Board logo

Metal question
gingerprince - 9/9/08 at 07:41 PM

I need a length of box section to act as a support for a sump guard. As it happens I have a piece the ideal size.

The metal is as bought from B&Q a while ago and is described as "cold rolled iron".

What exactly is the difference (in practical terms) between this stuff and mild steel as used in chassis. Heavier? Weaker?

Are there any pressing reasons why I shouldn't use this and go buy some mild steel instead? There's no welding involved, it'll be bolted, and painted of course.

Sorry might be a silly question, but I'm no metallurgist. In fact, I'm not allergic to anything really...

[Edited on 9/9/08 by gingerprince]

Alan B - 9/9/08 at 07:49 PM

Use it...it's fine.....the "cold rolled iron" will really be cold rolled mild steel

ashg - 9/9/08 at 08:41 PM

its only a sump guard donot worry about it.

the ideal is that it has a bit of give in it. reason being is you want it to bend before the chassis or any little bumps could get rather expensive to repair.

MkII - 9/9/08 at 08:42 PM

wot alan b said . its more likely to be cold formed mild steel hollow section .it should be ok for sump guard beam

C10CoryM - 10/9/08 at 02:09 AM

The only real difference is hot rolled usually has a coating on it which can be a real pain to grind/drill. I always buy cold rolled when I can.
Cheers.

mcerd1 - 10/9/08 at 07:32 AM

quote:
Originally posted by C10CoryM
The only real difference is hot rolled usually has a coating on it which can be a real pain to grind/drill. I always buy cold rolled when I can.
Cheers.

the two types are "cold rolled" and "hot finished"

hot actually has tigher corners and the residual stress from the forming has been relieved by heating after its been rolled

hot is a bit stronger but it doesn't make that much difference unless you are going to make use of its plastic strength or expose it to allot of heat

the stuff from B&Q is likley to be european structural mild steel (S235 = 235 N/mm^2) rather than british mild (S275 = 275 N/mm^2) - but I wouldn't worry about it for what your using it for

gingerprince - 10/9/08 at 08:14 AM

OK cheers all. Saved me a couple of quid

Good point about it wanting to be weaker than the chassis anyway!