When calculating sound levels inside a building due to external sources, should some value be added to the expected sound level? ATSM E966 recommends adding 6 dB to this level. It has been theorized that this is due to pressure doubling. The effect of pressure doubling on the calculated exterior to interior sound transmission in the direct field is, however, often misunderstood. Most texts on the subject simply list a 5- or 6-dB correction factor that is applied to the transmission loss value. The reasoning of this particular number is neither expounded upon nor explained. This paper investigates and explains this correction factor.
Many current metal additive manufacturing (AM) systems employ powder bed fusion processes. Thin layers of powder are applied to a substrate, and an energy source such as a laser is used to fuse the powder into specific geometries, building a part layer-by-layer [1]. In this investigation, single laser-melted weld tracks of Inconel 625 are analyzed by electron backscatter diffraction (EBSD) to determine the heat effect of and grain morphology produced by laser powder bed fusion (LPBG). Previous research without EBSD has been reported on 316L stainless steel using the same experimental setup [2]. Depending on alloy composition and cooling conditions, rapid solidification can produce a wide variety of microstructures [3]. This variation leads to difficulty in modeling and predicting material properties. The purpose of this research is to determine if EBSD can be used to better understand grain morphology and ultimately assist in identifying processing parameters to improve the overall AM process.
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