Bainite vs Martensite - Which is tougher?

Thank you very much for this article!!!! It’s super well explained, but I need to read more two three times to absorb everything.

Regarding marquenching, I wander why so few people use it (I only know Haakonsen, with his V4e and Kornalski, from Poland)?

I know an English maker that makes 52100 (and 75cr1) Blades with partial bainite heat treatment and he keeps the blades in a molten salt bath for 30 minutes, as you mentioned in the article! He gets 58hrc with 52100 and 55hrc with 75cr1. I have one of his 52100 blades but haven’t the chance to test it properly (knife collecting is my thing, more than using Knives). Also have a Bohler K600 Steel knife bainite heat treated and my guy put the knife for over 30 hours at 300C (can’t remember temperature correctly, just above Martensite temperature formation) to allow complete bainite formation. He got 49hrc testing (as mentioned in the article, high alloy steels like this need a lot of time to allow bainite transform and low hrc is expected (the steel only has 0,45% carbon)).
 
I think the main reason few people heat treat for bainite is because few people have salt pots. They are more expensive, more difficult to maintain, and more dangerous than oil or aluminum plates. Marquenching oils are also relatively uncommon.
 
I believe the new and affordable salt pots from Evenheat will bring a new era of metallurgical HT. With a price less than a good grinder, they will surely start showing up in more shops. A set of high-temp salt pot and low-temp salt pot will allow warp free HT and experimentation in bainite. The pair cost about what a TW-90 runs.

I don't know that bainite is all that great for knives, but the experimentation will allow real world testing.
 
My industrial experiences always get in the way ! One of the knife steels has a bainite transformation STARTING at 20 hours ! $$

Stacy, I will let you or Larrin pick someone to get a set of those salt pots --and I will pay for it . Find someone who is high on the knowledge list and can find the time to do something for metallurgy . I'd let Larrin set up testing procedures . :)
 
mete said:
My industrial experiences always get in the way ! One of the knife steels has a bainite transformation STARTING at 20 hours ! $$

Stacy, I will let you or Larrin pick someone to get a set of those salt pots --and I will pay for it . Find someone who is high on the knowledge list and can find the time to do something for metallurgy . I'd let Larrin set up testing procedures . :)
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Quite an offer Mete. I nominate Warren. He does lots of testing and seems to have a good bit of knowledge on the subject.
 
From the beginning of my website, I had this on the How You Can Help Page: "Specialty heat treatment types I am very interested in comparing are various types of multiple quenches as well as comparisons between conventional, martempering, and austempering." So I for one would be excited if someone was willing to do some salt pot heat treatments.
 
Waren is very thorough (almost OCD) in his testing.

What would make the testing really good is Warren doing the various HT regimens and Larrin doing the metallurgical analysis. That would make it blind from bias, as the fellow doing the HT isn't deciding his results based on his HT presumptions, and the fellow doing the analysis isn't deciding the results based on his HT expectatio

Down the road I am adding a set of salt pots, but it will be a year or so before I am ready for them. These results would be very interesting.
 
I vote for Kuraki.
He’s been one of the most helpful guys on this forum for me and several others.
 
I downloaded his first version years ago . That group in Cambridge U does great work and it's all for public use .
 
Interesting. The partial bainite stuff really caught my attention when I read the basic Verhoeven paper. I sounds like a higher carbon plain steel like White #2 might be good for such an experiment. Would you still want to keep the austenizing temp down to restrict the amount of carbon going into solution or would it matter if you were going for say 20% bainite? I also seem to recall Verhoiven talking about 10% perhaps being good.
 
jdm61 said:
Interesting. The partial bainite stuff really caught my attention when I read the basic Verhoeven paper. I sounds like a higher carbon plain steel like White #2 might be good for such an experiment. Would you still want to keep the austenizing temp down to restrict the amount of carbon going into solution or would it matter if you were going for say 20% bainite? I also seem to recall Verhoiven talking about 10% perhaps being good.
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Somewhat higher austenitizing temperatures can be used for bainite as long as grain growth is not a problem. More carbon in solution lowers the Ms temperature allowing the use of lower austempering temperature for higher strength bainite. The issue with plate martensite isn't there with bainite so keeping the carbon content down isn't generally the goal, but ensuring sufficient hardness.
 
So how would that work if you are only going for 20% lower bainite? The other 80% is still going to be tempered martensite? Would it still have the potential plate/lathe issue?
Larrin said:
Somewhat higher austenitizing temperatures can be used for bainite as long as grain growth is not a problem. More carbon in solution lowers the Ms temperature allowing the use of lower austempering temperature for higher strength bainite. The issue with plate martensite isn't there with bainite so keeping the carbon content down isn't generally the goal, but ensuring sufficient hardness.
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