content of 0.0021%(mass fraction),the rare earth elements predominantly formed(La,Ce)Al_(2)O_(3)rare earth inclusions.These inclusions serve as deoxidizers and modifiers,transforming steel Al_(2)O_(3) inclusions.With an increase in the rare earth content in steel,the formation of rare earth inclusions shifts towards(La,Ce)AlO_(3)-(La,Ce)_(2)O_(2)S and(La,Ce)_(2)O_(2)S inclusions.These inclusions mainly reduce the formation of sulfides in the steel.However,their influence on the numerous Al_(2)O_(3)inclusions formed during temperature drops and secondary oxidation in steel is limited.Consequently,this leads to a significant increase in the number density of Al_(2)O_(3) inclusions in steel with a high rare earth content.Furthermore,rare earth treatment induced notable spheroidization of inclusions in casting billets.However,during the subsequent hot-rolling process,minimal differences were observed in the average aspect ratio of inclusions between conventionally treated plates and those treated with rare earth.Therefore,the primary factor influencing the aspect ratio of inclusions is the relevant process parameters of the rolling process.