Bolt head marking

[CdotS]

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.

 

[SnTMan]

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

 

[TenPenny]

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.

 

[unclesyd]

Here are the more common types of Plow Bolts.

http://www.masterbolt.com/plow_bolts.html

 

[CdotS]

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.

 

[desertfox]

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

 

[CdotS]

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.

 

[desertfox]

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

 

[IceStationZebra]

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