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Firstly, pardon my ignorance about this topic because I am an electronics engineer.

I designed a 3 mm thick mounting bracket for one of my products. For this, I need to cut a galvanized metal sheet and bend it 90 degrees.

Maybe I am being over cautious, but (per my reasoning) since the galvanized coating is only in the outer section of sheet metal, the 3 mm wide edges will be uncoated, therefore susceptible to corrosion.

Also the 90 degree bent part will be stretched, so coating thickness will be reduced.

Are these effects real? Do they make any practical difference?

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    $\begingroup$ galvanizing is usually applied one the components have their final form. $\endgroup$
    – Solar Mike
    Nov 18 '20 at 14:54
  • $\begingroup$ Is it safe to laser cut galvanized steel? Zinc fumes are apparently very toxic and you're not supposed to burn or heat galvanized parts for that reason. $\endgroup$
    – DKNguyen
    Nov 20 '20 at 15:20
  • $\begingroup$ ZnO , not toxic but will give you chills for 24 hours if you breath in much. $\endgroup$ Nov 20 '20 at 21:40
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You put it well ; " no practical difference." The zinc as a sacrificial coating protects nearby steel provided there is electric conductivity such as a film of water . Lazer cutting will burn off little zinc very close to the cut ,but not significant. From your description this sounds like a component that will be inside so corrosion potential would be low . If you were submerging it in sea water ,you would need aluminum anodes , and again the lost zine would make no practical difference.

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Zinc protects by sealing the steel, but also protects it by acting as a sacrificial anode if that seal is breached.

So yes, exposed edges does make the steel more susceptible to corrosion, but not altogether unprotected as long as zinc remains to act as an anode. However, once the zinc is consumed then that protection no longer exists.

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