Effects of Al-5Ti-1B grain refiner on the structure, hardness and tensile properties of a new developed super high strength aluminum alloy

Al-5Ti-1B alloys are the most commonly used grain refiners in the casting of aluminum alloys. In this study the effect of Al-5Ti-1B grain refiner on the structural characteristics, hardness and tensile properties of Al-12Zn-3Mg-2.5Cu aluminum alloy was investigated. The optimum amount for Ti containing grain refiners was selected as 2 wt.%. T6 heat treatment, heating at 460 degrees C for 1 h and water quenching to room temperature and aging at 120 degrees C for 24 h, was applied for all specimens before tensile testing. Significant improvements in mechanical properties have been obtained with a combination of grain refiner and T6 heat treatment. After heat treated specimens, the average tensile strength of 495 MPa was found to be increased to 605 MPa for sample refined with 2 wt.% Al-5Ti-1B (0.1 wt.% Ti). The fractography of the fractured faces and microstructure evolution of Al-12Zn-3Mg-2.5Cu aluminum alloy was characterized by SEM ( Scanning electron microscopy) and optical microscopy. In this study the relation between the value of grain refiner with average grain size, hardness and tensile properties has been studied.