Engine Titanium Consortium - Center for Nondestructive Evaluation ...

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C2b – Alkaline De-rust Solution B C5 – Alkaline Gel Cleaner B1– Plastic media blast (at 80 and 40 psi) for 30 sec • Soot on nickel-based specimens C3 – Alkaline De-rust Solution A C7a – Ultrasonic w/Alkaline De-rust Solution B B1– Plastic media blast (at 80 and 40 psi) for 30 sec • Varnish/Coke on nickel-based specimens C3 – Alkaline De-rust Solution A C5 – Alkaline Gel Cleaner C7a – Ultrasonic w/Alkaline De-rust Solution B B1– Plastic media blast (40 psi) for 30 sec Visually, almost all of the specimens were evaluated as having a surface that appeared to be clean following the initial cleaning attempt. At the very least, two out of the three specimens for a particular contaminate/cleaning method combination were assessed as visually clean. However, crack crevice cleaning as evaluated by brightness was a different story. Many of the specimens showed reduced brightness with respect to baseline brightness and in some cases no indication could be discerned either by photometer or by a more sensitive though qualitative visual black light examination. The C4 four-step alkaline process for nickel-based materials (alkaline rust remover, acidic scale conditioner, alkaline permanganate, alkaline rust remover) proved successful for removing all three contaminants from the cracks and restoring much of the baseline fluorescent brightness. It was somewhat less effective on nickel oxidation. However, no cleaning process for titanium proved as effective as the four-step for nickel-based materials. For removal of oxidation on titanium, the cleaning difficulty was partly due to the higher degree of oxidation with to the nickel-based material. Oxidation on the titanium was estimated to be equivalent to 5,000 hours of engine run. It represents a heavy amount of oxidation that is now being seen on some of the hotter running titanium components. In addition, the method for producing soot by suspending specimens, crack opening down, over hot oil produced a blackened surface having somewhat of a sheen rather than a matte black finish. This condition would more likely be found on turbine engine hot section parts, but probably not on titanium cold section parts. The contaminant condition proved more resistant to some of the cleaning methods than typical soot. There were sometimes apparent inconsistent results for a particular contaminant/cleaning method that may be related to three different crack sizes being used. That is, perhaps a chemical cleaning method is more effective at removal of soot on a large, open crack than on a small, tight crack or Quarterly Report – January 1, 2002 –March 31, 2002 print date/time: 6/6/2002 - 8:39 AM – Page 81
aluminum oxide blasting is concealing the tighter cracks more so than the open cracks. Therefore the crack morphology is being considered in interpretation of the results. Some of the preliminary observations or conclusions include: • Vapor degreasing and aqueous cleaning both appear to be effective for removing oil. • Alkaline derust is not effective on oxidation/scale, or soot on Ti-6-4. Short soak, high or low concentrations do not effectively remove penetrating oil in Ti-6-4. Alkaline residue may reduce fluorescent penetrant brightness. • Alkaline gel was not an effective cleaning on either Ti-6-4 or INCO 718. • Wet glass-beading lead to loss of 4 of 6 cracks and significant brightness reductions in the other two cracks. • Aluminum oxide 500 mesh grit may be more suitable for critical rotating parts. Surface damage appears to occur for 240 and 320 mesh grit sizes. UVA Oct BL 00-067 UVA Oxidat. & scale An example of the data summaries that are being generated is shown above for sample 01-037. The information includes the original optical micrograph for the sample, three UVA indications taken at different times and under different conditions at Delta and the optical micrograph after processing. This particular sample underwent walnut shell media blast which has been coded as the “B6” method. The BT values are brightness readings. Note that for this sample the brightness decreased from the baseline run after use of the walnut shell blast. However, subsequent processing through ultrasonic agitation in an acetone bath returned the brightness to levels near the original baseline. This indicates that some media may have remained in the crack immediately after blasting which was removed by the subsequent “fluid processing”. Consideration is being given to recommending that a water wash step be added after all mechanical blasting operations used to clean parts. Quarterly Report – January 1, 2002 –March 31, 2002 print date/time: 6/6/2002 - 8:39 AM – Page 82
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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
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Deliverables: Fundamental propertie
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Small Diameter Billet Assessment: A
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Under normal circumstances one woul
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Plans (April 1, 2002 - June 30, 200
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Project 1: Task 1.2: Subtask 1.2.1:
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system will be at GE, and evaluatio
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fixed-focus transducers that were n
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Back-Wall Scan FBH scan 20% 57% 49%
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63% Back-Wall Scan 74% FBH scan 58%
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