Steel delamination,have you ever seen it before?

Certain types of steel will form a "pipe" as the ingot cools, if the ingot is rolled into a finished product the defect will appear as a lamination. I don't know how common this problem is now days as most everything is continuous cast, but back in the day as much as the top third of an ingot would have be scrapped in order to get a good slab.
 
Even in con casting, one can get voids but not common. Sometimes the Nitrogen/Argon gas that we bubble into the crucible can be trapped as the metal is drawn through the die. When this happens we can see remains of the bubbles either on the surface as the metal cooled the nitro was pushed out or we get a void in the upper half of the cast metal. When this happens, we just toss the bad parts back into the crucible.

When hand casting I see lots of pipe as the metal cools. At times I have a sprue that is as larger than the part so that liquid metal is drawn into the cooling part to prevent the formation of the void.
Pierre
 
I know that some steel is hot rolled and "folded" and rolled etc. to arrive at what they want. I suspect that two different grades/hardness/duct-ability can be hot rolled together to give a softer backing to a very hard top layer. That pix looks very much like that. (In fact, it looks like armor) If the steel is of a "random/unknown" source, it could be almost anything, and if it's from China .........???.
 
It was an issue in France in the 80's when steel started to be imported from eastern block countries. I remember a fishing boat made with Romanian steel peeling apart...
 
I saw something like this in the early 70s in a sheet metal shop where we made tool chests. Sometimes on the radius bends for a tool chest cover the steel would split open and de-laminate rather than forming a nice smooth surfaced radius. The sheet steel was being imported, but I am not sure from where.
 
I have seen it on chinese steel, also korean and Indian made steel, but chinese is generally the worst.
 
Probably not relevant to the case at hand but ...

I have see 'delamination' on a set of brake rotors. I put a set of new rotors on my autocross car. I had the new set cryogenically treated before I put them on. Near the end of the season I started getting a serious shudder when I stepped on the brakes. Inspection showed that two of the rotors had 'chunks' of the surface missing. Think of having a plywood rotor and the outer layer of veneer had simply disappeared in parts of the rotor face. There were 'holes' that were about an 1/8 of an inch deep and several inches in length and width. The next 'layer' down was what looked like a reasonably smooth surface of good metal.

I attributed it to defects in the casting where it was not as 'all one piece of metal' and homogeneous as one would hope it to be, followed by the cryogenic treatment causing the layering to disconnect from one another, followed by extremely high heats finally breaking the layers apart and the chunks coming out of the rotor face.

Had not seen that happen before trying out the cryogenic treating and have not had another set treated or experienced the delaminiation since.
 
Adding my own example from a few months ago. I wanted a spacer and found a washer which just needed a small amount to be bored from the inner diameter. I mounted in the chuck, started to bore with very light passes since the thin material could easily come loose in the chuck.

The washer did start to come loose. When I stopped the lathe I found this seemed to be due to the steel delaminating.

I expected this would not turn with a good finish due to likely being hot rolled steel and a stamped washer, but I was not expecting the delamination.

Washer_delaminated_7571.jpg
 
Fra_78 said:
It was an issue in France in the 80's when steel started to be imported from eastern block countries. I remember a fishing boat made with Romanian steel peeling apart...
Click to expand...
Yes, but wouldn't that be getting two boats for the price of one. :|
 
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