Ordered 50 x M10 Gr 8.8 bolts, opened the box to find they are 10.9's
too hard, they'll fail... 
have you check the reciept? they may have charged you for 10.9's
did I mention my curtains I ordered? wanted two 3m and a 1.5mm, got six 3m ones! ahhh! but now I know how to adjust curtains 
[Edited on 8/4/11 by Mr Whippy]
nope came out at 20p per bolt, they are over twice that for 8.8's on Namrick. They must be fake
bolt grades are from standard 8.8 to 12.9 high tensile, 10.9 is in the middle.
Why would they fail where a grade 8.8 would not, from Wikipedia
The numbers stamped on the head of the bolt are referred to the grade of the bolt used in certain application with the strength of a bolt.
High-strength steel bolts usually have a hexagonal head with an ISO strength rating (called property class) stamped on the head. And the absence of
marking/number indicates a lower grade bolt with low strength. The property classes most often used are 5.8, 8.8, and 10.9. The number before the
point is the tensile ultimate strength in MPa divided by 100. The number after the point is 10 times the ratio of tensile yield strength to tensile
ultimate strength. For example, a property class 5.8 bolt has a nominal (minimum) tensile ultimate strength of 500 MPa, and a tensile yield strength
of 0.8 times tensile ultimate strength or 0.8(500) = 400 MPa.
hth
I think Mr Whippy meant that with a healthy dose of sarcasm
Higher grade bolts are more brittle, i.e. more likely to snap rather than deform under excessive load (and perhaps less durable under excessive
vibration?)
quote:
Originally posted by HowardB
bolt grades are from standard 8.8 to 12.9 high tensile, 10.9 is in the middle.
Why would they fail where a grade 8.8 would not, from Wikipedia
The numbers stamped on the head of the bolt are referred to the grade of the bolt used in certain application with the strength of a bolt. High-strength steel bolts usually have a hexagonal head with an ISO strength rating (called property class) stamped on the head. And the absence of marking/number indicates a lower grade bolt with low strength. The property classes most often used are 5.8, 8.8, and 10.9. The number before the point is the tensile ultimate strength in MPa divided by 100. The number after the point is 10 times the ratio of tensile yield strength to tensile ultimate strength. For example, a property class 5.8 bolt has a nominal (minimum) tensile ultimate strength of 500 MPa, and a tensile yield strength of 0.8 times tensile ultimate strength or 0.8(500) = 400 MPa.
hth
what he ^^ said,there's a machine in work keeps stretching its bolts,making them appear they're loose,so stuck 10.9's in and they snapped a week later!We are talking a seriously damaged and twisted machine that has 50 plus tonnes dropped in it every 20 minutes tho, they're fine for normal uses,probably better for general stuff!
quote:
Originally posted by rodgling
Higher grade bolts are more brittle, i.e. more likely to snap rather than deform under excessive load (and perhaps less durable under excessive vibration?)quote:
Then why are these type bolts the norm for things like flywheels and prop shaft fixings, and I might add for conrods and bearing caps, where the use of 8.8's is not recomended? Ray