ano and changing properties?

[SR_matt]

Hey,

I have been having some conversations over on another site about anodized aluminium vs. bright AL vs. etched AL (etched being just diped quickly in caustic soda IIRC) and their strength.

The aloys used are 5154 for the etched and ano'ed and 5356 for the "bright".

So now that you have the background heres the thing i dont understand...

There are rings of 14 gauge wire with 3/8 inch inner diamater made from the 3 above materials and then just plain 5154 alloy rings. Some one did a test to see how much weight it would take to open the rings here are the results:

bright al-8244 grams
ano'ed- 7100 g
plain-6848 g
etched-6060 g

and now my question, how can the same alloy be weakned by just etching it but strengthened by anodizing it, what are the reasons that the ano'ed rings would be stronger?

Thanks
-matt

[destroyer125]

etching is cause it was dipped in acid which eats some aluminum away....annodizing creates a coating on the surface of the aluminum 1mil thick or close to it which was the Strenth ppl say of Stainless steel...Bright aluminum has a fairly decent amount of silicone in the aluminum

[SR_matt]

it just doesnt make sence to me how that thin of a layer can make that much of a differance
-matt

[rclint]

Originally Posted by SR_matt

it just doesnt make sence to me how that thin of a layer can make that much of a differance
-matt

The anodic layer actualy approaches the hardness of a diamond(depending on the type of anodizing, time etc), even a thin layer will increase structual properties, also the layer covers the entire surface, depending on the shape of the pieces being tested this could really add to the strength as well, even a round or square piece would get a lot of surface area working for it

[SR_matt]

alright that makes sence but now im confused how etching weakens that much
-matt

[acidrain]

I'm confused too... according to your results, the ano'd pieced take less weight to deform it. Are those numbers correct?
The ano layer is much stronger than aluminum... about the same as stainless steel in scratch resistance surface hardness.
The caustic etch is not an acid, but rather an alkali, and will remove .001in at normal etch times.

[SR_matt]

remember the Bright AL is a differantn alloy compared to the rest, the annoed gets an extra 200 grams to have to open it, but the etch removes enough to weaken it enought to need 800 grams less than plain AL

-matt

[destroyer125]

When I worked with Bright Aluminum for chainmail purposes awhile ago, I played heck tryin to find the stuff, when I found it I found out it had alot of other materials casted in with it, Has anyone tried annodizing Bright aluminum wire?

[SR_matt]

thats exactly what this is for
-matt

[andrewjb]

yippie for chainmaille!
thanks for those results , i always wondered if anodizing made the things stronger, now i know