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What stainless stock to use

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  • What stainless stock to use

    It has been requested of me to make several 6" long 1 1/4 dia. nozzles. I would like to make them out of stainless, but I am unsure of which to use. It should possess reasonable shock resistance, be relatively easy to machine/bore, be affordable, and be heat treatable. Is this asking too much?
    Location: North Central Texas

  • #2
    You're not really asking too much, something in the 400 series would probably work well. 416 is a free machining martensitic steel that can be hardened. It is equivalent to 410, just better machining properties. Since you want shock resistance, the core would need to stay annealed, the low carbon content of 416 would probably do it when heat treated. I would stay away from 440C, it will harden very well, but will probably not give you the shock properties you are looking for. It's also 50% more expensive.

    The 300 series will not take heat treating, but will work harden if that would be sufficient for what you are doing.

    I did a check on the prices at McMaster-Carr, 410/416 are about the same price as 303, so it's relatively cheap too.

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    • #3
      Thanks for the assist mb.
      Only the tip needs to be hard, the hollow body is what needs to be tough, it only has an 3/16" wall thickness. So I'm not sure how to keep the core annealed!
      I need to look for a cheap source who doesn't mind small quantities.
      Location: North Central Texas

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      • #4
        You should be able to case harden it, that will only harden the top and leave the inner core or wall softer and able to withstand the shock. Not knowing how this is going to be used, you may have to do some trial and error. If you find you need something harder at the end, maybe the 440C and only hardening the end would do the trick. The 440C has a higher yield strength, so with the thin wall, you may want to look at that.

        Mike

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        • #5
          Joel:
          Does this require chemical resistance or is it being used in a food in environment? If so, 303 is used for surgical instruments and 316 and 316L (cuts like butter) is used for piping in dairy and other food applications. If this is used for crop spraying brass can be used, but naval bronze has better chemical resistance.

          If you want a stainless for heat treating then use 440C - it is very expensive and realtively easy to machine in the annealed state. Once quenched and tempered it is difficult to machine and requires either T-15 or Carbide to cut it.

          Another material you could consider is 4130. If it is hardened and double tempered it it very tough. 4140 can be hardened deeper, it is sronger, but not as tough to impacts as 4130. This wouls also be much cheaper.

          Another material you could use is O-1. I would not use it if any part needs to be threaded as it is likely to fail after heat treating at the threads.

          More information would help give a better answer - but I am not asking you to discose anything confidential.

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          • #6
            Thanks Thrud,
            I had built (with this BBS help on heat treating) a piercing nozzle designed to go through car hoods and the like. I built it out of O1, and hardned just the tip. It works so well that several friends with neighboring departments want me to build them one. I wanted to use stainless for its resistance to rust, and its toughness. The hard tip on my O1 nozzle has taken much abuse without any sign of dulling so I guess I could stick with this, but I have concerns about it rusting internally over time. Since we all have tight budgets, even parts only costs need to be kept as low as is reasonable.
            Location: North Central Texas

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            • #7
              Hell joel- I remember you!!! you was the guy who punched holes in the Chiefs hood!!!! welcome back!
              Steve
              PS was it you or me that has been gone? one of those Senior moments here!

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              • #8
                Joel

                Why not make a tube of stainless with a screw on stainless nozzle? Or even a pressed in O-1 hardened nozzle (Pin it too)

                It would be easier to start with a tube and then attach an end. A stainless end could also be brazed or TIG welded to the tube. Less work than boring out a 6" chunk of stainless.

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                • #9
                  Was me Doc, don't feel bad as I have senior moments at 38.
                  I thought about using tubing, wasn't sure if I could get some with 1/4" wall. Another difficulty is that I have 3 rows of radial discharge holes, and the bore dia. gets progressively smaller with each row to maintain velocity. So the bore drops from 5/8, to 1/2, to 3/8 over a span of about 3/4 of an inch (or so) at the discharge end of the nozzle. Perhaps I need to reconsider the 2 piece tip design. Or maybe I can plate or coat the tip for the rust resistance and stick with the easy to deal with, O-1. I am trying to keep it simple/cheap, but part failure is not an option.

                  The experts on this BBS continue to amaze me with their wide degree of knowledge. I don't suppose any one has any expertise on fluid dynamics they would be willing to share?
                  Location: North Central Texas

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                  • #10
                    you can have the finished product plasma sprayed. They take your part and spray molten 316 SS onto the surfaces for protection this way you can make it out of O1 and still get the protection of SS. Try Impreglon in Atlanta.

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                    • #11
                      Thanks for the tip. Sounds pricey, but I will see what they say.
                      Location: North Central Texas

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