gsport
Well-known member
what's the difference?? what's the best for making brackets and stuff in an automotive environment?? same guage, which would be stronger??
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hot and cold roll steel...
- Thread starter gsport
- Start date
well hot roll is more bendable than cold roll. cold roll is used for shafts and etc.
at work we use hot roll for 'making' stuff, and cold roll for line shafts, bushings etc.
It's not technically strength, but the properties that the metal has because of the way it was formed.
hot roll = bendable/ wont snap as easily.
cold roll= stiff as can be but can snap, break, etc.
at work we use hot roll for 'making' stuff, and cold roll for line shafts, bushings etc.
It's not technically strength, but the properties that the metal has because of the way it was formed.
hot roll = bendable/ wont snap as easily.
cold roll= stiff as can be but can snap, break, etc.
what's the difference?? what's the best for making brackets and stuff in an automotive environment?? same guage, which would be stronger??
Hot rolled is formed when the steel is still an ingot (before it has solidified). Cold rolled is after the ingot has solidified. It's all about the crystallization of the atoms in the steel. Hot rolled is above the recrystallization temperature, cold rolled is below the recrystallization temperature.
As far as bracket making, dunno, depends on what exactly your plans are. You can get them both in the same alloy of steel (like say 1018). Hot rolled will still have mill scale on it, cold rolled is usually without mill scale, so hot rolled is going to need more prep work to finish. Cold rolled usually holds tighter tolerances to spec out of the mill.
Stronger is a matter of opinion. Hot rolled will be more ductile (easier to bend), where cold rolled will be more brittle because it has been strain hardened through the forming process. Overall tensile strength should be about the same.
Cold rolled is typically about 10% stronger in ultimate / breaking condition. Often much stronger in yeild. Meaning it will hold a lot more before bending, but just a little more before breaking.
Flats for example are typically much more square and true dimensionally. HR edges are usually rounded where CR are flat.
Flats for example are typically much more square and true dimensionally. HR edges are usually rounded where CR are flat.
Cold roll is also a lot cleaner to work with. There is no slag layer pressed into the surface during forming as with hot roll. The slag can be a pain to remove. If you plan to Tig weld you want to remove the slag as it tends to flake up and contaminate the torch as well as the weld.
zmotorsports
ALLIANCE MEMBER
The differences have been made fairly well above. Personally when building brackets, tabs, etc. in the shop I use cold rolled, on the thin stuff I use P & O steel (pickled & oiled) so it doesn't have the mill scale. This is especially important if I am going to weld on it, it just makes a nicer weld without all of the prep work. If I have a bracket that I am going to have to bend in the brake then I use hot rolled as the cold will generally brake when bent beyond about 30 degrees. Just remember if using hot rolled to remove the mill scale. I remove it prior to bending because it is much easier to remove than after the piece is bent and ready for welding.
As far as thicknesses it really depends on what the brackets are for and what kind of weight they will be carrying as well as how they can be supported or triangulated. I stock .125", .187", .250" and .375" in 1", 1.5", 2", 3" and 4" widths so I always have whatever I need with minimal cutting. I would say the ones I seem to have to replenish the most are the .125" x 1.5" and the .187" x 2". Mike.
As far as thicknesses it really depends on what the brackets are for and what kind of weight they will be carrying as well as how they can be supported or triangulated. I stock .125", .187", .250" and .375" in 1", 1.5", 2", 3" and 4" widths so I always have whatever I need with minimal cutting. I would say the ones I seem to have to replenish the most are the .125" x 1.5" and the .187" x 2". Mike.
rsanter
Well-known member
hot roll is exactly that. its rolled out to dimension hot
it will have a scale on it that can and will need to be removed with a sander or grinder
its less expensive, but is not as consistent dimensionally
good for general purpose stuff
cold rolld is rolled out to dimension cold. this has the effect of 'work hardening' the material. it will be a little stronger but more susceptable to 'over working' and then cracking if you are going to be beating on it and bending it.
it has very nice flat parallel surfaces as it showes up (or in the case of a round stock it very round) and is ready to cut to shape and use
most of the time for general use you can do with hot rolled, for specific purposed you need cold rolled
bob
it will have a scale on it that can and will need to be removed with a sander or grinder
its less expensive, but is not as consistent dimensionally
good for general purpose stuff
cold rolld is rolled out to dimension cold. this has the effect of 'work hardening' the material. it will be a little stronger but more susceptable to 'over working' and then cracking if you are going to be beating on it and bending it.
it has very nice flat parallel surfaces as it showes up (or in the case of a round stock it very round) and is ready to cut to shape and use
most of the time for general use you can do with hot rolled, for specific purposed you need cold rolled
bob
Colded rolled costs more. Cold rolled has less impurities and machines better and comes with tighter tolerences, for example if you are making a shaft to fit properly through a bearing id, cold rolled would be the choice.
I associate cold rolled with accuracy and machine shops. I associate hot rolled to welded fabrication.
Brad
I associate cold rolled with accuracy and machine shops. I associate hot rolled to welded fabrication.
Brad
Underdog
Well-known member
Other than rounds do most steel supply yards carry both? I seem to see only one stack of flat stock in the different sizes. The flat stock bought in HD seems to be sheared to width and not very consistent in sizing.
rsanter
Well-known member
cold roll is much hight quality material
hot rolled has lots of misc stuff in it from the recycle process and can sometimes have hard spots in it and the exact alloy will vary a little more than cold roll
bob
hot rolled has lots of misc stuff in it from the recycle process and can sometimes have hard spots in it and the exact alloy will vary a little more than cold roll
bob