jdawgnc Posted November 21, 2016 Share Posted November 21, 2016 So I have a few lengths of S7 I am planning on making some punches and other hot work tools out of. After a lot of online research, I have what I believe to be the proper way to do this, but I'd like a little more clarification of a few points. The steel I have is from Mcmaster, so is already annealed and in it's ready to work state. For shaped punches, like eyes and such, all I need to do is grind them to shape then heat treat, correct? The heat treating of S7 is where I have found so many different methods that I am a bit confused. To heat treat it, I take my new formed punch, heat it up to a nice red heat (I don't have an accurate thermocouple or thermometer for that high but know it's supposed to be ~1725 and is NOT the non-magnetic Curie point) and then let it air cool (which is technically the quench for S7?) Immediately after is is air cooled (to where I can touch it I guess?) I temper it to around 1000 deg and then what and for how long? What is the best way to temper it without an oven that goes that high? I do have an oxy/acet setup, but have read there can be issues from the oxygen in the mix causing problems when it is used for heating. I'm certainly not building an atomic clock here, but would like my tools to be as good and hard as I can possibly make them. Also the difference in tempering and hardening the whole punch versus the "business end" that will come into contact with the hot metal is a concern to me as well. I see the appeal of both, but would like some opinions there too... What about pieces that I forge out to make chisels out of. After forging it into shape, the whole thing has been subjected to a lot of heat and stress. Do I need to normalize it or re-anneal it, or can I just proceed with the heat treating from there? They are just small tools, so not a ton of mass to deal with... Lastly, but not leastly, I have access to a lot of dry ice here at my shop. I've seen a few things about S7 being one of the tool steels that responds well to dry ice treating. Anyone have any experience with that? Is it even worth my doing it, and how would I go about interacting a hot (or cold) piece of steel with a block of dry ice anyway? So for myself and any other novice toolmakers out there here is my step by step plan... please let me know if I've got it right! 1) Take my nice piece of shiny new S7 and grind an eye on the end 2) Place it in my gas forge (don't have a coal one) til the whole thing is a nice red heat, then remove and set aside to air quench 3) Polish up the working edge so I can see the colors move and use my oxy/acet torch to heat it from the middle and watch the colors run out to the working edge til it is just past blue 4) Once it is at room temp I sit it in the cooler of dry ice for an evening and see how it goes from there Anything else? Any extra steps for pieces that have been forged? Quote Link to comment Share on other sites More sharing options...
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