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Thread: Information needed on 308 MOT stick rod

  1. #1
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    Information needed on 308 MOT stick rod

    Hi,
    30 years ago I bought a couple ton of rod from the US military. In it was some 308 - MOT series stick electrode. I've used it and would like to replace with similar but cannot find a supplier for the 308 with an MOT specification - nor can I find what the MOT specification means. Does anyone know a supplier or have an answer on the specification?
    Thanks,
    Ron

  2. #2
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    Re: Information needed on 308 MOT stick rod

    Look a bit closer Ron and see if it isn't marked 308MoL, (electrode designed for welding ASTM CF3M stainless castings).

    308MoT would be a designation for a bare TIG rod of similar purpose.

    Matt

  3. #3
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    Re: Information needed on 308 MOT stick rod

    Do a search online for 309 MOL rod. It is a stainless rod that is heat, crack, and corrosion resistant.

    Buy a small sample to try. I think you may find it welds the same.

    Scott
    Fab Manager
    Welders360.com
    New guy.

  4. #4
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    Re: Information needed on 308 MOT stick rod

    Hi Folks,
    What I have is very clearly 308 MOT. They even have it nicely printed on the rods. It was made by Alloy Rods whom was aquired by Esab.
    Thanks,
    Ron

  5. #5
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    Re: Information needed on 308 MOT stick rod

    Oh, Matt,
    Thanks for the reply. What I had was 1/8"x16" stick electrode. Nearly a white coating with black printing for the alloy spec.
    Thanks,
    Ron

  6. #6
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    Re: Information needed on 308 MOT stick rod

    Quote Originally Posted by Ron Ohler View Post
    Oh, Matt,
    Thanks for the reply. What I had was 1/8"x16" stick electrode. Nearly a white coating with black printing for the alloy spec.
    Thanks,
    Ron
    I'll see if I can find anything at the shop today in the old blue Alloy Rods catalogs.

    I'm guessing it's an 18-8 with something added. If you're welding dissimilar materials 309 is preferred these days.

    Matt

  7. #7
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    Re: Information needed on 308 MOT stick rod

    I couldn't find the blue stainless guide Ron, but did find it in the 1978 guide. Pics are below.

    You could ask your weld supplier armed with the chemistry, but I'm betting it will be a no go. I suspect they will point you to MIL 308 Mo which appears to have a safer chemistry all around.

    Current Esab page for MIL 308 Mo here; http://www.esabna.com/EUWeb/AWTC/Lesson5_28.htm

    Matt
    Attached Images Attached Images    

  8. #8
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    Re: Information needed on 308 MOT stick rod

    Hi Matt,
    WOW! You did find it. I'd contacted another welding supplier today. Airgas. They contacted Crown Alloys who said there was no such thing. I did make a mistake when I said they were 16" long rods. They were 14". What I was remembering was the full spec was 308 MOT-16. You showed this in your copies. I recalled being told it was used for welding armor plate. I used it for various cast steel and general hot rolled applications including gravel equipment joining of cutting edges and ripper teeth and repair of cast steel or some applications needing a tough weld suitable for dissimilar metals. Yes,
    I did do some stainless plumbing items also - assumed to be 308. I never had a failure with it in any application. Darn nice running rod - just heats up significantly like any stainless stick likes to. I don't know metalurgy well enough to know what issues you mention a concern with. Can you elaborate?
    Thanks so much,
    Best regards,
    Ron

  9. #9
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    Re: Information needed on 308 MOT stick rod

    Hi Ron, I don't like all the carbon in this rod for SS. It makes sense for manganese steel or joining manganese to carbon steel and welding of ASTM CF3M or ASTM CF8M castings.

    With the .15 carbon when welding an 18-8 (301,302,4,8 etc.) there is going to be some chrome carbide forming with the chance of the parent 18-8 going "lean" and losing chrome. Of lesser concern but should be noted is there will be some ferrite in the weld.

    It's safer and cheaper to use a recommended filler with 18-8. I bet it also would be cheaper to use 309 to weld dissimilar steels than to use MIL 308 Mo (.11 carbon) with strength only going down from 98ksi to 91ksi.

    Matt

    Matt

  10. #10
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    Re: Information needed on 308 MOT stick rod

    Hello Matt,
    Thank you so much for your help and efforts. I've tried to find this data since last year. Hard to believe that 3 different companies couldn't tell me what I had.
    Thank you,
    Ron Ohler

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