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本文利用快速冷却试样研究了铝脱氧钢液中氧化铝树枝晶的形核机理。通过理论分析认为:氧化铝具有很高的表面能,只能通过非均质过程形核。而硅酸盐夹杂物的表面能只为氧化铝的10~(-8),具备在钢液中均质形核的条件。通过实验研究发现,当钢液加铝脱氧时,溶解铝和硅酸盐夹杂物发生反应,生成部分反应的硅酸盐夹杂物。这些夹杂物具有高铝质的外壳和高硅质的内核,其外壳由于转变应力而开裂。这些裂缝随后则作为基底而形核、生长出氧化铝树枝晶。
In this paper, the nucleation mechanism of alumina dendrites in aluminum deoxidation molten steel was investigated by rapid cooling of specimens. Through theoretical analysis, it is concluded that alumina has a high surface energy and can nucleate only through heterogeneous processes. However, the surface energy of silicate inclusion is only 10 ~ (-8) of alumina, which has the condition of homogeneous nucleation in molten steel. The experimental study found that when the molten steel with aluminum deoxidation, dissolved aluminum and silicate inclusions react to generate partially reacted silicate inclusions. These inclusions have a high-aluminum outer shell and a high-silica inner core, the outer shell of which cracks due to stress transformation. These cracks then nucleate as a substrate, growing alumina dendrites.