Abstract
Many investigations have been made to get sound ingots by means of modifying the solidifiCation process. Scrape method is one of them. This method was developed from the experiments worked on Al-4% Cu alloy ingots. It is to make molten metal solidify by stirring with a rod after pouring. This is, however, not simple hydrodynamic stirring. The surface of the zone of partial solidification is scraped with the rod, and this zone is destroyed.
Hence, the successive progress of this zone from the scraped region is stopped and the whole bulk liquid is brought into a creamy state. The ingots obtained are segregationless and remarkably finegrained. The causes of these phenomena are considered to be the self-nucleation of crystals and the effect of turbulent flow by scraping.
We attempted to apply this method to two steel ingots; 800kg ingot poured into metal mold and 1600kg ingot poured into sand mold.
The results obtained are as follows;
(1) Scrape method could be applied to 800kg steel ingot successfully.
(2) Macro-structure of this ingot became remarkably fine by the application of Scrape method.
But, originally, segregation is slight in this size of steel ingot poured into metal mold and because of inadequate experimental condition it was impossible to check the effect of Scrape method on V and A ghost.
(3) The results of the experiment on 1, 600kg cast steel ingot in order to check the effect of this method on V and A ghost show that the branched columnar zone, so-called the hot-bed of A ghost was destroyed by scraping, thereby developing no A ghost and the exterior of ingot was cleen. In addition, the growth of V ghost was prevented.
