What's up with this piece of cast iron?

ballen · Jan 13, 2018

I am making something from a piece of cast iron. The material is GGL-25, grey cast iron with flake graphite, 40 x 110 x 300mm (1.5 x 4 x 12 inches). I milled off the surface and was surprised to find this "internal structure" inside. It's like a bunch of layers, including defects between these layers which telegraph to the surface. Here is a 40 x 110 face, freshly milled.

The strata are visible on all four faces.

Was this incorrectly poured or formed? Should I try to return it or replace it? I've never seen this inside a piece of cast iron bar before.

Cheers,
Bruce

johnoder · Jan 13, 2018

A guess was that it was continuous cast (a common process) and it was not ready to be considered a sellable product yet - like early in start up

You need a 100% refund

ballen · Jan 13, 2018

Hi John,

johnoder said:
A guess was that it was continuous cast (a common process) and it was not ready to be considered a sellable product yet - like early in start up

In other words, this was produced at the beginning of the continuous casting process and should have been discarded rather than sold?

acme thread · Jan 13, 2018

I've seen that a lot in brass and bronze bars, Never knew what caused it, But continuous cast makes perfect sense, dave [acme thread]

johnoder · Jan 13, 2018

That would be my guess. You are looking at multiple, repeating defects - not something anyone would want to buy

If there had been any NDT, (like UT) prior to sale it would not have been for sale

ballen said:
Hi John,

In other words, this was produced at the beginning of the continuous casting process and should have been discarded rather than sold?

Limy Sami · Jan 13, 2018

ballen said:
Hi John,

In other words, this was produced at the beginning of the continuous casting process and should have been discarded rather than sold?

Yup, ....shouldn't have gone through QC

FWIW I was taught that is known as a ''cold shut''

johnoder · Jan 13, 2018

Limy Sami said:
Yup, ....shouldn't have gone through QC

FWIW I was taught that is known as a ''cold shut''

I almost used that term Limy, but sort of remembered it was forging related

Richard King · Jan 13, 2018

When I buy continuous cast I try to buy the sawed at factory from a big plate as the top layer of the type you bought reminds me of hot rolled steel and they tell you if you need 1" they sell you 1 1/4" and expect you to mill through the layer of black crusty flux or what ever it is called. I suspect you only took off say 1/16" and your cutter was dull. Get a sharp 1" roughing carbide end mill and mill off another 1/16" in several passes and see if that improves the finish before sending it back. I would also mount it in 2 vise on a mill and not in 1 where the edges are not supported. If you only have one vise use jacks on each end and slow down the feed. I usually have that kind and the sawed cast Blanchard Ground as it comes off fast and it cleans up. John maybe right, but I have never had a piece not clean up when it has that look. But I buy direct from the factory Dura-Bar, no clue where yours came from. Rich

boslab · Jan 13, 2018

It's called a stop teem, the casting was momentarily interrupted, not a good structure to have, cold shunting tends to manifest as macroseggrigation in the direction of heat flow.
The section you have looks like a pipeing type of feature
Mark

Richard King · Jan 13, 2018

Mark...Thanks , it sounds like I learned something today.

Limy Sami · Jan 13, 2018

I bow to those of greater knowledge.

Mebfab · Jan 13, 2018

Send a picture to the seller, ask them. Better yet find out who made it and ask them. Then report back. I wouldnt do anything without their ok

ballen · Jan 13, 2018

Thanks everyone for the comments. I have written to the seller with a photo.

Richard, funny to see you here, this is my piece for practicing scraping oil pockets. But after I'm done with that, I plan to make another part from it. FWIW, I don't think this is going to mill out. I cut off the outer surface with a carbide face mill and did the edges with a side of an end mill. All of them those these internal features, and the features are continuous all around the block. I've prepared similar cast iron bars in the past with the same setup, and never saw anything like this before.

partsproduction · Jan 13, 2018

It looks like some of the discontinuities are deep, like it would break easily if you dropped it.

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