Engine Titanium Consortium - Center for Nondestructive Evaluation ...

Objective/Approach Amendments: Objective and approach remain as originally proposed in July
1998.
Progress (January 1, 2002 – March 31, 2002):
Several consortium conference calls were conducted during the quarter to discuss the details of the
subtask. A number of technical issues were discussed and decisions reached. The technical
issues and discussions are summarized into three primary areas, (1) Property Measurements, (2)
Noise Curvature Blocks, and (3) Synthetic Inclusion Disk and discussed separately below.
Property Measurements
One goal of the Fundamental Studies subtask is to document the manner in which ultrasonic
properties vary within representative Ti 6-4 forgings, and to relate those properties to the forging
microstructure. The ultrasonic data will then be used by Subtask 1.3.2 to design new forging
inspections which improve defect detection sensitivity four-fold: from the current #1 FBH level to a
#1/2 FBH level. Since backscattered grain noise is primarily responsible for determining defect
detection limits, the emphasis has been on grain noise measurement and analysis.
The overall plan calls for UT measurements on coupons cut from selected sites in three typical Ti 6-
4 forgings supplied by the OEMs. Approximately 8-10 coupons have now been cut from each
forging, with coupon sites chosen to provide a range of local microstructures (based on
backscattered noise C-scan, macroetch, and strain-map data). In previous quarters, grain noise
studies were concluded on suites of coupons cut from forged disks provided by GE and P&W.
During the Jan-Mar 2002 quarter, similar measurements were conducted on the coupons from the
Honeywell (HW) forging. The noise measurement and FBH normalization procedures were
identical to those reported in the Jan-Mar 2001 Quarterly Report. The noise measurement setup is
shown in Figure 1, together with the coupon sites for the HW forging.
Backscattered grain noise amplitudes for one case are shown in Figure 2. The noise C-scans for
the HW coupons generally showed little variation with position in the hoop direction; however in
some cases there was a strong variation with inspection direction or with radial/axial position. As
was done earlier, each coupon was divided into quadrants of approximately uniform noise
amplitude, and noise statistics for each quadrant were computed for the two inspection directions in
the radial-axial plane. Gated-peak noise amplitudes were measured relative to an available #1
FBH reference, namely a 0.5”-deep hole in an IN100 step block. ISU models were then used to
rescale the noise data relative to a hypothetical #1 FBH in Ti 6-4 at the same average depth as the
noise measurements. Resulting average and peak noise levels for the HW coupons are shown in
Figure 3.
Measured average and maximum gated-peak noise levels are compared for the three OEMsupplied
forgings in Table 1. When averaged over all coupons and inspection directions, results for
the three forgings were quite similar. The largest peak noise level seen in all of the cases studied
was 6.9% of the #1 FBH reference. This occurred within Honeywell coupon #5 which was located
in the OD portion of the forging, about midway between the “forward” and “aft” surfaces.
Quarterly Report – January 1, 2002 –March 31, 2002
print date/time: 6/6/2002 - 8:39 AM – Page 36