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晶粒细化是提高铝合金强度和塑性,改善铸件质量的重要途径。目前,铝合金的晶粒细化主要基于Al-Ti-B三元合金体系采用氟盐法制备,通过在熔融铝合金中添加Al-Ti-B细化剂棒使α-Al晶粒细化,从而获得均匀、细小、等轴晶粒组织。然而,该方法的KBF4和K2Ti F6混合卤盐,尤其是KBF4,增加了生产成本,引起更多的氟化物排放和难处理的残渣,且反应过程造成的热量损失很难由熔体自身的放热反应来弥补。因此,寻找一种更经济、更高效的化合物替代KBF4,为制备新型、质优的Al-Ti-B晶粒细化剂提供了方向。实验表明:用B2O3完全替代氟盐法中的KBF4盐,降低了晶粒细化性能,产生大量的残渣,且降低了熔体的流动性,使浇铸过程更加困难;当B2O3与除渣助熔剂预先混合,再与K2Ti F6混合加入到熔体中时,在不考虑添加物损失的情况下,铝熔体的微观组织结构和细化效率均会得到明显的改善;当B2O3和KBF4各添加50%时,钛的回收率和晶粒的细化效率,几乎与单独添加KBF4时一致。由此得出结论:在不损失晶粒细化效率的前提下,可以用B2O3部分替代KBF4,但绝非全部。该方法的优势在于:具有更低的氟化物排放量和颗粒物添加量,在相同质量下,B2O3提供的硼含量达到4倍,价格也更便宜。
Grain refinement is to improve the strength and ductility of aluminum alloy, an important way to improve the quality of castings. At present, the grain refinement of the aluminum alloy is mainly based on the Al-Ti-B ternary alloy system prepared by the fluorine salt method. The Al-Ti-B refiner rod is added to the molten aluminum alloy to refine the α-Al grain , To obtain uniform, fine, equiaxed grain structure. However, KBF4 and K2TiF6 mixed with halogen salts, especially KBF4, increase the production cost and cause more fluoride emission and refractory residue, and the heat loss caused by the reaction process is hardly caused by melt itself Hot reaction to make up. Therefore, looking for a more economical and efficient alternative to KBF4 compounds, for the preparation of new, high quality Al-Ti-B grain refiner provides the direction. The experimental results show that the complete substitution of KBF4 salt in the fluoride salt method with B2O3 can reduce the grain refinement property and produce a large amount of residue, and reduce the melt flowability, making the casting process more difficult. When B2O3 and the flux removal agent Pre-mixed, and then mixed with K2Ti F6 added to the melt, without considering the loss of additives, the aluminum microstructure and refining refinement efficiency will be significantly improved; when B2O3 and KBF4 each added 50 %, Titanium recovery and grain refinement efficiency, almost the same with the addition of KBF4 alone. From this, it is concluded that KBO4 can be partially replaced by B2O3 without loss of the grain refinement efficiency, but not by itself. The advantage of this method is that with lower fluoride emissions and particulate loading, B2O3 provides 4 times more boron at the same mass, which is cheaper.