Short Cycle Heat Treating with Fluidized Beds: Optimizing Mechanical Properties

摘要

Heat treatment of metallic alloys is often essential in order to achieve improved mechanical properties. However, the poor energy transfer of conventional convection furnaces often requires a lengthy heat treatment time from 6 to 30 hours. This lengthy time is a major constraint to the production flow in manufacturing operations and often heat treating is performed off-line in labor intensive operations. In contrast to conventional furnaces, the fluidized bed technology offers more efficient energy transfer to the part as well as excellent temperature control. Thus utilizing fluidized beds may not only open the door to significantly shorter heat treating times; but may also increase consistency in strength from part to part. Tensile properties as a function of soaking time for solution and aging were obtained from aluminum alloy A356.2 castings that were T6 heat treated in fluidized beds. Total solution time was varied from 0 to 3 hours and total aging time was varied from 0 to 6 hours. Most castings exhibited required tensile properties after only 30 minutes solution and 30 minutes artificial aging. Mechanical properties could be further optimized with small increases in either time or temperature of the heat treatment cycle.