MetalMuncher Posted October 23, 2008 Share Posted October 23, 2008 Hello everyone. I have finished my box bellows and am really happy with it. I am currently making a butchers knife for my sister who is a chef. It is a hidden tang knife forged from a leaf spring. I just need a few questions answered: Is leaf spring steel oil or water quenching? If so, at what temp? And I wanted to bring out a quenching line when finished. Will it come out with oil if it is to be quenched with oil? Thanks guys, I owe you one!! Quote Link to comment Share on other sites More sharing options...
coltpax Posted October 23, 2008 Share Posted October 23, 2008 I would try differentially hardening. Heat up a big chunk of metal to red, then place the spine of the blade on the metal. Watch the colors move up through the blade, and when the tip is around a blueish color, pull it off the chunk of metal and let it air cool. This is what I've done, but maybe some others will have a better method for you. Quote Link to comment Share on other sites More sharing options...
Frosty Posted October 23, 2008 Share Posted October 23, 2008 Heat to critical and quench in warm 110f give or take oil. I temper with a torch on the spine but the colors run fast and close so keep a close eye on it. If by quench line you mean a hamon I don't know. Frosty Quote Link to comment Share on other sites More sharing options...
MetalMuncher Posted October 23, 2008 Author Share Posted October 23, 2008 Hello Frosty, leaf spring steel is oil quenching then? By critical you mean 1,400 degrees right? The quench line is not the japanese iconic "hamon" line, its where you place the heated knifes edge in the quenching medium and later on it shows up or something, ive never done it, but have seen it online.Thanks for your help!! Quote Link to comment Share on other sites More sharing options...
happycat Posted October 24, 2008 Share Posted October 24, 2008 Your leaf spring is most likely 5160 which is a great steel for making kinves. I've been using it for about 6 years now. What Frosty said about the oil. It is an oil quench steel. I used olive oil for years with good results (I was heating to about 130-140). Prior to quench heat it to a dull red and let cool two or three times. This will help reduce the grain size (smaller grain= better performance)... If you want a quench line, only submerge the edge to about 1/3 of the way up the blade. Keep dipping it in and bringing it up and back down in a slightly different place as the oil will form a vapor barrier which will slow the cooling if you leave it still. Go vertically not side to side as this may cause warpage. Do this till the color leaves the spine then quench the whole thing until it cools. If you want to keep the line pretty even, you can put something in the oil that will stop the blade at the same depth every time you dip. I use a piece of sheet metal with holes drilled all over it for the oil to criculate through. It has long screws on the corners to adjust the height. After it cools test the edge with a dull file. It should skate and not bite in. If it bites its not hard enough and you'll have to harden it again. Critical temp is when it turns non-magnetic. Usually an orange color, but the magnet is much more accurate at telling you when. Let is soak at critical for a few min to make sure its all the way through, keep it moving so you don't get hot spots. If you did get it hard in the first quench, temper at 350 for two hours three times. If you really want flexibility (nice in a chef knife), set up a pan with water in it and prop the blade up in it with the water covering the edge. Draw the spine down to a blue color with a torch ( three times). The water will preserve the hardness of the edge and the rest will be nice and springy. Xxxx, did I just write all of that? Sorry, I get carried away as blades are my passion. Just trying to be helpful Ed Wilson Happycat Cutlery Quote Link to comment Share on other sites More sharing options...
happycat Posted October 24, 2008 Share Posted October 24, 2008 PS: If you want to see the quench line on 5160, you will probably have to give it a light etch for it to really be visible. I use ferric chloide and distilled water 4:1( water to ferric). Warm vinegar will also work and is not so toxic or hard to find. Ed Quote Link to comment Share on other sites More sharing options...
philip in china Posted October 24, 2008 Share Posted October 24, 2008 I don't do many blades but have done a lot of cooking! Don't over harden the blade. It needs to sharpen easily on a sharpening steel. Now that would be a project. How would you make a steel? I have no idea. Quote Link to comment Share on other sites More sharing options...
