bolts with letters on them. What are their grade?

[The motor guy]

I've noticed recently that on a lot of bolt heads instead of having markings to specify grade or the metric numbers on them like 8.8, 10.9 etc, they have like four letters bunched together. How do you tell what grade these bolts are? Are most of these just cheap bolts with low strength?

 

[CarbonSteel]

Try this one (is this what you mean?):

Bolt Markings

 

[JHZR2]

Lines and numbers indicate grade. Letters are a pricing code, I believe.

 

[The motor guy]

This is exactly my point. They don't have markings or numbers like shown in that chart they have letters on them and nothing else. I wish I had an example so I can explain it better but I don't have any of those bolts with me at the moment. So then I guess the ones you see at home depot which just have letters and no markings at all are just cheap bolts then that aren't even a grade 5. Cause I went their a few weeks ago and the only grade 5 bolts were in individual bags

 

[daman]

The higher the number the harder the bolt.

 

[CarbonSteel]

Originally Posted By: motor_oil_madman
This is exactly my point. They don't have markings or numbers like shown in that chart they have letters on them and nothing else. I wish I had an example so I can explain it better but I don't have any of those bolts with me at the moment. So then I guess the ones you see at home depot which just have letters and no markings at all are just cheap bolts then that aren't even a grade 5. Cause I went their a few weeks ago and the only grade 5 bolts were in individual bags

Check my post above^^^

 

[tom slick]

You are seeing the structural grade on the fastener such as "A325". Those are for bolting structures together such as buildings and bridges. You can't use SAE grade bolts in structures.

http://www.fastenal.com/content/feds/pdf/Article - Structural Bolts.pdf

 

[Cujet]

People often mistake metric 8.8 bolts for grade 8 bolts. They are not the same at all. Grade 8 is typically 150KSi and 8.8 is 120KSi. Big difference in tensile strength.

 

[doitmyself]

Many fasteners have letter markings that I.D. the manufacturer as shown in this PDF:

http://www.uspto.gov/web/offices/tac/fqa/active.pdf

Check out the last ten pages or so.

HHW = HO HONG WORKS CO., LTD. in Taiwan

 

[doitmyself]

No "tick" marks (SAE) or numbers (metric) usually indicates low grade/soft fasteners, but it can get tricky with very high grade bolts (aerospace, etc.), as tom slick points out above

A soft grade carriage bolt head: PB = Portland Bolt company.

 

[SHOZ]

I need a 1/4 diameter bolt softer that the grade 1 or 2. Are brass bolts softer yet? Any grading on them?

 

[doitmyself]

I'm not aware of grading of brass bolts. You could probably find charts that show shear and tensile strengths and compare them. Aluminum might be even weaker. Be careful of galvanic corrosion, if that matters.