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topic 4693

PRETREATMENT-ETCHING ALUMINUM PRIOR TO PENETRANT INSPECTION


(2000)

I AM IN CHARGE OF A PLATING SHOP. WE ETCHED 2024 T-8 ALUMINUM BELIEVING IT TO BE 2024 T-3. WE FIRST ETCHED A 2024 T-3 COUPON TO DETERMINE THE ETCH RATE IN ALUMINUX 1000, 6 OZ./GAL. FOR 5 1/2 MINUTES AT 160 F. WE THEN RAN THE 2024 ALUMINUM PARTS UNDER THESE SAME PARAMETERS AND THE PARTS PITTED BADLY. CAN ANYONE EXPLAIN WHY 2024 T-8 ALUMINUM PITS UNDER THE ABOVE CONDITIONS?

Jerry Wahlin
plating shop - Compton, California


(2000)

No. Did a coupon of T-8 material also pit? I think your processing solution is past its useful life.

tom pullizzi monitor
Tom Pullizzi
Falls Township,
   Pennsylvania 


(2001)

I know this comes a bit late and perhaps you might already know why your 2024 parts pitted and the coupon didn't. But why in the heck would you be etching 2024 at all under those conditions? You ween't prepping to plate for sure. And the amount of aluminum you removed would be significant. The heat treat designation from you coupon to your part is different. I have coupons also but they are not heat treated as the parts are. I also use them to set up a etch rate . I use 1 minute and determine from there. I think it has a lot to do with the difference in heat treat designation. but also WOW thats along etch time

Todd Huehn
- Minneapolis, Minnesota



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