Critical Assessment 32: Controling the melting behaviour of cast structures through solid-state deformation

Abstract

The role of solid-state deformation of cast structures in controlling the morphological transformations, accompanying their subsequent melting is critically assessed. When dendritic morphologies, present after casting, are subjected to solid-state deformation with a strain level sufficient to trigger recrystallisation, they are replaced by equiaxed grain structures. Heating of such structures to temperatures of the solidus-liquidus range initiates melting at triple junctions and along grain boundaries, causing disappearance of dendrites, which are replaced by globular features. The semisolid slurry formed this way exhibits thixotropic properties, positively affecting its flow behaviour and properties after solidification. Although a variety of conventional and exotic deformation techniques generate very fine grain structure after recrystallisation, it does not lead to substantial differences in morphological characteristics of the semisolid slurry.

Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

“…In particular, AlSi7Mg has attracted by far the greatest interest due to both its nearly eutectic composition that ensures a narrow solidification range and the high Si content that assures a good fluidity in the molten state. These are very important aspects in the L-PBF process as it makes it possible to reach full dense and crack-free parts [6][7][8]. The large interest in the AlSi7Mg alloy is proved by the large number of scientific papers available in the literature [9][10][11][12][13][14][15][16].…”