Mould thermal analysis in direct-chill casting of magnesium alloys

This study was performed to evaluate the major thermal parameters in the areas of primary and secondary cooling in the magnesium direct-chill (DC) casting process. The work was focused on rectangular bloom casting of AZ31 alloy in a water-jacketed mould. The analysis included comprehensive experimental study of the major thermal parameters of the process, as well as 3D computer simulation of the casting process and its verification based on the experimental data. Three segments of primary cooling were clearly identified along the mould. It has been shown that length of these segments depends greatly on mould cooling arrangement and casting speed. Some data has also been shown for the direct-chill water cooling (the first zone of secondary cooling). The results included evaluation of thermal conditions of the process that might cause casting defects, such as surface folding and radial cracking. The outcome of the study has been discussed from the point of view of further mould development for the DC casting of magnesium.