Sam Salvati Posted October 24, 2008 Share Posted October 24, 2008 Your leaf spring is most likely 5160 ..... Ed Wilson Happycat Cutlery Ed what do you base this info on? Quote Link to comment Share on other sites More sharing options...
Frosty Posted October 24, 2008 Share Posted October 24, 2008 Most leaf spring used in the US has been 5160 since the late 60's I believe. Most coil is or was 9260. Now though, who knows, some springs are fiberglass. What's critical temp for fiberglass? Arrrggggg! Frosty Quote Link to comment Share on other sites More sharing options...
MetalMuncher Posted October 24, 2008 Author Share Posted October 24, 2008 Thank you Happycat!!!! Exactly what I needed!!! I knew you could see the quench line. I will etch it after with ferric chloride (FEC13). I will post pictures as soon as it is finished. I owe you one!! Quote Link to comment Share on other sites More sharing options...
BeaverDamForge Posted October 24, 2008 Share Posted October 24, 2008 Prior to quench heat it to a dull red and let cool two or three times. This will help reduce the grain size (smaller grain= better performance)... [snip] Ed Wilson Happycat CutleryWhy would heating below critical temp change grain size? Doesn't crystaline structure (grain size) reset when the steel is heated through critical? I'm not sure if I understand properly, some procedures seem like voodoo... Good Luck! Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 24, 2008 Share Posted October 24, 2008 (edited) Ahh Coltpax what you are suggesting is differential *TEMPERING* not differential *HARDENING*. BDF: the triple heat/cool is called normalization and is an industry standard to refine grain size. It works through the alloying of modern steels, though some alloys, like S1 do not profit from it according to the ASM handbook. *Old* steels do not profit from it but we're talking more like 100+ years ago for them. I hate to rain on your parade; but---if you have to ask this kind of question making a large blade is a bit of a stretch. You may want to try a smaller one to get the new skills down with a minimum of destroyed pieces. Edited October 24, 2008 by ThomasPowers Quote Link to comment Share on other sites More sharing options...
divermike Posted October 24, 2008 Share Posted October 24, 2008 My oriental friend fooling yu puts a ceramic paste on the blade, heats it in the forge and quenches it, the ceramic slows the quench just enough to alter it slightly, actually I just saw this on the utube videos of samurai.... hyyyyyaaaah! Quote Link to comment Share on other sites More sharing options...
happycat Posted October 24, 2008 Share Posted October 24, 2008 Metal Muncher, glad to help. I'm sure she will love having a knife made by you. there's something about using a tool, be it pen, knife, whatever that was hand crafted (especially by someone you know), that is just a pleasure. I've made a few chef knives for friends, but mine generally turn out looking like something Steven Segal would use, kind of a tactical kitchen knife. Apprenticeman, pretty much what Frosty said. I couldn't quote you a source about 5160 leaf springs, its just something that I've been told, read about, heard about for years. Frosty thanks for the coil spring info. I didn't know that. Does it make good knives, tools etc? I've heard about people using coil spring for knives, just assumed it was 5160. Beaverdam, I didn't mention about the chicken blood, magnetic north, or the full moon...... You should see me forge on Halloween:o I'm not enough of a metalurgist to describe why normalizing works, but I've seen the results. Particularly if you forge really HOT, you get grain growth (large grain bad...), you can see the diff if you heat some high carbon steel up to almost yellow hot and quench it, then take a similar piece keep it down in the red/orange range, normalize, quench. Then break the two and look at the break. The "hot one" will be sparkley, the normalized one will be smooth and sort of satiny. You can really see the diff in the grain size. Ed Quote Link to comment Share on other sites More sharing options...
MetalMuncher Posted October 25, 2008 Author Share Posted October 25, 2008 The knife is almost done, I'll post pictures when it is. I made it as a hidden tang....I made the handle out of Ipe (a brazilian hardwood impossible to drive iron nails into. Its nick name is "iron wood". The name is pronounced "eppay"), it grows wildly down here in Rio. Its very pretty and the toughest wood I could think of. Quote Link to comment Share on other sites More sharing options...
