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Bolt head marking

Bolt head marking

Bolt head marking

(OP)
I have received a couple of bolts with a rather unique markings for failure analysis. It has two lines on its head. There is no such markings in the standards. I attach a photo of one of the bolts. If you know any info on this bolt, please let me know. Thanks.

RE: Bolt head marking

(OP)
Yes, I have tried the uspto site but this bolt marking is not listed. I will wait for awhile before paying for the second reference.

RE: Bolt head marking

Not professing any particular expertise here, but I suspect for whatever it is worth this "bolt" (or stud?) "head" may not be a high tensile variety, as I think most common standards require those at least to be recognizably marked.   

RE: Bolt head marking

(OP)
Thank you all for your immediate response.

RE: Bolt head marking

CdotS

your wecome, is the bolt an SAE grade 3?

desertfox

RE: Bolt head marking

(OP)
It could be SAE Grade 3 and I will report here once the chemistry and hardness are done. Not enough material for tensile testing.

RE: Bolt head marking

okay CdotS

thanks for updating us in advance

desertfox

RE: Bolt head marking

(OP)
Mizzoueng, believe me, it is a bolt with top view taken just to show the markings. Do not let your imganination run too far.  

RE: Bolt head marking

Looks like it might be a weld projection head, but it doesn't look like a typical example.

RE: Bolt head marking

[Just curious, exactly what kind of "head" is on this "bolt"?]

RE: Bolt head marking


If that's a "bolt head", how the heck do you tighten it?
 

RE: Bolt head marking

(OP)
It is a plow bolt. It has a small square section under the head. The part has a square hole with a countersink.

when I post hardness readings, I will include another photo for you. Please bear with the delay.

RE: Bolt head marking


So you tighten the nut on the other side, making it more of a headed stud than a bolt really, but I realise they may still call them bolts.

Do you think that maybe the marks are there just so that you can note the orientation of the square in the part, to check that it hasn't started to round out the hole when the nut is tightened and the head may be out of view?
  

RE: Bolt head marking

SincoTC,

Bolts are not tightened by applying torque to their head-- they are tightened by torquing the nut.  Screws are tightened by torquing their head.  This is the consensus definition used by IFI, ASME, ASTM, ISO, etc.

RE: Bolt head marking

TVP,

You're quite correct, that is the current consensus on the definition of bolts and screws, but nearly everyone in this thread has spoken of "bolt head" including the OP. I suppose in my first post, it would have been more correct to say how do you "stop it turning", but for an old fart like me, with my formative years spent in the "infernal combustion engine" business, a "screw head" will always be something to do with woodworking and there must still be loads of old flat-head engines about with "cylinder head bolts" and millions of "big end bolts" holding con-rods together, all with hex heads, all screwed into tapped holes and then torqued down by the head!

The essential point I was making in my second post is that in the absence of spanner flats or similar and with what appears to be a plain cylindrical head with a hidden way of stopping rotation, you need something (maybe the two marks) as a reference to indicate that it hasn't turned when the nut is tightened. The nut may have seized or run up against the end of the thread if a washer is left off or the part it secures has been machined down in thickness, without a suitable witness mark, all the torque applied to the nut may just be destroying the square under the head or the hole it fits in.
 

RE: Bolt head marking

CdotS, if you're still with us, can you contact your supplier?

Regards,

Mike

RE: Bolt head marking

(OP)
I am a bit surprised at the direction this post has taken.
I had only the head portion of a broken bolt and wanted to know what type of bolt that was. I figured out from the standards that was a Grade 3 bolt (thanks to those who helped me).

SnTman,
What kind of info do you want me to get from the bolt supplier? I do not know whether it is possible.

RE: Bolt head marking

CdotS, I guess I kind of misunderstood your O.P. did not realize they were broken. I thought you meant "recieved" as from a supply house or something.

Regards,

Mike

RE: Bolt head marking

From your description of the bolt use (ie, a plow bolt), it's what I would call a scraper blade bolt, used for attaching the replaceable scraper blades on graders, for example.

Typically you'll want Grade 8 or better, seems to me.

RE: Bolt head marking

(OP)
Just to conclude this post:

The bolt was a 0.30 carbon steel with an average hardness of around 40HRc. It was possibly heat treated. The hardness readings show higher than expected for a Grade 3 bolt. I do not know why a Grade 3 bolt was made from a 0.3 C steel and heat treated when the spec call for a cold worked material. I also do not know why they marked Grade 3 when the strength (based on hardness readings) exceeds the spec for Grade 3.

Thank you to all who have contributed to this discussion.

  

RE: Bolt head marking

hi CdotS

Thanks for the update, how much outside is the tensile strength of this fixing compared to a SAE grade 3. reason I ask is that nominal values for grades are quoted and in practice the actual fixing is equal to this nominal value or greater than it.
More importantly any idea on the failure mode?

desertfox

RE: Bolt head marking

(OP)
Hi desertfox

Failure mode: Unfortunately, the fracture surface was subsequently abrased by soil and therefore of no use. It was smooth and flat - failed possibly by a brittle fracture mode.

Strength: The hardness of the bolt (40 HRc) corresponds to an ultimate tensile strength (UTS) value of 184 ksi whereas the Grade 3 bolt spec says UTS of 100-110 ksi.  

RE: Bolt head marking

Hi CdotS
Pity the surface was eroded by soil. I wonder if anybody as a design calculation for the joint with pre-load values etc that might be a starting point although you would also need to know the external loads it was under to.

desertfox

RE: Bolt head marking

I tend to agree with TenPenny that the bolt appears to be off of a scraper or grader blade. The round portion of the head tells me that it is a thick blade. The two small slots could be used during the manufacturing process?

If this is off of a moldboard plow I have a hard time understanding why you are spending this much effort on a plow bolt? Having previously worked on plows for CaseIH, I know that there has been little real development done on plows in North America since the 70's. From a material perspective, the wear parts (share, shin and moldboard) are pressed against the frog, so the main loading is shear. And if the bolts were too hard they would abraid less than the shin/share/moldboard thus sticking out and causing scouring issues.

ISZ

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