Engine Titanium Consortium - Center for Nondestructive Evaluation ...

the high-noise coupons shown in the figure, resulting in 30.6%, 43.0% and 36% for the PW, HW
and GE coupons respectively.
In addition to the S/N measurements, sonic pulse volumes were also measured. First, the –6dB
beam diameter at the FBH depth was determined from a fine increment C-scan of the reference
hole in the PW coupon. Figure 4 illustrates the beam diameter determination for the same
example, leading to a value of 39.4 mils. Secondly, as illustrated in Figure 5, the pulse duration
was measured by finding the –6 dB points for the envelope function of the rectified FBH echo, and
this duration was translated to a pulse length in metal. For the case shown, the pulse length was
36.7 mils, leading to a measured pulse volume of (π/4)(39.4 mils) 2 (36.7mils) = 44,600 cubic mils.
Peak noise vs. pulse volume for all measurements is summarized in Figure 6.
PW8
Max. noise
30.6%
HW5
Max noise
43%
GE6
Max. noise
36%
#1/2 FBH ~ 80%
Figure 3. Example of S/N measurements in high-noise forging coupons. Here the FBH holes are
located at the focus of an F6 transducer.
Quarterly Report – January 1, 2002 –March 31, 2002
print date/time: 6/6/2002 - 8:39 AM – Page 61