Variation of texture anisotropy and hardness with build parameters and wall height in directed-energy-deposited 316L steel AITranslate

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DOI：https://doi.org/10.1016/j.addma.2020.101806

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Highlights • Walls built with high heat input shown to have significantly increased grain structure anisotropy. • Grain structure explained through cooling rate and melt pool size, varying with both processing parameters and build height. • Hardness shown to be directly related to grain structure, suggesting it can be controlled using the thermal signature. Directed energy deposition (DED) is an emerging technology with repair applications in critical aerospace components. Mechanical properties of DED components have been shown to vary significantly through a part, making it difficult to achieve the level of process control required for these applications. Using thermal data captured in-situ, cooling rates and melt pool dimensions were calculated and related to the final grain structure, captured by EBSD. The changes in cooling rate explain the microstructural variation between different processing parameters and through the build height. A new approach, using a cumulative anisotropy factor was implemented and correlates the variation in hardness with grain structure. Two regimes were found depending on the linear heat input in 316L, with high linear heat input resulting in great amounts of mechanical anisotropy on the component level. The relationships between thermal signature and mechanical properties suggest close control of anisotropy could be achieved by monitoring and controlling the melt pool size using a coaxial camera. Graphical Download : Download high-res image (421KB) Download : Download full-size image