Differences in hot rolled and cold rolled sheet steel?

I understand the differences in the processes but I am wondering if I would have a lot more cleanup on the hot rolled vs. the cold rolled sheet steel? Is the scale that is left behind on the hot rolled stuff a pain when I need to paint this? I am looking for the material for my floorboards.

 

hot rolled is a pain to clean ..i only use cold rolled

 

Cold rolled will be cleaner and tougher material. The process of cold rolling adds strength to the material by "cold working" the material.

 

I'd go with cold rolled.What gauge are you planning on using?

 

I would use cold rolled. The scale on hot rolled sometimes flakes after time. thats just my opion. also removing the scale for hot rolled is a pain in the ***.

 

Consider P&O hot rolled sheet. More expensive than hot roll, less than cold rolled.

P&O ("pickled and oiled") is a follow-on treatment to the steel as it comes off the hot roll mill. Basically, it removes the mill scale from the hot roll.

 

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If you can find "Pickled & Oiled" hot rolled, it'll probably be less expensive and even easier to work than cold rolled. Pickling removes the scale. The surface is not as smooth as cold rolled but given the surface prep that goes into pre paint, you'll never know the difference. The auto industry used a lot of H.R.P.& O. on interior stuff. (Remember: they made fenders and door skins that had to be paint ready right out of the die-they didn't have time for multiple coats of primer with sanding between coats.)

 

Use CRS and you'll avoid all the h***le of HRS.

 

CRS is the way to go, SAE 1018 is the most common. HRS is more readily machineable, but there is really no advantage using it for auto body work. I've used the pickled HRS stock before, which is not always easy to come by.

Bob

 

That's kinda the way I was leaning. I was looking at cold rolled 1018 in a 22 gauge or possibly a 20 at the heaviest.

 

I'd recomend 20ga. CRS as a minimum. Even with beads 22 is kind of lite for floors. If the floor is fairly flat I would bump it up to 18 maybe even 16ga.

 

I used 18 ga. mild steel for my 37's floor. I will use the same metal for body patch panels.

 

I used some cold rolled 18 ga in my hotrod .... rolled some beads in it and it worked out great

 

No opinion over hot versus cold rolled, always used cold so I wouldn't know the difference. Took a cl*** years ago from Ron Covell. His opinion was that 20 guage was good for most patch panels. Most cars up into the 70s used 19 gauge to start with and by the time you factor in rust, sandblasting, and sanding its now thinner. Thats what I have used and it always seems to work out about right. 18 guage is harder to work with but if I was going to do a floor or something I might go with that. On the 40 Chevy truck I built awhile back I actually used the skin off an old fridge! It was pretty thin at only 23 guage but none of the pieces were all that big and it was plenty strong. Cheap as well!

 

Steel's down. Buy the cold roll sheet. 18 gauge is the ticket

 

Root, I would not go thinner than 18g. But since you have the Golden Gate bridge for a subfloor you prob will get away with 20g

 

I'm familiar with the pickled and oiled HRS. Does anyone know if that's what NASCAR uses? I read that they use a double annealed steel, but I've never seen it available in catelogs.

 

I've never heard of "Double Annealed" steel, but there is a product called AKDQ steel that is made for Deep draw work. It is very soft and malleable.
AKDQ = Aluminum Killed Draw Quality. AKDQ is a cold rolled product. They add aluminum to the steel to make it bend and stretch better.


You won't find HRS or HRP&O in any gage thinner then 16 ga. (.06")
.

 

i have some AKDQ here, it is not something you would use for a floor unless you were stamping it, even then, the factories use cheaper stuff since the wrinkles in a floor pan are not an issue. My AK steel came from a local hood scoop company, needed it for its deep drawing capabilities. Great for complex repair pieces.

 

Tman,
I wasn't saying that he should use it for his floor pan. Just trying to answer the question about "Double Annealed". Thanks for clearing that up.
.

 

Thanks for the reply CD, didn't mean to off the subject.

 

I am not gonna run anything as thick as 16 or 18.
I think I will use 20 gauge. The substructure should be plenty. Once it is glued into place it will essentially be one giant truss anyway.

 

No worries, my reply was to others who might get confused. AKDG came up a few times before and I found it better to steer the talk premptively!

Like I said Mr Lagrange, your car is prob one of the few that could use the thinner floor and be safe.

 

I agree, and..........
You can depend on what Tman says.

 

I thought only aluminum could be annealed? If you can anneal steel someone needs to do a tech on it!

 

The difference between CR and HR is tensile strength, but in most situations where Weight/strength ration isn't an issue,(hot rod structure and brackets, etc), cold rolled is my choice(more mallable, etc).

 

Quote: "Once it is glued into place it will essentially be one giant truss anyway."
I had a truss, once.<!-- / message --><!-- sig -->

 

aluminized steel would be great for a floor, its used lots now days, pretty much any appliance manufacturing plant will have it as s****, comes in lots of gages, i have some thats been sitting outside for 10 years and no rust yet, can be painted, one thing about hot rolled is the steel mills say it has a .010 tolerance, doesnt sound like much but it can add up, cold rolled usely will be right on the money or maybe .001 tolerance, hot rolled has a difference in hardness between the edges and the center of the sheet, cold rolled will be the same.


http://en.wikipedia.org/wiki/Aluminized_steel

 

AK steel is not Aluminized.