Casting failure

[emonje]

This is a cast steel spelter socket. Failed after 24 hours of service.
Trying to guess what might have been the issue before sending out for tests.

Fracture started here??:

Other side of the same leg. Gas porosities??:

The legs are bent, yielding after fracture??:

Also these opened up on one of the legs:

Any observation is highly appreciated.

Thanks.

 

[arunmrao]

emonje,

A Happy New Year and hope 2017 augurs well for you.

I am surprised at the quick succession of failures. I will suspect the end user abuse.

I hope, these castings are from the same vendor and have performed satisfactorily in the past. This would eliminate design and process parameters. There may be deviations in process controls. This failed casting apparently looks better than the previous one, unless major welding repairs have been performed. Please ask for the thermal history of this casting.

I do not suspect it to be a case of Rock Candy fracture. I have provided a link describing the failure.





"Understanding rock candy fracture"

https://www.thefreelibrary.com/Understanding+'rock+candy'+fracture+in+steel+castings.-a054169575

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[emonje]

This later casting is from a different foundry, we are using them for the first time. Similar designs have been working in other sites for years with failures occurring very very rarely.

First casting is from a foundry that we've been using for quite some time & hasn't seen problems like this before.

 

[arunmrao]

emonje,

Your work is simpler now. Please audit the foundry thoroughly and place controls to avoid such disasters.I suspect the scrap control. Look for trace elements.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[mrfailure]

Just as a future housekeeping note, this latest failure would have been good to have posted separately to prevent any confusion.

I'm most struck by the fact the fracture appears to be oriented perpendicular to the plane I would have expected based on the photos provided. In other words, I would have thought normal service loading would more likely have caused fracture in one of the lugs through from the pin holes. In this instance a key question you need to answer is how you get loads that start fracture inside the rectangular groove as shown, and whether such a load is expected. Could the lugs be pulling apart during service loading in order to induce such loading? (I noticed the pin is only welded on one end, so this is in the realm of possibilities).

As before, this is the type of failure you need a metallurgical lab that performs industrial failure analysis to look at. Good luck!

 

[MJCronin]

emonje,

When you do get a final report from an authoritative metalurgical lab, please respect us...

Complete the thread with the cause of the failure and any other information that can help us learn ...

Thank You

MJCronin
Sr. Process Engineer

 

[emonje]

Definitely I will.

BTW, I have opened another thread for this new failure here:

http://www.eng-tips.com/viewthread.cfm?qid=419104

 

[IRstuff]

Seems to me the bending of the metal needs to be explored more thoroughly. My understanding is that the loading of such devices is typically longitudinal, so bending would seem to be a large anomaly.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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