This study investigates the influence of grain refiner and cooling rate on the grain size of CuZn19Al6 alloy, a vital bronze material utilized in aviation. The grain size was changed by both the addition of Al5Ti1B grain refiners and alterations in the cooling rate. The cooling rate obtained was changed by using sand mold and permanent mold while 0, 0.1, and 0.25 wt. % grain refiner was added metal cast in both mold types. The casting samples were examined microstructurally, and hardness test, tensile strength, drilling, and corrosion tests were performed. The results show that grain size decreased with both grain refiner additions and increasing cooling rates. The smallest grain size was observed in the sample cast in the permanent mold with 0.25 wt. % grain refiner. As the grain size reduced, hardness and strength increased, while ductility was found to vary depending on the method of grain refinement. The increase in hardness, attributable to alterations in grain size, resulted in elevated forces during drilling. Concurrently, this led to improved burr formation and enhanced surface quality. Moreover, the results from potentiodynamic polarization testing revealed that both grain refinement and enhanced cooling rates contributed to improved corrosion resistance.