BeaverDamForge Posted October 26, 2008 Share Posted October 26, 2008 Metal Muncher, glad to help. I'm sure she will love having a knife made by you. there's something about using a tool, be it pen, knife, whatever that was hand crafted (especially by someone you know), that is just a pleasure. I've made a few chef knives for friends, but mine generally turn out looking like something Steven Segal would use, kind of a tactical kitchen knife. Apprenticeman, pretty much what Frosty said. I couldn't quote you a source about 5160 leaf springs, its just something that I've been told, read about, heard about for years. Frosty thanks for the coil spring info. I didn't know that. Does it make good knives, tools etc? I've heard about people using coil spring for knives, just assumed it was 5160. Beaverdam, I didn't mention about the chicken blood, magnetic north, or the full moon...... You should see me forge on Halloween:o I'm not enough of a metalurgist to describe why normalizing works, but I've seen the results. Particularly if you forge really HOT, you get grain growth (large grain bad...), you can see the diff if you heat some high carbon steel up to almost yellow hot and quench it, then take a similar piece keep it down in the red/orange range, normalize, quench. Then break the two and look at the break. The "hot one" will be sparkley, the normalized one will be smooth and sort of satiny. You can really see the diff in the grain size. EdThanks for the reply (and also Thomas)! I understand that the grain will grow at temps higher than critical and being held at higher temps. Hammering will break it down. But I thought normalizing involved bringing the steel to critical and letting it air cool (for most steels). That would provide the reset in grain size, and not holding it at or above critical doesn't let them grow. This is from my father's old mechanical engineering book The Working, Heat Treating, and Welding of Steel (1942; $2.10 (used, I think, but for a college text...)) "When a piece of annealed steel composed of large grains of ferrite and pearlite is heated, the size of the grains is not changed until the lower critical temperature is reached. At this temperature the pearlite changes to austenite, and the coarse grains of ferrite gradually dissolve in the austenite as the temperature is raised through the critical range. The average minimum grain size is attained near the upper critical temperature, where the transformation to austenite is completed. When this piece of steel is cooled slowly from a temperature slightly above critical range, small grains of ferrite and pearlite will be retained at room temperature." It doesn't say specifically*, but that seems to agree with what I've been told 'normalizing' is. At any rate, this is where I got the idea that grain size is not affected at less than critical, is that wrong? Good Luck! *Normalizing isn't mentioned until later, in the heat treating chapter. They show the 'normalizing range' above the 'heat treating and annealing range'. They mention it being a prep for annealing, but no mention of multiple cycles (third times the charm ). Maybe without the multiple cycles parts of the steel don't get hot enough, especially when done in large batches. Quote Link to comment Share on other sites More sharing options...
John B Posted October 26, 2008 Share Posted October 26, 2008 (edited) Text books usually cater for industrial applications and 'correct' scanarios. Normalising and annealling are done in these establishments under strict controlled conditions, temperatures being raised and held in a prescribed gradual manner, usually in large batches for economy purposes, Timing is critical as well as temperature, for others like myself who do not have the technology available to achieve this, do so by using their own methods that works for them, but it is still based on the critical points in the heating range. Edited October 26, 2008 by John B spelling Quote Link to comment Share on other sites More sharing options...
Frosty Posted October 27, 2008 Share Posted October 27, 2008 (edited) Ed: As far as I've been able to determine, 9260 and 5160 work, heat treat and behave pretty much the same. Both can be made plenty hard for cutting tools or tough for prying or impact tools and both are very forgiving in heat treatment. The spring shop I used to get drops from heat treated leaf springs from a short soak at critical in cold water and tempered by bringing them to dull red and oil quenching. The shop foreman said I could do pretty much what I wanted to it as long as it was new steel. No guarantees on old spring steel of course. I have water quenched both but draw the temper down below purple in those cases, I'm just not as confident as the spring shop guy. Frosty Edited October 27, 2008 by Frosty Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 27, 2008 Share Posted October 27, 2008 change in state is not generally universal; repeating can nudge things that have "hung" so to speak; why triple tempering is often suggested. Quote Link to comment Share on other sites More sharing options...
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