30 minute bainite.

jmforge

Well-Known Member
A couple of years back, Larrin was talking about marquenching for bainite and discussed the possibility that a relatively quick say 30 minute soak right above Ms to get like an 80/20 martensite to bainite mix. IIRC, he was using 52100 as an example of a steel where this could work to some benefit. Has anyone tried this or heard of someone who has? I was also wondering about this in the context of soe "Deep' hardening steels like 52100 perhaps being not as well suited for low tempt salt, etc quench as deeper hardening steels like O1 and L6. I seem to recall that when Kevin Cashen did his experiments with 52100 and slightly lower austenizing temps, things worked better with medium speed oil quenches.
 

Doug Lester

Well-Known Member
I tried it with quenching in hot oil (I was out of my mind). Low temperature molten salts would be a lot safer. The steel was 52100 and it held up well in the chopping test and slicing fibrous rope. When I tried to bend it to 90° the blade creaked and popped up to when it broke just a little shy of 90°. That could also be because I forged the blade too thick

My question for you is what are you trying to achieve? An identical test blade that was quenched and tempered in warm oil and the kitchen oven gave better performance. I had to beat on it with a 4lb hammer to get it to break. Again the thickness of the blade made it resist breaking but it showed that it was stronger than the blade with bainite.

Doug
 

jmforge

Well-Known Member
I tried it with quenching in hot oil (I was out of my mind). Low temperature molten salts would be a lot safer. The steel was 52100 and it held up well in the chopping test and slicing fibrous rope. When I tried to bend it to 90° the blade creaked and popped up to when it broke just a little shy of 90°. That could also be because I forged the blade too thick

My question for you is what are you trying to achieve? An identical test blade that was quenched and tempered in warm oil and the kitchen oven gave better performance. I had to beat on it with a 4lb hammer to get it to break. Again the thickness of the blade made it resist breaking but it showed that it was stronger than the blade with bainite.

Doug
How long did you leave it in the hot oil once you put the fire out? :eek: ;) I'm just kind of thinking out loud. I have a bunch of Cru Forge V, but it may not be deep hardening enough for salt or marquench oil.
 

Doug Lester

Well-Known Member
First of all go to ASM International and look up the TTT diagram for the steel that you want to try and get an idea of where it falls into the bainite region. My recollection is that, due to the limit of my oil's flash point, I had to quench at 450° for two hours to get full conversion to martensite and bainite. Doing this with peanut oil, which was what I used, is not good. First it was very dangerous and I could have had a very bad fire. Second having the oil that hot decreases the cooling rate and decreased if effectiveness as pointed out to me by Kevin Cashen. And then did I mention that it was very, very dangerous.

You seen to know that you either need a marquenching oil or a low temperature salt pot but then again I have to ask. What are you trying to achieve?

Doug
 

jmforge

Well-Known Member
First of all go to ASM International and look up the TTT diagram for the steel that you want to try and get an idea of where it falls into the bainite region. My recollection is that, due to the limit of my oil's flash point, I had to quench at 450° for two hours to get full conversion to martensite and bainite. Doing this with peanut oil, which was what I used, is not good. First it was very dangerous and I could have had a very bad fire. Second having the oil that hot decreases the cooling rate and decreased if effectiveness as pointed out to me by Kevin Cashen. And then did I mention that it was very, very dangerous.

You seen to know that you either need a marquenching oil or a low temperature salt pot but then again I have to ask. What are you trying to achieve?

Doug
What am I trying to achieve? Super sexy specs. ;) I'm not sure where I would find the TTT diagram for CFV as it was never in general circulation.
 

Doug Lester

Well-Known Member
What super sexy specs would those be? I've only done two knives with bainite. The other one I recall only rises to being a knife shaped object. It bends easily but without any cracking. That said, bainite is pretty much considered the red headed step child of the steel structures. Go for it if that's what you want to do but I think you will come to the same conclusion about forming bainite in your blade.

Doug
 
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