Which is more cold weather resistant, Grade 10.8 or 10.9 bolts? What is their main difference? Is there a chart or specifications that I could look at that could tell me their main differences (specifically when it comes to cold weather)?


Thank you,

10.9 compared to 12.9 you mean?

Not sure how temperature effects them,but 12.9 are a higher tensile,so stronger

I would have thought it's very dependent on the application - an exposed bolt into a nut is going to behave very differently to a bolt into a threaded hole within a larger mass. And the size will make a difference too.

I would also have thought that - if it's anywhere - it'll be in the ISO?

in the world of Offshore and Subsea a 12.9 bolt that might be exposed to salt spray was not acceptable as the rate of corrosion/failure was deemed to be much higher.
12.9 is high carbon high tensile, 10.9 is next lower and 8.8 lower still, I believe there are 6,5 and 4 versions, each with lower carbon content and lower tensile strength

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Originally posted by danicortes22
Which is more cold weather resistant, Grade 10.8 or 10.9 bolts? What is their main difference? Is there a chart or specifications that I could look at that could tell me their main differences (specifically when it comes to cold weather)?


Thank you,

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Originally posted by snapper

quote:

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Originally posted by danicortes22
Which is more cold weather resistant, Grade 10.8 or 10.9 bolts? What is their main difference? Is there a chart or specifications that I could look at that could tell me their main differences (specifically when it comes to cold weather)?


Thank you,

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Why do you want to know?

There is much more not said than said in your question.

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Bolt materials are specified in ISO 898-1

the standard grades are 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9 and 12.9 - but only 4.6, 8.8, 10.9 and 12.9 are common in the UK with use of the others actively discouraged.


So grade 10.8 doesn't really exist in the ISO system - 10.9 is the correct grade at this tensile strength (nominally 1000 N/mm² )

The second number in the grade ".9" relates to the ratio of yield / 0.2% proof stress to tensile stress:
for a 10.9 bolt 0.2%proof stress = 900 so 900/1000 = 0.9 (or 90%)
so a lower second number in the bolt grade will yield sooner, but also give more warning that higher grade that is more likely to suffer a sudden brittle fracture




For structural use in low temperature it brittle fracture you'd worry about (same as any steel) - in general temps down to -20°C are fine but bellow that you should be specifying a min. test temperature at which the bolts should achieve a charpy v-notch impact toughness of at least 27J


so if the expected min service temp is warmer than -20°C then I wouldn't worry too much (UK outdoors is typically -15°C for structures) - but if you are concerned you need to specify the extra testing on your bolt batches to be done the manufacturer


from a automotive point of view I know that Ford use 10.9 for most of the suspension, brake and chassis / sub-frame bolts and 8.8 on various other parts

[Edited on 2/4/2019 by mcerd1]

A bit of information here
http://www.spartaengineering.com/effects-of-low-temperature-on-performance-of-steel-equipment/

and I thought the Wurth site was going to give the info you needed, but almost seems like this article was cut off before it ended, but still interesting.
https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_01_DINO_techn_Teil.pdf

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Originally posted by mcerd1
Bolt materials are specified in ISO 898-1

the standard grades are 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9 and 12.9 - but only 4.6, 8.8, 10.9 and 12.9 are common in the UK with use of the others actively discouraged.


So grade 10.8 doesn't really exist in the ISO system - 10.9 is the correct grade at this tensile strength (nominally 1000 N/mm² )

The second number in the grade ".9" relates to the ratio of yield / 0.2% proof stress to tensile stress:
for a 10.9 bolt 0.2%proof stress = 900 so 900/1000 = 0.9 (or 90%)
so a lower second number in the bolt grade will yield sooner, but also give more warning that higher grade that is more likely to suffer a sudden brittle fracture




For structural use in low temperature it brittle fracture you'd worry about (same as any steel) - in general temps down to -20°C are fine but bellow that you should be specifying a min. test temperature at which the bolts should achieve a charpy v-notch impact toughness of at least 27J


so if the expected min service temp is warmer than -20°C then I wouldn't worry too much (UK outdoors is typically -15°C for structures) - but if you are concerned you need to specify the extra testing on your bolt batches to be done the manufacturer


from a automotive point of view I know that Ford use 10.9 for most of the suspension, brake and chassis / sub-frame bolts and 8.8 on various other parts

[Edited on 2/4/2019 by mcerd1]

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Originally posted by redturner
That is really interesting. However, what kind of strength would Ford use in something like a crank pulley bolt which has to support several items and of course needs to be tight...

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Originally posted by redturner
That is really interesting. However, what kind of strength would Ford use in something like a crank pulley bolt which has to support several items and of course needs to be tight...

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