Ingot casting and casthouse metallurgy of aluminium and its alloys

Thermoelectric Materials and Applications: A Review

“…Despite being considered a conventional methodology, melting the mixed raw materials is still largely used to fabricate polycrystalline powders to produce bulk TEMs because of high productivity and scalability, low cost, and ease of operation. The process takes place in an evacuated and sealed quartz tube or container, where the high purity precursor powders are heated up over their melting point and kept at high temperature for a determined amount of time, being finally slowly cooled down to room temperature (cooling can take place also in the presence of oil, water, or liquid N 2 to accelerate the process or achieve a particular ingot internal structure) [213][214][215]. Annealing is often carried out after ingot fabrication to increase stability, mechanical properties (ductility, hardness, etc.)…”

Sensitivity study of the influence of the water boiling parameters on aluminum semi-continuous DC casting

“…The basics of butt curl formation are that the exterior of the ingot is cooled down by water while the interior is cooled down slowly by conduction, causing different contraction rates. [6] This differential in contraction produces stresses, as one part of the casting restrains another. [41] An overview of the different steps and phenomena at casting start allow to better understand the butt curl occurrence and helps choosing of a criterion to characterize butt curl sensitivity to boiling parameters.…”

“…Although the process involves a combination of hydrodynamic (flow of molten metal), heat transfer (water cooling) and mechanical stress (thermal contraction) mechanisms, the thermal aspect is dominant. In steady state, 80% of the total energy contained in the ingot [5] (superheat of the molten metal ≈ 5%, latent heat of solidification ≈ 35% and the sensible heat of the solid metal ≈ 60% [6]) is evacuated by secondary cooling (water jet and free-falling water) compared to only 20% within the mold (primary cooling zone). For this reason, water is often suspected as a potential cause for the issues related to the ingot quality.…”

“…At the impingement point, the water jets hit the solidified surface, which is at a temperature between 250 C and 300 C. [6] Since this temperature is much higher than the boiling point, bubble nucleation occurs at the surface but in most of the time the bubbles collapse rapidly inside the liquid film of water. This phenomenon is called jet impingement boiling on a vertical surface.…”

On the intermetallic constituents in the sodium-induced edge cracking of hot-rolled AA5182 aluminum alloys

“…Through the inverse segregation and volume contraction, the solute-rich liquid moves in the opposite direction of the solidification front by penetrating into the network of solidifying dendrites in the mushy zone [8]. Owing to the fluctuation of the melt pressure, the movement of the liquid level, and the surface tension of the liquid, meniscus bands also form on the ingot surface at regular intervals, through which the inverse segregation is further extended toward the bulk [9,10]. Prior to hot rolling, the ingot is homogenized, and the surface zone is scalped off from the rolling faces of the ingot.…”