Abstract
It is reported that 65% of blade failure in turbo machinery is due to mechanical failures of the blades themselves [1]. The applied stress together with the higher temperatures can have a direct impact on the life of the impeller. It is therefore critical to evaluate the mechanical properties of materials and their durability at the relevant operating temperatures [1, 2]. In this study we will demonstrate the potential of different aluminum alloys to extend the life of a system by evaluating their durability over time at common operating temperatures. With appropriate testing that simulates the mechanisms involved at working conditions, one can benchmark the performance of different products. Comparisons between different alloys used as impellers in turboexpanders, turbo-blowers, turbopumps, turbochargers and superchargers are made. The most common products used in these applications is 2618-T8 and this alloy has been compared with the more recent 2027-T8 that is designed to withstand temperatures above 100°C. The applications demonstrated here for turbopumps and turbochargers will analyze the performance of 2618-T8 and be compared to the new 2027-T8.
The microstructural differences between the two alloys are presented and will be related to the mechanical properties studied. Overall, 2027-T8 demonstrates improved performance at 150°C compared to 2618-T851 in all aspects of material performance: tensile properties, thermal stability, fracture toughness, fatigue and creep performance. These properties are all critical for choosing the appropriate alloy for an impeller or rotor in order to allow either improved performance or increased component lifetime due to over-performance of this newly studied alloy, 2027-T8.
