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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#1
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Heat Treating 440C
Does anyone have detailed instructions on heat treating 440C? A couple of sites that I have found on the Net show different times to "soak" the blade: This site says five minutes, which I find hard to believe. www.admiralsteel.com/reference/sstltech.html This one says " Soak times can generally be taken as one hour per inch of thickness. For example 15 minutes would be about right for a quarter inch thick blade." www.knives.com/heatreat.html Most other sites say to hold for 30 minutes. |
#2
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Kevin, 10-15 minutes is plenty for the transformation to occur when you are dealing with sections as thin as most knife blades. |
#3
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Thanks Don, a couple more questions: Do you place the blade in a cold oven and ramp the temperature up slowly, or do you place the cold blade into the oven at "temperature"? Do you "presoak" the blade at a lower temperature, before raising it to the "critical" temp.? |
#4
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Start with a cold oven. Crucible's data sheet for 440C says: "Large sections or complex parts should be preheated to 1425 F, equalize, then raise to the autienizing temperature (1850-1900 F)" I would just ramp right up from a cold oven to 1875 F, hold for 10 minutes, and air quench. Tempering, (2 hours each temper) should be: for 59 RC- 212F for 56 RC- 400F for 54 RC- 600F Be sure to use foil wrap (or some other decarb preventive measure). |
#5
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Sub-0 Quench
Kevin I have been heat treating 440C for about 20 years. All of the previous replies are correct. My rule of thumb is 1 hour per inch of thickness...+ or - a minute or two...best to go a little over than under on the time. Carpenter Steel recomends a double quench at 550 degrees...on hour each time. I also Sub-0 (Zero) quench using liquid nitrogen. I live in a rural area, a farming community....large dariy farm where they do artificial breeding. The bull seamen is, of course, stored in these tanks. When I pick a day that I am going to heat treat I give the local ABS ( American Breaders Society) man a call and he drops of a tank ( with out the bull stuff). I Sub-0 quench the blade after tempering ( place in the tanks at room tempature)....I leave them there for about 24 hours. Sub-0 quench will add about 1 or 2 point to the hardness and add alot of toughness. If you choose the Sub-0 quench you might want to throw a drill bit or two into the quench.....makes them tough too.....The most important thing to remember is not to put the knives in the liquid nitrogen....HOT.....remember room tempature! I have a rockwell tester that I purchased some time back and it helps but I have found that if you do your heat treading and Sub-0 quench the same way every time the hardness of your blades will not vary much at all on the RC scale. My most recent purchase is a digital parameter to double check the parameter on my Paragon Oven.... I have found that the analog parameter will vary as much a 10 degrees at different times......I don't know why.....I just feel it is always good to have a back-up and a good double check. If you have any other question drop me an E-mail. I hope we have helped. Jim |
#6
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Thanks for all the info guys, I really appreciate it. Does anyone "sub-zero quench" with dry ice? |
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blade, knife, knives |
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BCROB, caribou, chall, cnccutter, coldtracker, HBrand, JEtzler1, Matt Bufford, sanguip, TDPurcell |
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