The grade should be marked on the head of the bolt. IE, 8.8 is grade 8, 10.9 is grade 10.cheers mate...I never gave it a thought before, was just going to get M8x22!.. I inherited my Dad's tools and part of that is a box full of "come in handy" bolts....I wonder!
Don't know if you're aware, but the second number denotes the bolts yield value. On a grade 10 bolt "10.9" means the yield is at 90% of ultimate tensile strength. The first number, 10 means it's ultimate tensile strength is 100kN/mm2
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