Engine Titanium Consortium - Center for Nondestructive Evaluation ...

63%
Back-Wall Scan
74%
FBH scan
58%
40%
64%
60%
59%
57%
42%
61%
68%
47%
33%
37%
35%
37%
57%
56%
64%
71%
68%
55%
69%
66%
64%
48%
49%
46%
38%
66%
66%
36%
(a)
Amplitude (%FSH)
(c)
Comparison of Normalized
BW and FBH variations
(5-MHz Phased Array; Focused on Backwall; Trial 1)
80
70
60
50
40
30
20
10
FBH PA-foc_at_back
Average for all sites = 50%
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Measurement Site
BW PA-foc_at_back
FBH Amplitude (% FSH)
(b)
Correlation Between Norm'ed
BW and FBH variations
(5-MHz Phased Array; Focused on Backwall; Trial 1)
80
70
y = 1.005x
R 2 60
= 0.7744
50
40
30
(d)
Trendline thru origin
20
10
0
0 10 20 30 40 50 60 70 80 90 100
BW Amplitude (% FSH)
Figure 4. Measurements on a Ti 6-4 billet segment using a 5-MHz phased-array transducer
focused near the billet back wall, following the style of Figure 1. Beam diameters (-6 dB) near the
back wall are approximately 200 mils x 380 mils (axial x hoop).
Evaluation of Transducers
The two 7.5 MHzF/10 aperture elliptical transducers were evaluated in more detail than the
preliminary evaluation reported in the previous quarterly. Frequency measurements were made
using the echoes from #2FBH targets in 10” diameter calibration standards. Tables 1 and 2
compares these frequency measurements with those supplied by the manufacturer, which had
been measured on a flat brass target, located at the near focal point, in water.
In order to assess the performance relative to the #1FBH sensitivity program goal, a number of
scans were made using the 10 inch diameter Ti 64 ETC standards, which contain targets of various
diameters down to 0.4 mm (1/64 inch). These scans were done as closely as possible to
production inspection conditions, with the exceptions that the scan index was reduced to 0.01” in
order to capture the peak signals, and the gate length was reduced where necessary to avoid back
surface signals in the gate. For the zone 2 transducer, targets at 0.9”, 1.35” and 1.8” (start, center,
Quarterly Report – January 1, 2002 –March 31, 2002
print date/time: 6/6/2002 - 8:39 AM – Page 28