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Thread: Millscale

  1. #51
    Join Date
    Aug 2010
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    NJ
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    327

    Re: Millscale

    Quote Originally Posted by rockland View Post
    So what are other differences between HRS and CRS?

    Hot roll is rolled out red hot. It's often got carbides and carbon and inclusions in it from the rolling. This is why machine operations on hot roll are often remarked upon with negative sentiment. There are tough spots hard spots and other things that make machining an unpleasant experience. It is also almost never square. IT moves around rather a hot under the force of rolling out. So the dramatic trapezoid is the norm not the exception.

    Hot Roll has more carbon than cold roll and it is not standardized, so black-smithing the stuff can be tedious.

    Hot roll can come scale free if it was acid pickled and oiled to prevent rust the finishing process is often abbreviated as P&O.
    In that state it is hard to distinguish from coll roll

    Cold roll is rolled out cold, it is buttery to machine, but it also gets a skin on the outsides that can cause all manner of problems when that skin is machined away. The stress on one side with the skin versus that where it was removed can cause a part to turn bananna shaped.

    So if you are going to machine the skin off your stock hot roll may be the better choice. If you are just going to drill it full of holes cold roll might be better, but cold roll is more expensive because the process is more energy intensive.
    Hey~!! It's a hobby. It's not supposed to make sense~!!

  2. #52
    Join Date
    Jul 2013
    Location
    Central Florida
    Posts
    74

    Re: Millscale

    Excuse me Stick-man, do you feel that "Tiger Paw is the best disk? Thanks, MagicHat.

  3. #53
    Join Date
    Nov 2009
    Location
    Hellinois
    Posts
    5,707

    Re: Millscale

    Quote Originally Posted by MagicHat View Post
    Excuse me Stick-man, do you feel that "Tiger Paw is the best disk? Thanks, MagicHat.
    I can't compare it to anything but horrible frieght. I really just started using them for this, because I didn't realize how fast they actually remove material.
    "Where's Stick man????????" - 7A749
    "SHHHHHH!! I sent him over to snag that MIC-4 while tbone wasn't looking!" - duaneb55
    "I have bought a few of Tbone's things unlike Stick-Man who helps himself" - TozziWelding
    "Stick-man"

  4. #54
    Join Date
    Jul 2013
    Location
    Central Florida
    Posts
    74

    Re: Millscale

    Thank you! I was surprised to hear about the material removal too. MagicHat

  5. #55
    Join Date
    Apr 2012
    Location
    Prewitt, New Mexico
    Posts
    150

    Re: Millscale

    What I have noticed is if the end product is gonna be outside in the elements the mill scale resists rusts. I have some bbg grates I have made and i have ground it all to shiny metal but even a small amount of humidity will have alot of surface rust within hours. if I just grid down the parts needed welded and leave mill scale on the rest it doesnt rust if left out a week or so.

    If I grind everything shiny then use it the same day over a fire the black coating will also protect it from rust a bit to unlesss its raining decent and it washs off.
    HH140

    ---------------------------
    https://www.facebook.com/brandon.pike.9

  6. #56
    Join Date
    Nov 2010
    Posts
    144

    Re: Millscale

    Do you also get more spatter with mill scale on ?
    Miller 350P
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  7. #57
    Join Date
    Apr 2012
    Location
    Prewitt, New Mexico
    Posts
    150

    Re: Millscale

    I havent noticed a difference in spatter but I use flux core at home so theres a bit of spatter anyways. The mill scale around the area being welded peels off from the heat.
    HH140

    ---------------------------
    https://www.facebook.com/brandon.pike.9

  8. #58

    Re: Millscale

    Surfaces on which weld metal is to be deposited shall
    be smooth, uniform, and free from fins, tears, cracks, and
    other discontinuities which would adversely affect the
    quality or strength of the weld. Surfaces to be welded,
    and surfaces adjacent to a weld, shall also be free from
    loose or thick scale, slag, rust, moisture, grease, and
    other foreign material that would prevent proper welding
    or produce objectionable fumes. Mill scale that can withstand
    vigorous wire brushing, a thin rust-inhibitive coating,
    or antispatter compound may remain with the
    following exception: for girders in cyclically loaded
    structures, all mill scale shall be removed from the surfaces
    on which flange-to-web welds are to be made.
    The source of this information is AWS D1.1 so I would say yes it should be removed.

