Impact of Different Grain Refiner Addition Ratios on the Microstructural Properties of 6082 Aluminum Alloy

This study examines the impact of grain refiners on the microstructural properties of 6082 aluminum alloy, emphasizing the effect of varying addition rates on grain size and refinement efficiency. Four grain refiners (GR1, GR2, GR3, GR4) were tested at different rates, with results assessed through chemical composition analysis, microstructural examination, and grain size measurements. The findings reveal that lower addition rates proved more effective: for instance, GR3 at 0.33 kg/t achieved a grain size of 110 μm, while at 0.76 kg/t it reached 105 μm; GR4 achieved comparable grain sizes (131 μm at 0.30 kg/t) with high efficiency. In contrast, higher rates (e.g., GR1 and GR2 at 1.48-1.53 kg/t) yielded lower efficiency despite smaller grain sizes. These findings suggest that excessive addition rates are redundant, with optimized lower rates yielding finer grains and higher efficiency. Chemical analysis confirmed that changes in Ti and B concentrations aligned with addition rates, yet lower rates offered superior recovery and effectiveness. Microstructural analysis further demonstrated that GR3 and GR4 at reduced rates produced homogeneous, fine-grained structures, enhancing casting quality and cost-effectiveness. This study highlights that optimizing grain refiner addition rates enhances microstructural control and economic efficiency in 6082 alloy casting. Future research should focus on fine-tuning these rates and exploring alternative refinement techniques to further improve the mechanical properties and castability of aluminum alloys. This study uniquely demonstrates that optimized low addition rates enhance microstructural homogeneity while providing significant cost and environmental benefits, addressing a critical gap in industrial grain refinement practices.