Failure of tube/pipe 1

[M. BR]

Hello Guys,

Need help understanding where this failure started. This is a 410 stainless steel.

The tube failed with 0h of service. I think is torsional overload, starded on the radius at 11/12 o clock (not sure), and also not sure the if its propagate to the left "anticlokwise".

Do you agree with my marks (in red)?

 

[LittleInch]

What's the outer skin?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[M. BR]

It is also a 410 steel the same hardness (40 - 44HRC).

Atteched the side cut of the fracture.

 

[M. BR]

Another picture

 

[BAretired]

Do you agree with my marks (in red)?

What's to agree with? They are not legible. What is the meaning of "PVOP"?

 

[GBTorpenhow]

Looks like the forcing cone of a revolver. Torsional overload at 0 hours of service? This happened as the barrel was being screwed into the receiver/frame? Your highlighted spot could be suspect, I would also look at where the shoulder that is now mostly missing on the left hand side of the barrel in the sectioned picture contacts the receiver/frame.

 

[BAretired]

Looks to me like lamellar tearing. That usually comes from tension perpendicular to the plate. Torsional rotation would cause circumferential shearing stress in a tube which seems unlikely to cause the type of failure observed here. If it is lamellar tearing, it may have been exposed to perpendicular tension during the fabrication process, possibly due to uneven heating.

 

[M. BR]

Do you agree with the start point. The red arrow.

What is the meaning of "PVOP" - This mean propagation

 

[M. BR]

[highlight #FCE94F]Torsional overload at 0 hours of service?[/highlight]
I thought it maybe could happend during the assembly, excess of torque during the assembly... ?

[highlight #FCE94F]This happened as the barrel was being screwed into the receiver/frame?[/highlight]
Yes, you are right!

 

[M. BR]

Wouldn't lamellar tearing only happen in weld areas? There is no weld in this section, the tube is screwed to the frame.

 

[LittleInch]

So from the three phots provided, it looks to me like someone just seriously over torqued the shaft. You seem to have a small bearing area where the screwed in shaft contacts the element it is being screwed into and if there is any sort of bending going on at the same time you can initiate failure.

what sort of torque were you using?

If makes life much easier if you attach images

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BAretired]

Wouldn't lamellar tearing only happen in weld areas? There is no weld in this section, the tube is screwed to the frame.

Usually only happens in weld areas. I wondered if the 410SS plate had been exposed to excessive heat in one area during the manufacture of the tube, but admittedly, that seems unlikely.

 

[M. BR]

Hi guys, just made some some pictures of the microstructure.

Remembering its a 410 Stainless steel.

Does the cracks looks like intergranular cracks? For me not.... What do you Think?