COMPUTER SIMULATION OF HEAT TREATMENT PROCESS FOR ALUMINIUM ALLOY

Abstract

Temperature of aluminium alloy is simulated using MATLAB programming language for annealing, soaking to have uniformity of microstructure and quenching treatment processes. Workpiece selected for the study was aluminum alloy 6061-O, T1, T4 and T6 of different shapes: plate, cylindrical, rectangular, cubic and spherical aluminum alloy. The simulation identified the following properties: geometry (size), thermal conductivity, density, load pattern or shape which determine possibility of good heat treatment. Temperature of treated specimen were analysed using Finite Difference Method. At annealing temperature of 409.5 oC, fracture resistance of 670.5MPa and ultimate tensile strength value 298 MPa were achieved with 4% of ductility. Holding this temperature of 409.5 oC was necessary for achieving uniform microstructure at about 600 seconds which later quenched in water for 799 seconds to room temperature of 28 oC. Therefore the aluminum has equivalent length (thickness) treated of 25mm in plate section. The workpiece in the study increases in strength with increase in temperature for annealing therefore increases in thermal conductivity of the specimen was experienced. However, heat treatment in plate section of aluminium (6061-O) was faster in comparing to rectangular and cylindrical surfaces. Heat transfer coefficient was 1384W/m2K in plate and 692 W/m2K in cylindrical specimen of Biot number 0.2. The heat treatment processing was completed after 2256 seconds and aluminium 6061-O is more easily heat treatable to aluminium 6061- (T1, T4, T6) under the same condition. However, annealing of aluminium 6061 would negate effect of cold working at strain of 0.002 with yield strength of 149 MPa at ductility of 0.2%.