Bolt Failure

[DWM]

Hello , first time I see on a friend Enfield Nº 4 a bolt faliure like this one , not hot loads mostly S&B and Privi , just after firing have problem to open the bolt , then discover it's a piece falling , the left lug , remove the bolt and found it cracked , it's a Fazakerley 53... new bolt installed ...Attachment 94303Attachment 94302Attachment 94304Attachment 94305

a problem with temper... too britlle

Best Regards

Daniel

Information

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[Gil Boyd]

DWM,
That doesn't look quite right there, where did you buy the bolt from, its almost cast in its entirety?

[30Three]

Who installed the new bolt? I presume from the result that it was not bearing properly on both lug's.
Worth getting someone like Brian Dick to inspect the part's of that bolt; check out the quality of the steel.

[GeeRam]

DWM,
That doesn't look quite right there, where did you buy the bolt from, its almost cast in its entirety?

Looks like a perfect example of Brittle fracture of steel to me.

[Mk VII]

Take it to a university metallurgy department and have them analysis the steel. They'll probably be glad of the practice.

[Brit plumber]

I hope the new bolt was properly fitted or there could be a repeat.

[breakeyp]

As a product engineer at Ford Motor Co., I had some experiences with failure analysis of bolts that could no longer carry a load. (Legal department said we could not say failure) I had a very good section of materials engineers to call upon. I even took a course on failure analysis. Unless things have drastically changed, I think the following comments still apply:

Failed parts have to be visually analyzed. The faces of the failure can tell you if the failure occurred catastrophically or over time. There is no way to analyse the steel content vs. the heat treat. You can determine the various materials that make up the steel. If you cut and polish the part for heat treat investigations you can see the depth of the heat treat using the proper etching dyes. It is not possible to work backwards on the part to determine how the heat treat was done. The major reason for bolt failures was improper heat treatment leading to hydrogen embrittlement. I suggest googling hydrogen embrittlement as I will probably be taken to task with my poor explanation. During the heat treat process unless certain processes are done, hydrogen is formed in the steel, causing the steel to be weakened. Suspect parts have to be cut up and prepared for laboratory microscopic analysis. We never found a way to determine HE without destroying the part.

I suspect the bolt under discussion may have been the victim of hydrogen embrittlement. With only photos to look at, the failure face shows catastrophic failure.

My comments are opinion and people with better explanations are encourage to comment.

[mmppres]

Its a good thing no one was hurt or killed by this

[Paul S.]

Its a good thing no one was hurt or killed by this

That, in the greatest part and for the firer in particular, due to the Enfield's rear locking bolt. The firer would probably have copped the rear end of the bolt in the face if that had been a Mauser.