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What causes steel plate opens up like a book?
- Thread starter damianyu
- Start date
TugboatEng
Marine/Ocean
Lamellar corrosion is the name. It occures in extruded and rolled shapes.
EdStainless
Materials
Corrosion will preferentially work along these inclusions and result in long layers of attack.
As the material corrodes the corrosion products take up more volume than the original steel.
This is what causes the swelling and pealing of the layers.
Even without excessive inclusions you will get this as the surface corrodes and separates
it will accelerate corrosion in the crevice below it. And this keeps repeating.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
As the material corrodes the corrosion products take up more volume than the original steel.
This is what causes the swelling and pealing of the layers.
Even without excessive inclusions you will get this as the surface corrodes and separates
it will accelerate corrosion in the crevice below it. And this keeps repeating.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
- Thread starter
- #5
TugboatEng
Marine/Ocean
Use a zinc based coating on the bare steel but you'll want an epoxy coating on top to build thickness and durability. The zinc coating protects the metal if the outer epoxy coating gets damaged or has voids.
Will you be able to dry this tunnel out for painting?
Will you be able to dry this tunnel out for painting?
EdStainless
Materials
Your coating supplier can give you options.
Often these are three layer systems.
You blast back to rough white metal, prime (Zn rich), build coat (also Zn), top sealer/protectant.
Clean, dry, and the correct blast profile are critical.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
Often these are three layer systems.
You blast back to rough white metal, prime (Zn rich), build coat (also Zn), top sealer/protectant.
Clean, dry, and the correct blast profile are critical.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
- Thread starter
- #9
hello Damianyu
I mean that it is normal to experience corrosion because carbon steel material will corrode when exposed to free water that dissolves oxygen : the painting system has to remain in good condition (repair of the painting may be required time to time) otherwise CS will corrode.
in addition, we can see on your pictures that the corroded zone delaminates following a dominant orientation : this shows that your material is a plate that was rolled, and the rolling operation oriented the microstructure and led to this layered aspect of the corroded zone.
in brief, CS needs a consistent painting system otherwise it will corrode when in contact with air and water.
I mean that it is normal to experience corrosion because carbon steel material will corrode when exposed to free water that dissolves oxygen : the painting system has to remain in good condition (repair of the painting may be required time to time) otherwise CS will corrode.
in addition, we can see on your pictures that the corroded zone delaminates following a dominant orientation : this shows that your material is a plate that was rolled, and the rolling operation oriented the microstructure and led to this layered aspect of the corroded zone.
in brief, CS needs a consistent painting system otherwise it will corrode when in contact with air and water.
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