Steve Sells Posted March 28, 2009 Share Posted March 28, 2009 (edited) [steve sells] JJ was making a joke, but I think his Idea was a good one. JJ was asking about a blade taking abuse, like a garden hoe, so how about we touch on the topic of our blades holding up to the task we desire? [JJ] it is not easy t o make a b lade that will stand up to rocks. [steve sells] the garden how is extreme, but a good example of abrasion as the sand is eating away at the metal every usage. so what can WE do as makers to help our blades hold up ? I will use the garden hoe as an example [JJ] here's my difficulty steve: the edge I like will hold up to rocks and not chip...so it has to be hard but tempered soft enough not to chip...and on a 6" wide hoe, that's not an easy heat treat. [steve sells] ok lets work on the Hoe. starting with the abuse it is going to receive., a 10 Series is not going to hold up as well as other steels we have available [lobodag] Steve whats the knife subject tonite? [steve sells] we covered some metal additions for forming hard carbides. this application is a good place to use them. Chrome isone that we may think of because we wants deep hardening. it does from carbides but not the type we need here, Wolfram is a good choices here, but Moly and vanadium will be nice too. These carbides are in the melt, we can not add them by ourselves. but but knowing what they do we can look for an alloy with these additions, one easy to find steel for this is D-2 with lots of chrome and some very hard carbides it is very hard to grind with the machines we use, so it will last well in the dirt. [Rich Hale] Tempering D 2 is not for the weak at heart [m_brothers] Care to explain the HT process for D-2? [steve sells] D2 is C 1.50 Mn .40 Si .40 Cr 12.00 Va .95 Mo .90 Hardening: Preheat very slowly to 1500 F and then increase temperature to 1850 F. Hold at 1850 F for 20 to 45 minutes and air cool (air quench). ... Tempering may be done in the range of 400 F for Rockwell C 61 to 1000 F for Rockwell C 54. ... Forging may be done in the range of 1950 F down to 1750 F. Do not forge below 1700 F. . [JJ] anyone want to know how i get Rc 61 out of D-2 in a propane forge? [lobodag] go for it [m_brothers] I do. [JJ] OK...this ain't rocket science, but in my forge the results are consistent... [m_brothers] please explain JJ [JJ] i wrap the b lade in stainless foil (it's a good wrap, b ut not what i would call fully air tight).... I take the piece up with a very low heat to what i judge to b e 1700 to 1800f, let it soak a b it, then just turn the forge off and walk away. the next morn ing it's ready. a 60 rockwell file will barely scratch it, and a 65 will easily sc ratch it. that's it. [lobodag] what i judge to be 1700 to 1800f, ? [JJ] i took one treated this way to Rich's shop and his rockwell tester said 61. [m_brothers] So I take it if you quenched it in a liquid it would not be pretty? Cool JJ [Rich Hale I think it was a whole lot harder than that JJ [JJ] dag, unless i feel it necessary to put a pyrometer in the forge, i judge by color. I brought 2 samples with me...one was ab out 87, the other was 61. and i wrote it on each one in black marker as you tested. the 87 Rockwell, was harden and air cooled by hanging in front of my shop fan . [steve sells] that is some serious work to re sharpen LOL [m_brothers] That's crazy, that would be so sharp, yet very brittle, lol [steve sells] not that ya could lose that edge if done correct the first time, over kill for a straight razor too [m_brothers] steve, would it be possible to actually sharpen or remove metal at that hardness? [JJ] b ack t o the hoe...(same situation in hardening and tempering a peeling sput for a logger).... one difficult part on a hard steel is to NOT make a transition line that will crack. [steve sells] it can be sharpened, but not easy. Also... a not so easy to find steel, is a stainless called 20cv, it has C 1.2 Mn .3 Ch 20 Va 4.0 Mo 1.0 W .6 average Rhc or 60 has a lot of carbide formers, for an expensive extreme to the Hoe [JJ] even heat on 6" wide blade only 1/2" up the blade is difficult. (that's the treatment most blacksmiths use on a chisel) [steve sells] but the impact for a how vs a knife, I would full harden a hoe or machete, anything that needs to stand up to very hard use [JJ] right steve, what i am leading into is that the traditional blacksmith application of heat treat will not work well in this case. [steve sells] what is traditional ? [JJ] 1harden only the tip [steve sells] : all heat treat jobs NEED to be tailored to the job, NOt just because WE like dont things that way [m_brothers] so for something with high impact should be completely hardened and not differential? [JJ] 10:33 pm: ti can be done, but it is not easy to get an ev en heat across a 6" blade. [steve sells] JJ i normally full harden, then differential temper... I rarely differential harden ! but I understand, and AGREE not all jobs can be done the same way VERRY Good point [m_brothers] Steve, how do do a diferential temper without like a torch, and make it still accurate? [JJ] Steve, on a 5/8" dia chisel 10" long that is both way more work and un n ecessary. we only harden the tip, and mayb e the end we hammer, drawing different te mpers on each end, but leav ing the m iddle soft.What i am saying is that there are time the blacksmith must turn to blade smith methods for a long lasting job. [steve sells] the main thing I want to get through to any blade maker, knife sword, garden hoe chisel, is that we must plan ahead, and think about the use for the tool. I agree JJ, and to be honest I think you have been making blades longer than I have. I KNOW you have been a smith longer [steve sells] we covered the hoe, but lets finish it, , HOW do we want the edge ? flat? accute, ot long sharp edge ? [m_brothers]good point [steve sells] ok the hoe wont need a sparp attack , also that make a weak point in the design so forget the long tapering tip [steve sells] flat or axe type edge ? I feel either will work. but in this case, I return to physics class, and remoind everyone that the perfect point is a CIRCLE [steve sells] I would round the cutting portion s little, leaving the most metal possible, while allowing it to cut into sod, hard clay etc. not a point but a rounded blunt/... comments ? [Rich Hale] How we gonna attach a wooden handle? [lobodag] no ivory? scale prototype [steve sells] JJ didnt cover that part, I figure a few options, full tang, hidden tang, or socket are the 3 I can think of... [steve sells] Hidden is the weakest, and this is an abuser... so full tang and sockets are left, what are the merits and faults of each.. LOBO want to start? [lobodag] well built solid hidden is as strong if built to use [Rich Hale] For a hidden tang you would need a thicker piece of meetal and the whole front plate would need to be thinned down to make the blade [lobodag] 1 coke bottle style is fun and strong also [steve sells] even a full tang has the problem of having to cut into the handle, making that handle weaker,, a socket would be the striongest, and easiest to replace later when the handle breaks... as the handle will flex during use... [lobodag] spine support to the blade [steve sells] as the handle will flex during use...one nice advantage of 20cv or the D2, is the high chrome content protects the blade from moisture I think the 20cv is cost prohibitive. but D2 is available, and dont cost too much [Rich Hale] Right [steve sells] 220 grit the a buff and ready to go [m_brothers] you can get D-2 from speedymetals.com for a good price [lobodag] Why are we talking garden tools on a knife forum? [steve sells] I thought we explained that ? it has a blade, and its function is an extreme of abrasion resistance.. as a blade need to stand up to abrasion, but some, like machete and garden tools are exposed to higher abrasion [lobodag] i guess its a blacksmith site not a knife site I understand [steve sells] I thought I explained that at the start [Rich Hale] : Lobo a few weeks back Steve spoke about the ingredients in the steels we use for blades [lobodag] hmmmm [Rich Hale] This was an exercise to use that information and select a steel by what it is made of for a specific application That make sense? Edited June 9, 2009 by mod07 Quote Link to comment Share on other sites More sharing options...
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