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  1. mrbebu

    Heat Treatment of 1144

    Tmoose, yes those are all pictures of the fracture surface.
  2. mrbebu

    Heat Treatment of 1144

    Torque tightened. I'd rather not get into the torque value discussion at this moment. As for pictures, not much else detail for obvious reasons, but here you go:
  3. mrbebu

    Heat Treatment of 1144

    In their SEM/EDS analysis it is mentioned that it "...disclosed no evidence of fatigue or any clear evidence of hydrogen embrittlement..." As for the limit of 37RC, that is already my max limit called out on all prints. I may lower this to 36RC in future revision, or I may also consider just...
  4. mrbebu

    Heat Treatment of 1144

    Perhaps anecdotal, but in my case there are thousands of these plated nuts from different batches out in service at HRC34-37 without a single failure over the last 5-6 years. That said, I will most certainly reconsider HE baking though. Ed, any recommendation for documentation for this alloy...
  5. mrbebu

    Heat Treatment of 1144

    My initial thought when I first found out of the failures was hydrogen embrittlement, which is why I sent them to a lab for analysis immediately. But, they ruled that out as they found no clear evidence of it. I was then a bit shocked to see what they measured for hardness, so I confirmed that...
  6. mrbebu

    Heat Treatment of 1144

    Hello All, I have a situation where a batch of parts (highly re-used specialized M12 to M14 sized hex nuts) are undergoing brittle failure in initial tightening cycles (fail in the 2nd to 5th tightening cycles). My spec calls for 34-37 HRC and the parts came in at 41-42 HRC, although the...
  7. mrbebu

    Failure Mode of Fastener...

    I really think this may be an embedment related incident as well considering what I'm observing on my bench testing rig with the aluminum wheel lug seat. Stud clearance holes on rotors are typically very large, like +2mm or so since it relies on the hub for locating. I don't have the rotor...
  8. mrbebu

    Failure Mode of Fastener...

    Not oval, "road" racing as we like to call it in the states. 2500-2800lbs cars with 300+bhp. Shooting the wheel studs by the hub with an infrared temp sensor after a stint I was only seeing 220-240F max. I should disclose that running 2 piece style brake rotors with aluminum centers helps...
  9. mrbebu

    Failure Mode of Fastener...

    My mistake, didn't mean to come across stating that insufficient preload/installation torque as being the definite. It's at/near the top of the list of probable causes based on much of the literature I'm reviewing and persons I'm conversing with. I will most certainly send the failed...
  10. mrbebu

    Failure Mode of Fastener...

    Thank you everyone for your input. Now to give more detail: This is an automotive wheel joint that was in a endurance circuit racing application (think 24 Hours of LeMans but on an amateur level with converted street cars). The studs were recently installed with approximately 9 total hours...
  11. mrbebu

    Failure Mode of Fastener...

    Hello all, Experienced fastener failures recently and wanted to get some input as to what could've been the cause. Before I give more context and detail, I would just like to see what the trained eyes of this forum have to says solely in regards to the pattern. Pics are of the same...

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