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Welding 1/2" Stainless

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  • #16
    Heat

    Originally posted by joebass
    If it gets that hot I would use 310 or 321 SS. Not sure why they would recomend 316 anyways. I always thought that that was used mostly in the marine industry.
    Joe..

    The people in question recommended SS Period to them... I figured that 321 would be the first choice since the chromium is combined at High Temps stabilizing it, and 321 also adds Titanium, But these grates will have to be made over & over as they wear out... So the cost of 321 aircraft spec is a factor...

    I figured 316L because it has typically 3% Carbon, so less is available to precipitate with the chromium. When chromium Carbides form under high heat it causes intergranular corrosion, and decreases fatigue resistance. So I figured 316L is the way to go for the cost. 321 would be my first choice.

    But I'm not familiar enough with using SS in a High Temp Application... So if any of you think that it will warp excessively under these conditions... I will have to tell them to reconsider using it...

    Can anyone recommend another material... That I could weld up for them... If SS is not a good choice?

    Thanks,

    Tony
    Miller Dynasty 300DX Runner
    Roadster BWE

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    • #17
      I wonder how long plain old A36 would last, i have it in my coal fired forge and no sign of wear, and that sees temps upwards of 5000*, but it also depends on the oxidizing, neutral, or reducing atmosphere that the grates will be in. I think the stainless would fair well so long as the heat was relatively consistent throughout the grate. But, I work with stainless very little, so
      hre

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      • #18
        It's been my experience that intergranular corrosion is only a factor under extremely HIGH stress loads. For instance..... We used 17-4 PH H900 stainless for high tension studs to joint a 15-5 PH H1150M cylinder block to a class 30 cast iron machine base. The CI base held, the 17-4 studs held, but the 15-5 suffered stress corrosion cracking and a HUGE conical piece of metal would crack out of the block of 15-5....You could see the cracks starting at the base of each thread caused by the chlorine content of the tapping fluid used when tapping the threads for the studs.
        I think 1/2" or 3/4" HR A36 would be fine, expecially if your going to make a few of these.
        Denny
        MillerMatic 185
        HyperTherm 600
        Dynasty 200 DX
        Will-Weld 200A Buzzbox
        O/A torch

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        • #19
          SS Vs Steel

          Originally posted by Coalsmoke
          I wonder how long plain old A36 would last, i have it in my coal fired forge and no sign of wear, and that sees temps upwards of 5000*, but it also depends on the oxidizing, neutral, or reducing atmosphere that the grates will be in. I think the stainless would fair well so long as the heat was relatively consistent throughout the grate. But, I work with stainless very little, so
          Coalsmoke,

          You hit the nail on the head... That's just it. I quote: I think the stainless would fair well so long as the heat was relatively consistent throughout the grate. End Quote.

          You see the grate supports the Coals themselves... So The Temps the grate will be exposed to will be wildly inconsistant. And Because SS does not transfer heat, being a poor themal conductor... The heat will take a long time to spread out... So one part of the grate will get red hot, and another part not... So When it expands unequally I think it will bend like a banana... And crack the welds & fall apart... Steel is 219% better of a heat conductor... So maybe it will heat and expand more equally.... What do you guys think?

          Tony
          Miller Dynasty 300DX Runner
          Roadster BWE

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          • #20
            i built some really heavy duty burn off racks for a company once, they were out of a36 and they held up real good, in my opinion, if they go through these frequently.......i would definately consider some heavy mild steel and weld it with something that will let it flex from heating and cooling.
            hope this helps

            marty
            Miller Synchrowave 250
            OTC 300DM with external wire feeder
            Miller XLi Dale Sr., fibre metal hoods
            Metaltek of Ky. Inc.
            Home of the Stephensburg weld

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            • #21
              Rage, I think that's going to be the issue. Considering that this grate in mild would only be 20% of the SS, I would make a mild steel one first, if it doesn't work out, then go to SS. One thing for sure, if you build the SS one first and it goes south, the customer will not be happy.
              hre

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              • #22
                How about coating a mild steel version with a ceramic? The ceramic may allow the life of the part to extend many times, and it might not be too expensive. I am not sure the JetHot stuff would work, but maybe they can point you in the right direction...

                Just brainstorming here,
                Joshua

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                • #23
                  RoydRage

                  I'm just imagining the shape of this grate so this may not be possible...couldn't you make a mild steel frame and cut slots for cast iron bars to rest in.....seems it would cut down on expansion and cracking concerns and bars could be replacable.
                  Ooops...just did a search and could only find one inch thick cast bar.

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                  • #24
                    Ideas

                    Thanks for the ideas guys...

                    This thing is pretty complicated... It has to fit in a frame, and pivot to dump the coals... So I'm pretty limited to 1/2" The original Cast Iron piece really has triangular bars... that go from 3/4" on the top where the coals sit to 3/8" at the bottom... So I opted for 1/2 flat stock.

                    There is another problem... There is 1" round stock on each side that the grate pivots on... Now I don't envision my welder being able to weld these 2" long 1" dia jobs to the side of the 1/2" flat bars... So I'll maybe have to make them thread in.

                    Now My Tig Calculator says "3 Passes" How do you go about this... It will be corner joins... So do you do them 1-2-3... Or I'm thinking the center first, and then join them further out on each side?

                    Thanks,

                    Tony
                    Miller Dynasty 300DX Runner
                    Roadster BWE

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                    • #25
                      The original Cast Iron piece really has triangular bars... that go from 3/4" on the top where the coals sit to 3/8" at the bottom
                      They are tapered so nothing gets stuck between them. With 2" flatstock, you may have a problem with coals of the correct size getting jammed between the bars.

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                      • #26
                        Right On!

                        Originally posted by calweld
                        They are tapered so nothing gets stuck between them. With 2" flatstock, you may have a problem with coals of the correct size getting jammed between the bars.
                        You are really on the ball! That's exactly right... To stop that from happening, I decided to add an extra bar & space them closer together..

                        Thanks,

                        Tony
                        Miller Dynasty 300DX Runner
                        Roadster BWE

                        Comment


                        • #27
                          Here is a link to Miller's weld calculators

                          http://www.millerwelds.com/education/calculators/
                          Rich Ferguson
                          Sales Technician
                          Jackson Welding Supply Co.
                          "Keep America Strong.....Weld It"
                          www.jacksonweldingsupply.com

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                          • #28
                            RoydRage

                            Don't be scared off by the high numbers the miller calculator puts out. They speculate that you are using large pieces of the given thickness (which act as a heat sink) and are welding for the highest production rate. In your case, to weld a 2" long piece of 1" round bar to a 1/2" bar you are not going to need or want 400 amps. Three passes at 150 amps will be fine and about as high a heat as you can control. If possible, you might want to drill through your flat bar and insert the round for a fillet on either side or put a chamfer inside or out and then weld to finish flush.

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