New Item API Standard 6A718 Proposed New Macro Etchant Paul Maxwell 30 June 2011

Stated Goal: Add “Dilute Aqua Regia-Heated” Etchant as an approved etchant for the requirements stated in API Standard 6A718(Sec ) Current Macro Etchants –Option A: Canada’s Etchant 100 ml H2SO4,100ml HF, 50ml HNO3, 400 ml H2O, Etch at 160°F to 180°F (71°C to 82°C) –Option B: Aqua Regia 200 ml HCl, 100 ml HNO3 –Option C: Kalling’s No ml Methanol, 200 ml HCl, 10 g CuCl2 –Option D: Hydrochloric-Peroxide H2O2 (30 %) 100 ml, HCl 200 ml, H2O 300 ml, Remove stains with 50 % HNO3

Materials: Alloy 718 Order/Heats utilized in the evaluation: 4 orders/heats & associated locations were evaluated for each etchant W77942/ – 1A,1X See photos1(API 6A718 Option B etch) & 2 (“Dilute Aqua Regia-Heated” etch) W79943/ – 1A, 1X See photos 3(API 6A718 Option B etch) & 4 (“Dilute Aqua Regia-Heated” etch). W79939/ – 2A, 2X See photos 5(API 6A718 Option B etch) & 6 (“Dilute Aqua Regia-Heated” etch). W74406/ – 3A, 3CO See photos 7(API 6A718 Option B etch) & 8 (“Dilute Aqua Regia-Heated” etch)

Materials (Continued) Etchants Utilized: Specified - API 6A718 Option B Etchant - Aqua Regia: 200 ml HCL, 100 ml HNO3. Unheated - Room Temp (72F/23C). Proposed - “Dilute Aqua Regia-Heated” Etchant: Aqua Regia, 250 ml HCL, ml HNO3 Processing Temp - 140F – 165F.

Test Methodology Same orders/heats, locations, and disc specimens utilized. Prep the surface of the specimens prior to etching process. Etch the specimens utilizing either the API 6A718 Option B etchant or the “Dilute Aqua Regia-Heated” etchant. API 6A718 Option B etchant will be unheated (room temp - 72F/23C). “Dilute Aqua Regia-Heated” etchant will be heated to 40F to165F. Specimen etching time will be approximately 25 to 30 minutes for each etchant type. Specimens will be rinsed and air dried. Inspect specimen surface to determine if the visual results are similar.

Results: Specimens for all four orders/heats reveal same macrostructure results. See attached photos regarding visual comparison.

Summary: Specimens from four Alloy 718 orders/heats and locations were processed utilizing the API 6A718 Option B etchant and the “Dilute Aqua Regia- Heated” etchant. The etchant composition and etching temperature were the only process variables that were changed. Visual inspection of the specimens revealed same macrostructure results (see photos). Benefits of utilizing the “Dilute Aqua Regia-Heated” etchant include, but are not necessarily limited to, longer time period prior to burning of surface and better repeatability. As a result of the items mentioned above, Carpenter is proposing to have the “Dilute Aqua Regia-Heated” etchant balloted as an approved etchant for the requirements stated in API Standard 6A718, Section

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