Cylinder head failure

Question

Cylinder head failure

metgeek (Materials)

(OP)

4 Oct 21 13:33

What are the dark areas on the fracture surface of an aluminum die casting?

Pud (Mechanical) · Answer 1 · 2021-10-04 14:21:55

Any pictures? They say a 1000 words.

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metgeek (Materials) · Answer 2 · 2021-10-04 16:04:46

Area of interest is upper left portion below as cast surface. Also, to the left of the tear on the right side.

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MintJulep (Mechanical) · Answer 3 · 2021-10-04 16:14:06

RE: Cylinder head failure

MintJulep (Mechanical) 4 Oct 21 16:14

They might be carbon.

IRstuff (Aerospace) · Answer 4 · 2021-10-04 16:46:22

The shiny edges of the breaks would suggest that it cracked, and oil, etc., got into the cracks and then the fracture completed and the part broke free

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Tmoose (Mechanical) · Answer 5 · 2021-10-05 16:10:23

Got any pix of the entire cylinder head ? Engine, air compressor, vacuum pump, or ???

enginesrus (Mechanical) · Answer 6 · 2021-10-06 05:20:09

Areas cracked first and carbon forced in the crack. Anything in that photo looked like shadows from lack of light to me.

metgeek (Materials) · Answer 7 · 2021-10-06 13:23:46

Thank you all for the replies.
Apologize for the poor photo of this small piece. I've seen this failure before on a non engine application. It was a structural member that failed exhibiting the dark areas on the fracture surface. It was due to a casting defect from the producer but can't remember what was wrong in the casting process. The producer eventually fixed the problem.

GregLocock (Automotive) · Answer 8 · 2021-10-08 00:26:15

Sometimes the shiny surface of the grains gets dulled by rubbing as the crack vibrates.

Cheers

Greg Locock

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swall (Materials) · Answer 9 · 2021-10-10 10:18:53

It just looks like the fracture is dirty. Try sticking it in an ultrasonic cleaner for about 30 seconds.

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Cylinder head failure