BS in Materials Engineering
Materials Engineering Department
In an effort to maximize grain growth of open-die forged 6061 aluminum alloy parts, samples from three of Weber Metals’s suppliers (Hidal Co-Almex USA Inc., TST Inc., and Vista Metals Corp.; to be called Supplier H, Supplier T, Supplier V respectively) were cut into cylinders with diameters of 0.75˝ and heights of 2˝, and put through a simulated forging process and heat treatment. It is possible that additional alloying elements may be promoting or inhibiting grain growth in the final part. Maximizing grain growth for aluminum alloy parts results in improved resistance to intergranular corrosion. Samples from each vendor had grain size analysis performed prior to running the experiment. Samples were heated to just over 650ºF so that when placed in the Instron compression machine for simulated forging they would be between the usual forging temperatures for aluminum of 550 to 650ºF. Samples were compressed at a rate of 50 mils/second to final strain values of 0%, 5%, 10%, 20%, and 50%. The samples were then heat treated at 1050ºF for a soak of 4 hours. This allows for maximum grain growth to occur before being removed and quenched in water to room temperature. A sectioning, sanding to 600 grit sandpaper, etching with 10% NaOH, and desmut with 33.33% nitric acid allows for grain size analysis to determine which vendor had the largest grain size at each strain value. Grain size measurements were made according to the Heyn Lineal Intercept Procedure from ASTM E0112-12.1 Supplier H’s alloy with 0% forging strain applied provided the largest average grain size at 1754 µm.