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  • Hot rolled or Cold Rolled

    I could use a little education if some of you don't mind...

    I am going to start a small home project where I'll be making a vine trellis for the garden. I'll be bending and welding "3/8 and "1/4 round rod. What's the difference between hot rolled and cold rolled, and which should I use?

    Thanks a lot!

  • #2
    You'll be using hot rolled rounds. Easy to tell the difference. Hot rolled will be dark grey (it has some very light scale on it) and cold rolled will be satin grey and appreciably more expensive.

    Hot rolled is just that and cold rolled is rolled from cold billets. It heats up during the rolling process but it don't start hot.

    95% of rounds generally available are hot rolled. Cold rolled rounds are a specialty item.
    So little time...So many machine tools.........
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    • #3
      I made one for my wife a few years ago. We mainly have cold rolled in our shop. After a couple of years and after being painted it started rusting in spots. I would definitely use hot rolled.

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      • #4
        hot rolled will have a scale you'll have to grind off before welding.. cold rolled wont have the scale....

        hot roll is considered 1018
        cold roll is considered 1020

        not much difference in the two materials, i doubt there will be much difference in price.. i like cold rolled myself
        .

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        • #5
          Originally posted by brucer View Post
          hot rolled will have a scale you'll have to grind off before welding.. cold rolled wont have the scale....

          hot roll is considered 1018
          cold roll is considered 1020

          not much difference in the two materials, i doubt there will be much difference in price.. i like cold rolled myself
          There is a big difference in price because of the manufacturing differences. I ought to know, I work for the second largest processor of flat rolled material in the country.

          Generically they are 1018-1020 but the alloy differences make up about a hundred derivatives in each format.

          HR has ver little mill scale and most times none because 99% of the HR material is acid pickled prior to sale.
          So little time...So many machine tools.........
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          • #6
            all the hot roll ive seen in the last 22yrs in a machine shop and tool&die shop has had scale on it..

            the cold roll does not have scale on it..

            1018 .18% carbon
            1020 .20% carbon... they have a % range of carbon and manganese content they hit during processing...

            basicly angle iron is hot roll.. hence the scale.
            yes hot roll will be cheaper, dont know how much cheaper havent bought any lately to compare...

            cold rolled will have a closer final tolerance and be more square than the same size piece of hot rolled..

            hot roll is rolled while its still hot enough to produce scale.. cold rolled is rolled well below scaling temperature, meaning no scale..


            copied and pasted this, pretty good explanation..

            Why does Hot Rolled Steel have a rough, blue-grey finish, while Cold Finished Steel has a smooth grey finish?
            Hot Rolled Steels are just that - They are heated up red-hot and pushed through rollers that squeeze the metal, literally squishing it into a particular profile, depending on the shape of the rollers. The process takes a long time, and because the steel is so hot for so long in the open air of the steel mill, the surface of the metal has has a long time to oxidize, producing a thick, tough oxide scale with the characteristic blue grey finish of the final product.
            Cold Finished Steels are just that - the final rolling is done when the steel is cold (room temperature), the whole operation bathed in oil, so the finished product is unoxidized, the grey of the actual steel, and as smooth as the rollers that do the processing.
            Last edited by brucer; 11-17-2010, 01:41 AM.
            .

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            • #7
              Whatever. I only have 30 years in the industry.
              So little time...So many machine tools.........
              www.flipmeisters.com

              Miller, Hobart & Lincoln TIG/MIG/-
              Hypertherm Plasma (Thanks Jim)
              Plasma-Cam DHC (coming shortly)
              Harris OA
              Too many motorcycles.............-
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              • #8
                If you are going to do machining on the semi-finished weldment, realize that CRS has a much greater tendency to have internal stresses built into it from the forces involved in the cold rolling process. Those stresses can/will relieve themselves during and after any machine work you may do. Otherwise, as has been said, CRD is more expensive, so it may come down to dollars and cents or personal preference as to which product you use for a non-machined piece.
                Miller 251, Lincoln PrecisionTig 275, Miller DialArc 250 AC/DC, Hypertherm 900, Bridgeport J-head, Jet 14" lathe, South Bend 9" lathe, Hossfeld bender with a collection of dies driving me to the poorhouse, Logan shaper, Ellis 3000 bandsaw, Royersford drill press and a Victor Journeyman O/A.

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                • #9
                  http://www.metalreference.com/index1.html
                  Ed Conley
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                  • #10
                    I prefer cold rolled. It's cleaner, no scale, and truer sizes. It's stiffer to work with, but it also bends smoother with the right equipment. I do ornamental work and I just like the CR better. Yes, it's more $$, but on a lot of what I do the material costs are not a big factor. I'm going for whatever gives me the best finished product.
                    Jim

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                    • #11
                      Long long ago in a simpler time.
                      CRS was called "machine-steel".

                      It was intended to be stocked and sold,
                      in enough standard cross-sections to be used as is.
                      You would design your tool / machine to be built from
                      CRS sawed to lenght, maybe ends trimmed on a Cincinatti
                      or a Milwaulee. Holes added where needed. DONE.

                      Size was / is held to nominal - .002" or so.
                      The "cold rolling" that produced the reliable size
                      and good finish, also packs in stresses near the surface.
                      =========
                      No matter, milling partial shapes was not the intended use.
                      HRS was the intended product if eneven and / or considerable
                      material was to be removed.
                      The HRS bars are basicly self-stress-releiving.

                      Obviously this is why a weldment or HRS holds shape
                      so much better than CRS..... the welds on CRS will be
                      just as good but the weld heat thermally releives stresses
                      from the side welded, leaving the opposite side in it's stessed
                      condition.......hence warpage.
                      vg
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                      • #12
                        Originally posted by brucer View Post
                        hot rolled will have a scale you'll have to grind off before welding.. cold rolled wont have the scale....

                        hot roll is considered 1018
                        cold roll is considered 1020
                        not much difference in the two materials, i doubt there will be much difference in price.. i like cold rolled myself
                        I see 1018 cold rolled 1/4 rod is about 68cents per foot. Hot rolled CQ (1015)is about 50cents per foot. Thats a substantial cost difference over a large project.

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                        • #13
                          The difference is just in the way they are created at the mill. This is the best article I could find that describes the difference the best:

                          http://metalsupermarkets.com/blog/di...-rolled-steel/

                          What are you trying to do?

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                          • #14
                            Originally posted by mmarshawn View Post
                            The difference is just in the way they are created at the mill. This is the best article I could find that describes the difference the best:

                            http://metalsupermarkets.com/blog/di...-rolled-steel/

                            What are you trying to do?

                            Its a 4 year old thread. You dug that up for your first post?
                            "never argue with an idiot; he'll bring you down to his level, and win by experience"

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                            • #15
                              Originally posted by mmarshawn View Post
                              The difference is just in the way they are created at the mill. This is the best article I could find that describes the difference the best:

                              http://metalsupermarkets.com/blog/di...-rolled-steel/

                              What are you trying to do?
                              Not nearly as good as the one posted by Broccoli 4 years ago. And the OP is unlikely to reply, since his last post was also 4 years ago.

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