Grade 8.8, 10.9, 12.9 mechanical properties
Grade 8.8, 10.9, 12.9 mechanical properties
(OP)
Hi, does anyone know what the typical uniaxial mechanical properties of these Metric grade bolts are.
I am aware of the proof/yield stress and UTS but NOT the elongation values which is what i am really after?
i want to know how much strain do the bolts undergoe before actual fracture? For example similar quench and tempered plate grade 700 has approx same yield and UTS and elongation is ~18% min.
I am not after and elongation data for preload purposes but failure seperation of the joint in the inelastic region.
thanks
I am aware of the proof/yield stress and UTS but NOT the elongation values which is what i am really after?
i want to know how much strain do the bolts undergoe before actual fracture? For example similar quench and tempered plate grade 700 has approx same yield and UTS and elongation is ~18% min.
I am not after and elongation data for preload purposes but failure seperation of the joint in the inelastic region.
thanks





RE: Grade 8.8, 10.9, 12.9 mechanical properties
They allow the uniform reduced section to stretch (elastically and plastically) before the threaded section. "Regular" bolts have a severe stress concentration at the thread roots which governs their plastic flow.
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
RE: Grade 8.8, 10.9, 12.9 mechanical properties
if one machined a standard unaxial test specimen from a bolt what would be the elongation %?
RE: Grade 8.8, 10.9, 12.9 mechanical properties
RE: Grade 8.8, 10.9, 12.9 mechanical properties
It depends on the diameter, perhaps a bit less for big stuff.
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
RE: Grade 8.8, 10.9, 12.9 mechanical properties
i have to balance out that an 8.8 while not as strong may prevent seperation of a joint under dynamic load compare to a 12.9 which might be stronger but more likely to fracture
RE: Grade 8.8, 10.9, 12.9 mechanical properties
You can do a lot worse than have bolts made from HY80, or the latest improved version whose name/number escapes me right now.
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
RE: Grade 8.8, 10.9, 12.9 mechanical properties
I found this site which gives some idea of the stress/strain curves for bolt materials:-
http://
desertfox
RE: Grade 8.8, 10.9, 12.9 mechanical properties
I'm interested in why you need the strain rates for the bolt materials,normally bolted joints are designed based on the proof stress, after a bolt exceeds its proof stress it would be deemed to have taken a permanent set and any further external load would allow the clamped components to seperate and the joint considered failed.
desertfox
RE: Grade 8.8, 10.9, 12.9 mechanical properties
RE: Grade 8.8, 10.9, 12.9 mechanical properties
RE: Grade 8.8, 10.9, 12.9 mechanical properties
If you don't need high strength, consider HY80, one of the toughest steels made.
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
RE: Grade 8.8, 10.9, 12.9 mechanical properties
As Metalguy said 8.8 would be tougher than the 10.9 or 12.9 however there are lots of other factors to consider which were not party to in relation to your application, so its hard for us to give any further recommendation unless you can tell us more about your situation.
Have you considered asking a fastener supplier for the information your seeking?
desertfox
RE: Grade 8.8, 10.9, 12.9 mechanical properties
Standards like ISO 898-1 and SAE J429 have requirements for minimum elongation in a tensile test:
8.8 according to ISO 898-1 : 12% min
10.9: 9% min
12.9: 8% min
Grade 5 according to SAE J429 : 14% min
Grade 8 : 12% min
The Fastenal link provided by desertfox shows elongation in inches rather than %, but this appears to be for a standard 2 inch gage length, which means that the Grade 5 has ~ 25% elongation and the Grade 8 ~ 11.5% Since toughness is related to area under the stress-strain curve, you can see that a Grade 5 (~ PC 8.8) is much tougher than a Grade 8 (~ PC 10.9).