Effect of Copper Chill and Al5Ti1B Grain Refiner on Mechanical Characteristics of LM6 alloy Casting

Aluminum-silicon alloys, particularly LM6, are widely used in the automobile industry due to their excellent casting and machining properties. The mechanical behavior of LM6 largely depends on solidification and casting conditions. This study examines the influence of copper chill thickness and Al5Ti1B grain refiner on its mechanical properties. Grain refiner was added at three levels (0.25, 0.50, and 1 wt%), while copper chill thicknesses of 10, 20, and 40 mm were applied. Casting simulation with AutoCast-X1 optimized parameters, and sand casting experiments were conducted. A full factorial orthogonal array was employed, considering tensile strength and hardness as responses. Mathematical models were developed from test data. Results indicate that grain refiner and external chill significantly enhance casting quality. The optimum combination of 40 mm copper chill and 1 wt% Al5Ti1B produced maximum improvement, with tensile strength increasing by 30.05% and hardness by 4.76%.