Investigation of the Intermetallic Compounds Fragmentation Impact on the Formation of Texture during the as Cast Structure Thermomechanical Treatment of Aluminum Alloys

Abstract

In this work, the influence of the intermetallic particle fragmentation during hot rolling of the as cast structure on the evolution of textures in aluminum alloys 8011, 5182 and 1565 was investigated. For this purpose, laboratory multi-pass rolling of the cast material was carried out. At various degrees of hot rolling deformation, the process was stopped, and the metal was quenched and sent for optical and electron microscopy to investigate the large intermetallic particles. In addition, the grain structure was studied and an X-ray analysis was carried out in order to determine the main texture components. Some of the samples were held at a temperature above the recrystallization threshold and then cooled in air; the grain structure and texture composition were also studied. In addition, the simulation of the texture evolution was carried out under various modes of rolling of aluminum alloys, taking into account the process of fragmentation of intermetallic particles. The investigation showed that intermetallic compounds with a deformation degree of 1.8, on average, decrease the particle size by 5–7 times. The large eutectic particles remaining after homogenization are drawn out in the direction of deformation and are crushed, increasing their number accordingly. Therefore, the most favorable stage for the formation of recrystallization nuclei on particles is the moment when they are already numerous and their sizes are much larger than subgrains. Simulation of hot rolling of the investigated alloys showed that considering the factor of fragmentation of intermetallic particles during hot deformation of the as-cast structure significantly increases the accuracy of the results.

Influence of Fe and Mn on the Microstructure Formation in 5xxx Alloys—Part II: Evolution of Grain Size and Texture

“…The variation in the casting cooling conditions S-C and NR-C mainly influences the refinement of the primary phase and the casting grain and accompanying texture modifications will be observed in the comparison of the individual alloys. As both casting processes do not involve any special operations or directed solidification, the formation of pronounced texture components in the as-cast state is not promoted [21] and, thus, the transfer of orientations, such as Cube, to the final soft annealed states is unlikely to occur [54].…”

“…For the formation of the recrystallization structures, the PSN mechanism also needs to be taken into account, as the occurring fragmentation of primary phase particles during rolling can significantly increase the number of potential PSN nuclei (Figures 2, 3, 4, 5 and 6b), thus altering the resulting texture [21]. The PSN related texture component P was slightly more favorably observed for the low Mn alloys; in the case of the high Mn alloys, however, the expansion of the P-oriented nuclei is likely to be retarded by dispersoid pinning effects [23][24][25]68,69].…”

“…With regard to the effects of primary and secondary phases on the recrystallization processes and, thus, on the evolution of microstructure, texture and the final properties, two fundamentally different mechanisms must be taken into account: particle stimulated nucleation (PSN) and grain boundary pinning [14,20,21]. In general, the PSN mechanism occurs in the vicinity of rather large (primary) particles (>1 µm), where the accumulation of dislocations and the formation of recrystallization nuclei are favored.…”