Shear bolt

[550Doug]

My Bush hog recently snapped the grade 5 bolt I had in as a shear pin. The only bolt that I had that would fit is a stainless steel bolt. Just wondering how it's hardness compares with a grade 5. The head of the stainless has 2 marks on the top; don't know what they mean. I suspect that it may be too hard to act as a shear pin. Thoughts?

 

[Steve@Advance]

It will be softer.

The 2 marks is a grade 2 bolt.

 

[Steve@Advance]

Make that a grade 3, typo..

 

[johnofnewhaven]

I thought you added 2 to the amount of marks. Is stainless steel different?

 

[Mark-Ia]

Grade 2 Bolts

Grade 2 bolts are the most common grade of bolts and are also the least expensive. Grade 2 bolts are found mostly in household fasteners like carriage bolts, and machine screws. The usually have no head marking, but may sometimes contain manufacturer markings.


Grade 5 bolts are commonly found in many automotive applications that call for a hardened bolt but not as brittle as fully hardened. Grade 5 bolts are case hardened, meaning the bolt has been heated enough to hardened the outside of the bolt but not enough to harden the inside portion. Grade 5 bolts are identified by 3 evenly spaced radial lines on the head.

Intense amount of weight or pressure
Grade 8 Bolts

Grade 8 bolts are common in heavy manufacturing like large trucks and tractors. They are fully heat treated all the way through which create a bolt that is very hard but somewhat brittle. Because of their hardness, grade 8 bolts are more likely to snap off than bend under extreme loads. Grade 8 bolts are identifiable by 6 evenly spaced radial lines on the head

 

[Steve@Advance]

John, you're right, having a senior moment there!

I did some more research, the 2 mark stainless refers to the alloy 18-8, 18% chromium and 8% nickel.

Then found this chart that explains the 18-8 characteristics, which puts it in a relatively soft range for yield strength, but a wide range for tensile strength.

That's where I get lost, which number would apply for shear strength?

I would still think it is a relatively soft bolt, most stainless bolts are.
Bolt Grade Markings

 

[JD Seller]

Stainless steel bolts will shear easier. I often use them in some places just because of that. They shear smooth/clean. Sometimes a grade 2 bolt will kind of smear and not shear clean. It is then hard to get the broken part out. So put a stainless steel bolt in the same place and it will shear clean and be easier to replace.

 

[Texasmark1]

Interesting. I do just the opposite because the smear helps me to locate the hole in the shaft and because a grade 2 will take several hard whacks before it shears all the way. Different Stokes for Different Folks.....TV show.