What causes steel plate opens up like a book?
What causes steel plate opens up like a book?
(OP)
The picture shows a 1/2" ASTM A36 steel plate from the mid-1970's. It is part of a tunnel with segmented steel liners. The tunnel is under groundwater so there has been leaking. I am puzzled what can cause a corrosion like this.

RE: What causes steel plate opens up like a book?
RE: What causes steel plate opens up like a book?
RE: What causes steel plate opens up like a book?
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.
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P.E. Metallurgy, consulting work welcomed
RE: What causes steel plate opens up like a book?
RE: What causes steel plate opens up like a book?
Will you be able to dry this tunnel out for painting?
RE: What causes steel plate opens up like a book?
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.
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P.E. Metallurgy, consulting work welcomed
RE: What causes steel plate opens up like a book?
RE: What causes steel plate opens up like a book?
RE: What causes steel plate opens up like a book?
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.
RE: What causes steel plate opens up like a book?
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates
-Dik