Study of the Influence of Technological Factors on the Surface Structure of Aluminum 6000 Series Alloys Ingots

The structure and chemical composition of the surface layers of aluminum 6000-series alloys after crystallization and homogenization annealing at 580 °C were investigated. It is shown that the state of the surface significantly depends on the presence of impurities in the coolant of the crystallizer, which deteriorate the continuity of the oxide film, which leads to the formation of light color of individual parts of the ingot surface.

FEM Analyses of the Radiation in Heating Forging Furnace

The purpose of this study was to identify possible causes of longitudinal surface cracks found during early stages of ingot breakdown. However, these cracks need not necessarily form during forging or as a result of poor quality of the surface in metallurgical terms. Under certain conditions, they may occur even as the ingot is being heated in the furnace to the forging temperature. The cracks probably form within a few minutes after placing the ingot in the furnace as a result of the temperature gradient, which is most severe on the ingot surface. A numerical model was created to represent the case of three ingots in a furnace. Upon casting, the ingots are cooled down to no more than 600°C and then placed in a furnace at 1,100 - 1,200°C. Numerical simulations were used to analyse their internal stresses and temperatures.

Effect of Out-Phase Electromagnetic Field on the HDC Casting Process of Commercial Aluminum

Commercial aluminum ingot with the diameters of 100 mm is produced by conventional out-phase electromagnetic field HDC casting process. The out-phase electromagnetic field is applied on the HDC casting process. The effect of out-phase electromagnetic filed on the ingot surface and structure is investigated. The result shows that the out-phase electromagnetic field is more effective in improving the upper surface, while, has little function on the bottom surface. The macro/microstructure of the ingot is changed by the out-phase electromagnetic field. Very long and coarse columnar grains evolve to short and thin columnar grains with the application of the out-phase electromagnetic field.

Aluminum Ingot Thermal Stress Development Modeling of the Wagstaff® EpsilonTM Rolling Ingot DC Casting System during the Start-up Phase

Based on sequentially coupled CFD and FEM models, aluminum alloy rolling ingot thermal stress simulations have been conducted in order to understand start-up phase cold cracking phenomena and optimize tooling designs for 520×2120 mm rolling ingot casting on Wagstaff® Epsilon™ Ingot Tooling. In the CFD model, ingot surface temperature dependant and water flow rate dependant water boiling curves are applied. Thermal boundary conditions for the complex water intrusion phenomena under the ingot butt have been attempted. Temperature dependant elastic-plastic materials constitutive relationship has been employed in the transient thermal stress FEM model. Results of thermal stress development at ingot surface and inside the ingot are presented; Connection of cold cracking (ingot butt quarter and center cracks) with near surface stress development at the ingot butt is shown and the effect of water intrusion under the ingot butt on the butt stress development is also discussed. The predicted temperatures are validated against temperatures measured from cast-in thermocouples at strategic locations in field ingots in order to obtain realistic thermal boundary conditions. The predicted butt curl is also verified through field observation and measurement.

The Effect of Casting Speed on Sump Shape and Ingot Surface of HDC Casting 7075 Aluminum Alloy Ingot

7075 aluminum alloy ingot with the diameter of 100 mm has been produced by horizontal direct chill casting in different casting speed. The effect of casting speed on the sump profile and the ingot surface quality was studied by sump profile observation. It was found that increasing the casting speed results in the deepening of the liquid pool, the adding of segregation knots and the reducing of cold shouts in the ingot surface. It is also found that the depth of the liquid pool is directly proportional to the casting speed and the squared radius of the ingot.