Specifically, with "air hardening" steels, and cryo treatment.
One thing I have been curious about in my process, is WHEN exactly to cryo. For example, the write-up on Larren's site says "Delay between quenching and cold treatments, interrupted quenching, or tempering prior to cold treatments all stabilize austenite making less of it transform during cold treatments." I know Roman Landes also emphasized this a great deal, too. But what I have always wondered, is at what point should you put your blade in Cryo. I usually wait until it is just warm to the touch (Martensite Finish, according to my understanding), and then I put it in LN2. But should I be putting it in sooner than that?
Also, I've only ever done cryo for 30 minutes, since Landes always said that it doesn't benefit from a soak longer than that. But it seems like most people soak for much longer than that, some people even over night! Does soaking for longer periods have any affect on RA stabilization?
Another thing I haven't been able to get satisfying answers to, is why exactly you need to interrupt an oil quench with these steels? So you cool to below 1000F where pearlite can't form, but then why do you need to slow the quench between 1000F and oil temp? Does it have to do with martensite formation? But even if it did, isn't that process started at 400F? But then why don't we interrupt closer to 400F instead of right below 1000 then? Also, why don't you interrupt a plate quench? Or even further, what if you interrupted oil quench and then plate quenched to MF temp?
I've also had people tell me that they think aluminum plate quenching is almost as fast as oil quenching. But if that's the case, then I would think that there really isn't much difference between an uninterrupted oil quench and a plate quench. Unless the sole reason for an interrupted quench is to prevent warpage, which is something I have also wondered.
In the case of what I usually quench, with blades roughly 100 thousandths thick, (AKS Z-Wear, or 3V), they go from 1950 to 900F in about 2.5 to 3 seconds of quenching in 175F Citgo 521 (16 second oil "medium" speed oil.). Is aluminum much slower than that?
Also, another question I have had, is why do people have better results quenching in plates rather than still air, if the steel supposedly only needs to cool in minutes, not seconds to fully harden? I've been told in previous posts about interrupted oil quenching, that there is no benefit over plate quenching due to the hardenability of the steel. So then it leads me to the above question.
I've also wondered if the differences in quench speeds has more to do with carbide formation, which is something I understand very little about.
I have been trying to get my hands on a good hardness tester to really do a bunch of my own testing, but ultimately I still wish I knew exactly what was going on in the process, and why I am doing what I am doing! But y'all can bet I will post my findings of oil quench vs. plate quench, once I get a tester! I'd love to get my hands on a Rams 30-R but they seem pretty rare!
One thing I have been curious about in my process, is WHEN exactly to cryo. For example, the write-up on Larren's site says "Delay between quenching and cold treatments, interrupted quenching, or tempering prior to cold treatments all stabilize austenite making less of it transform during cold treatments." I know Roman Landes also emphasized this a great deal, too. But what I have always wondered, is at what point should you put your blade in Cryo. I usually wait until it is just warm to the touch (Martensite Finish, according to my understanding), and then I put it in LN2. But should I be putting it in sooner than that?
Also, I've only ever done cryo for 30 minutes, since Landes always said that it doesn't benefit from a soak longer than that. But it seems like most people soak for much longer than that, some people even over night! Does soaking for longer periods have any affect on RA stabilization?
Another thing I haven't been able to get satisfying answers to, is why exactly you need to interrupt an oil quench with these steels? So you cool to below 1000F where pearlite can't form, but then why do you need to slow the quench between 1000F and oil temp? Does it have to do with martensite formation? But even if it did, isn't that process started at 400F? But then why don't we interrupt closer to 400F instead of right below 1000 then? Also, why don't you interrupt a plate quench? Or even further, what if you interrupted oil quench and then plate quenched to MF temp?
I've also had people tell me that they think aluminum plate quenching is almost as fast as oil quenching. But if that's the case, then I would think that there really isn't much difference between an uninterrupted oil quench and a plate quench. Unless the sole reason for an interrupted quench is to prevent warpage, which is something I have also wondered.
In the case of what I usually quench, with blades roughly 100 thousandths thick, (AKS Z-Wear, or 3V), they go from 1950 to 900F in about 2.5 to 3 seconds of quenching in 175F Citgo 521 (16 second oil "medium" speed oil.). Is aluminum much slower than that?
Also, another question I have had, is why do people have better results quenching in plates rather than still air, if the steel supposedly only needs to cool in minutes, not seconds to fully harden? I've been told in previous posts about interrupted oil quenching, that there is no benefit over plate quenching due to the hardenability of the steel. So then it leads me to the above question.
I've also wondered if the differences in quench speeds has more to do with carbide formation, which is something I understand very little about.
I have been trying to get my hands on a good hardness tester to really do a bunch of my own testing, but ultimately I still wish I knew exactly what was going on in the process, and why I am doing what I am doing! But y'all can bet I will post my findings of oil quench vs. plate quench, once I get a tester! I'd love to get my hands on a Rams 30-R but they seem pretty rare!
