Fracture faces

[Paul Teggart]

Hi, first post on here so please bear with me if I am showing my ignorance this early.
I was wondering if someone could help me with their opinion on what may have happened here.

This rotating drum pulley was returned from our customer and the faces of the failure have got me scratching my head.

There is a heavy 50mm boss welded onto the face of the 12mm plate with a fillet weld, or at least the joint should be composed like, but we think there is a possibility it was assembled as in file name. I have attached these for you consideration, as well as the pictures to give you some perspective on the failure, and show the faces of the failure in detail. The "swirly" nature of the faces has confused me.

I am so grateful to anyone who considers this even if they have nothing to add, and if anyone has any more questions please do not hesitate to ask me.

Many thanks in advance.

 

[LittleWheels]

I don't know enough to make any sensible comments but was there sufficient RPM that you may have significant frictional heating when it separated?

 

[mrfailure]

It looks like molten metal as it resolidified. I am not quite sure what is supposed to be there, but if this is the location of the weld then I would suspect from your pictures that there was a lack of fusion when applied.

 

[weldstan]

There is so much smearing and resolidified molten metal, I cannot say what the original fracture was. Agree with mrfailure regarding lack of fusion comment above.

 

[Paul Teggart]

Guys, thanks so much for replies so far. Yes, I am off the same opinion that it looks like re-solidified metal, which means that the the 12mm plate was a smaller ring welded into a bigger ring, 2 parts when it should have been one. This is what I thought in the beginning but then I wondered was it some strange fatigue pattern which propogated from a toe crack at the base of the 50mm boss. Seems silly noe lol. Thanks for the feedback again folks. I really appreciate it.

 

[Tmoose]

Is the designed construction the same on both ends of the roll?
is the actual construction on both ends of the failed roll the same?


The OD of the shaft is way smaller than the ID of diaphragm/plate welded in the roll, if I understand your pictures correctly.

I see it even worse than shown in "possible incorrect make up".
The result is one entire weld os missing. That is the second weld that secures the shaft to something.

 

[Dhurjati Sen]

Ask the customer for certain feedback, not as a basis of litigation, but for the benefit of both parties.

Was there any mal-operation?
Did they hear any abnormal sound?
Was there a fire?

Unless these and may be other relevant questions are answered satisfactorily, the same problem could recur.



DHURJATI SEN
Kolkata, India

 

[Paul Teggart]

Hi guys, thanks for the feedback so far.
Few questions for me in there which I'm not sure I fully understand. I have already responded to the supplier my belief that he has made what should have been a single plate assembly, a 2 plate assembly.

Thanks again everyone.