Difference between 10.9 and SAE grade 8
Difference between 10.9 and SAE grade 8
(OP)
Hi, I am evaluating the differences between the two mentioned grades of materials. While comparing the specifications I am noticing small discrepancies, but no major differences. I'm soon to conclude that they are very similar, and thus interchangeable. Is there some big difference (chemical, mechanical etc) I am missing? Would assuming they're interchangeable be an issue?
FYI, this is not for any sort of safety critical application.
Thanks for any feedback!
FYI, this is not for any sort of safety critical application.
Thanks for any feedback!





RE: Difference between 10.9 and SAE grade 8
RE: Difference between 10.9 and SAE grade 8
The material for 12.9 screws have ultimate stresses approximately equivalent to SAE grade 8 screws. 10.9 screws are closer to SAE grade 5. I have an old Machinery's Handbook which explains that the ultimate stress of a 12.9 screw is 120kg/mm2. The 26th edtion claims that 12 is approximately one hundredth the minimum tensile stress in megapascals. English conversions I have seen, are closer to the kilogram values. The 0.9 value is the ratio of yield stress to ulitimate stress.
You realize of course that 10.9 and 12.9 screws are metric and the SAE screws are Unified National. Screws in tapped holes are not interchangeable. Nuts and bolts have slightly different tensile stresses, and different stress areas.
RE: Difference between 10.9 and SAE grade 8
He is correct regarding the threads, one is inch-based, the other is metric, so you will need to choose one or the other.
RE: Difference between 10.9 and SAE grade 8
RE: Difference between 10.9 and SAE grade 8
For instance could I expect different behaviors in cold service, corrosive environments or some other uncommon service conditions?
Has anyone ever seen a situation where they are different?
I was also told one of them (I think grade 5) goes through a double heat treat, does anyone know how that differentiates the two materials?
RE: Difference between 10.9 and SAE grade 8
RE: Difference between 10.9 and SAE grade 8
Fasteners with property class 10.9 do not have to use an alloy steel. Common alloys are 10B21, 19 MnB 4, 1541, 4037, and 32 CrB 4.