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5513.001 Thermal Aging Study for Additively Manufactured F357 Aluminum
There are a number of sustainment critical parts that have historically been produced using titanium alloys for their high strength capabilities. Titanium is however expensive and difficult to machine. High strength aluminum alloys such as F357 make it possible to pursue high temperature applications such as heat exchangers at substantial cost savings. Laser powder bed fusion (LPBF) technology has shown promise in producing high strength components in aluminum alloys, achieving comparable specific strength. Unfortunately, there is not a wealth of public data to help the adoption of F357 aluminum as an additive manufacturing material.
The objective of this program is to enable the use of aluminum alloys for high temperature applications by understanding the effects of thermal treatments and service temperatures on the long term performance of this alloy. Specifically, this effort seeks to document the material state and microstructure of F357 aluminum for certification and qualification of components that are critical for sustainment of legacy defense systems.
The University of Texas at El Paso (UTEP) is leading the effort. The first phase involves material parameter verification including powder acquisition and characterization, material parameter validation, and the builds of sample analysis cubes for characterization. Up to five post processing techniques for heat treatment are being investigated resulting in a down-selection for examining the thermal treatments and service temperature effects on F357 aluminum. Tensile samples are being constructed in the EOS M290 and SLM M280 system in the Z and XY orientations. Specimens are post processed in the “as built,” T6, HIP, HIP +T6 states, with up to two additional heat treatment identified and developed. Subsequently 100 and 1000 hours of exposure at an aging temperature of 350°F are being studied.