T.O. 33B-1-1 5-36 Table 5-3 Continued Incident longitudinal wave angle in plastic (degrees) Refracted shear wave angle in test materials (degrees) Steel Stainless Steel 302 Stainless Steel 410 Ti 150A Al 1100-0 Al 2014-T4 Inconel Wrought Magne -sium AM 35 62 46.9 49.1 52.0 49.1 49.5 49.5 51.3 49.5 63 47.4 49.7 52.7 49.7 50.1 50.1 52.0 50.1 64 48.0 50.3 53.4 50.3 50.7 50.7 52.6 50.7 65 48.5 50.9 54.0 50.9 51.3 51.3 53.3 51.3 66 49.0 51.4 54.7 51.4 51.9 51.9 53.9 51.9 67 49.5 52.0 55.3 52.0 52.5 52.5 54.4 52.5 68 50.0 52.5 55.9 52.5 53.0 53.0 55.1 53.0 69 50.5 53.0 56.5 53.0 53.5 53.5 55.6 53.5 70 51.0 53.5 57.0 53.5 54.0 54.0 56.2 54.0 71 51.4 54.0 57.6 54.0 54.5 54.5 56.7 54.5 72 51.8 54.5 58.1 54.5 55.0 55.0 57.2 55.0 73 52.2 54.9 58.6 54.9 55.5 55.5 57.7 55.5 74 52.6 55.3 59.1 55.3 55.9 55.9 58.2 55.9 75 53.0 55.8 59.6 55.8 56.3 56.3 58.6 56.3 76 53.3 56.1 60.0 56.1 56.7 56.7 59.1 56.7 77 53.7 56.5 60.5 56.5 57.1 57.1 59.5 57.1 c.     Note the serrations on the wedges in Figure 5-36 and Figure 5-38.  These serve to dampen and scatter reflected  sound  that  does  not  initially  enter  the  test  part.    The  serrations,  therefore,  reduce  spurious signals. d.     The configurations of the wedges in Figure 5-36 and Figure 5-38 may be modified as required to take care  of  special  geometry  situations.    In  all  cases,  wedges  shall  be  fabricated  to  provide  the  proper refracted  angle  for  the  desired  mode  of  vibration.    In  addition,  they  shall  provide  for  transmission  of sound into the test part at the locations required to cover the areas of suspected flaws. e.     Figure  5-37  shows  how  the  coupling  fixture  is  used  with  the  wedge  in  Figure  5-38.    A  few  drops  of couplant material is needed between the search unit and any wedge to ensure good sound transmission. f.      Figure 5-39 shows a typical shoe used for curved surfaces.  This example may be used as a guideline for fabrication of shoes for curved surfaces.  Dimensions may be changed to accommodate the specific part to be inspected.