Steel vs Aluminium strength

[smashweld]

assuming the same wall thickness I'm wondering what size of alloy box section, angle etc would be needed to get the same strength you'd get in any given mild steel box section, or angle, tube, flat bar etc

from what I can gather, for aluminium it seems you need almost twice the size of steel - so if you were using 25x25x3 mild steel box you'd need need 50x50x3 aluminium to get the same strength... is that reasonable?


also wondering how stainless steel compares compared to mild steel

any help appreciated!

 

[Kent]

Depends which way it's stressed also what ali you choose it comes in various properties

The exam above the ali will bend a lot easier ( bent the easy way) than the steel. In fact it could prove hard to rack without putting a kink in it

 

[smashweld]

the standard alloy or steel box,angle etc lengths you'd get from a stockholder, like....
https://www.metals4u.co.uk/aluminiu...2aN7VqcSnDwgDYQCcHc8ThynKvuhK8IYEfBoC9_jw_wcB
https://www.metals4u.co.uk/mild-steel/box-section/25mm-x-25mm-x-3mm/p2297
https://www.metals4u.co.uk/stainless-steel-box-section/25mm-x-25mm-x-3mm-304-dull-polished/p10489

and like for like for strength test - yield strength is what I think I need to know

 

[Rocketman]

Massively depends on the grade of ali you are comparing the mild steel to as Kent alluded to. Put it this way the top end of the ali market is pretty close in strength to mild steel - welding exotic ali can be very troublesome. I guess you are look at cheap grade ali?

 

[smashweld]

yeah just the bog standard that you'd get if you asked for aluminium box section, like what you'd find in a Road Transport catalogue, or like these - I assume these are the same thing

https://www.metals4u.co.uk/aluminiu...2aN7VqcSnDwgDYQCcHc8ThynKvuhK8IYEfBoC9_jw_wcB

https://www.themetalstore.co.uk/products/aluminium-box-section

wall thickness is the only choice you get from places like above, or at least there's definitely some kind of standard?

edit - I'm not 100% but it looks like it's 6063 or 6082 that's commonly used for box section/.tee etc?