Microstructures and Macrosegregation of Al–Zn–Mg–Cu Alloy Billet Prepared by Uniform Direct Chill Casting

Abstract

In this study, large-sized Al–Zn–Mg–Cu alloy billets were prepared by direct chill casting imposed with annular electromagnetic stirring and intercooling; a process named uniform direct chill casting. The effects of uniform direct chill casting on grain size and the alloying element distribution of the billets were investigated and compared with those of the normal direct chill casting method. The results show that the microstructures were refined and the homogeneity of the alloying elements distribution was greatly improved by imposing the annular electromagnetic stirring and intercooling. In uniform direct chill casting, explosive nucleation can be triggered, originating from the mold wall and dendrite fragments for grain refinement. The effects of electromagnetic stirring on macrosegregation are discussed with consideration of the centrifugal force that drives the movement of melt from the central part towards the upper-periphery part, which could suppress the macrosegregation of alloying elements. The refined grain can reduce the permeability of the melt in the mushy zone that can restrain macrosegregation.

Numerical investigation of pull in control of rectangular AA1050 rolling ingot through the design of convex mould during direct chill casting process

“…During the direct chill semi continuous aluminum alloy casting process, the FEA model shown in figure 1(b) is built to forecast the temperature distribution and thermal stresses that are present in a rectangular-shaped aluminum alloy ingot. It is anticipated that the final ingot produced by the direct chill semicontinuous aluminum alloy casting process will be greater than the pure elastic nature; hence, the viscoelastic mechanism will be responsible for relieving the thermal stress (Yang et al [2]). In order to investigate the effects of shrinkage on ingots, a process called transient structural-thermal simulation is carried out.…”

“…The variety of end products produced from aluminum alloy requires large size rolling ingots and billets as raw material. The production of high quality ingots and billets of large enough size required for further application is the main hurdle to cope up with the increasing demand [2]. The direct chill casting is the most widely used manufacturing process for the manufacture of large sized ingots and billets of Al, Cu, Mn, Zn alloys [3][4][5][6][7][8].…”

Influence of Gating System Parameters of Die-Cast Molds on Properties of Al-Si Castings

“…In the simulation, the observed determining parameter of the design suitability was the ratio of shrinks in the cast body and the gating channels after solidification. Figure 10 shows a simulation of the gating system and distribution of defects after completion of the casting cycle [26].…”

“…The melt loses pressure and speed, resulting in premature cooling and thus solidifying the ingate. Resistance pressure loses its effect and can be observed as shrinks due to material shrinkage when transiting from the liquid to the solid state [26]. The simulation and visual representation proved that the numerical design proposal of the gating system was not suitable.…”

Effects of Intercooling Intensity on Temperature Field and Microstructure of Large-Scale 2219 Al Alloy Billet Prepared by Internal Electromagnetic Stirring Casting

“…Coarse and inhomogeneous microstructures always occur during conventional direct chill casting (DCC) of billets, an issue that usually worsens as the scale of the billet and range of solidification increases [ 1 , 2 , 3 , 4 ]. Deformation processes, such as rolling and forging, can refine a microstructure, but cannot significantly improve its inhomogeneity [ 5 ].…”