Fatigue Endurance Of Alsi10mg Post Hip Heat Treatment With High Duration Thermal Aging

AlSi10Mg is one of the cornerstones of additive manufacturing (AM), with its materialproperties and relatively low cost making it extremely popular as an AM metal choice, specifically using Laser Powder Bed Fusion (LPBF). Many publications have focused on this material, studying tensile strength, fatigue, heat treatments, and more. However, an area that requires further study is the effect of aging on the materials fatigue properties, with this study examining an industry standard heat treatment of Hot Isostatic Pressing (HIP). Using studies that have already been completed, AlSi10Mg was fatigue tested at near 100% UTS and 75% yield strength after HIP and aged 0, 10, 100, or 1000 hours. The discovery from testing was that aging reduced the material fatigue strength, with effects seen from as little as 10 hours of aging. This is likely due to the over-aging precipitates of Si forming in the internal microstructure, changing the originally ordered microstructure from the as-built and heat-treated to have increasingly granular Si precipitates with respect to aging. Their removal from the structure likely causes microvoids to form, leading to crack propagation once the material is sufficiently stressed, reducing the fatigue performance.