this old blacksmith Posted March 9, 2009 Share Posted March 9, 2009 Can antone give some info in heat treating toolsteel to keep the blade very hard and the back softer to keep the knife from breaking. Thank much T,O,B Quote Link to comment Share on other sites More sharing options...
jeremy k Posted March 9, 2009 Share Posted March 9, 2009 go to the knife making category then to>>>>>> Knife stickies here Start here for the important information -JK Quote Link to comment Share on other sites More sharing options...
this old blacksmith Posted March 9, 2009 Author Share Posted March 9, 2009 Thanks for the reference on where to ask the ?? JK Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 9, 2009 Share Posted March 9, 2009 Next you need to refine the question---each of the hundreds of tool steel alloys has different heat treating requirements---what works for one alloy may very well destroy another. Nobody is going to type out a thousand or more pages of information for you; so be specific! Note too that there are more than one way to go about your wish: differential hardening, differential tempering, differential alloy construction---is there a particular one of these you are thinking of? Quote Link to comment Share on other sites More sharing options...
this old blacksmith Posted March 9, 2009 Author Share Posted March 9, 2009 Thanks I'll try to figure out what tpe it is then ask again later. For as where it came from was the ring gear of Cat 100 ton Haul truck. I thought it was tool steel for when I heated it to bright yellow white and struck it. It decided to crumble on me. A friend stated that it was tool steel and only work it while it was a dual yellow to bright red. But since there so many types my question and discription is quit pointless. Thanks any way Ragards and thanks for the explanation Quote Link to comment Share on other sites More sharing options...
this old blacksmith Posted March 9, 2009 Author Share Posted March 9, 2009 Also Thomas. I wanted to make the edge very hard and the back soft to prevent breakage. Apprecite all the info. Just thought it would be cool to make a knife from a Caterpillar rear Ring Gear tooth. At the very least it would be a conversation piece correct. Thanks again Thomas Quote Link to comment Share on other sites More sharing options...
John Martin Posted March 10, 2009 Share Posted March 10, 2009 Did you figure it out? I can' tell from your post. If not, search for "edge quench" or "differential hardening" Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 10, 2009 Share Posted March 10, 2009 Differential hardening is is *one* of the three ways you can get a hard edge and a soft back. Differential tempering will also produce a hard edge and a soft back; as well as welding up a billet where the back will be a lower carbon steel than the edge. High alloy tool steels do tend to crumble like cottage cheese when over heated and be a pain to forge when at lower heats with a high hot hardness. I would strongly suggest you learn the basics of bladesmithing with easier alloys and expand into the harder to forge stuff when you are ready for it. Quote Link to comment Share on other sites More sharing options...
MattBower Posted March 10, 2009 Share Posted March 10, 2009 Not to get too far afield from the question, here, but while I know that the soft back/hard edge (however one achieves it) is all the rage, I'm not so convinced that it's useful on a typical knife blade made of suitable, good quality modern steel. Just something else to consider. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted March 10, 2009 Share Posted March 10, 2009 For most small blades it is not needed. The larger the blade the more it may effect its usage. Quote Link to comment Share on other sites More sharing options...
nitewatchman Posted March 11, 2009 Share Posted March 11, 2009 (edited) Since this material is a ring gear it is most likely an AISI 8620 forging. This is a very tough steel commonly used in gears. It will appear to be very hard since the usual heat treatment is a case hardening with a quench. This results in a surface that is Rc 58 to 64 and .100" or less deep. The core is hardened to Rc 44 to 48 and due to the high nickle content is very tough and resistent to cracking due to stress risers. (Think gear tooth roots radii) The result is an extremely tough gear that can absorb high shock loads but due to the case hardening from carburization or nitriding is also very wear resistant. I suspect that what you saw crumbling was the high carbon case. We use this material to make high performance railroad joint bars. If it is in fact 8620, it likely will not harden to the extent that you want for a blade. The Q&T hardness range is Rc 40 to 50. Attached is a link to material properties.http://www.corusnz.com/downloads/CaseHard_AISI8620.pdf nitewatchman Edited March 11, 2009 by nitewatchman Stoopid Fangers! Quote Link to comment Share on other sites More sharing options...
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