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
Here's another larger list, but you have to pay for it:
http://
RE: Bolt head marking
RE: Bolt head marking
RE: Bolt head marking
Have a look at this site two lines shown here is an SAE grade 3 medium carbon steel.
http://shopswarf.orconhosting.net.nz/boltid.htm
hope this helps
desertfox
RE: Bolt head marking
RE: Bolt head marking
your wecome, is the bolt an SAE grade 3?
desertfox
RE: Bolt head marking
RE: Bolt head marking
thanks for updating us in advance
desertfox
RE: Bolt head marking
http://www.mlevel3.com/BCIT/rivetID.htm
RE: Bolt head marking
RE: Bolt head marking
RE: Bolt head marking
RE: Bolt head marking
If that's a "bolt head", how the heck do you tighten it?
RE: Bolt head marking
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
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
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
Regards,
Mike
RE: Bolt head marking
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
Regards,
Mike
RE: Bolt head marking
Typically you'll want Grade 8 or better, seems to me.
RE: Bolt head marking
http://www.masterbolt.com/plow_bolts.html
RE: Bolt head marking
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
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
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
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
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