Determination of heat transfer coefficient between AK7ch (A356) aluminum alloy casting and no-bake mold

Abstract

Determined the iHTC (interface Heat Transfer Coefficient) between AK7ch (A356) aluminum alloy casting and no-bake mold. The heat transfer coefficient is determined by minimizing the error function values, representing the difference between the experimental and calculated temperature in the mold values during pouring, solidification and cooling. Determined the values of the heat transfer coefficient above the liquidus temperature of the alloy hL = 900 W/(m2·K) and below the solidus temperature hS = 600 W/(m2·K). Changing of the heat transfer coefficient within hL = 900÷1200 W/(m2·K) and hS = 500÷900 W/(m2·K) has no sufficient effect on the error value, and it remains within ~22 °C. It was shown the usability of the simplified approach using constant heat transfer coefficient h = 500 W/(m2·K), whereas error value is 23,8 °C. Changing of iHTC as function of height of the cylindrical ingot was experimentally confirmed. This owes to the different values of metallostatic pressure applied to the solid skin of the solidifying casting, leads to closer contact of the metal and mold in the bottom of the casting.