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Chrome & aluminium !!!!

2185 Views 12 Replies 10 Participants Last post by  bumblebee
On another thread i was being told that chrome weakens aluminum. Can anyone direct me to some evidence?? Me and a friend are debating this topic!! I told him maybe it has something to do with an aluminum alloy being plated. Gasman maybe u can add to your thread Gasman Wants To Know!!Thanks for any help!! :dthumb:
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I've never heard that before...
mlkx3 said:
Tensile strength is the pulling of a material until it tears apart.
The higher the tensile strength, the more susceptible it is to embrittlement.
When you chrome a part, hydrogen is soaked into the material as it
is plated, the plating then holds it in. Once inside it will spread
to all areas, where it is relatively harmless. When stress is
applied, the hydrogen re-distributes itself, concentrating on the
point of stress. Think of it as trying to escape, and its only way
out, is a crack. Metallurgists do not know how a crack is formed.
That is still in debate. The moving and concentration however,
is not. "Presently this phenomenon is not completely understood
and hydrogen embrittlement detection, in particular, seems to be one
of the most difficult aspects of the problem. Hydrogen embrittlement
does not affect all metallic materials equally. The most vulnerable
are high-strength steels, titanium alloys and aluminum alloys."
When enough hydrogen accumulates, and a crack is
established, it focuses on the end points of the crack. Until it
becomes so weak that the end of the crack moves, the hydrogen then
follows to the new highest stress point. The new end of the crack. Until
the whole thing fails suddenly.
Interesting information...FWIW, I have seen chromed wheels that were bent under a heavy impact (pothole) and didn't crack. The plating flaked off but the wheel appeared to bend in the same fashion as non-chromed ones. My guess is because most chroming on motorcycle parts is show quality surface treatment and not hardened quality it probably doesn't penetrate the material as well. It could also be that the inside of the spokes aren't sealed entirely and the hydrogen has a way to escape.

Personally, I have never heard of a chromed motorcycle part failing suddenly and that includes hardened parts such as fork tubes. Granted my experience is not scientific research (I leave that to my brother), I just want to make sure this doesn't turn into a "the sky is falling" discussion.

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