  9. #59

    Re: Millscale

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    First time posting Pics, hope it works. I got some scrap steel from a friend that has a gray coating on it. I used a 80 grit wheel and cleaned both sides, but when I ran some TIG beads on it, it smelled bad and on the back side (on my table) it left a white residue. I assume this is not good to breath? Does anyone know what it is?

  10. #60
    Join Date
    May 2014
    Location
    Arkansas
    Posts
    5

    Re: Millscale

    I have used concrete cleaning acid to remove mill scale. It is fairly quick acting but very dangerous. I have looked for other means other than grinding and did an experiment. I took some scrap pieces of hot rolled and put them in a plastic coffee can and covered it with 5% acid white vinegar and left for about 2 days. I took steel wool and rubbed the mill scale and it had dissolved and came off easily. I bought some 2 1/2 inch pvc pipe 9ft. long and glued a cap on one end. I degreased 3 8ft. sticks of handrail cap and 2 8ft. sticks of 1 inch punched channel. I was able to put all this in the pipe and poured in the vinegar.It only took 1 and a half gallons to cover the steel by a couple of inches. I plan on pickeling the steel for 48 hours and then pour off the vinegar and wipe the steel with steel wool and see how this works. I will post the results!
    Last edited by Grady_Fab._&_Forge; 05-09-2014 at 06:50 PM.

  11. #61
    Join Date
    Jan 2012
    Posts
    326

    Re: Millscale

    I use vinegar as well. It works great. Usually 48 hours does it, and I can just hose the dissolved scale off. Cheap and green!

    Sent from my SCH-I545 using Tapatalk

  12. #62
    Join Date
    Jan 2012
    Posts
    326

    Re: Millscale

    It also strips rust really well.

    Sent from my SCH-I545 using Tapatalk

  13. #63
    Join Date
    May 2014
    Location
    Arkansas
    Posts
    5

    Re: Millscale

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  14. #64
    Join Date
    Mar 2004
    Location
    B.C. Canada
    Posts
    2,733

    Re: Millscale

    I toured a large manufacturing plant making backhoes and they had minimal ventilation and none localized. They used hard wire (GMAW). I asked the guy taking us around and he said the major amount of smoke is caused by oxide scale on the plate. Since all their material was cut, formed and sand blasted/wheelabraded before delivery they had no smoke problem. I seemed to have some truth to the statement because there was no smoke evident even around the robotic arm that welded on one piece for over a shift.

  15. #65
    Join Date
    Sep 2014
    Location
    Ontario Canada
    Posts
    11

    Re: Millscale

    Is Acetone safe to weld on after....like I know its ok if you get it all off but lets say u miss a spot and tig weld on it, can it affect u the fumes from the acetone?

  16. #66
    Join Date
    Dec 2010
    Location
    Utah
    Posts
    2,080

    Re: Millscale

    If you let a spark get into the trash can where you tossed the tag you might get a surprise. (Don't ask how I know)

  17. #67
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,269

    Re: Millscale

    Zap, was the grinder in the picture the one that bit you? I have its little pygmy twin brother. the barrel is just big enough a gloved hand (I got stubby fingers) doesn't get a real good grip. Once it got me on the other hand with a hard disc so white knuckle bone was visible. A few days ago on start up it leaped from my hand and skittered across the floor ruining a Norton Blaze disc. I have a newer DeWalt 4.5 higher powered version with soft start. Its behavior is much better.

