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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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7075-T6 Anodising Poor Appearance
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Q. Hi there.
I have a question about anodising 7075-T6, we machine a lot of parts and have excellent results with certain mills that produce the material.
Some other mills material seems to produce a much more dull and pitted appearance.
I'm sure its down to the chemical make up of the bar.
Of the 2 bars below one anodises very very well and the other does not.
Looking at the chemical makeup any idea why one of the bars does not??
______Si___Fe___Cu__Mn___Mg___Cr___Zn___Ti
Bar1 0.09 0.15 1.30 0.06 2.30 0.19 5.6 0.04
Bar2 0.14 0.10 1.51 0.03 2.35 0.20 5.6 0.03
- United Kingdom
June 16, 2022
A. It's probably not the composition. Both analyzes are normal. The microstructure and e.g. the purity of the melt (e.g. oxides, impurities) have a major influence. Would also compare the strength, hardness and electrical conductance.
Pictures of the anodized surfaces would also be helpful.
- Hallau, Switzerland
A. Heat from either heat treatment or dull machining can move the zinc to the surface and affect the anodic film.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
June 24, 2022
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