danicortes22
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 posted on 1/4/19 at 02:56 PM |
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Bolt Grade Specifications
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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CosKev3
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| posted on 1/4/19 at 03:35 PM |
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10.9 compared to 12.9 you mean?
Not sure how temperature effects them,but 12.9 are a higher tensile,so stronger
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jps
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| posted on 1/4/19 at 04:32 PM |
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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?
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HowardB
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| posted on 1/4/19 at 05:03 PM |
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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
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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snapper
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| posted on 2/4/19 at 06:24 AM |
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quote:
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,
Why do you want to know?
There is much more not said than said in your question.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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nick205
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| posted on 2/4/19 at 08:06 AM |
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quote:
Originally posted by snapper
quote:
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,
Why do you want to know?
There is much more not said than said in your question.
I'm not a material scientist or thread expert, but I do agree with...
Why?
Dimensions?
Application?
Temperature range(s)?
Can you give a bit more information about what you want to do?
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mcerd1
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| posted on 2/4/19 at 09:12 AM |
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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]
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hughpinder
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| posted on 2/4/19 at 10:21 AM |
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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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redturner
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| posted on 4/4/19 at 01:28 PM |
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quote:
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]
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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mcerd1
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| posted on 4/4/19 at 01:46 PM |
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quote:
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...
The crank pulley bolt should't be taking any of the load directly (for a start its on the same axis as the crank)
most of the load will be transferred by friction (all of the load on cranks without keys) and the bolt only has to be strong enough to generate a
sufficient pre-load to prevent slip
from memory the likes of a pinto uses an 8.8 bolt and I think a zetec is a 10.9 with a higher torque setting - but the pinto uses a much bigger bolt
too - so horses for courses
for structural use 8.8 and 10.9 bolts are both commonly used for friction grip assemblies depending on the pre-load required (each with their own
special nuts and washers)
[Edited on 4/4/2019 by mcerd1]
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jps
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| posted on 4/4/19 at 04:35 PM |
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quote:
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...
I torqued one a few days ago on a Pinto. The Haynes manual has different torque ratings for 8.8 and 10.9. Mine was 10.9.
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