Pin S45C broken

[newbies022014]

Hi all.

I am looking for other potential root cause for pin broken.

After induction hardening, both pin were broken after use.
After counter check the hardness, the hardness range from 52-60hrc.

Will the slightly increasing of hardness cause the pin failure?
any other potential root cause?

Spec:
Material : S45C
Treatment : Induction Hardening (Hardness : 48-52 HRC)

 

[Tmoose]

Have these pins given acceptable service previously?
Is the first of a batch, the First of a kind, or ??? and ?
Are you a new supplier of these parts to the OEM?

Are some pieces of the broken pin missing ?

What is the plating ?

The machined finish looks rather "hurried."
Is there a nicely formed radius between the pin shank and head?

How long did the parts last previously?

Are there some others available that have been in service for a while that could be LP or MT inspected?
Are there some from the same batch that have not been in service that could be LP or MT inspected?

I'm thinking the induction hardening may be required just on the tapered cone portion of the head for wear resistance.
What are your hardness requirements?
What areas of the broken pin were hardness tested?

===========.
"However, the case requires tempering to reduce the risk of cracking."

http://ro.uow.edu.au/cgi/viewcontent.cgi?article=4430&context=eispapers

===========.


9 down, 11 to go.
Plus drawings and pictures of the arrangement, and description of service and perhaps the forces used for design.

 

The way you have posed your question seems to indicate you want to jump directly to the root cause of a fracture.
A failure investigation first requires interrogation of the process and history, then appropriate laboratory testing and examination, then analysis of the findings that, if done sufficiently thoroughly, should point directly to the root cause(s).
w.r.t. NDE of fasteners from the same batch placed in service, my advice would be: if there is any question of integrity, and the service is in any way critical, just scrap and replace them all.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[dbooker630]

The reported hardness suggests the shaft did not receive an adequate temper after induction hardening, if it was tempered at all. The high end hardness is typical of as-quenched S45C (SAE 1045). I would get a qualified materials lab to check hardness, depth of hardening, chemistry, and microstructure.