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Opinions on tools steels for general shop projects?

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  • #16
    Originally posted by cameron View Post
    Does heating to the non-magnetic temperature get you to an effective quenching temperature for all steel alloys, most of them, or only the simpler high carbon types?

    I don't mean the ideal quenching temp, just what works reasonably well in the home shop.
    https://www.bladesmithsforum.com/ind...r-curie-point/
    Last edited by MichaelP; 05-08-2017, 02:50 PM.
    Mike
    WI/IL border, USA

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    • #17
      Originally posted by cameron View Post
      Does heating to the non-magnetic temperature get you to an effective quenching temperature for all steel alloys, most of them, or only the simpler high carbon types?

      I don't mean the ideal quenching temp, just what works reasonably well in the home shop.
      Some steels need to be heated more; IIRC A2 tool steel is one example although it's been a while since I've worked with it.

      "Non-magnetic" works well with the simple high carbon steels though, like O1, W1, 1095, 1085, etc. For anything else, you'd better look up the proper heat treatment if you want to get it right.

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      • #18
        Some good basic ferrous (steel) metallurgy info to be found here: http://www.cashenblades.com/info.html
        To get in a little deeper do a Google search containing the author's name "Kevin Cashen".

        A few of hints regarding 'tool steel' and DIY heat treat:
        - become familiar with TTT or better yet CCC diagrams which, for a given steel, tell you how much time you have to initiate quench
        - bladesmiths (and thus knife making forums) are ahead of most HSM's in learning basic metallurgy and practical heat treat tech
        - O-1 tool steel tools can be tempered (I didn't say heat treated) in some toaster ovens ($5-$10 at Goodwill stores); 4140 can't
        - don't even think about heat treating with molten salts unless you're specially qualified
        - understand the significance of surface decarburization
        - don't even think about controlled furnace atmosphere unless you're specially qualified
        - understand what depth of hardening means and how it relates to what size of workpiece can be fully hardened
        - 'tool steels' are marketed by reputation; comprehensive published data on strength related properties are hard to come by
        - not just chemical composition but also the steel maker's melt process and QC as relates to amount, type, size, shape and distribution of harmful inclusions can be a major factor in determining strength and toughness (crack resistance) in the final application
        - understand the significance of surface decarburization

        David Merrill

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        • #19
          And understand that most need tempering or drawing... Very crucial on tools that take impact.

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          • #20
            Thank you all for taking the time to reply. I think some O1 and W1 in a couple of sizes to keep around for now. Plenty of old files and assorted semi-mystery steel to work with for when that is appropriate, but it's nice to have some good stock with predictable qualities for when you want it.

            A couple of additional questions. I noted in some of the pages referred to, it seems to stress that going right into tempering very soon after hardening and quenching is important. Just how critical are we talking about here? Minutes, hours, days? I will be doing my heating in a small electric kiln with a good PID controller so I can accurately hit temps I want for hardening. Once I quench I was thinking to cool that down and use the same kiln for tempering. Will cooling that down take longer than I want to wait? The kiln is small (~5" cube heated space) but will probably take an hour or more to cool to tempering temps. Would that be too long? Am I just over thinking this?

            And Dave Merrill, that is a good list of points to consider. No interest in molten salts, I've used those in a industrial setting for an entirely different application (stripping film coated magnet wire, believe it or not) and it was icky and a hassle, and the potential for things to go badly fast is more than I care to deal with for what I am doing at home. I am curious if you would care to elaborate on your point about controlled atmosphere furnaces. I was thinking that if I were to do much of this, adding an argon purge to my little kiln would not be such a big deal as I keep an argon tank around for my welders. Would there be a downside to doing so?

            Again, I appreciate the input. Hoping to give this another try tomorrow night.

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            • #21
              Originally posted by alanganes View Post
              I noted in some of the pages referred to, it seems to stress that going right into tempering very soon after hardening and quenching is important. Just how critical are we talking about here? Minutes, hours, days?
              Ideally, minutes. That's why waiting for the kiln to cool down for tempering is not a good idea. Tempering can be easily done in your kitchen oven.
              Mike
              WI/IL border, USA

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              • #22
                Re: Furnace Atmospheres

                My personal experience was limited to running experiments in a small industrial Lindberg furnace equipped with a hydrocarbon gas control that was setup by an experienced plant engineer. A comprehensive discussion of atmosphere control can be found starting in section 42 of this book:
                https://app.knovel.com/web/toc.v/cid...ok-volume-04/?
                This is an expensive book but you might be able to find a copy at the library of a college that offers technical programs. (Librarians tend to be helpful toward serious outside users.)
                Or try: https://www.google.com/?gws_rd=ssl#q...lume+4&spf=640

                IIRC there was some discussion on one of the forums relating to possible adverse reactions between some purge gases and hot heating elements of electric HT furnaces. I'd suggest some research before experimenting.

                David Merrill

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                • #23
                  Interesting info. The ASM books may be diving a bit deeper than I probably have need to, but I get that this is where the info is. Should it come to that the university here will without doubt have these, being strong on its engineering programs.

                  I did read a few references to attempts at controlled atmosphere killing heating elements though most of those related to putting charcoal and other such stuff in the furnace to create a strongly reducing atmosphere in there, and that (if I understood it correctly) is what deteriorates the heater wires. I guess it also can make large amounts of carbon monoxide (makes sense and bad in an enclosed space) that in addition to possibly poisoning you can apparently flash off when you open the furnace door and burn your eyebrows and maybe your face off. Pretty sure I don't want any part of either of those. I'd think an inert gas like argon would avoid all that, but I'm no chemist either. I'll do some reading should I ever decide I need to go that far.

                  All interesting stuff. Again, thanks for chiming in.

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