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I Forge Iron

thingmaker3

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Posts posted by thingmaker3

  1. The added carbon is not "just at the surface." It is, however, more concentrated at the surface. "Case depth" is usually the depth where a quenched part will be 50% martensite. (This measure is easy for the QA folk to test with an etch.)

    Diffusion rate of carbon in steel is proportional to the difference in carbon levels. So a low-carbon piece in a carbon rich atmosphere will carburize at a higher rate than a medium-carbon piece. A high-carbon piece in a carbon free atmosphere will decarburize at a higher rate than a medium-carbon piece.

    As noted earlier, temperature plays a geometric role.

    The diffusion rate is a rate, so more time means more difference. Of course the rate changes over time because concentrations change over time.


  2. What would work well for you is a 50AMP "spider" box like the construction guys use... It has one 50amp input (your 30 amp in this case with a 50 amp plug) and several outlets all with there own breakers.. Two 220V (one 50, on 30 amp ) and 6 120V all GFI.. You can by one on craigslist for less than $100 if you watch ( I have three bought that way)
    50 amp plugs won't fit into 30 amp receptacles - the pin configurations are different. Of course, one could either change out the plug or buy an adapter.

    The purpose of the green wire (sometimes a bare wire) is to keep the case of your equipment at ground potential - zero volts relative to ground. This is the same potential your body is usually at. As Glen wisely noted, the "neutral" wire is not always at ground potential and should never be connected to equipment case or conduit or anything else anyone might touch.
  3. "Bend resistant" usually means "flexural yield strenght exceeds demand of application." In your case it means a flexural yield strength exceeding 23.6ksi. "Exceeds" usually means by a factor of two, for safety. Any plain-carbon cold-rolled steel would do the deed. So would most hot-rolled low-alloy steels.

    What kind of steel are you using now?

  4. Ya'all made me think on this one so I googled the msds sheets for ferric chloride: says it is an acid.

    Now you've got my curiosity piqued. (Tit for tat, eh?) I browsed a few MSDS sheets myself as a result. Most did not contain the word "acid," but one did say "inorganic acidic salt."

    Additional surfing turned up several kinds of Windex.
  5. Ferric Chloride is not an acid*. It is a corrosive salt. Baking soda won't "neutralize" it. Niether will isopropanol* (aka Windex).

    Instead of "dipping" the piece in water, try rinsing it off really well - even scrubbing with a soft cloth or brush.

  6. I have found, and use this often, that if I want more carbon in an end of a bar, I simply heat it in the coal forge to a welding heat.
    ...
    It's also a very deep penetration of carbon, not just on the surface.


    The "secret" here is the very high temperature. Rate of carbon diffusion into (or out of) steel is proportional to the square of the Kelvin temperature. A 16 percent increase in temperature (from 1700F to 2000 F)gives almost 36 percent increase in diffusion rate.
  7. All steels go non-magnetic at essentially the same temperature, the Curie point, which is right around 1415 to 1420 F, depending on your reference.
    I've seen a chart in one of the ASM books showing non-magnetic (which is indeed the "Curie point") decreasing as carbon content increases to eutectoid, and then holding steady thereafter. The nonmagnetic Curie point also depends on composition - for instance: enough nickel will push "nonmagnetic" down below room temperature. (This is why magnets don't stick to 300 series stainless.)

    I would not use superquench for 1040. Too much carbon for that harsh a quench.
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