harlequin Posted September 24, 2008 Share Posted September 24, 2008 (edited) I like working with railroad spikes. They make very interesting knives but they are not so keen to hold an edge. Don't think I needed to tell you all this but anyway, I have been looking in to case hardening but I am wrought with questions. I need to know the best way to get the most carbon into the steel just along the edge if nothing else. Also, if I case harden, will I then need to temper the blade? After I case harden, will sharpening the knife take the hardened layer off of the blade? Or can I repeat the case hardening so that I can get more carbon into the knife so that I can sharpen it many times? Thanks guys. Edited September 24, 2008 by harlequin Quote Link to comment Share on other sites More sharing options...
Quenchcrack Posted September 24, 2008 Share Posted September 24, 2008 Don't waste your time trying to case harden a spike knife. You will never get much of a case and it will be removed when you sharpen it. Enjoy making the spike knives and accept the fact that even the HC (high carbon) spikes are too low to make a good knife. These are curiousities, not working knives. I have one on the book case in my office that I made years ago and it tends to have a calming effect on anyone that comes into my office with a complaint. Quote Link to comment Share on other sites More sharing options...
bg7m Posted September 24, 2008 Share Posted September 24, 2008 I agree that case hardening would probably be a waste of time. A friend of mine came by the shop last week with 5 spike knives. He split about 1 1/2" of the point of each spike and inserted a piece of high carbon steel in and forge welded it and forged to a knife shape. He hardened them in oil. They cut very well and held a good edge. Quote Link to comment Share on other sites More sharing options...
Woody Posted September 25, 2008 Share Posted September 25, 2008 Remember that HC on a RR spike does not mean HIGH CARBON, it means HIGHER CARBON than the mild steel run of the mill spikes. Carbon Content of a HC spike is 30 points or .30%. To be fully hardenable plain carbon steel must be at least 60 to 65 points carbon that is .60% to .65% carbon. Quote Link to comment Share on other sites More sharing options...
Max Mulholland - Tetnum Posted September 26, 2008 Share Posted September 26, 2008 they will work well if brine quenched and super quench works well also Quote Link to comment Share on other sites More sharing options...
dragonflySmithy Posted September 30, 2008 Share Posted September 30, 2008 Remember that HC on a RR spike does not mean HIGH CARBON, it means HIGHER CARBON than the mild steel run of the mill spikes. Carbon Content of a HC spike is 30 points or .30%. To be fully hardenable plain carbon steel must be at least 60 to 65 points carbon that is .60% to .65% carbon. Have you never used super quench? If it will give 1018 a RC of 40-45 just think what it wouyld do for a knife made from a HC spike. Would it be my first choise.. No but if it's what the OP likes to make then this might be a way for him to make a better blade without having to forge weld in blade steel. Quote Link to comment Share on other sites More sharing options...
harlequin Posted September 30, 2008 Author Share Posted September 30, 2008 I'll do the super quench and see how that does. Thanks guys. Quote Link to comment Share on other sites More sharing options...
Quenchcrack Posted September 30, 2008 Share Posted September 30, 2008 Super Quench is, at best, a superficial treatment. It cannot extract heat at any rate faster than heat flows through the metal. The coefficient of thermal diffusion is the rate limiting factor. If you have a steel with very low hardenability, it will not transform to martensite when the heat extraction rate is below the threshold for missing the pearlite nose regardless of what you quench it in. You still can't make a silk purse from a sows ear! Quote Link to comment Share on other sites More sharing options...
EWCTool Posted October 4, 2008 Share Posted October 4, 2008 The best way to make a desent rr spike knife is to forge the handle from the spike and weld a steel blade to it. I have mig welded the blade to the handle and ground and polished the welded area down to give the impresion that the entire knife was initialy one piece. Doing this also results in haveing more material for the handle. Quote Link to comment Share on other sites More sharing options...
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