Engine Titanium Consortium - Center for Nondestructive Evaluation ...

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Peak-Noise-to-Signal (% FSH) 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 Peak Noise Levels for Ti 6-4 High Noise Coupons #1 FBH at 12 dB above 80% or at 318.5% on this scale 56.6% (3 dB below 80%) For each specimen, Rule-of-Thumb would predict a straight line passing thru origin. Slope dependent on FOM PW8 HW5 GE6 F5 @ 0dB F5 @ -3dB F6 @ 0dB F6 @ -3dB F8 @ 0dB 1.6 usec time gate 0 100 200 300 Sqrt (Pulse Volume in cubic mils) #1/2 FBH approx at 80% on this scale. Figure 6. Peak noise vs. pulse volume measurements performed at GE-QTC. PW8, HW5, and GE6 denote the highest noise coupons cut from three Ti 6-4 forgings. From Figure 6 one can conclude that choosing the square root of pulse volume to be 240 mils 3/2 or smaller likely ensures that the peak noise is at least 3 dB below the response from a #1/2 FBH for the “noisiest” PW and GE coupons. For this choice, the peak noise in the noisiest HW coupon would be near to but slightly above the 3dB level. If we assume that the typical pulse duration is equal to 37 mils (average of measured values) the limitation on the beam diameter would be about ( π × ) ⎤ 1/2 240 ⎡⎣4 / 37 ⎦ or about 45 mils. Thus, we estimate that a forging inspection which achieves #1/2 FBH sensitivity, requires a beam diameter that does not exceed 45 mils at any depth within the region of interest. Our next objective was to design an inspection that covered 3.2” of material depth using the minimum number of zones and ensuring that the beam diameter did not exceed 0.045” at any depth. We note that 3.2” is the maximum depth required to inspect forgings selected for this task from all OEMs. An optimization procedure was employed to determine the maximum zone size and to design a transducer for each zone. First the water path was fixed at 3” with the transducer diameter and focal length treated as unknown “fitting” parameters. Since the entry surface is flat for this exercise, one needs to consider spherically focused probes only. The beam diameter for a given transducer at a given depth was calculated using the Gaussian- Hermite beam model developed by Iowa State University. It was determined that a 7/16”-wide zone Quarterly Report – January 1, 2002 –March 31, 2002 print date/time: 6/6/2002 - 8:39 AM – Page 63
size was adequate to support a 0.045” maximal beam diameter. Eight such zones are needed to cover 3.2” of material and nine zones would cover almost 4”. If the water path were fixed such an inspection would require nine different transducers. We determined that by varying the water path one transducer could be used to inspect three zones. Thus, for nine zones, three transducers are required. The parameters of these three probes are listed in Table 1. These are the transducers originally designed for zones 2, 5 and 8 for the original inspection scheme that used a fixed 3” water path. For example, the zone 2 transducer (transducer #1 in Table 1) can also inspect zones 1 and 3 with 4.8” and 1.2” water paths respectively. The final inspection scheme that utilizes three transducers is presented in Table 2. For this scheme, the on-axis profile (of pressured squared) is shown in Figure 7. The amplitude of an echo from a small defect is approximately proportional to pressure squared, so Figure 7 displays the manner in which defect signal amplitude depends on depth when the proposed scheme is used without a DAC. On-axis profile for 3-transducer 7/16" zone design Ammplitude 8E-04 7E-04 6E-04 5E-04 4E-04 3E-04 2E-04 1E-04 Zone1 Zone2 Zone3 Zone4 Zone5 Zone6 Zone7 Zone8 Zone9 0E+00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Depth, in Figure 7. Predicted on-axis, pressure-squared, beam profile for each zone using the 3-transducer 7/16” zone inspection scheme. The designed optimal transducers have diameters that are not exactly multiples of 1”. However, by slightly varying the water paths, we believe the inspection can be performed by three F6 transducers with diameters of 1”, 2” and 3”. The 1” diameter F6 transducer is already available, and the 2” diameter transducer has been ordered. The intent is to test the proposed inspection for the first 6 zones during the next quarter. Based on those results the decision will be made on how to proceed. The use of a DAC to produce a uniform amplitude for #1/2 FBHs throughout a zone will also be investigated in the upcoming quarter. Quarterly Report – January 1, 2002 –March 31, 2002 print date/time: 6/6/2002 - 8:39 AM – Page 64
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Engine Titanium Consortium Quarterl
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Project 1: Task 1.1: Subtask 1.1.1:
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findings for the first billet studi
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measured P(L) curve, and tabulate t
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1.2 1.0 0.8 V-DIE-A coupon "D" (axi
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Attenuation (dB/in) . Waspalloy Att
Page 13 and 14: Deliverables: Fundamental propertie
Page 15 and 16: Small Diameter Billet Assessment: A
Page 17 and 18: Under normal circumstances one woul
Page 19 and 20: Plans (April 1, 2002 - June 30, 200
Page 21 and 22: Project 1: Task 1.2: Subtask 1.2.1:
Page 23 and 24: system will be at GE, and evaluatio
Page 25 and 26: fixed-focus transducers that were n
Page 27 and 28: Back-Wall Scan FBH scan 20% 57% 49%
Page 29 and 30: 63% Back-Wall Scan 74% FBH scan 58%
Page 31 and 32: Figure 6. Noise and target amplitud
Page 33 and 34: Original Date Revised Date Descript
Page 37 and 38: Objective/Approach Amendments: Obje
Page 39 and 40: (a) Transducer is: 15 MHz 0.5”-Di
Page 41 and 42: FOM (std. units) 0.20 0.18 0.16 0.1
Page 43 and 44: Peak> Range of Ave. Range of Peak G
Page 45 and 46: The average noise characteristics,
Page 47 and 48: Noise C-scans through the “Flat S
Page 49 and 50: 4.0” Convex Block; Flat Side Insp
Page 51 and 52: % FSH Noise Measurements from flat
Page 53 and 54: Original Revised Description Status
Page 57 and 58: possible candidates. Development wo
Page 59 and 60: Forging Calibration Standard #1 1.7
Page 61 and 62: Surface Finish Studies The plans fo
Page 63: Figure 4. Beam diameter determinati
Page 67 and 68: phased array instruments. The desig
Page 71 and 72: Task 2: Task 2.1: Subtask 2.1.1: In
Page 73 and 74: Objective/Approach Amendments: Obje
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Page 77 and 78: Publications and Presentations: Dat
Page 79 and 80: Survey of common practices (industr
Page 81 and 82: include air drying, oven drying, an
Page 83 and 84: aluminum oxide blasting is conceali
Page 89 and 90: the methodology. These may be thoug
Page 91 and 92: model parts across 17 micrograph pl
Page 93 and 94: Z Y X Figure 4. Angle View of Void
Page 97 and 98: A report documenting the relative e
Page 101 and 102: naturally occurring flaws in forgin
Page 103 and 104: Milestones: Revised dates of TBD ar
Page 109 and 110: 7a-7l 6 8 9 10 Key additional ingre
Page 111 and 112: incorporating the results of the pr
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