  18. #68
    Join Date
    Dec 2011
    Location
    Texas
    Posts
    631

    Re: Millscale

    Quote Originally Posted by richy.tig.stick View Post
    Is Acetone safe to weld on after....like I know its ok if you get it all off but lets say u miss a spot and tig weld on it, can it affect u the fumes from the acetone?
    Acetone not sure. But chlorinated compounds (some brake cleaners, TCE, etc.) can generate phosgene gas in a welding arc. One whiff can kill you and that is no joke or urban myth.

  19. #69
    Join Date
    Feb 2014
    Location
    VIRGINIA,MN
    Posts
    291

    Re: Millscale

    mill scale, oxides, surface trash, whether it be HRS CRS SST or Alum, if you are welding on it, grind it off. can't count how many times I have watched guys fight with a weld, then grind it clean and say "ohh, that is much better".. 5 minutes with a grinder is better that every day looking at a poor weld because of lazy prep.... just my $0.02

  20. #70
    Join Date
    Apr 2013
    Posts
    28

    Re: Millscale

    Hi Fellow Sparks.. When evr I TIG on hot rolled 1" sqr tub, I get a weld puddle that looks like a has bubles just under the flwoing hot metal and when they break surface it loks like a worm pile sometimes. Very weird, tried to just boil the bubbles out and that did not work

    any suggestions ?? i alsu just use 100% argon gas and 2% thoriaed


    Keep Sparkin..... WWoW (Whild Welder own Wheels)

  21. #71
    Join Date
    Jan 2009
    Location
    NY
    Posts
    97

    Re: Millscale

    U tell them ae

  22. #72
    Join Date
    Jun 2012
    Location
    Laredo, Tx
    Posts
    4,302

    Re: Millscale

    Quote Originally Posted by WWOW View Post
    Hi Fellow Sparks.. When evr I TIG on hot rolled 1" sqr tub, I get a weld puddle that looks like a has bubles just under the flwoing hot metal and when they break surface it loks like a worm pile sometimes. Very weird, tried to just boil the bubbles out and that did not work

    any suggestions ?? i alsu just use 100% argon gas and 2% thoriaed


    Keep Sparkin..... WWoW (Whild Welder own Wheels)
    Well first of all, have you properly ground off/removed the millscale?

    If you have, then you have a gas shielding issue. You cannot "run over" the wormholes with the tig torch that is carrying contaminated shielding gas, or otherwise suffering from improper gas shielding. You need to find the gas issue first----check every single fitting from the argon bottle all the way to the tig torch connector under the handle to the torch head and consumables.
    1st on WeldingWeb to have a scrolling signature!

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  23. #73
    Join Date
    May 2016
    Posts
    21

    Re: Millscale

    ive seen people do a vinegar bath with big pieces instead of wasting abrasives.

  24. #74
    Join Date
    Dec 2013
    Location
    Mount Tabor VT
    Posts
    6,269

    Re: Millscale

    Quote Originally Posted by RodJ View Post
    Acetone not sure. But chlorinated compounds (some brake cleaners, TCE, etc.) can generate phosgene gas in a welding arc. One whiff can kill you and that is no joke or urban myth.
    I buy non chlorinated brake cleaner. I like acetone, but using a wire brush or paper towel to wipe leaves bits of lint, so last thing is a squirt of non chlorinated brake cleaner. I've considered one of those refillable spray cans you use with compressed air, & acetone.

    Willie
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  25. #75

    Re: Millscale

    Quote Originally Posted by Nick_Reno View Post
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    First time posting Pics, hope it works. I got some scrap steel from a friend that has a gray coating on it. I used a 80 grit wheel and cleaned both sides, but when I ran some TIG beads on it, it smelled bad and on the back side (on my table) it left a white residue. I assume this is not good to breath? Does anyone know what it is?
    That coating looks like cold galvanizing or zinc that was sprayed on? Try grinding it off.

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