Internal cooling process to prepare aluminium rheocasting feedstock

Abstract

Immersion cooling and stirring are two elements of the internal cooling process recently proposed to produce aluminium rheocasting feedstock. They were employed in various combinations to identify the impact of each on the evolution of globular structures. AlSiMg melt sample water quenched above the liquidus point and after cooling into the semisolid temperature range produces predominantly dendritic dendritic features, typical of conventionally cast structures. Improvement in slurry features is noted when cooling below the liquidus temperature involves either stirring or immersion cooling. Internal cooling process which employs both immersion cooling and stirring produces smaller globules than those possible with stirring alone. Globular structures are obtained earlier and are refined further when internal cooling is extended to achieve higher solid fractions before quenching.

Response to artificial ageing of dendritic and globular Al–7Si–Mg alloys

“…The melts thus obtained were processed conventionally as well as with the semi-solid route: directly cast into a permanent mould to obtain dendritic samples and cooled into the semi-solid temperature range with the internal cooling process [13,14] before casting to obtain globular structures. Samples sectioned from these ingots were solutionized at 540 • C for 8 h and then quenched in * Tel.…”

Solid fraction analysis with DSC in semi-solid metal processing

“…3b). The cooling rate employed in this experiment, 40 K min −1 , is very similar to that employed in the internal cooling process to produce rheocasting feedstock [27,37]. The fractional solidification has occurred this time largely during rapid cooling and only a small fraction of solidification was noted during the isothermal step implying that solid-liquid equilibrium has already been established at the start of semi-solid holding.…”

Effects of process parameters on microstructure and properties of AZ91 alloy prepared by cooling/stirring and rolling process

“…8,9 Semisolid processing technique has the advantages of easy forming, good product microstructure and performances. [10][11][12][13] Therefore, it is an ideal way to fabricate magnesium alloy products because of good flowability. Many slurry preparation processes have been developed, such as mechanical stirring, 14 magneto hydro dynamic stirring, 15 melt conditioner direct chill casting, 16 bubble stirring and so on.…”