HackleBear
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| posted on 8/10/14 at 06:09 PM |
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Is this steel suitable for chassis?
the Steel is listed as, Grade 43a mild steel. the box section is 25mm X 25mm with a 2mm thickness.
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Dualist
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| posted on 8/10/14 at 06:23 PM |
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Yes, '43a' is common bog stock mild steel.
Though I used 1.5mm, 2mm will be ok.
[Edited on 8/10/14 by Dualist]
Rotary build coming soon...
quote:
Originally posted by RichardK
I recently discovered that pigs can p i s s sideways when being transported 
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ashg
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| posted on 8/10/14 at 06:23 PM |
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should be ok its a pretty common structural steel. 43a is an older bs standard but it basically means 430N/mm². i think the next up is 50d
edit. there is a bit more info on the mig welding forum http://www.mig-welding.co.uk/mild-steel.htm
[Edited on 8/10/2014 by ashg]
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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HackleBear
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| posted on 8/10/14 at 06:55 PM |
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Thank you for the reply's.
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brum_gustavo
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| posted on 8/10/14 at 11:51 PM |
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2mm is much easier to tack-weld with a standard arc welder, if you don't want to spend on a Mig welder you can rent or borrow one when you
finish assembling the chassis.
I used it in my first locost chassis (project abandoned a few years ago). Now I've built one with 1.5mm, and its much trickier to weld.
Build diary: http://gustavobrum.wordpress.com/
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mcerd1
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| posted on 9/10/14 at 08:34 AM |
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quote:
Originally posted by HackleBear
the Steel is listed as, Grade 43a mild steel.
I would Not use that stuff - as its not been tested for brittle fracture
(see my comments on sub-grades below)
43a is the old BS 4360 name for S275 - which is bog standard British mild steel
the old name related to its Tensile Strength (i.e. the breaking point)
the new name relates to its Min. Yield Strength (i.e. the point it starts to fail which is far more useful to know!)
50d mentioned above is now called S355-J2, which is a typical 'high yield' structural steel used all over Europe
btw beware of the European mild steel - this is the S235 stuff - its easily available and cheap, but significantly weaker !
the suffix on the end is the steel quality or sub-grade (b, c, d on the old ones or JR, J0, J2 on the new ones) relates to its impact resistance at a
given temperature - steel can suffer from brittle fracture at low temps (google for 'liberty ships' if you want a good example)
JR is impact tested at +20°C and must achive more than 27J
J0 must achieve the same at 0°C
J2 must achieve the same at -20°C - therefore this is much better quality steel
these test temps don't directly relate to the temp the steel will be used at though - generally speaking for thin steel (i.e. less than 10mm
thick) JR will be good enough for anything outdoors in the UK down to -15°C
the A suffix on the 43A means its NOT BEEN TESTED for brittle fracture - avoid this stuff like the plague for anything that needs to be strong
and/or is ever going to be used out doors !!!
just to complicate things even more, Hollow sections [aka tubes] are actually made and tested to different standards....
first off there are 2 kinds: 'Hot Finished' to EN10210 and 'Cold Formed' to EN10219
*Hot ones have small radii in the corners and have been heat treated to remove the residual stresses caused by the forming process.
*Cold ones have large radii (which makes them a PITA to work with) and still have all the residual stresses which makes them more prone to cracking
when you weld near the corners and also they have a lower buckling resistance.
so you should really stick to the Hot Finished ones made to BS EN 10210.
These hollow sections also come with there own sub-grades - basically the same as above but with an 'H' on the end as its a different test
procedure.
Most places only tend to stock the nasty untested S235 stuff or the much better S355-J2H
Almost no one makes S275-J2H tubes anymore which would have been fine, but S355-J2H is better anyway 
to sum that all up - ask for:
Flats and Plates in S275-JR or better (to BS EN 10025)
'Hot finished' tubes in S275-J2H or S355-J2H (to BS EN 10210)
and these days they should even provide you with CE marked copies of the material test certificates for the batches your steel came from...
(sorry that's probably more than you wanted to know - I design structures with these steels every day and it annoys me when the stock holders
try and sell 'garden gate' grade stuff to everyone  )
[Edited on 9/10/2014 by mcerd1]
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Mr Whippy
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| posted on 9/10/14 at 11:55 AM |
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^ tbh this should be a sticky at the top of section as it's rather important info...
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Ian-B
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| posted on 9/10/14 at 07:00 PM |
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Whilst the comments about improved impact resistance are correct, they really only become significant at larger section thicknesses, for normal
chassis construction thickness 2mm and less, they are not especially relevant, indeed many of the steel standards for thin section steels (such as
those used in car body construction) make no reference to impact toughness for this reason
[Edited on 9/10/14 by Ian-B]
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mcerd1
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| posted on 9/10/14 at 08:24 PM |
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^^ fair comment
the plate standard I'm referring to start from 3mm thick and the tubes start from 20x20x2mm
but the Hot Finished vs Cold formed tubes can still be a big issue anyway
[Edited on 9/10/2014 by mcerd1]
[Edited on 9/10/2014 by mcerd1]
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britishtrident
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| posted on 9/10/14 at 08:54 PM |
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1.5 or 1.6 is significantly easier and quicker to cut than 2mm using a 24tpi blade.
For the rookie welder using a home MIG 1.5/1.6 is slightly easier to get decent full penetration welds with first time.
Of course the bare chassis will also be 33 percent heavier in 2mm than 1.5mm
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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