Six specimens, having roughly similar microstructures, were machined from different angular positions within a forged disk of Ti 6-4 alloy. The "upper" surfaces of the six specimens each had a different cylindrical curvature (3 concave, 2 convex, 1 flat). The opposite "lower" surfaces were flat. Using a focused ultrasonic transducer, backscattered grain noise measurements were first made through the (flat) "lower" surfaces to quantify the effects of the minor microstructural differences between specimens. Grain noise was then measured through the "upper" surfaces to assess the effect of surface curvature. Measured root-mean-squared (rms) and gated-peak noise levels, corrected for microstructural differences, were compared to the predictions of a single-scatterer noise model. Model predictions of grain noise levels were generally found to be in good agreement with experiment.
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