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  #1  
Old 07-24-2009, 01:56 PM
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nhrocker nhrocker is offline
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Hot vs. Cold Rolled Steel Plate

When dealing with plate, how much of a difference is there between hot and cold rolled plate? I know the difference manufacturing wise, but I don't have any experience working with cold rolled. I've been told it's stiffer and more brittle than HR. Is that true? And if so is it enough of a difference to avoid it? Most of my use would be off road fabrication (mounting tabs for bumpers/axles, winch plates, gussets, the usual generic stuff). Also is there any way to tell the difference between HR and CR?

Asking this because the shop I usually buy steel through has two pallets loaded about 3ft. high with scrap plate, ranging from 3/16" up to 3/8". Mixed HR and CR. The majority is 1/4" CR, all cut to about the same size (around 10"x40" from memory, some larger). I was told it was all acquired in some trade and they'll give me as much as I want, $10 for each piece, and any smaller chunks I can have for free. Sounds like a pretty decent deal to me (don't buy much plate so I could be off here), but I don't want to mess with it if it's not up to par with the normal HR steel I use.
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Old 07-24-2009, 03:00 PM
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If you do a quick search under my user name I have posted on the subject in the past.. Hot rolled scale needs more attention before welding and it realy does not take powdercoat well for the long hall. Cold roll obveuosly is cleaner, but I think I had some more detail then this in the post I had made. IT was more toward the Idiots saying they sell A-50 plate when there is NO such thing. Only grades and they very, But I see it as a crap sales tactic to the un-knowing person making them think they are getting something special. 2 Vendors come to mind that I will let you figure out on your own.
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Old 07-24-2009, 03:37 PM
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Quote:
Originally Posted by Rock4XFab View Post
If you do a quick search under my user name I have posted on the subject in the past.. Hot rolled scale needs more attention before welding and it realy does not take powdercoat well for the long hall. Cold roll obveuosly is cleaner, but I think I had some more detail then this in the post I had made. IT was more toward the Idiots saying they sell A-50 plate when there is NO such thing. Only grades and they very, But I see it as a crap sales tactic to the un-knowing person making them think they are getting something special. 2 Vendors come to mind that I will let you figure out on your own.
We get in some A572 or A576 plate (dont remember which) that sometimes gets referred to as GR-50. Maybe thats what the vendors are doing not knowing any better (or trying to pass off something for what its not?)
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Old 07-24-2009, 05:31 PM
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Defender Chassis Defender Chassis is offline
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There is no difference in stiffness between HR & CR.

When welded, the heat affected zone in CR will revert back to the properties of HR.
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Old 07-24-2009, 06:37 PM
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Originally Posted by DpSyChO View Post
We get in some A572 or A576 plate (dont remember which) that sometimes gets referred to as GR-50. Maybe thats what the vendors are doing not knowing any better (or trying to pass off something for what its not?)
Exactly there is Grade 50 or GR 50 for short but no such thing as A-50 plate. The Companys in question label there product as A-50 Plate Better then eveyone else using standard A-36.. But my issue with there deception is I can get A-36 plate with a Grade 50 rating and for a basic BS tab the difference is miniscuel and I persoanly could care less. But they are decieving people either knowing or not, just shows they dont have a clue and are nieve enough to not know what they are selling or they are just plain deceptive in there practice.
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Old 07-24-2009, 06:50 PM
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i can tell you this much coldfinish is no where near as formable has hotrolled is ,

we use alot of A36 and 44w , they all form really well and are typically pickled and oiled or acid washed plate as we get it lasercut and the machine has a contact head so only very clean steel gets cut . on the subject with laser cutting and forming becarefull of the edges spliting on tight bends the kerf from the laser causes sheerlines and it can crack m grinding the kerf line out helps alot .

Last edited by mikefrombc; 07-24-2009 at 06:53 PM.
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Old 07-24-2009, 06:55 PM
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Originally Posted by Defender Chassis View Post
There is no difference in stiffness between HR & CR.

When welded, the heat affected zone in CR will revert back to the properties of HR.

CF will Flame/work harden easier then HR when in a flatbar state
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Old 07-24-2009, 07:00 PM
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Originally Posted by mikefrombc View Post
i can tell you this much coldfinish is no where near as formable has hotrolled is ,

we use alot of A36 and 44w , they all form really well and are typically pickled and oiled or acid washed plate as we get it lasercut and the machine has a contact head so only very clean steel gets cut . on the subject with laser cutting and forming becarefull of the edges spliting on tight bends the kerf from the laser causes sheerlines and it can crack m grinding the kerf line out helps alot .
Ya I forgot about that, My press brake operator likes it best when we do Hot rolled because the CR can and does Crack, depending on the bend and thickness. And if memory serves correct you can only get CR in flat plate up to 3/16. everything above that is generaly HRPO. Hot roll pickeled and oil IF it is realy clean.
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Old 07-24-2009, 09:29 PM
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Originally Posted by Rock4XFab View Post
Ya I forgot about that, My press brake operator likes it best when we do Hot rolled because the CR can and does Crack, depending on the bend and thickness. And if memory serves correct you can only get CR in flat plate up to 3/16. everything above that is generaly HRPO. Hot roll pickeled and oil IF it is realy clean.
I have personally work on a piece of cold rolled plate that was 12 inches thick. It was a burn out from a bigger plate that was cut into a circle for a fixture I was working on. So they do make cold rolled in thicker that 3/16. I also use 1/2 inch all of the time. It is more of a bar than plate but it can get really big. Just depends on your supplier.
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Old 07-24-2009, 10:06 PM
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Thanks for all the quick responses.

Rock4XFab- I had found and read your posts about it before, did shed a little more light on it, but you hadn't mentioned the hardness/brittleness/forming side of it that I was worried about.

My sizing was off, they're actually 11"x48" chunks. I don't think that's bad for $10 each? Picked up a few when I went back. I don't have any way of bending plate at the moment anyway, so cracking from that is not an issue. When I do get around to making a press brake I'll just try to make sure I'm using HR for that stuff. Sounds like the CR should work fine for most of my stuff.

Thanks again guys!
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Old 07-25-2009, 12:25 AM
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Quote:
Originally Posted by nhrocker View Post
Thanks for all the quick responses.

Rock4XFab- I had found and read your posts about it before, did shed a little more light on it, but you hadn't mentioned the hardness/brittleness/forming side of it that I was worried about.

My sizing was off, they're actually 11"x48" chunks. I don't think that's bad for $10 each? Picked up a few when I went back. I don't have any way of bending plate at the moment anyway, so cracking from that is not an issue. When I do get around to making a press brake I'll just try to make sure I'm using HR for that stuff. Sounds like the CR should work fine for most of my stuff.

Thanks again guys!
i use CR for jigs and fixtures and tools and such it saves lots of time anytime you want precision , and if i use HR i get it blanchard ground on both faces
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