dodo knives Posted September 1, 2016 Share Posted September 1, 2016 hey guys so the only steel I have used so far is 1084 and now mostly 440c. I want to start learning a couple other steels, I have a small bar of CPM S35VN. I am also thinking about CPM 154. So either way lets use the CPM S35VN for this conversation.. as far as the quench goes the spec sheet says, " Quench: Air or positive pressure quench (2 bar minimum) to below 125°F (50°C), or salt or interrupted oil quench to about 1000°F (540°C), then air cool to below 125°F (50°C)." ok so I don't have access to any salt tanks so as far as the other ways. First am I right to assume that by interrupted oil quench it is just like a regular oil quench but when the blade cools to about 1000 deg. pull it out and let it cool in air, that's it? Second how does a positive pressure quench work I read somewhere that you make a container that you put the knife in as soon as it comes out of the oven and then blow compressed air in to that container? that's all I read there wasn't any details of how it is actually done. I did do some searching for info on positive pressure quench and couldn't find anything this so if anyone can give me some information on it or if you can point me in the right direction to where I may find more info on this it would really be appreciated! yes I understand that it can be just air quenched (or maybe plate quenched) but I have been told by a couple of knife makers that have been doing there own heat treat for a long time that usually the easiest way (air) is usually the worst way and I did find that air and plate quenching on 440c although it did harden a oil quench hardens just the same but the grain was a lot better in a oil quench. either way if I am going to start a new steel I would like to do testing on more than one method to see what works best for me. any info on this positive pressure quench would really help...thanks guys Quote Link to comment Share on other sites More sharing options...
CMS3900 Posted September 1, 2016 Share Posted September 1, 2016 That's exactly what they mean. interrupted oil quench is quenching in oil to a temp, then removing it. Positive Pressure Quench is the same as a plate quench. Take the blade out, put it between the plates, blast it with the air nozzle. 2 Bar is roughly 30 PSI of air. Quote Link to comment Share on other sites More sharing options...
dodo knives Posted September 1, 2016 Author Share Posted September 1, 2016 oh ok I didn't know you use the plates on a positive pressure someone described it to me as basicly a small piece of stove pipe nailed to the wall and ya know how stove pipe 0kinda clips togather on the seem well they said to leave that seam open about a inch and there is a hook inside the blade hangs on and air is sparyed though the seem that is still open...thinking about it I think it would cool quicker your way in the plates....can the air be sprayed at a higher psi like is it a minimum of 30 psi but say 60 psi still good or it needs to be right on at 30? Quote Link to comment Share on other sites More sharing options...
CMS3900 Posted September 1, 2016 Share Posted September 1, 2016 It can be higher. I would suggest googling "CPM S35VN heat treat" and reading what other bladesmith's do or suggest. From what I read that steel also likes a cryo cycle to covert retained austenite. Quote Link to comment Share on other sites More sharing options...
dodo knives Posted September 2, 2016 Author Share Posted September 2, 2016 I have read the spec sheet but haven't read to much of what other knife makers have done with it I will make a point to check it out cryo wont be a problem planed on doing that anyway I have a 35 liter dewar full of liquid nitrogen I have been using it with 440c Quote Link to comment Share on other sites More sharing options...
CMS3900 Posted September 2, 2016 Share Posted September 2, 2016 Nice. LN dewar is important if you plan on doing more stainless. Quote Link to comment Share on other sites More sharing options...
dodo knives Posted September 2, 2016 Author Share Posted September 2, 2016 yeh I actually started getting pour into a Styrofoam cooler (the really thick ones that food and dry ice is packed into) the only problem with that is it would only last 2-3 days so I had to get a batch (usually 10) blades ready for heat treat and do them all at once to make it worth it money wise. I just got the dewar 2 months agao....sooooo much better Quote Link to comment Share on other sites More sharing options...
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